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Inadequate nutrient intake leads to oxidative stress disrupting homeostasis, activating signaling, and altering metabolism. Oxidative stress serves as a hallmark in developing prostate lesions, and an aggressive cancer phenotype activating mechanisms allowing cancer cells to adapt and survive. It is unclear how adaptation and survival are facilitated; however, literature across several organisms demonstrates that a reversible cellular growth arrest and the transcription factor, nuclear factor-kappaB (NF-κB), contribute to cancer cell survival and therapeutic resistance under oxidative stress. We examined adaptability and survival to oxidative stress following nutrient deprivation in three prostate cancer models displaying varying degrees of tumorigenicity. We observed that reducing serum (starved) induced reactive oxygen species which provided an early oxidative stress environment and allowed cells to confer adaptability to increased oxidative stress (H2O2). Measurement of cell viability demonstrated a low death profile in stressed cells (starved + H2O2), while cell proliferation was stagnant. Quantitative measurement of apoptosis showed no significant cell death in stressed cells suggesting an adaptive mechanism to tolerate oxidative stress. Stressed cells also presented a quiescent phenotype, correlating with NF-κB nuclear translocation, suggesting a mechanism of tolerance. Our data suggests that nutrient deprivation primes prostate cancer cells for adaptability to oxidative stress and/or a general survival mechanism to anti-tumorigenic agents.

Neurite outgrowth involves reciprocal signaling interactions between tumor cells and nerves where invading tumor cells have acquired the ability to respond to pro-invasive signals within the nerve environment. Neurite outgrowth could serve as a mechanism leading to invasion of cancer cells into the nerve sheath and subsequent metastasis. Snail transcription factor can promote migration and invasion of prostate cancer cells. We hypothesized that prostate cancer cell interaction with nerve cells will be mediated by Snail expression within prostate cancer cells. For this study we utilized various prostate cancer cell lines: C4-2 non-silencing (NS, control); C4-2 Snail shRNA, (stable Snail knockdown); LNCaP Neo (empty vector control) and LNCaP Snail (stably over-expressing Snail). Cancer cell adhesion and migration towards nerve cells (snF96.2 or NS20Y) was examined by co-culture assays. Conditioned media (CM) collected from C4-2 cells was cultured with nerve cells (PC-12 or NS20Y) for 48 h followed by qualitative or quantitative neurite outgrowth assay. Our results showed that cancer cells expressing high levels of Snail (LNCaP Snail/C4-2 NS) displayed significantly higher migration adherence to nerve cells, compared to cells with lower levels of Snail (LNCaP Neo/C4-2 Snail shRNA). Additionally, LNCaP Snail or C4-2 NS (Snail-high) CM led to a higher neurite outgrowth compared to the LNCaP Neo or C4-2 Snail shRNA (Snail-low). In conclusion, Snail promotes migration and adhesion to nerve cells, as well as neurite outgrowth via secretion of soluble factors. Therefore, targeting cancer cell interaction with nerves may contribute to halting prostate cancer progression/metastasis.

The sixth International African–Caribbean Cancer Consortium (AC3) Conference was held 6–9 October 2017 in Miami, Florida, U.S.A. The conference was open to all researchers, trainees, clinical and public health professionals, and community members, and served as an international hub for the United States, the Caribbean, and Africa. Sessions included AC3 collaboration meetings, cancer surveillance and research skills training workshops, and a community cancer prevention conference.

Creosote bush (Larrea tridentata, LT) leaves extracts were tested for their potential efficacy to mitigate cellular oxidative stress on human SH-SY5Y cells. Here, the differential nuclear staining assay, a bioimager system, and flow cytometric protocols, concurrently with several specific chemicals, were used to measure the percentage of cell viability and several facets implicated in the cytoprotective mechanism of LT extracts. Initially, three LT extracts, prepared with different solvents, ethanol, ethanol:water (e/w), and water, were tested for their capacity to rescue the viability of cells undergoing aggressive H2O2-induced oxidative stress. Results indicate that the LT extract prepared with a mixture of ethanol:water (LT-e/w, 60:40% v/v) displayed the most effective cytoprotection rescue activity. Interestingly, by investigating the LT-e/w mechanism of action, it was found that LT-e/w extract decreases the levels of H2O2-provoked reactive oxidative species (ROS) accumulation, mitochondrial depolarization, phosphatidylserine externalization, caspase-3/7 activation, and poly (ADP-ribose) polymerase (PARP) cleavage significantly, which are hallmarks of apoptosis. Thus, out of the three LT extracts tested, our findings highlight that the LT-e/w extract was the most effective protective reagent on SH-SY5Y cells undergoing oxidative stress in vitro, functioning as a natural anti-apoptotic extract. These findings warrant further LT-e/w extract examination in a holistic context.

Studies have shown that High mobility group A2 (HMGA2), a non-histone protein, can promote epithelial-mesenchymal transition (EMT), which plays a critical role in prostate cancer progression and metastasis. Interestingly, full-length or wild-type HMGA2 and truncated (lacking the 3'UTR) HMGA2 isoforms are overexpressed in several cancers. However, there are no studies investigating the expression and differential roles of WT vs truncated HMGA2 isoforms in prostate cancer. Immunohistochemical staining of prostate tissue microarray revealed low membrane expression in normal epithelial prostate cells, and that expression increased with tumor grade as well as a switch from predominantly cytoplasmic HMGA2 in lower tumor grades, to mostly nuclear in high grade and bone metastatic tissue. LNCaP cells stably overexpressing wild-type HMGA2 displayed nuclear localization of HMGA2 and induction of EMT associated with increased Snail, Twist and vimentin expression compared to LNCaP Neo control cells, as shown by immunofluorescence and western blot analyses. This was associated with increased cell migration on collagen shown using boyden chamber assay. Conversely, LNCaP cells overexpressing truncated HMGA2 showed cytoplasmic HMGA2 expression that did not induce EMT yet displayed increased cell proliferation and migration compared to LNCaP Neo. Both wild-type and truncated HMGA2 increased levels of phospho-ERK, and interestingly, treatment with U0126, MAPK inhibitor, antagonized wild-type HMGA2-mediated EMT and cell migration, but did not affect truncated HMGA2-mediated cell proliferation or migration. Therefore, although both wild-type and truncated HMGA2 may promote prostate tumor progression, wild-type HMGA2 acts by inducing EMT via MAPK pathway.

Triple-Negative Breast Cancers (TNBCs) are the most difficult to treat subtype of breast cancer and are often associated with high nuclear expression of Snail and Cathepsin L (Cat L) protease. We have previously shown that Snail can increase Cat L expression/activity in prostate and breast cancer cells. This study investigated the role of CUX1 (a downstream substrate of Cat L) in TNBC. We showed that Cat L and CUX1 were highly expressed in TNBC patient tissue/cell lines, as compared to ER-positive samples, using cBioportal data and western blot/zymography analyses. Additionally, luciferase reporter and chromatin immunoprecipitation assays showed that CUX1 directly bound to estrogen receptor-alpha (ER-α) promoter in MDA-MB-468, a representative TNBC cell line, and that CUX1 siRNA could restore ER-α transcription and protein expression. Furthermore, Snail and CUX1 expression in various TNBC cell lines was inhibited by muscadine grape skin extract (MSKE, a natural grape product rich in anthocyanins) or Cat L inhibitor (Z-FY-CHO) leading to decreased cell invasion and migration. MSKE decreased cell viability and increased expression of apoptotic markers in MDA-MB-468 cells, with no effect on non-tumorigenic MCF10A cells. MSKE also decreased CUX1 binding to ER-α promoter and restored ER-α expression in TNBC cells, while both MSKE and CUX1 siRNA restored sensitivity to estradiol and 4-hydoxytamoxifen as shown by increased cell viability. Therefore, CUX1 activated by Snail-Cat L signaling may contribute to TNBC via ER-α repression, and may be a viable target for TNBC using natural products such as MSKE that targets cancer and not normal cells.

African Americans (AA) have higher death rates due to prostate and breast cancer as compared to Caucasian Americans (CA), and few biomarkers have been associated with this disparity. In our study we investigated whether epithelial-mesenchymal transition (EMT) with a focus on Snail and Cathepsin L (Cat L), could potentially be two markers associated with prostate and breast health disparities. We have previously shown that Snail can increase Cat L protein and activity in prostate and breast cancer. Western blot and real-time PCR analyses showed that mesenchymal protein expression (Snail, vimentin, Cat L) and Cat L activity (shown by zymography) was higher in AA prostate cancer cells as compared to CA normal transformed RWPE-1 prostate epithelial cells, and androgen-dependent cells, and comparable to metastatic CA cell lines. With respect to breast cancer, mesenchymal markers were higher in TNBC compared to non-TNBC cells. The higher mesenchymal marker expression was functionally associated with higher proliferative and migratory rates. Immunohistochemistry showed that both nuclear Snail and Cat L expression was significantly higher in cancer compared to normal for CA and Bahamas prostate patient tissue. Interestingly, AA normal tissue stained higher for nuclear Snail and Cat L that was not significantly different to cancer tissue for both prostate and breast tissue, but was significantly higher than CA normal tissue. AA TNBC tissue also displayed significantly higher nuclear Snail expression compared to CA TNBC, while no significant differences were observed with Luminal A cancer tissue. Therefore, increased EMT in AA compared to CA that may contribute to the more aggressive disease.

Typically the normal epithelial cells are a single layer, held tightly by adherent proteins that prevent the mobilization of the cells from the monolayer sheet. During prostate cancer progression, the epithelial cells can undergo epithelial-mesenchymal transition or EMT, characterized by morphological changes in their phenotype from cuboidal to spindle-shaped. This is associated with biochemical changes in which epithelial cell markers such as E-cadherin and occludins are down-regulated, which leads to loss of cell-cell adhesion, while mesenchymal markers such as vimentin and N-cadherin are up-regulated, thereby allowing the cells to migrate or metastasize to different organs. The EMT transition can be regulated directly and indirectly by multiple molecular mechanisms including growth factors and cytokines such as transforming growth factor-beta (TGF-β), epidermal growth factor (EGF) and insulin-like growth factor (IGF), and signaling pathways such as mitogen-activated protein kinase (MAPK) and Phosphatidylinositol 3-Kinase (PI3K). This signaling subsequently induces expression of various transcription factors like Snail, Twist, Zeb1/2, that are also known as master regulators of EMT. Various markers associated with EMT have been reported in prostate cancer patient tissue as well as a possible association with health disparities. There has been consideration to therapeutically target EMT in prostate cancer patients by targeting the EMT signaling pathways.

The purpose of this review is to stimulate new ideas regarding low-dose environmental mixtures and carcinogens and their potential to promote invasion and metastasis. Whereas a number of chapters in this review are devoted to the role of low-dose environmental mixtures and carcinogens in the promotion of invasion and metastasis in specific tumors such as breast and prostate, the overarching theme is the role of low-dose carcinogens in the progression of cancer stem cells. It is becoming clearer that cancer stem cells in a tumor are the ones that assume invasive properties and colonize distant organs. Therefore, low-dose contaminants that trigger epithelial–mesenchymal transition, for example, in these cells are of particular interest in this review. This we hope will lead to the collaboration between scientists who have dedicated their professional life to the study of carcinogens and those whose interests are exclusively in the arena of tissue invasion and metastasis.

Goodson, William H. et al., © The Author 2015. Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but credible estimates from the World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to toxic environmental exposures is between 7% and 19%. To explore the hypothesis that low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to environmental carcinogenesis, we reviewed 11 hallmark phenotypes of cancer, multiple priority target sites for disruption in each area and prototypical chemical disruptors for all targets, this included dose-response characterizations, evidence of low-dose effects and cross-hallmark effects for all targets and chemicals. In total, 85 examples of chemicals were reviewed for actions on key pathways/ mechanisms related to carcinogenesis. Only 15% (13/85) were found to have evidence of a dose-response threshold, whereas 59% (50/85) exerted low-dose effects. No dose-response information was found for the remaining 26% (22/85). Our analysis suggests that the cumulative effects of individual (non-carcinogenic) chemicals acting on different pathways, and a variety of related systems, organs, tissues and cells could plausibly conspire to produce carcinogenic synergies. Additional basic research on carcinogenesis and research focused on low-dose effects of chemical mixtures needs to be rigorously pursued before the merits of this hypothesis can be further advanced. However, the structure of the World Health Organization International Programme on Chemical Safety 'Mode of Action' framework should be revisited as it has inherent weaknesses that are not fully aligned with our current understanding of cancer biology., We gratefully acknowledge the support of the National Institute of Health-National Institute of Environmental Health Sciences (NIEHS) conference grant travel support (R13ES023276); Glenn Rice, Office of Research and Development, United States Environmental Protection Agency, Cincinnati, OH, USA also deserves thanks for his thoughtful feedback and inputs on the manuscript; William H.Goodson III was supported by the California Breast Cancer Research Program, Clarence Heller Foundation and California Pacific Medical Center Foundation; Abdul M.Ali would like to acknowledge the financial support of the University of Sultan Zainal Abidin, Malaysia; Ahmed Lasfar was supported by an award from the Rutgers Cancer Institute of New Jersey; Ann-Karin Olsen and Gunnar Brunborg were supported by the Research Council of Norway (RCN) through its Centres of Excellence funding scheme (223268/F50), Amancio Carnero’s lab was supported by grants from the Spanish Ministry of Economy and Competitivity, ISCIII (Fis: PI12/00137, RTICC: RD12/0036/0028) co-funded by FEDER from Regional Development European Funds (European Union), Consejeria de Ciencia e Innovacion (CTS-1848) and Consejeria de Salud of the Junta de Andalucia (PI-0306-2012); Matilde E. Lleonart was supported by a trienal project grant PI12/01104 and by project CP03/00101 for personal support. Amaya Azqueta would like to thank the Ministerio de Educacion y Ciencia (‘Juande la Cierva’ programme, 2009) of the Spanish Government for personal support; Amedeo Amedei was supported by the Italian Ministry of University and Research (2009FZZ4XM_002), and the University of Florence (ex60%2012); Andrew R.Collins was supported by the University of Oslo; Annamaria Colacci was supported by the Emilia-Romagna Region - Project ‘Supersite’ in Italy; Carolyn Baglole was supported by a salary award from the Fonds de recherche du Quebec-Sante (FRQ-S); Chiara Mondello’s laboratory is supported by Fondazione Cariplo in Milan, Italy (grant n. 2011-0370); Christian C.Naus holds a Canada Research Chair; Clement Yedjou was supported by a grant from the National Institutes of Health (NIH-NIMHD grant no. G12MD007581); Daniel C.Koch is supported by the Burroughs Wellcome Fund Postdoctoral Enrichment Award and the Tumor Biology Training grant: NIH T32CA09151; Dean W. Felsher would like to acknowledge the support of United States Department of Health and Human Services, NIH grants (R01 CA170378 PQ22, R01 CA184384, U54 CA149145, U54 CA151459, P50 CA114747 and R21 CA169964); Emilio Rojas would like to thank CONACyT support 152473, Ezio Laconi was supported by AIRC (Italian Association for Cancer Research, grant no. IG 14640) and by the Sardinian Regional Government (RAS); Eun-Yi Moon was supported by grants from the Public Problem-Solving Program (NRF-015M3C8A6A06014500) and Nuclear R&D Program (#2013M2B2A9A03051296 and 2010-0018545) through the National Research Foundation of Korea (NRF) and funded by the Ministry of Education, Science and Technology (MEST) in Korea; Fahd Al-Mulla was supported by the Kuwait Foundation for the Advancement of Sciences (2011-1302-06); Ferdinando Chiaradonna is supported by SysBioNet, a grant for the Italian Roadmap of European Strategy Forum on Research Infrastructures (ESFRI) and by AIRC (Associazione Italiana Ricerca sul Cancro; IG 15364); Francis L.Martin acknowledges funding from Rosemere Cancer Foundation; he also thanks Lancashire Teaching Hospitals NHS trust and the patients who have facilitated the studies he has undertaken over the course of the last 10 years; Gary S.Goldberg would like to acknowledge the support of the New Jersey Health Foundation; Gloria M.Calaf was supported by Fondo Nacional de Ciencia y Tecnología (FONDECYT), Ministerio de Educación de Chile (MINEDUC), Universidad de Tarapacá (UTA); Gudrun Koppen was supported by the Flemish Institute for Technological Research (VITO), Belgium; Hemad Yasaei was supported from a triennial project grant (Strategic Award) from the National Centre for the Replacement, Refinement and Reduction (NC3Rs) of animals in research (NC.K500045.1 and G0800697); Hiroshi Kondoh was supported in part by grants from the Ministry of Education, Culture, Sports, Science, and Technology of Japan, Japan Science and Technology Agency and by JST, CREST; Hsue-Yin Hsu was supported by the Ministry of Science and Technology of Taiwan (NSC93-2314-B-320-006 and NSC94-2314-B-320-002); Hyun Ho Park was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) of the Ministry of Education, Science and Technology (2012R1A2A2A01010870) and a grant from the Korea Healthcare Technology R&D project, Ministry of Health and Welfare, Republic of Korea (HI13C1449); Igor Koturbash is supported by the UAMS/NIH Clinical and Translational Science Award (UL1TR000039 and KL2TR000063) and the Arkansas Biosciences Institute, the major research component of the Arkansas Tobacco Settlement Proceeds Act of 2000; Jan Vondráček acknowledges funding from the Czech Science Foundation (13-07711S); Jesse Roman thanks the NIH for their support (CA116812), John Pierce Wise Sr. and Sandra S.Wise were supported by National Institute of Environmental Health Sciences (ES016893 to J.P.W.) and the Maine Center for Toxicology and Environmental Health; Jonathan Whitfield acknowledges support from the FERO Foundation in Barcelona, Spain; Joseph Christopher is funded by Cancer Research UK and the International Journal of Experimental Pathology; Julia Kravchenko is supported by a philanthropic donation by Fred and Alice Stanback; Jun Sun is supported by a Swim Across America Cancer Research Award; Karine A.Cohen-Solal is supported by a research scholar grant from the American Cancer Society (116683-RSG-09-087-01-TBE); Laetitia Gonzalez received a postdoctoral fellowship from the Fund for Scientific Research–Flanders (FWO-Vlaanderen) and support by an InterUniversity Attraction Pole grant (IAP-P7-07); Laura Soucek is supported by grant #CP10/00656 from the Miguel Servet Research Contract Program and acknowledges support from the FERO Foundation in Barcelona, Spain; Liang-Tzung Lin was supported by funding from the Taipei Medical University (TMU101-AE3-Y19); Linda Gulliver is supported by a Genesis Oncology Trust (NZ) Professional Development Grant, and the Faculty of Medicine, University of Otago, Dunedin, New Zealand; Louis Vermeulen is supported by a Fellowship of the Dutch Cancer Society (KWF, UVA2011-4969) and a grant from the AICR (14–1164); Mahara Valverde would like to thank CONACyT support 153781; Masoud H. Manjili was supported by the office of the Assistant Secretary of Defense for Health Affairs (USA) through the Breast Cancer Research Program under Award No. W81XWH-14-1-0087 Neetu Singh was supported by grant #SR/FT/LS-063/2008 from the Department of Science and Technology, Government of India; Nicole Kleinstreuer is supported by NIEHS contracts (N01-ES 35504 and HHSN27320140003C); P.K. Krishnakumar is supported by the Funding (No. T.K. 11-0629) of King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia; Paola A.Marignani is supported by the Dalhousie Medical Research Foundation, The Beatrice Hunter Cancer Institute and CIHR and the Nova Scotia Lung Association; Paul Dent is the holder of the Universal Inc.Chair in Signal Transduction Research and is supported with funds from PHS grants from the NIH (R01-CA141704, R01-CA150214, R01-DK52825 and R01-CA61774); Petr Heneberg was supported by the Charles University in Prague projects UNCE 204015 and PRVOUK P31/2012, and by the Czech Science Foundation projects P301/12/1686 and 15-03834Y; Po Sing Leung was supported by the Health and Medical Research Fund of Food and Health Bureau, Hong Kong Special Administrative Region, Ref. No: 10110021; Qiang Cheng was supported in part by grant NSF IIS-1218712; R. Brooks Robey is supported by the United States Department of Veterans Affairs; Rabindra Roy was supported by United States Public Health Service Grants (RO1 CA92306, RO1 CA92306-S1 and RO1 CA113447); Rafaela Andrade-Vieira is supported by the Beatrice Hunter Cancer Research Institute and the Nova Scotia Health Research Foundation, Renza Vento was partially funded by European Regional Development Fund, European Territorial Cooperation 2007–13 (CCI 2007 CB 163 PO 037, OP Italia-Malta 2007–13) and grants from the Italian Ministry of Education, University and Research (MIUR) ex-60%, 2007; Riccardo Di Fiore was a recipient of fellowship granted by European Regional Development Fund, European Territorial Cooperation 2007–2013 (CCI 2007 CB 163 PO 037, OP Italia-Malta 2007–2013); Rita Dornetshuber-Fleiss was supported by the Austrian Science Fund (FWF, project number T 451-B18) and the Johanna Mahlke, geb.-Obermann-Stiftung; Roberta Palorini is supported by a SysBioNet fellowship; Roslida Abd Hamid is supported by the Ministry of Education, Malaysia-Exploratory Research Grant Scheme-Project no: ERGS/1-2013/5527165; Sabine A.S.Langie is the beneficiary of a postdoctoral grant from the AXA Research Fund and the Cefic-LRI Innovative Science Award 2013; Sakina Eltom is supported by NIH grant SC1CA153326; Samira A.Brooks was supported by National Research Service Award (T32 ES007126) from the National Institute of Environmental Health Sciences and the HHMI Translational Medicine Fellowship; Sandra Ryeom was supported by The Garrett B. Smith Foundation and the TedDriven Foundation; Thierry Massfelder was supported by the Institut National de la Santé et de la Recherche Médicale INSERM and Université de Strasbourg; Thomas Sanderson is supported by the Canadian Institutes of Health Research (CIHR; MOP-115019), the Natural Sciences and Engineering Council of Canada (NSERC; 313313) and the California Breast Cancer Research Program (CBCRP; 17UB-8703); Tiziana Guarnieri is supported by a grant from Fundamental Oriented Research (RFO) to the Alma Mater Studiorum University of Bologna, Bologna, Italy and thanks the Fondazione Cassa di Risparmio di Bologna and the Fondazione Banca del Monte di Bologna e Ravenna for supporting the Center for Applied Biomedical Research, S.Orsola-Malpighi University Hospital, Bologna, Italy; W.Kimryn Rathmell is supported by the V Foundation for Cancer Research and the American Cancer Society; William K.Decker was supported in part by grant RP110545 from the Cancer Prevention Research Institute of Texas; William H.Bisson was supported with funding from the NIH P30 ES000210; Yon Rojanasakul was supported with NIH grant R01-ES022968; Zhenbang Chen is supported by NIH grants (MD004038, CA163069 and MD007593); Zhiwei Hu is grateful for the grant support from an institutional start-up fund from The Ohio State University College of Medicine and The OSU James Comprehensive Cancer Center (OSUCCC) and a Seed Award from the OSUCCC Translational Therapeutics Program.

Metastatic prostate cancer (mPCa) relapses after a short period of androgen deprivation therapy and becomes the castration-resistant prostate cancer (CR PCa); to which the treatment is limited. Hence, it is imperative to identify novel therapeutic agents towards this patient population. In the present study, antiproliferative activities of novel imidazopyridines were compared. Among three derivatives, PHE, AMD and AMN, examined, AMD showed the highest inhibitory activity on LNCaP C-81 cell proliferation, following dose- and time-dependent manner. Additionally, AMD exhibited significant antiproliferative effect against a panel of PCa cells, but not normal prostate epithelial cells. Further, when compared to AMD, its derivative DME showed higher inhibitory activities on PCa cell proliferation, clonogenic potential and in vitro tumorigenicity. The inhibitory activity was apparently in part due to the induction of apoptosis. Mechanistic studies indicate that AMD and DME treatments inhibited both AR and PI3K/Akt signaling. The results suggest that better understanding of inhibitory mechanisms of AMD and DME could help design novel therapeutic agents for improving the treatment of CR PCa.

High mobility group A (HMGA2), a non-histone protein, is up-regulated in several cancers. Due to chromosomal rearrangement of HMGA2 gene, full-length or wild-type HMGA2 can be truncated leading to loss of the C-terminus and the 3’UTR. Both wild-type and truncated isoforms have been detected in uterine leiomyoma patients. However, the functional role of truncated HMGA2 has not been investigated. We hypothesize that truncated HMGA2 plays a role in prostate cancer progression. We analysed expression of wild-type vs truncated HMGA2 in a panel of prostate cancer cell lines using real-time PCR and western blot analyses. We utilized LNCaP cells stably overexpressing wild-type HMGA2 or truncated HMGA2 in LNCaP cells to detect the basal reactive oxygen species (ROS) levels using DCFDA dye. We analysed Jun-D expression, a putative downstream effector of HMGA2, by western blot analysis, and utilized siRNA to knockdown Jun-D. We performed migration and cell viability assays following Jun-D knockdown. Additionally, we performed proteomic analysis following immunoprecipitation with HMGA2 antibody in nuclear extracts from LNCaP cells overexpressing wild-type HMGA2 WT or cytoplasmic extracts from cells overexpressing truncated HMGA2. Finally, we utilized tissue microarray to analyse expression of HMGA2 by immunohistochemisty. Our results showed that prostate cancer cell lines expressed varying amounts of wild-type and truncated HMGA2. LNCaP cells overexpressing truncated HMGA2 exhibited increased nuclear expression of Jun-D, as well as increased ROS compared to LNCaP cells overexpressing wild-type HMGA2 or empty vector Neo control. Knockdown Jun-D in LNCaP cells overexpressing truncated HMGA2 abrogated ROS induction and cell migration with no effect on cell proliferation. Additionally, truncated HMGA2 interacted with a number of proteins, including Ras GTPase-activating protein-binding protein 1(G3BP1), a cytoplasmic stress granule protein that responds to oxidative stress. Truncated HMGA2 is mainly localized to the cytoplasm, and interestingly we also observed cytoplasmic HMGA expression in prostatic tissue with chronic inflammation. Therefore, truncated HMGA2 may promote prostate cancer progression via Jun-D-mediated ROS. GRANT SUPPORT: NIH 1P20MD002285 and NIH/NCRR/RCMI G12RR003062-22 Citation Format: Ohuod Hawsawi, Veronica Henderson, Liza Burton, Jodi Dougan, Ana Cecillia Millena, Vanessa Adams, Elshaddai Z. White, Guang Di Wang, Qiang Zhang, Cimona Hinton, Shafiq Khan, Valerie Odero-Marah. Novel role of truncated HMGA2 in regulating reactive oxygen species in prostate cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 877.

Prostate Cancer is the most common non-cutaneous cancer and second leading cause of cancer related death in American men. Epithelial Mesenchymal Transition (EMT), a key event in prostate cancer metastasis, is a process in which polarized epithelial cells undergo biochemical changes, allowing them to assume mesenchymal morphologies, enhancing invasiveness and migration. Reactive Oxygen Species (ROS) are chemically reactive molecules of cellular metabolism that induce oxidative stress, and increase levels of SNAI1 (Snail) transcription factor while also promoting EMT. In Phase II clinical trials, patients were treated with natural product, Muscadine Grape Skin Extract (MSKE), and patients with SOD2 Ala/Ala single nucleotide polymorphism (SNP) responded better than those with Val/Val SNP. Ala/Ala SNP is associated with higher dismutase activity [superoxide (O2-) to hydrogen peroxide (H2O2)] than Val/Val. We hypothesize that SOD2 Ala/Ala genotype is associated with increased H2O2 and EMT, potentially antagonized by MSKE in prostate cancer cells. Prostate cancer cell lines were analyzed for SOD2 SNPs by pyrosequencing. Site-directed mutagenesis was conducted to create the Ala/Ala and Val/Val SNP vectors. LNCaP prostate cancer cells were transiently and subsequently stably transfected with SOD2 Val/Val cDNA, as well as empty vector (Neo) control, and verified through western blot analysis. ROS activity was evaluated for baseline ROS activity. Our results showed that most prostate cancer cell lines were heterozygous for SOD2 SNP (Ala/Val), although several had extra copies, for example, LNCaP had Val/Val/Ala, suggesting multiple copy numbers. Only metastatic MDA PCa 2a and MDA PCa 2b contained Ala/Ala homozygous SNP. LNCaP cells transiently and stably transfected with Val/Val showed partial induction of EMT, concomitant with higher levels of Snail and Vimentin, as compared to LNCaP Neo control. Furthermore, data also suggested that transient transfection marginally affected ROS activity while stable transfection caused significant changes in ROS activity compared to LNCaP Neo cells. We have begun to stably transfect Ala/Ala cDNA into LNCaP cells and are interested to see the differences in ROS activity and EMT induction between the two clone cell types (LNCaP Ala/Ala and Val/Val). As previous data suggests, we believe that Ala/Ala will show a higher expression of SOD2 and mesenchymal markers Snail and Vimentin, demonstrating full induction of EMT. In future we will test ROS activity, EMT marker expression in response to treatment of LNCaP Ala/Ala and Val/Val cells with MSKE. These studies may uncover the differential functions and response to treatment of SOD2 SNPs. Acknowledgements: These studies were supported by the NIH/NIMHD/RCI Grant #5G12MD007590-31, NIH/NIGMS/RISE Grant #5R25GM060414, and https://www.thecommunityfoundation.org/ Citation Format: Janae D. Sweeney, Valerie Odero-Marah, Channing Paller. Novel roles for manganese superoxide dismutase polymorphisms in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1047.

Peroxidasin (PXDN), a human homolog of Drosophila PXDN, belongs to the family of heme peroxidases and has been found to promote oxidative stress in cardiovascular tissue, however, its role in prostate cancer has not been previously elucidated. We hypothesized that PXDN promotes prostate cancer progression via regulation of metabolic and oxidative stress pathways. We analyzed PXDN expression in prostate tissue by immunohistochemistry and found increased PXDN expression with prostate cancer progression as compared to normal tissue or cells. PXDN knockdown followed by proteomic analysis revealed an increase in oxidative stress, mitochondrial dysfunction and gluconeogenesis pathways. Additionally, Liquid Chromatography with tandem mass spectrometry (LC-MS/MS)-based metabolomics confirmed that PXDN knockdown induced global reprogramming associated with increased oxidative stress and decreased nucleotide biosynthesis. We further demonstrated that PXDN knockdown led to an increase in reactive oxygen species (ROS) associated with decreased cell viability and increased apoptosis. Finally, PXDN knockdown decreased colony formation on soft agar. Overall, the data suggest that PXDN promotes progression of prostate cancer by regulating the metabolome, more specifically, by inhibiting oxidative stress leading to decreased apoptosis. Therefore, PXDN may be a biomarker associated with prostate cancer and a potential therapeutic target.

Reactive oxygen species (ROS) play a central role in oxidative stress, which leads to the onset of diseases, such as cancer. Furthermore, ROS contributes to the delicate balance between tumor cell survival and death. However, the mechanisms by which tumor cells decide to elicit survival or death signals during oxidative stress are not completely understood. We have previously reported that ROS enhanced tumorigenic functions in prostate cancer cells, such as transendothelial migration and invasion, which depended on CXCR4 and AKT signaling. Here, we report a novel mechanism by which ROS facilitated cell death through activation of AKT. We initially observed that ROS enhanced the expression of phosphorylated AKT (p-AKT) in 22Rv1 human prostate cancer cells. The tumor suppressor PTEN, a negative regulator of AKT signaling, was rendered catalytically inactive through oxidation by ROS, although the expression levels remained consistent. Despite these events, cells still underwent apoptosis. Further investigation into apoptosis revealed that expression of the tumor suppressor pVHL increased, and contains a target site for p-AKT phosphorylation. pVHL and p-AKT associated in vitro, and knockdown of pVHL rescued HIF1α expression and the cells from apoptosis. Collectively, our study suggests that in the context of oxidative stress, p-AKT facilitated apoptosis by inducing pVHL function.

Muscadine grape skin extract (MSKE) is derived from muscadine grape (Vitis rotundifolia), a common red grape used to produce red wine. Endoplasmic reticulum (ER) stress activates the unfolded protein response (UPR) that serves as a survival mechanism to relieve ER stress and restore ER homeostasis. However, when persistent, ER stress can alter the cytoprotective functions of the UPR to promote autophagy and cell death. Although MSKE has been documented to induce apoptosis, it has not been linked to ER stress/UPR/autophagy. We hypothesized that MSKE may induce a severe ER stress response-mediated autophagy leading to apoptosis. As a model, we treated C4-2 prostate cancer cells with MSKE and performed a quantitative Tandem Mass Tag Isobaric Labeling proteomic analysis. ER stress response, autophagy and apoptosis were analyzed by western blot, acridine orange and TUNEL/Annexin V staining, respectively. Quantitative proteomics analysis indicated that ER stress response proteins, such as GRP78 were greatly elevated following treatment with MSKE. The up-regulation of pro-apoptotic markers PARP, caspase-12, cleaved caspase-3, -7, BAX and down-regulation of anti-apoptotic marker BCL2 was confirmed by Western blot analysis and apoptosis was visualized by increased TUNEL/Annexin V staining upon MSKE treatment. Moreover, increased acridine orange, and LC3B staining was detected in MSKE-treated cells, suggesting an ER stress/autophagy response. Finally, MSKE-mediated autophagy and apoptosis was antagonized by co-treatment with chloroquine, an autophagy inhibitor. Our results indicate that MSKE can elicit an UPR that can eventually lead to apoptosis in prostate cancer cells.

Prostate cancer is the second most frequently diagnosed cancer and the sixth leading cause of death from cancer in men. Epithelial-mesenchymal transition (EMT) is a process by which cancer cells invade and migrate, and is characterized by loss of cell-cell adhesion molecules such as E-cadherin and increased expression of mesenchymal proteins such as vimentin; EMT is also associated with resistance to therapy. Snail, a master regulator of EMT, has been extensively studied and reported in cancers such as breast and colon; however, its role in prostate cancer is not as widely reported. The purpose of this review is to put together recent facts that summarize Snail signaling in human prostate cancer. Snail is overexpressed in prostate cancer and its expression and activity is controlled via phosphorylation and growth factor signaling. Snail is involved in its canonical role of inducing EMT in prostate cancer cells; however, it plays a role in non-canonical pathways that do not involve EMT such regulation of bone turnover and neuroendocrine differentiation. Thus, studies indicate that Snail signaling contributes to prostate cancer progression and metastasis and therapeutic targeting of Snail in prostate cancer holds promise in �future.

Reactive oxygen species increases in various diseases including cancer and has been associated with induction of epithelial-mesenchymal transition (EMT), as evidenced by decrease in cell adhesion-associated molecules like E-cadherin, and increase in mesenchymal markers like vimentin. We investigated the molecular mechanisms by which Snail transcription factor, an inducer of EMT, promotes tumor aggressiveness utilizing ARCaP prostate cancer cell line. An EMT model created by Snail overexpression in ARCaP cells was associated with decreased E-cadherin and increased vimentin. Moreover, Snail-expressing cells displayed increased concentration of reactive oxygen species (ROS), specifically, superoxide and hydrogen peroxide, in vitro and in vivo. Real time PCR profiling demonstrated increased expression of oxidative stress-responsive genes, such as aldeyhyde oxidase I, in response to Snail. The ROS scavenger, N-acetyl cysteine partially reversed Snail-mediated EMT after 7 days characterized by increased E-cadherin levels and decreased ERK activity, while treatment with the MEK inhibitor, UO126, resulted in a more marked effect by 3 days, characterized by cells returning back to the epithelial morphology and increased E-cadherin. In conclusion, this study shows for the first time that Snail transcription factor can regulate oxidative stress enzymes and increase ROS-mediated EMT regulated in part by ERK activation. Therefore, Snail may be an attractive molecule for therapeutic targeting to prevent tumor progression in human prostate cancer.

Prostate Cancer (PCa) is the second leading cause of cancer death in American men. PCa patients' mortality is mainly attributed to complications caused by metastasis of the disease to organs critical for survival, such as bone. As such, it is important to understand cancer-bone microenvironment interactions in order to develop therapeutics that will slow or halt the process of cancer metastasis. Snail1 is a zinc-finger transcription factor that induces epithelial-mesenchymal transition (EMT) which is associated with cell migration and metastasis in cancer. We hypothesized that cancer cell-bone interactions would promote higher calcium release from bone, more specifically by cancer cells overexpressing Snail, which would lead to increased paracrine cell signaling and migration. For this study, we utilized various prostate cancer cell lines: LNCaP (Snail-low), C4-2 (Snail-high), E006AA (Snail-high), E006AA HT (Snail-high) and C4-2 with stable Snail knockdown. Cancer cells were co-cultured with Hydroxyapatite (HA; inorganic component of bone) of different densities to represent the African American vs Caucasian bone ratio (since African Americans have higher bone density than any other race). The conditioned media was then used to assay calcium levels, perform paracrine migration assays using LNCaP cells, and examine paracrine signaling effects of the various conditioned media on LNCaP cells by western blotting. We observed that calcium levels were elevated in conditioned media from cancer cell-bone co-cultures, compared to media or cancer cells alone, and this could be antagonized by EGTA, a calcium chelator. C4-2 cancer-bone co-culture conditioned media increased paracrine cell migration which was decreased by Snail knockdown as well as lower bone density. We also observed increased STAT3 phosphorylation and paracrine cell migration in LNCaP cells incubated with conditioned media from C4-2, E006AA or E006AA HT cells co-cultured with HA; this phosphorylation and cell migration could be antagonized by Snail knockdown or STAT3 inhibitor (WP1066). An in vivo study was also done using nude mice that were surgically implanted with either 40mg HA or 100mg HA and subcutaneously injected with either C4-2 NS or C4-2 Snail shRNA cells into a position close to the shoulder from the surgical HA implant site in the mouse. At week 2 and week 4, Snail shRNA cells injected mice showed larger tumors than C4-2 NS injected mice, however, mice implanted with cancer cells plus higher bone density resulted in larger tumors than those with lower bone density. In conclusion, our study shows that Snail can mediate cancer-bone microenvironment interactions via STAT3 signaling, that can possibly promote increased paracrine cell migration towards bone of high mineral density. Therefore, targeting cancer-bone micronenvironmental interactions is an important avenue to consider for therapeutic targeting of prostate cancer. Citation Format: Veronica M. Henderson, Ohuod Hawsawi, Liza J. Burton, Kennedi Trice, Jodi Dougan, Simone M. Howard, Valerie A. Odero-Marah. STAT3 pathway regulates the cancer-bone microenvironment interactions mediated by Snail [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1096.

Prostate cancer is the most highly diagnosed cancer in men and the second leading cause of death in the United States. Epithelial-mesenchymal transition (EMT) plays a critical role in cancer progression and metastasis. High mobility group A (HMGA2), a non-histone protein, has been shown to promote EMT in separate studies. Interestingly, wild-type HMGA2 and truncated (lacking the 3'UTR) HMGA2 isoforms are overexpressed in many cancers, but have not been investigated in prostate cancer. Jun-D is a transcriptional factor that might be regulated by HMGA2. Moreover, the function for each individual isoform is still not well understood. We hypothesize that each of the two isoforms of HMGA2 in will have different functions in prostate cancer. We stably overexpressed wild-type HMGA2 and truncated HMGA2 in LNCaP cells and measured the expression and the localization of EMT markers. We also measured reactive oxygen species (ROS) levels using DCFDA dye, since ROS has been associated with EMT. We performed migration and cell viability assays as well as Jun-D knockdown, a putative downstream effector of HMGA2. Our results showed that the overexpression of HMGA2 in LNCaP cells led to an increase in cell viability and migration for both wild-type and truncated HMGA2. We observed that wild-type, but not truncated HMGA2 promoted EMT. Additionally, Jun-D and ROS levels increased for truncated, but not significantly for wild-type HMGA2. Jun-D knockdown with siRNA decreased ROS and cell migration in cells with truncated HMGA2, but not in cells overexpressing wild-type HMGA2. Therefore, wild-type HMGA2 is the isoform that induces EMT, while the truncated form appears to have an alternate role in upregulating ROS via Jun-D. In conclusion, we show a link between HMGA2 and JunD/ROS for the first time, and data that wild-type and truncated HMGA2 may have differing functions that converge to increase cell proliferation and migration, and may in future instruct on more precise therapeutic targeting in patients with these isoforms. GRANT SUPPORT: NIH 1P20MD002285 and NIH/NCRR/RCMI G12RR003062-22 Citation Format: Ohuod A. Hawsawi, Liza Burton, Jodi Dougan, Ana Cecillia Millena, Peri Nagappan, Shafiq Khan, Valerie Odero-Marah. Role of high mobility group A2 (HMGA2) in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1089.

BACKGROUND Snail transcription factor induces epithelial–mesenchymal transition (EMT) via decreased cell adhesion-associated molecules like E-cadherin, and increased mesenchymal markers like vimentin. We previously established Snail-mediated EMT model utilizing androgen-dependent LNCaP cells. These cells express increased vimentin protein and relocalization of E-cadherin from the cell membrane to the cytosol. Interestingly, Snail transfection in LNCaP cells resulted in cells acquiring a neuroendocrine (NE)-like morphology with long neurite-like processes. METHODS We tested for expression of NE markers neuron-specific enolase (NSE) and chromogranin A (CgA) by Western blot analysis, and performed proliferation assays to test for paracrine cell proliferation. RESULTS LNCaP cells transfected with Snail displayed increase in the NE markers, NSE and CgA as well as translocation of androgen receptor (AR) to the nucleus. LNCaP C-33 cells that have been previously published as a neuroendocrine differentiation (NED) model exhibited increased expression levels of Snail protein as compared to LNCaP parental cells. Functionally, conditioned medium from the LNCaP-Snail transfected cells increased proliferation of parental LNCaP and PC-3 cells, which could be abrogated by NSE/CgA siRNA. Additionally, NED in LNCaP-C33 cells or that induced in parental LNCaP cells by serum starvation could be inhibited by knockdown of Snail with siRNA. CONCLUSION Overall our data provide evidence that Snail transcription factor may promote tumor aggressiveness in the LNCaP cells through multiple processes; induction of EMT may be required to promote migration, while NED may promote tumor proliferation by a paracrine mechanism. Therefore, therapeutic targeting of Snail may prove beneficial in not only abrogating EMT but also NED. Prostate 70: 982–992, 2010. © 2010 Wiley-Liss, Inc.

Zinc-finger enhancer binding protein (ZEB1) is a transcription factor involved in the progression of cancer primarily through promoting epithelial to mesenchymal transition (EMT). ZEB1 represses the expression of E-cadherin by binding to E-box sequences in the promoter, thus decreasing epithelial differentiation. We show that ZEB1 and androgen receptor (AR) cross-talk in triple negative breast cancer cell lines. Chromatin immunoprecipitation analysis demonstrates that ZEB1 binds directly to the E-box located in the AR promoter. ZEB1 suppression by stably transfecting shRNA in a triple negative breast cancer cell line resulted in a decrease of AR mRNA, protein, and AR downstream targets. ZEB1 knockdown in triple negative breast cancer cells sensitized the cells to bicalutamide by reducing migration compared to the control cells. Conversely, blockade of AR signaling with bicalutamide resulted in a suppression of ZEB1 protein expression in two triple negative breast cancer cell lines. Furthermore, using a breast cancer tissue microarray, a majority of triple negative breast cancers exhibit positive staining for both ZEB1 and AR. Taken together, these results indicate that ZEB1 and AR regulate each other to promote cell migration in triple negative breast cancer cells.

Reactive oxygen species (ROS) are implicated in many human diseases, including cancer. We have previously demonstrated that ROS increased the expression and activity of the chemokine receptor, CXCR4, which enhanced metastatic functions in prostate cancer cells. Studies have also revealed that CXCR4 and its ligand, SDF-1α, promoted ROS accumulation; however the source of ROS was not investigated. Recent evidence suggested that ROS accumulation in prostate cancer cell lines was contributed by the NADPH oxidase (NOX) family of enzymes. Herein, we sought to determine whether the CXCR4/SDF-1α signaling axis mediates ROS production through NOX in prostate cancer. We observed an increase in intracellular ROS generation in prostate cancer cells upon SDF-1α stimulation compared to untreated samples. Conversely, lower levels of ROS were detected in cells treated with AMD3100 (CXCR4 antagonist) or the ROS scavenger, N-acetyl-cysteine (NAC). Markedly reduced levels of ROS were observed in cells treated with apocynin (NOX inhibitor) compared to rotenone (mitochondrial complex I inhibitor)-treated cells. Specifically, we determined that NOX2 responded to, and was regulated by, the SDF-1α/CXCR4 signaling axis. Moreover, chemical inhibition of the ERK1/2 and PI3K pathways revealed that PI3K/AKT signaling participated in CXCR4-mediated NOX activity, and that these collective signaling events resulted in enhanced cell movement towards a chemoattractant. Finally, NOX2 may be a potential therapeutic target, as Oncomine microarray database analysis of normal prostate, benign prostatic hyperplasia (BPH) and prostatic intraepithelial neoplasia (PIN) tissue samples determined a correlation between NOX2 expression and prostate cancer. Taken together, these results suggest that CXCR4/SDF-1α-mediated ROS production through NOX2 enzymes may be an emerging concept by which chemokine signaling progresses tumorigenesis.

Prostate cancer is the most diagnosed cancer in men and the second leading cause of death in the United States. African American men have the highest incidence and mortality rates of prostate cancer compared to any other race. Epithelial-mesenchymal transition (EMT) plays a critical role in cancer progression and metastasis. Mesenchymal cells are migratory, invasive, and more resistant to apoptosis. Reactive Oxygen Species (ROS) has been shown to promote EMT. High mobility group A (HMGA2) is a non-histone protein that is highly expressed during the embryogenesis, whereas the gene expression is very low or absent during adulthood. Recent studies have been reported an overexpression of HMGA2 protein in malignant cancers. Loss of Let-7 miRNA (repressor of HMGA2) has been found to induce EMT via upregulation of HMGA2 in prostate cancer. There has been no link between ROS and HMGA2. We have reported that camalexin, a 3-thizol-2-yl-indole, may be a candidate treatment for aggressive prostate cancer cells by ROS-mediated apoptosis. The study demonstrated that treating the prostate cancer cell with camalexin increased ROS levels which contributed to decreased cell proliferation and increased apoptosis. We hypothesize that HMGA2 may regulate EMT in part by inducing ROS and that camalexin may antagonize HMGA2 signaling. We analysed HMGA2 and EMT marker expression in a panel of prostate cancer cell lines by western blot analysis. We also transiently and stably overexpressed wild-type HMGA2 and mutant HMGA2 (missing Let-7 binding site) in LNCaP cells. We measured ROS levels using DCFDA dye that detects hydrogen peroxide. We treated ARCaP-M (mesenchymal) cells with different concentrations of camalexin to analyse HMGA2 expression. Our results showed that HMGA2 is highly expressed in aggressive prostate cancer cell lines (C4-2, ARCaP, E006AA) as compared to RWPE1 and LNCaP cells. The transient overexpression of HMGA2 in LNCaP cells decreased E-cadherin more markedly than with mutant HMGA2 but did not show any changes in ROS. We will repeat this experiment with stable clones from HMGA2 overexpression. ARCaP-M cells treated with camalexin induced ROS and decreased HMGA2 expression. We are currently performing in vivo studies using ARCaP-M cells injected subcutaneously into nude mice followed by treatment with camalexin after the tumor grows to 50 mm3. In conclusion, HMGA2 promotes EMT, even more markedly if its Let-7 suppressor binding site is eliminated, and camalexin may target HMGA2 to decrease prostate cancer progression. GRANT SUPPORT: 1P20MD002285; 8G12MD007590 Citation Format: Ohuod A. hawsawi, Basil Smith, Jodi Dougan, Liza J. Burton, Valerie A. Odero-Marah. HMGA2 induces EMT in prostate cancer cells and may be antagonized by camalexin. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1595.

Prostate Cancer (PCa) is the second leading cause of cancer death in American men and African Americans are twice as likely to get PCa as their Caucasian counterparts. As with most forms of cancer, PCa patients’ mortality is mainly attributed to complications caused by metastasis of the disease to organs critical for survival such as bone. As such, it is important to understand cancer-bone microenvironment interactions in order to develop therapeutics that will slow or halt the process of cancer metastasis. It is also known that African Americans have a higher bone mineral density compared to any other race. Snail1 is a zinc-finger transcription factor that induces epithelial-mesenchymal transition (EMT) which is associated with cell migration and metastasis in cancer cells. In preliminary studies, cancer cells co-cultured with bovine bone discs led to increased calcium release that was higher in cancer cells overexpressing Snail, as well as in bone discs of higher density. We hypothesized that cancer cell-bone interactions would promote higher calcium release from bone by cancer cells overexpressing Snail, which would lead to increased paracrine cell migration. For this study, we utilized prostate (ARCaP) or breast (MCF-7) cancer cells stably overexpressing Snail as well as prostate (C4-2) cancer cells with stable Snail knockdown. Cancer cells were co-cultured with bovine bone disc or Hydroxyapatite (HA; inorganic component of bone) of different densities to represent the African American vs Caucasian bone ratio. The conditioned media was then used for to assay calcium levels, test paracrine cell viability and migration assays using C4-2 parental cells. We observed that calcium levels were elevated in conditioned media from cancer cell-bone co-cultures, compared to media alone or media plus bone, and this could be antagonized by EGTA, a calcium chelator. It was increased with higher bone density as well as with bone co-cultured with MCF-7-Snail, ARCaP-Snail and C4-2 cancer cells as compared to MCF-7 Neo, ARCaP-Neo or C4-2 with Snail knockdown. When we utilized the conditioned media for a paracrine cell viability assay, there was no significant differences. However, C4-2 cancer-bone co-culture conditioned media increased paracrine cell migration which was decreased by Snail knockdown as well as lower bone density. Hence Snail expressing PCa cells co-cultured with HA led to increased paracrine cell migration. We are currently studying the signaling mechanism(s) involved in this cancer-bone interactions. In conclusion, our study shows that Snail can mediate cancer-bone microenvironment interactions that can possibly promote increased cell migration towards bone of high mineral density such as is found in African Americans. GRANT SUPPORT: 1P20MD002285 Citation Format: Veronica M. Henderson, Liza J. Burton, Simone M. Howard, Valerie A. Odero-Marah. Role of snail in cancer-bone microenvironment interactions. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1692.

Prostate cancer (PCa) is the most frequently diagnosed cancer in men, the second leading cause of male cancer deaths in the U.S, and also presents the greatest racial disparity of any cancer in the U.S. The incidence and mortality of PCa is higher in African-American men (AA), compared to other ethnic groups. The Epithelial Mesenchymal Transition (EMT) is a key event in tumor migration and invasion processes whereby epithelial cells lose polarity together with cell-cell contacts associated with loss of epithelial markers such as E-cadherin and then undergo a dramatic remodeling of the cytoskeleton associated with expression of mesenchymal markers such as vimentin, as well as increased production of extracellular matrix (ECM)-degrading proteases. Snail promotes EMT by using its zinc finger domains to repress epithelial-associated target genes such as E-cadherin and occludin. Cathepsin L (Cat L) is a cysteine protease involved in cell invasion and has recently been associated with poor prognosis in colon and breast cancer when Cat L is localized in the nucleus. CDP/CUX can be proteolytically activated by Cat L from p200 inactive form to p110 and p90 active forms, and subsequently repress E-cadherin and activate Snail by binding to their promoter regions. We recently published that Snail could up-regulate Cat L expression and activity in prostate cancer cells. We hypothesized that nuclear Cat L may promote EMT and prostate cancer progression and that antagonizing Cat L activity would lead to Mesenchymal Epithelial Transition (MET). We stained African American and Caucasian human normal and prostate cancer tissue from the Fox Chase Cancer Center for Snail and Cat L to examine expression. We utilized prostate cancer cell lines and EMT models to analyze EMT markers and Cat L expression by western blot analysis, Q-PCR and immunofluorescence. We also examined Cat L activity using gelatin zymography and subsequently treated mesenchymal cells with 1 µM, 5 µM or 20 µM Z-FY-CHO (Cat L specific inhibitor) for 72 hours. We also performed invasion and migration assays. Staining of human prostate patient tissue revealed that Snail and Cat L levels were lower in normal tissue vs cancer tissue and nuclear localization of Cat L appeared in earlier stages of prostate cancer in African American tissue compared to that of Caucasian cancer tissue. Interestingly, analysis of epithelial (ARCaP-E) and mesenchymal (ARCaP-M or ARCaP-E overexpressing Snail) prostate cancer cells revealed that mesenchymal cells displaying higher Snail expression showed increased Cat L expression and activity, in addition to Cat L being localized in the cytoplasm and nucleus, whereas Cat L was predominantly cytoplasmic in epithelial cells with low Snail expression. Additionally, the African American cell lines (E006-AA and E006-AA ht) displayed high Snail and Cat L expression/activity compared to LNCaP cells. Mesenchymal cells expressed higher p110 and p90 active form of CDP/CUX than epithelial cells that expressed the p200 inactive form. Additionally, Snail overexpression increased p110/90 CDP/CUX in the nuclear fraction of ARCaP-E overexpressing Snail cells. Treatment of mesenchymal cells with Cat L inhibitor, Z-FY-CHO resulted in decreased vimentin and Cat L expression, while E-cadherin increased, suggestive of MET. This was associated with decreased cell migration and invasion. We further observed that treatment with Z-FY-CHO changes the localization of Cat L from nuclear to cytoplasmic. Overall, our novel data suggests that Snail may promote nuclear Cat L that may be associated with proteolytic degradation of CDP/CUX and EMT, and the inhibition of Cat L could play a role in reverting EMT and preventing tumor progression. Citation Format: Liza J. Burton, Jodi Dougan, Valerie Odero-Marah. Nuclear cathepsin L (cat L) is associated with epithelial mesenchymal transition (emt) in prostate cancer cells. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr B93.

Background Maspin, a putative tumor suppressor that is down-regulated in breast and prostate cancer, has been associated with decreased cell motility. Snail transcription factor is a zinc finger protein that is increased in breast cancer and is associated with increased tumor motility and invasion by induction of epithelial-mesenchymal transition (EMT). We investigated the molecular mechanisms by which Snail increases tumor motility and invasion utilizing prostate cancer cells. Methods Expression levels were analyzed by RT-PCR and western blot analyses. Cell motility and invasion assays were performed, while Snail regulation and binding to maspin promoter was analyzed by luciferase reporter and chromatin immunoprecipitation (ChIP) assays. Results Snail protein expression was higher in different prostate cancer cells lines as compared to normal prostate epithelial cells, which correlated inversely with maspin expression. Snail overexpression in 22Rv1 prostate cancer cells inhibited maspin expression and led to increased migration and invasion. Knockdown of Snail in DU145 and C4-2 cancer cells resulted in up-regulation of maspin expression, concomitant with decreased migration. Transfection of Snail into 22Rv1 or LNCaP cells inhibited maspin promoter activity, while stable knockdown of Snail in C4-2 cells increased promoter activity. ChIP analysis showed that Snail is recruited to the maspin promoter in 22Rv1 cells. Conclusions Overall, this is the first report showing that Snail can negatively regulate maspin expression by directly repressing maspin promoter activity, leading to increased cell migration and invasion. Therefore, therapeutic targeting of Snail may be useful to re-induce expression of maspin tumor suppressor and prevent prostate cancer tumor progression.

Loss of PTEN is frequently observed in androgen-independent prostate cancer, resulting in the deregulation of metastatic events. SDF1α activation of CXCR4 induces signaling pathways that have been implicated in prostate metastasis and progression to an advanced disease. The pathways of CXCR4 and PTEN converge, leading to the promotion and regulation of tumorigenesis, respectively. However, loss of PTEN may permit CXCR4 to progress prostate cancer to an advanced disease. In the present study, we investigated the involvement of PTEN in CXCR4-mediated tumorigenesis. When screening advanced metastatic prostate cancer cell lines for PTEN, we observed a loss of expression in PC3 and LNCaP cells whereas Du145 expressed wild-type PTEN. All three cell lines were positive for surface expression of CXCR4. Reconsitution of PTEN induced a mesenchymal to epithelial like morphologic change and inhibited CXCR4-mediated migration and proliferation in PC3 cells. Downregulation of PTEN by siRNA enhanced the CXCR4-mediated migratory behavior of Du145 cells. By Western blot analysis, we observed that PTEN inhibited basal AKT phosphorylation but not ERK1/2 phosphorylation in PTEN-expressing cells. Upon CXCR4 stimulation, PTEN inhibited ERK1/2 phosphorylation but not phosphorylation of AKT. The CXCR4-mediated migration of PC3 cells was through the ERK1/2 pathway, as confirmed by chemical inhibitors. On the basis of these studies, we suggest that loss of PTEN permits CXCR4-mediated functions in prostate cancer cells through the ERK1/2 pathway. Antagonizing CXCR4 and downstream signaling cascades may provide an efficient approach for treating patients with advanced prostate cancer when hormone therapy fails to the stop the growth and containment of tumors. Mol Cancer Res; 9(1); 90–102 ©2010 AACR.

The epithelial-to-mesenchymal transition (EMT) is crucial for the migration and invasion of many epithelial tumors, including prostate cancer. Although it is known that ZEB1 overexpression promotes EMT primarily through down-regulation of E-cadherin in a variety of cancers, the soluble ligands responsible for the activation of ZEB1 have yet to be identified. In the present study, we investigated the role of insulin-like growth factor-I (IGF-I) in the regulation of ZEB1 during EMT associated with prostate tumor cell migration. We found that ZEB1 is expressed in highly aggressive prostate cancer cells and that its expression correlates directly with Gleason grade in human prostate tumors (P < 0.001). IGF-I up-regulates ZEB1 expression in prostate cancer cells exhibiting an epithelial phenotype. In prostate cancer cells displaying a mesenchymal phenotype, ZEB1 inhibition reverses the suppression of E-cadherin protein and down-regulates the expression of the mesenchymal markers N-cadherin and fibronectin. Furthermore, ZEB1 blockade decreases migratory and invasive potential in ARCaPM compared with the control. These results identify ZEB1 as a key transcriptional regulator of EMT in prostate cancer and suggest that the aberrant expression of ZEB1 in prostate cancer cells occurs in part in response to IGF-I stimulation. [Cancer Res 2008;68(7):2479–88]

Androgen refractory cancer of the prostate (ARCaP) cells contain androgen receptor (AR) and synthesize and secrete prostate specific antigen (PSA). We isolated epithelia-like ARCaP(E) from parental ARCaP cells and induced them to undergo epithelial-mesenchymal transition (EMT) by exposing these cells to soluble factors including TGFbeta1 plus EGF, IGF-1, beta2-microglobulin (beta2-m), or a bone microenvironment. The molecular and behavioral characteristics of the resultant ARCaP(M) were characterized extensively in comparison to the parental ARCaP(E) cells. In addition to expressing mesenchymal biomarkers, ARCaP(M) gained 100% incidence of bone metastasis. ARCaP(M) cells express receptor activator of NF-kappaB ligand (RANKL), which was shown to increase tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts in culture, and when metastatic to bone in vivo. We provide evidence that RANKL expression was promoted by increased cell signaling mediated by the activation of Stat3-Snail-LIV-1. RANKL expressed by ARCaP(M) cells is functional both in vitro and in vivo. The lesson we learned from the ARCaP model of EMT is that activation of a specific cell signaling pathway by soluble factors can lead to increased bone turnover, mediated by enhanced RANKL expression by tumor cells, which is implicated in the high incidence of prostate cancer bone colonization. The ARCaP EMT model is highly attractive for developing new therapeutic agents to treat prostate cancer bone metastasis.

Cancer is not a single cell disease and its existence and behavior are constantly modulated by the host. Cancer gene expression and genetics are also highly dynamic and are regulated epigenetically by the host. In this chapter, we describe the molecular pathways leading to an unusual property of cancer cells: the ability to mimic the host microenvironment, and, in particular, the characteristics of osteomimicry and vasculogenic mimicry. We also discuss the importance of host inflammatory and stem cells, which contribute to the growth and survival of cancer cells. By understanding the salient features of cancer-host interaction, novel therapeutics may be developed to target both cancer and host in the treatment of lethal prostate cancer metastases.

Cancer is not a single-cell disease, and its existence and behavior are constantly modulated by the host. Cancer gene expression and genetics are also highly dynamic and are regulated epigenetically by the host through gene-environment interaction. In this article, we describe the molecular pathways leading to an unusual property of cancer cells: the ability to mimic the host microenvironment and, in particular, the characteristics of osteomimicry and vasculogenic mimicry, which are likely to be regulated by soluble and insoluble factors in the tumor-adjacent microenvironment. We also discuss the importance of host inflammatory and stem cells that contribute to the growth and survival of cancer cells. By understanding the salient features of cancer-host interaction, novel therapeutics might be developed to target the cancer and its host in the treatment of lethal prostate cancer metastases.

BACKGROUND The ARCaP cell line was established from the ascites fluid of a patient with metastatic prostate cancer. This study characterized the host microenvironmental role in cancer progression, epithelial to mesenchymal transition (EMT), and bone and adrenal metastasis in parental ARCaP and its derived cell subclones. METHODS Cytogenetic profiles, growth, migration, invasion, cellular interaction, drug sensitivities, and gene expression of ARCaP cell subclones were compared. In vivo gene expression, behavior, and metastasis of ARCaP subclones were analyzed by serial intracardiac injections into SCID mice. RESULTS ARCaPE cells, with cobblestone morphology, underwent EMT through cellular interaction with host bone and adrenal gland. Lineage-derived ARCaPM cells, with spindle-shape fibroblastic morphology, exhibited decreased cell adhesion and increased metastasis to bone and adrenal gland. Cytogenetic analyses of parental and ARCaP subclones confirmed their clonality. CONCLUSIONS ARCaP uniquely models the molecular basis of prostate cancer bone and adrenal metastases and epithelial to mesenchymal transition. Prostate 66: 1664–1673, 2006. © 2006 Wiley-Liss, Inc.

Maspin, a unique serine proteinase inhibitor (serpin), plays a key role in mammary gland development and is silenced during breast cancer progression. Maspin has been shown to inhibit tumor cell motility and invasion in cell culture, as well as growth and metastasis in animal models. In this study, we investigated the effect of maspin on the regulation of hypoxia-induced expression of urokinase-type plasminogen activator (uPA) and its receptor (uPAR), with respect to invasive potential in metastatic breast cells MDA-MB-231. We hypothesized that maspin can neutralize or mitigate hypoxia- induced expression of uPA/uPAR in metastatic breast cancer cells, resulting in suppression of their invasive potential. To test our hypothesis, we employed the highly invasive MDA-MB-231 breast cancer cells that are devoid of maspin, and transfected them with the maspin gene, and then determined the effect of hypoxia on uPA/uPAR expression. Normal mammary epithelial cells 1436N1 were used as a control. Our findings demonstrate that maspin downregulated the basal and hypoxia-induced uPA/uPAR expression and reduced the stimulatory effect of hypoxia on the in vitro invasive ability of MDA-MB-231-cells. In addition, maspin also inhibited the enzymatic activity of secreted and cell associated uPA in MDA-MB-231 cells. These results indicate that maspin inhibits hypoxia-induced invasion of metastatic breast cancer cells by blocking the uPA system, thus illuminating an important molecular pathway for therapeutic consideration.

Death from prostate cancer is usually attributable to the development of bone and visceral organ metastases. The spine, pelvic bones, and ribs are among the most frequent sites of prostate cancer bone metastases. The peripheral skeleton and skull are less frequent sites (1,2). There are two hypotheses for the preferential homing of prostate cancer cells to bone. The first is that the mechanical hemodynamics of blood flow from prostate to bone favor the spread of prostate cancer cells to specific anatomical sites (3). A second theory holds that prostate cancer cells have a specific affinity to bone, which attracts and colonizes prostate cancer cells in a relationship like the “seed” (cancer cell) and “soil” (bone microenvironment) hypothesis originally proposed by Paget (4). Understanding the molecular mechanism underlying prostate cancer tropism to bone and the evolutionary process leading to androgen independence and invasiveness will allow us to develop better therapies for the management of prostate cancer bone metastasis.

Prostate cancer (PCa) is the most frequently diagnosed cancer in men, the second leading cause of male cancer deaths in the U.S, and also presents the greatest racial disparity of any cancer in the U.S. The incidence and mortality of PCa is higher in African-American men (AA), compared to other ethnic groups. Snail transcription factor expression is increased in prostate cancer and associated with epithelial-mesenchymal transition (EMT), whereby epithelial cancer cells expressing epithelial markers such as E-cadherin transition into spindle-shaped mesenchymal cells expressing markers such as vimentin. Snail can turn on proteases like MMP-9 to increase degradation of basement membrane and extracellular matrix proteins prior to cancer cell invasion and migration. We have preliminary data showing that muscadine grape skin extract (MSKE), derived from muscadine grape (Vitis rotundifolia), a common red grape used to produce red wine can decrease Snail expression in prostate cancer cells. Cathepsin L is a cysteine cathepsin that is overexpressed in prostate cancer and involved in the repression of E-cadherin, a hallmark of EMT. We investigated whether there could be a link between Snail and Cathepsin L. We hypothesize that the Snail expression may be increased in African American tissue as compared to other races and that Snail can induce the increased activity of Cathepsin L which can be antagonized by MSKE. Initially, we examined the expression of Snail and Cathepsin L in prostate cancer cells by Western blot analysis and Cathepsin L Activity via Zymography. The cell lines utilized in this study are LNCaP, C4-2 (the aggressive subline of LNCaP), mesenchymal ARCaP (ARCaP-M) and epithelial ARCaP (ARCaP-E). Preliminary results suggest that Snail expression and Cathepsin L activity is high in prostate cancer cells compared to normal prostate epithelial cells. We also obtained human prostate cancer tissue from the Bahamas which we are currently staining for Snail and Cathepsin L, to compare to staining from tissue microarrays. We have observed so far that there is both Snail and Cathepsin L expression in the tissue samples. We then utilitized LNCaP and ARCaP-E prostate cancer cells stably transfected with an empty Neo vector (LNCaP Neo; ARCaP Neo) or constituitively active Snail cDNA (LNCaP Snail; ARCaP Snail) that have been shown previously to represent an EMT model, to examine Cathepsin L and Stat-3 activity. We observed that Snail overexpression led to increased Cathepsin L and Stat-3 activity compared to cells with the Neo vector. Additionally ARCaP-E cells overexpresing Snail, C4-2, or ARCaP-M cells treated with MSKE (5ug/mL and 20ug/mL) for a period of 72hrs led to decreased Cathepsin L and Stat-3 activity. Furthermore, MSKE reverted EMT as shown by increased E-cadherein expression, decreased vimentin expression and decrease in cell migration. Taken together, these findings suggest that Snail my increase Cathepsin L activity via the Stat-3 signaling pathway in prostate cancer cells and MSKE could potentially be a promising bioactive compound for human cancer prevention and therapy. Citation Format: Liza Burton, Peri Nappagan, Basil Smith, Manu Platt, Camille Ragin, Valerie Odero-Marah. Snail transcription factor can regulate cathepsin L activity in prostate carcinomas. [abstract]. In: Proceedings of the Sixth AACR Conference: The Science of Cancer Health Disparities; Dec 6–9, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2014;23(11 Suppl):Abstract nr C57. doi:10.1158/1538-7755.DISP13-C57

Prostate cancer that is hormone refractory and has metastasized preferentially to bone is the main cause of prostate cancer death, especially in African American men. Receptor activator of nuclear factor kappa B ligand (RANKL) and its receptor (RANK) contributes to bone metastatic lesions and bisphosphonates such as Zometa and Fosamax have been used as antagonists of RANKL for the treatment of breast and prostate cancer metastasis. African American men have the highest bone mineral density compared to any other race, and the role this may play in prostate cancer metastasis to bone is not clear. A better understanding of bone metastasis may lead to alternative treatment options for metastatic prostate cancer. Snail transcription factor is important early in development and in cancer cells and promotes cancer cell migration and progression by inducing epithelial mesenchymal transition (EMT). We have observed increased expression of Snail in prostate cancer bone metastatic human patient samples. We hypothesized that Snail can mediate EMT-mediated prostate cancer migration towards bone of high bone mineral density and mediate the vicious cycle of tumor-tumor microenvironment reciprocal interactions through calcium and RANKL signaling. We generated an EMT model for prostate and breast cancer utilizing the ARCaP human prostate and MCF-7 breast cancer cells overexpressing Snail and identified increased RANKL expression that was associated with increased osteoclastogenesis both in vitro and in vivo, as well as decreased bone volume and density. We utilized pre-molded bone discs which are allograft bone/polyurethane (PUR) composite bone void fillers with tunable properties that have advantage over existing bone implant models in that it contains bigger pore sizes that support rapid cellular infiltration and remodeling. We treated the bone discs with hydrochloric acid which decreased the bone density to a ratio of 1:1.18 for low (HCL-treated): high (untreated) bone density, which is quite close to the 1: 1.2 ratio seen in Caucasian vs African American men. Incubation of these bone discs with prostate or breast cancer cells overexpressing Snail led to increased calcium release from bone of high density as compared to low density. We are currently testing whether this increased calcium release in response to Snail may promote paracrine cell proliferation. Since Snail is not required by adult cells except during injury, targeting Snail that is mainly expressed by cancer cells may antagonize metastatic lesions in bone without affecting normal bone in other areas of the body. Citation Format: Basil A. Smith, Veronica Henderson, Christopher Coke, Jerald Dumas, Cimona Hinton, Manu Platt, Leland K. Chung, Majd Zayzafoon, Valerie A. Odero-Marah. Snail transcription factor contributes to bone metastasis in prostate and breast cancer cells. [abstract]. In: Proceedings of the Sixth AACR Conference: The Science of Cancer Health Disparities; Dec 6–9, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2014;23(11 Suppl):Abstract nr C60. doi:10.1158/1538-7755.DISP13-C60

Snail transcription factor and MAPK/ERK signaling regulate EMT and chemotherapy resistance in various tumor models by binding to target promoters (i.e., E-cadherin, maspin, ER-α). ERK1 is expressed during embryogenesis and in non-metastatic cells; ERK2 is implicated during vasculogenesis and promotes stem cell phenotype in triple negative breast cancer. Nuclear-localized ERK is associated with more active and potentially metastatic breast and ovarian carcinoma cells; cytoplasmic-localized ERK is a good prognostic factor. The role that Snail plays during the transition from cytoplasmic ERK1 to nuclear ERK2 has not been investigated. We hypothesized that both nuclear Snail and ERK2 are required for breast cancer cells to become resistant to 4-hydroxytamoxifen (4-OHT). We utilized MCF-7 breast adenocarcinoma cells, MCF-7 transfected stably with empty Neo vector control (MCF-7 Neo) or constitutively active Snail cDNA (MCF-7 Snail). MCF-7 Neo and MCF-7 Snail have previously represented a breast cancer EMT model; we used this model to analyze ERK signaling and therapy response. Preliminary data suggest that MCF-7 Neo express higher levels of p-ERK, ER-α, and E-cadherin and no Snail. MCF-7 Snail expressed higher levels of Snail and vimentin, low levels of p-ERK, and low ER-α and no E-cadherin. MCF-7 Neo expressed higher ERK1 and MCF-7 Snail expressed higher ERK2. Immunocytochemistry indicated that p-ERK was nuclear and cytoplasmic in MCF-7 Neo, but mostly nuclear in MCF-7 Snail. We treated MCF-7 Neo and MCF-7 Snail with control siRNA, ERK1 siRNA, or ERK2 siRNA, then determined the expression of Snail, p-ERK1/2, ERK1/2, E-cadherin, and ER-α. We found that ERK1 siRNA decreased E-cadherin, while ERK2 siRNA increased E-cadherin in MCF-7 Neo. ERK2 siRNA decreased Snail, but ERK1 siRNA had no effect on Snail. ERK1 siRNA increased active ERK2 and ERK2 siRNA increased ERK1 in MCF-7 Neo and MCF-7 Snail. To determine the role that Snail plays in resistance, we treated MCF-7 Neo and MCF-7 Snail with 4-OHT and/or UO126 then mitochondrial permeability and caspase-3/7 activity assays. MCF-7 Neo had higher mitochondrial permeability than MCF-7 Snail, indicative of the dimmer staining using TMRM stain, and MCF-7 Neo had higher caspase-3/7 activity after treatments. Overall, cell death in MCF-7 Snail was caspase-independent. These data imply that Snail and ERK2 collaborate through an unknown mechanism to promote EMT and therapy resistance in breast cancer cells. Targeting Snail and/or ERK2 in advanced breast cancer may be a potential therapeutic or preventive strategy. Citation Format: Bethany N. Smith, Peri Nagappan, Latonia Taliaferro-Smith, Roman Mezencev, Clayton Yates, Cimona Hinton, Valerie Odero-Marah. Snail- and ERK2-dependent signaling enhances breast cancer cell resistance to hydroxytamoxifen. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1131. doi:10.1158/1538-7445.AM2014-1131

Background Snail transcription factor can induce epithelial-mesenchymal transition (EMT), associated with decreased cell adhesion-associated molecules like E-cadherin, increased mesenchymal markers like vimentin, leading to increased motility, invasion and metastasis. Muscadine grape skin extract (MSKE) has been shown to inhibit prostate cancer cell growth and induce apoptosis without affecting normal prostate epithelial cells. We investigated novel molecular mechanisms by which Snail promotes EMT in prostate cancer cells via Reactive Oxygen Species (ROS) and whether it can be antagonized by MSKE. Methods ARCaP and LNCaP cells overexpressing Snail were utilized to examine levels of reactive oxygen species (ROS), specifically, superoxide, in vitro using Dihydroethidium (DHE) or HydroCy3 dyes. Mitosox staining was performed to determine whether the source of ROS was mitochondrial in origin. We also investigated the effect of Muscadine grape skin extract (MSKE) on EMT marker expression by western blot analysis. Migration and cell viability using MTS proliferation assay was performed following MSKE treatments. Results Snail overexpression in ARCaP and LNCaP cells was associated with increased concentration of mitochondrial superoxide, in vitro. Interestingly, MSKE decreased superoxide levels in ARCaP and LNCaP cells. Additionally, MSKE and Superoxide Dismutase (SOD) reverted EMT as evidenced by decreased vimentin levels and re-induction of E-cadherin expression in ARCaP-Snail cells after 3 days, concomitant with reduced cell migration. MSKE also decreased Stat-3 activity in ARCaP-Snail cells. Conclusions This study shows that superoxide species may play a role in Snail transcription factor-mediated EMT. Therefore, therapeutic targeting of Snail with various antioxidants such as MSKE may prove beneficial in abrogating EMT and ROS-mediated tumor progression in human prostate cancer.

Snail is a zinc finger transcriptional repressor that induces epithelial-mesenchymal transitions (EMT) and is expressed at high levels in tumors. Snail contributes to chemotherapy resistance in ovarian, liver, colorectal, and breast carcinomas by activating the MAPK/ERK1/2 (ERK1/2) pathway . ERK1/2 controls cell proliferation, survival, migration, and adhesion. However, a role for MAPK in Snail-mediated EMT in breast cancer is unclear. We hypothesized that Snail promotes EMT by decreasing cell adhesion and increasing cell migration through the MAPK pathway, resulting inresistance to Tamoxifen chemotherapy. Preliminary results suggest that breast cancer cells express variable levels of Snail that is higher than in normal MCF10A cells. We utilized MCF-7 breast adenocarcinoma cells transfected stably with empty Neo vector control (MCF-7 Neo) or constitutively active Snail cDNA (MCF-7 Snail). MCF-7 Neo and MCF-7 Snail have previously represented a breast cancer EMT model; we used this model to examine cell adhesion and cell migration. We injected these cells into female nude mice to examine tumor size. We also examined activation of MAPK pathway using phospo-ERK (p-ERK) antibodies in response to Snail overexpression and the effect of inhibiting this pathway with UO126 (MEK inhibitor, 20uM). Finally, we tested how Snail overexpression affects response to UO126 and/or Tamoxifen treatments using MTS cell proliferation assay. Our results showed that Snail overexpression led to decreased cell adhesion and increased cell migration on collagen and fibronectin in vitro, and increased tumorigenicity in vivo. Interestingly, immunofluorescent analysis revealed that activated ERK1/2 (p-ERK) had cytoplasmic localization in MCF-7 Neo, and exclusive nuclear localization in MCF-7 Snail. Inhibition of activated ERK1/2 with UO126 antagonized cell adhesion primarily in MCF-7 Neo cells, while it decreased cell migration primarily in MCF-7 Snail cells. This would suggest that cytoplasmic p-ERK may be important for cell adhesion while nuclear p-ERK may be important for cell migration. MCF-7 Neo proliferation was consistently higher than MCF-7 Snail indicating that Snail may not play a significant role in cell proliferation, but other EMT functions like migration and adhesion. Tamoxifen treatment did not affect MCF-7 Snail cells morphologically, but led to sickly-appearing MCF-7 Neo cells. Additionally, MCF-7 Snail cells treated with Tamoxifen proliferated at similar rates to control untreated cells but co-treatment with UO126 greatly inhibited cell proliferation. This suggests that antagonizing nuclear p-ERK may sensitize breast cancer cells to Tamoxifen therapy. In conclusion, our study shows that Snail activation of MAPK pathway specifically within the nucleus promotes resistance to Tamoxifen and future ERK1/2 inhibition within the nucleus may sensitize cells to chemotherapy. Citation Format: Bethany N. Smith, Peri Nagappan, Mahandranauth Chetram, LaTonia Taliaferro-Smith, Clayton Yates, Cimona Hinton, Valerie Odero-Marah. Snail activation of MAPK pathway may contributes to tumor insensitivity to tamoxifen chemotherapy in breast cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1485. doi:10.1158/1538-7445.AM2013-1485

Snail (Snail1) is a zinc finger transcription factor that can induce EMT and is expressed at high levels in tumors. Maspin is a potential tumor suppressor, whose expression is lost as breast and prostate tumors progress during EMT. Maspin can be transcriptionally repressed by androgen receptor (AR) in prostate cancer cells. We hypothesized that overexpression of Snail will inhibit maspin expression and confer resistance to chemotherapy. Initially, we examined the expression of Snail and maspin in a panel of breast epithelial and breast cancer cells by RT-PCR and Western blot analysis. Preliminary results suggest that breast cancer cells express variable levels of Snail that is higher in breast cancer cells than in the normal MCF10A cells. We then utilized MCF-7 cells transfected stably with an empty Neo vector (MCF-7 Neo) or constitutively active Snail cDNA (MCF-7 Snail) that have been shown previously to represent an EMT model, and examined maspin, estrogen receptor alpha (ER-α) and AR levels by western blot analysis. MCF-7 Snail cells had upregulated levels of Snail and lower levels of maspin, ER-α and AR, as compared to MCF-7 Neo. MCF-7 Neo and MCF-7 Snail cells were also xenografted into nude mice and tissue sections stained immunohistochemically for Snail, maspin, and ER-α. Tumor volumes of MCF-7 Snail tumor xenografts were significantly larger than the MCF-7 Neo xenografts. MCF-7 Snail tissue sections expressed higher levels of Snail and lower levels of maspin and ER-α as compared to MCF-7 Neo sections. MCF-7 Neo and MCF-7 Snail cells were also treated with estradiol (E2, 0.01uM), tamoxifen (TAM, 10uM), and docetaxel (DOX, 1uM) individually; and in combination with E2 plus TAM and TAM plus DOX for periods of 24h and 72h to analyze changes in cell morphology and EMT marker expression. No effect on cell morphology or cell death was observed in MCF-7 Snail cells after TAM treatments, whereas TAM induced cell death in MCF-7 Neo. Expression of Snail was increased with E2 treatments and decreased with TAM, DOX, and combination treatments in MCF-7 Neo and MCF-7 Snail. AR expression decreased further in MCF-7 Snail cells and MCF-7 Neo following treatments with TAM and DOX. Overall, the Snail overexpression appears to promote resistance to TAM and DOX chemotherapeutic agents. The mechanism of Snail-regulated EMT needs to be investigated further to determine changes in breast cancer progression. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5747. doi:1538-7445.AM2012-5747

Snail transcription factor induces epithelial-mesenchymal transition (EMT) via decreased cell adhesion-associated molecules like E-cadherin, and increased mesenchymal markers like vimentin. We previously established Snail-mediated EMT model utilizing androgen-dependent LNCaP cells. These cells express increased vimentin protein and relocalization of E-cadherin from the cell membrane to the cytosol. Interestingly, Snail transfection in LNCaP cells resulted in cells acquiring a neuroendocrine-like morphology with long neurite-like processes. We tested for expression of neuroendocrine markers neuron specific enolase (NSE) and chromogranin A (CgA) by Western blot analysis, and performed proliferation assays to test for paracrine cell proliferation. LNCaP cells transfected with Snail displayed increase in the neuroendocrine markers, NSE and CgA as well as translocation of androgen receptor to the nucleus. We found that LNCaP C-33 cells that have been previously published as a Neuroendocrine Differentiation (NED) model exhibited increased expression levels of Snail protein as compared to LNCaP parental cells. Functionally, conditioned medium from the LNCaP-Snail transfected cells increased proliferation of parental LNCaP and PC-3 cells. In addition, NED in LNCaP-C33 cells or that induced in parental LNCaP cells by serum starvation could be inhibited by knockdown of Snail with siRNA. Knockdown of NSE and CgA with siRNA abrogated Snail induced paracrine cell proliferation in parental LNCaP and PC3 cells. Immunohistochemical staining of prostate cancer patient tissue revealed increased expression of Snail with prostate cancer progression and bone metastasis. Higher Snail staining was observed in primary prostate cancer tissue containing a neuroendocrine component (identified by CgA staining) as compared to primary cancer with no neuroendocrine differentiation. However, in metastatic tissue, Snail was highly expressed in both neuroendocrine and non-neuroendocrine cancer tissue. Overall our data provide evidence that Snail transcription factor may promote tumor aggressiveness in the prostate cancer cells through multiple processes; induction of EMT may be required to promote migration, while NED may promote tumor proliferation by a paracrine mechanism. Therefore, therapeutic targeting of Snail may prove beneficial in not only abrogating EMT but also NED. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3415. doi:10.1158/1538-7445.AM2011-3415

PURPOSE: The purpose of the study is to determine the role of Snail transcription factor on cellular adhesion to fibronectin and collagen, in human prostate cancer cells. Adhesion of cells to one another or the extracellular matrix (ECM) is responsible for normal and abnormal cellular activity, such as cell migration, invasion, metastasis of tumor cells, and angiogenesis. Snail transcription factor induces epithelial-mesenchymal transition (EMT) in which epithelial cells loose expression of specific genes and acquire traits of mesenchymal genes. We hypothesized that Snail will lead to decreased cellular adhesion to fibronectin and collagen matrix, concomitant with increased cell migration. DESIGN METHODS: We stably overexpressed Snail in LNCaP (LNCaP-Snail) and ARCaP (ARCaP-Snail) prostate cancer cells, or stably knocked down Snail in C4-2 and ARCaP-Snail cells using shRNA. We performed cell adhesion and migration assays on fibronectin and collagen I matrices using these cell models. Flow cytometry was also used for integrin expression analysis. RESULTS: We found that ARCaP prostate cancer cells transfected with Snail displayed decreased adhesion to fibronectin and collagen I, which was reversed by Snail knockdown. Additionally we have seen a decrease in the expression of the α5 and α2 integrin among ARCaP cell lines over expressing Snail, concomitant with an increased migration in cell lines overexpressing Snail. CONCLUSION: We have shown that Snail decreases cell adhesion to fibronectin and collagen, and inversely increases cell migration. These studies define a new role for Snail transcription factor that may be crucial for cell detachment and subsequent metastasis. Supported by grants P20MD002285-01 & G12RR003062-22 Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1550. doi:10.1158/1538-7445.AM2011-1550

Purpose: The purpose of the study is to determine the role of Snail transcription factor on cellular adhesion to fibronectin and collagen, in human prostate cancer cells. Background: Cell adhesion plays an integral role in cell communication and regulation, subsequently it is of fundamental importance in the development and maintenance of tissue architecture. The adhesion process is involved in stimulating signals that regulate cellular differentiation, cell cycle, and cell survival. Adhesion of cells to one another or to the extracellular matrix (ECM) is responsible for a wide array of normal and abnormal cellular activity, such as a cell migration, invasion, metastasis of tumor cells, and angiogenesis. Integrins are receptor proteins that play an important role in cellular signaling and can bind a wide range of ligands for example vitronectin, collagen, fibronectin and laminin. Proteins such as Src, Erk and FAK play a crucial role in cell signaling and can be activated by integrins leading to activation of cellular pathways inside the cell. Snail transcription factor induces epithelial-mesenchymal transition (EMT) in which the epithelial cells loose their expression of specific genes, such as E-Cadherin, that codes for cell-to-cell adhesion and acquire traits of loosely associated mesenchymal genes, such as vimentin expression leading to increased invasion and migration. In order for cancer cells to metastasize, they must first detach from their extracellular matrix. Very little is known about the role of Snail in cellular adhesion. We hypothesized that Snail will lead to decreased cellular adhesion to fibronectin and collagen matrix, concomitant with increased cell migration. Methods: We stably overexpressed Snail in androgen dependent LNCaP (LNCaP-Snail) and androgen independent ArCaP (ARCaP-Snail) prostate cancer cells using lipofectamine 2000, or stably knocked down Snail in androgen-independent C4-2 and ARCaP-Snail cells using shRNA. We performed cell adhesion and migration assays on fibronectin and collagen I matrices using these cell models, and also performed RT-PCR to evaluate expression of fibronectin and collagen. Results: We found that ARCaP prostate cancer cells transfected with Snail displayed decreased adhesion to fibronectin and collagen I, which was reversed by Snail knockdown. Additionally we have seen a decrease in expression of fibronectin and collagen I in the cells lines over expressing Snail by RT-PCR, concomitant with increased migration on collagen. Conclusion: We have shown that Snail decreases cell adhesion to fibronectin and collagen, and inversely increases cell migration. Additionally, Snail leads to decreased expression of fibronectin and collagen mRNA. These studies define a new role for Snail transcription factor in cell adhesion to specific matrices like fibronectin and collagen that may be crucial for cell detachment and subsequent metastasis. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3916.

Abstract #3054 Introduction: Approximately 60-80% of breast tumors are positive for androgen receptor (AR) and negative for estrogen receptor (ER) and progesterone (PR) (Isola et al. J Pathol. 1993). This suggests that AR may function independently of ER and PR to cross-talk with other factors such as Zinc-finger enhancer binding protein (ZEB1). ZEB1 is a transcription factor involved in the progression of breast cancer primarily through promoting epithelial to mesenchymal transition (EMT). ZEB1 represses the expression of E-cadherin by binding to E-box sequences in the promoter, thus decreasing epithelial differentiation and promotes cell migration. Methods: We established a stable control and ZEB1 knockdown using shRNA in MDA-MB-231 cells, a highly metastatic triple negative breast cancer cell line with mesechymal morphology. The stable cell lines were characterized by immunoblot and RT-PCR analysis and were stimulated with synthetic androgens or an androgen antagonist and cell growth and migration were monitored. Results: ZEB1 regulated the expression of AR in triple breast cancer cell lines. AR promoter contains two E-boxes, which may be critical to the transcriptional regulation of this gene. ZEB1 suppression by stably transfecting shRNA in MDA-MB-231 cells resulted in a decrease of AR mRNA, protein and AR downstream targets. In addition, ZEB1 suppression reduced the protein expression of Cyclin D1 and decreased cell proliferation. Conversely, blockade of AR signaling with bicalutamide resulted in suppression of ZEB1 protein expression in two triple negative breast cancer cell lines. ZEB1 knockdown in MDA-MB-231 cells sensitized the cells to bicalutamide by inducing a greater amount of cell death and a reduction in migration compared to the control cells. Conclusions: Taken together, these results indicate that ZEB1 and AR regulate each other to promote cell growth and cell migration in triple negative breast cancer cells. Inhibition of AR signaling could decrease cell proliferation via ZEB1 in a subset of triple negative breast cancers. The growth of triple negative breast cancers that express ZEB1 and AR could be inhibited by antiandrogen treatment. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3054.