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Supplementary Table S1 and Fig S1 and S2. Supplementary Table 1: qPCR primers used in this study; Supplementary Figure S1: Structures of compounds screened in Figure 1A and 1B; Supplementary Figure S2: Proximity ligation assay (PLA) analyzing SIN3A-MAD interactions

Supplementary Table S2. List of genes with expression regulated by selamectin treatment

Triple-negative breast cancers (TNBC) lacking estrogen, progesterone, and HER2 receptors account for 10% to 20% of breast cancer and are indicative of poor prognosis. The development of effective treatment strategies therefore represents a pressing unmet clinical need. We previously identified a molecularly targeted approach to target aberrant epigenetics of TNBC using a peptide corresponding to the SIN3 interaction domain (SID) of MAD. SID peptide selectively blocked binding of SID-containing proteins to the paired α-helix (PAH2) domain of SIN3, resulting in epigenetic and transcriptional modulation of genes associated with epithelial–mesenchymal transition (EMT). To find small molecule inhibitor (SMI) mimetics of SID peptide, we performed an in silico screen for PAH2 domain–binding compounds. This led to the identification of the avermectin macrocyclic lactone derivatives selamectin and ivermectin (Mectizan) as candidate compounds. Both selamectin and ivermectin phenocopied the effects of SID peptide to block SIN3–PAH2 interaction with MAD, induce expression of CDH1 and ESR1, and restore tamoxifen sensitivity in MDA-MB-231 human and MMTV-Myc mouse TNBC cells in vitro. Treatment with selamectin or ivermectin led to transcriptional modulation of genes associated with EMT and maintenance of a cancer stem cell phenotype in TNBC cells. This resulted in impairment of clonogenic self-renewal in vitro and inhibition of tumor growth and metastasis in vivo. Underlining the potential of avermectins in TNBC, pathway analysis revealed that selamectin also modulated the expression of therapeutically targetable genes. Consistent with this, an unbiased drug screen in TNBC cells identified selamectin-induced sensitization to a number of drugs, including those targeting modulated genes. Mol Cancer Ther; 14(8); 1824–36. ©2015 AACR.

Supplementary Table S3. Ingenuity Canonical Pathways modulated by selamectin treatment

// Yeon-Jin Kwon 1 , Boris A. Leibovitch 1 , Nidhi Bansal 1 , Lutecia Pereira 2 , Chi-Yeh Chung 1 , Edgardo V. Ariztia 1 , Arthur Zelent 2 , Eduardo F. Farias 1 and Samuel Waxman 1 1 Icahn School of Medicine at Mount Sinai, The Tisch Cancer Institute, New York, NY, USA 2 University of Miami, Sylvester Comprehensive Cancer Center, Florida MI, USA Correspondence to: Samuel Waxman, email: samuel.waxman@mssm.edu Eduardo F. Farias, email: eduardo.farias@mssm.edu Keywords: triple negative breast cancer, invasion, SIN3A, TGIF1, Wnt, metastasis Received: May 20, 2016 Accepted: July 23, 2016 Published: August 19, 2016 ABSTRACT Cancer cell invasion is an obligatory step for metastatic dissemination that contributes to rapid relapse and a poorer survival in triple negative breast cancer (TNBC) patients. Development of novel therapeutic strategies to block tumor invasion is an unmet need in the treatment of cancer. We reported that the selective inhibition of the PAH2 domain of SIN3A protein function markedly suppressed metastatic dissemination to the lungs in TNBC xenograft bearing mice. Here, we show that TNBC cell lines treated with Sin3 interaction domain (SID) decoy peptides that bind to PAH2 display a strong in vitro inhibition of transwell invasion. This is accompanied by actin cytoskeleton reorganization with increased cortical actin deposition and downregulation of known Wnt target genes that are associated with epithelial to mesenchymal transition (EMT) and cancer cell invasion. Wnt pathway inhibition by SID decoy peptide was confirmed by decreased Wnt reporter activity and altered cytoplasmic localization of nuclear β-catenin. TGIF1, a transcription factor that modulates Wnt signaling and known to interact with the PAH2 domain of SIN3A, can be dissociated from the SIN3A complex by SID decoys. TGIF1 knockdown inhibits WNT target genes and in vitro cell invasion suggesting that TGIF1 might be a key target of the SID decoys to block tumor invasion. Taken together, targeting SIN3 function using SID decoys is a novel strategy to reverse invasion and the EMT program in TNBC translating into the inhibition of metastasis dissemination and eradication of residual disease.

We have previously shown that lysophosphatidic acid (LPA) promotes the ovarian cancer metastatic cascade. In this study, we evaluated the role of LPA on endometrial cancer invasion.Transient mRNA knockdown was accomplished using pre-designed siRNA duplexes against LPA receptor 2 (LPA2) and human matrix metalloproteinase-7 (MMP-7). RT-PCR was used to characterize LPA receptor and MMP-7 expression. Analysis of in vitro invasion was performed with rat-tail collagen type I coated Boyden chambers. Gelatin zymography was used to evaluate the MMP activity in cell culture conditioned media. Cell-cell and cell-matrix attachment was also assessed upon LPA2 knockdown to further illuminate the LPA2 cascade.LPA increases HEC1A cellular invasion at physiologic concentrations (0.1-1 muM). Of the four principle LPA receptors, LPA2 is predominantly expressed by HEC1A cells. Transient transfection of LPA2 siRNA reduced LPA2 mRNA expression in HEC1A cells by 93% (P0.01). Silencing LPA2 eliminated the LPA-stimulated increase in invasion (P0.05) and reduced LPA-induced MMP-7 secretion/activation, without significantly affecting cell-cell or cell-matrix adhesion. Silencing MMP-7 reduced overall invasion but did not eliminate LPA's pro-invasive effect on HEC1A cells, as compared to negative control (P0.05). Gelatin zymography confirmed that LPA2 and MMP-7 knockdown reduced MMP-7 activation in HEC1A conditioned media.LPA2 mediates LPA-stimulated HEC1A invasion and the subsequent activation of MMP-7.

Objectives. To evaluate the role of LPA in regulating E-cadherin cell surface expression, adhesion, and invasion in epithelial ovarian carcinoma (EOC) cells. Methods. E-cadherin mRNA expression in OVCA429 and IOSE-29 cells was evaluated by real-time RT-PCR. Immunofluorescence and Western blot analysis were performed to determine cell surface expression and shedding of E-cadherin 80-kDa soluble fragment by LPA. Kinetics of LPA-induced uPA activity was followed with a colorimetric enzymatic assay. Invasion assays were performed in a modified Boyden chamber where cells were allowed to migrate to the bottom compartment through a porous filter coated with collagen. Additionally we measured the 80-kDa form from the ascites of women with stage III/IV EOC. Results. LPA induces E-cadherin shedding of a soluble 80-kDa fragment. We found that this process is mediated by the uPA proteolytic cascade. High levels of soluble E-cadherin were found in the ascites from women with advanced stage EOC. LPA and a soluble recombinant E-cadherin-Fc chimera promotes invasion of OVCA429 cells. Conclusions. LPA induces shedding of an 80-kDa E-cadherin-soluble fragment in an uPA-dependent manner and promotes in vitro invasion. High levels of soluble E-cadherin in malignant ascites may also affect ovarian metastasis.

// Nidhi Bansal 1 , Kevin Petrie 2 , Rossitza Christova 2,* , Chi-Yeh Chung 3,* , Boris A. Leibovitch 1 , Louise Howell 2 , Veronica Gil 2 , Yordan Sbirkov 2 , EunJee Lee 4 , Joanna Wexler 1 , Edgardo V. Ariztia 1 , Rajal Sharma 1 , Jun Zhu 4 , Emily Bernstein 5 , Ming-Ming Zhou 1 , Arthur Zelent 6 , Eduardo Farias 1 and Samuel Waxman 1 1 Division of Hematology and Oncology, The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, USA 2 Division of Clinical Studies, Institute of Cancer Research, Sutton, United Kingdom 3 Department of Oncological Sciences, Department of Genetics and Genomic Sciences, Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, USA 4 Genetics and Genomic Science, Icahn School of Medicine at Mount Sinai, New York, USA 5 Department of Oncological Sciences, Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, USA 6 Division of Hemato-Oncology, Department of Medicine, Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Florida, USA * These authors have contributed equally to this work Correspondence to: Samuel Waxman, email: // Keywords : epigenetics, SIN3, PF1, triple negative breast cancer, cancer stem cells Received : July 17, 2015 Accepted : September 24, 2015 Published : October 09, 2015 Abstract Triple negative breast cancer (TNBC) is characterized by a poorly differentiated phenotype and limited treatment options. Aberrant epigenetics in this subtype represent a potential therapeutic opportunity, but a better understanding of the mechanisms contributing to the TNBC pathogenesis is required. The SIN3 molecular scaffold performs a critical role in multiple cellular processes, including epigenetic regulation, and has been identified as a potential therapeutic target. Using a competitive peptide corresponding to the SIN3 interaction domain of MAD (Tat-SID), we investigated the functional consequences of selectively blocking the paired amphipathic α-helix (PAH2) domain of SIN3. Here, we report the identification of the SID-containing adaptor PF1 as a factor required for maintenance of the TNBC stem cell phenotype and epithelial-to-mesenchymal transition (EMT). Tat-SID peptide blocked the interaction between SIN3A and PF1, leading to epigenetic modulation and transcriptional downregulation of TNBC stem cell and EMT markers. Importantly, Tat-SID treatment also led to a reduction in primary tumor growth and disseminated metastatic disease in vivo . In support of these findings, knockdown of PF1 expression phenocopied treatment with Tat-SID both in vitro and in vivo . These results demonstrate a critical role for a complex containing SIN3A and PF1 in TNBC and provide a rational for its therapeutic targeting.

Malignant ovarian ascites are rich in cellular components, membrane-bound vesicles, and soluble proteins. This study focused on the structure of membrane-bound vesicles and their ability to promote invasion in cultured malignant ovarian epithelium. Membrane vesicles were derived from women with stage I–IV malignant ovarian ascites and from nonmalignant gynecologic ascites. Isolated vesicles were characterized by immunofluorescence and Western blot analysis. Using gel zymography for matrix metalloproteinase (MMP) detection and a colorimetric assay for urokinase-type plasminogen activator (uPA) analysis, we analyzed the proteinase activities of MMP-2, MMP-9, and uPA from the prepared vesicles, whole cells isolated from ascites, and the cell-free ultracentrifuged supernatant. The invasiveness of established cultured malignant ovarian epithelium on addition of ascites-derived vesicles was tested using a Matrigel-based invasion assay. Fractionation of malignant ascites revealed that extracellular matrix-degrading proteinases including MMPs and uPA are localized preferentially in membrane vesicles. All malignant vesicles tested, regardless of cancer stage, stimulated invasion. Furthermore, the combination of ovarian cancer cells and membrane vesicles resulted in greater uPA activation than that of cells or vesicles alone. Membrane vesicles from malignant ascites were also found to contain activated MMP-2, MMP-9, and uPA. Our data suggest that vesicle-stimulated proteinase activation leads to increased extracellular matrix degradation, which may facilitate tumor cell invasion and metastasis.

Triple-negative breast cancers (TNBC) lacking estrogen, progesterone, and HER2 receptors account for 10% to 20% of breast cancer and are indicative of poor prognosis. The development of effective treatment strategies therefore represents a pressing unmet clinical need. We previously identified a molecularly targeted approach to target aberrant epigenetics of TNBC using a peptide corresponding to the SIN3 interaction domain (SID) of MAD. SID peptide selectively blocked binding of SID-containing proteins to the paired α-helix (PAH2) domain of SIN3, resulting in epigenetic and transcriptional modulation of genes associated with epithelial–mesenchymal transition (EMT). To find small molecule inhibitor (SMI) mimetics of SID peptide, we performed an in silico screen for PAH2 domain–binding compounds. This led to the identification of the avermectin macrocyclic lactone derivatives selamectin and ivermectin (Mectizan) as candidate compounds. Both selamectin and ivermectin phenocopied the effects of SID peptide to block SIN3–PAH2 interaction with MAD, induce expression of CDH1 and ESR1, and restore tamoxifen sensitivity in MDA-MB-231 human and MMTV-Myc mouse TNBC cells in vitro. Treatment with selamectin or ivermectin led to transcriptional modulation of genes associated with EMT and maintenance of a cancer stem cell phenotype in TNBC cells. This resulted in impairment of clonogenic self-renewal in vitro and inhibition of tumor growth and metastasis in vivo. Underlining the potential of avermectins in TNBC, pathway analysis revealed that selamectin also modulated the expression of therapeutically targetable genes. Consistent with this, an unbiased drug screen in TNBC cells identified selamectin-induced sensitization to a number of drugs, including those targeting modulated genes. Mol Cancer Ther; 14(8); 1824–36. ©2015 AACR.

Cancer cell invasion is an obligatory step for metastatic dissemination that contributes to rapid relapse and a poor survival in TNBC patients. Development of novel therapeutic strategies to block tumor invasion is an unmet need for TNBC treatment and for other tumor types. We reported that decoys with the SID sequence designed to bind and inhibit the function of PAH-2 domain of Sin3A protein markedly prolong survival in the adjuvant setting due to inhibition of metastatic dissemination to the lungs and bone marrow in TNBC mouse models. Here, we show that TNBC cell lines treated with SID decoys (peptides) display a strong in vitro inhibition of migration and invasion. This is accompanied by actin cytoskeleton reorganization with increased cortical actin, and inhibition of proteolytic enzymes (MMP9; MT-MMP1 and uPA) involved in extracellular matrix degradation. DNA microarray and Ingenuity pathway analysis (IPA) showed that the SID decoys inhibit Wnt and TGFβ signaling that is associated with epithelial to mesenchymal transition (EMT). Treatment with SID decoy peptide downregulated WNT/β-catenin-driven transactivation as measured by decreased promoter H3K4me3 and decreased expression of Wnt target genes like LEF1 and TCF7L2. We also show that SID decoys induce translocation of nuclear β-catenin to the cytoplasm in TNBC at 24 hours. Wnt/β-catenin is critical for EMT, cancer stem cell self-renewal, and early invasion in TNBC. TGIF1, a transcription factor that modulates TGFβ and Wnt signaling pathways and known to to interact with the PAH2 domain of Sin3A, can be dissociated from Sin3A complex by SID decoy treatment as measured by co-immunoprecipitation (Co-IP) and proximity linked assay. DNA microarray of SID peptide treated TNBC cells shows inhibition of TGFβ signaling evidenced by downregulation of MMP9, MT1-MMP and PLAU, known target genes of this pathway. This is in line with inhibition of the EMT program predicted by the IPA analysis in SID peptide treated TNBC. Taken together, the results indicate that SID decoys have potential value as therapeutic agents to revert the EMT program in TNBC that should translate into the inhibition of metastasis dissemination and eradication of residual disease in TNBC. To test this in clinic future investigations will involve the use of our previously identified small molecule mimetic of SID peptide, selamectin that is also a FDA approved drug. Use of a recently constructed cyclic stapled peptide that inhibits PAH-2 binding and invasion at Citation Format: Yeon-Jin Kwon, Boris A. Leibovitch, Nidhi Bansal, Lutecia Pereira, Edgardo V. Ariztia, Kevin Petrie, Arthur Zelent, Ming-Ming Zhou, Eduardo F. Farias, Samuel Waxman. Inhibition of triple negative breast cancer cell invasion by the targeted interference of Sin3A function affecting Wnt and TGFβ signaling. [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 4115.

Lysophosphatidic acid (LPA) has potent growth-regulatory effect in many cell types and has been linked to the in vivo tumor growth and metastasis in several malignancies. The goal of this study was to assess the regulation of (EC) microenvironment by LPA through the examination of its effect on cell proliferation, migration, invasion, uPA activity, and matrix metalloproteinase (MMP) secretion/activation.All experiments were performed in vitro using an EC cell line, HEC-1A. Cell proliferation was determined using the Promega MTS proliferation assay following 48 h of exposures to different concentrations of LPA (0.1, 1.0 and 10.0 microM). Cell invasion was assessed using a modified Boyden chamber assay with collagen I coated on the membrane. HEC-1A motility was examined by Boyden chamber migration assay as well as the scratch wound closure assay on type I collagen. MMP secretion/activation in HEC-1A conditioned medium was detected by gelatin zymography. MMP-7 mRNA expression was determined using real-time PCR. uPA activity was measured using a coupled colorimetric assay.LPA, at the concentrations of 0.1 and 1.0 microM, significantly induced the proliferation of HEC-1A cells (p0.01). At 10 microM, LPA- induced HEC-1A proliferation to a less extent and showed no significant effect on HEC-1A invasion and migration (p0.05). Gelatin zymogram showed that HEC-1A cells secreted high levels of MMP-7, while MMP-2 and MMP-9 are barely detectable. In addition, LPA significantly enhanced uPA activity in HEC-1A conditioned medium in a concentration-dependent manner.LPA is a potent modulator of cellular proliferation and invasion for EC cells. It also has the capacity to stimulate the secretion/activity of uPA and MMP-7. Those results suggest that LPA is a bioactive modulator of EC microenvironment and may have a distinct regulation mechanism as observed in epithelial ovarian cancer.

The 16S-like ribosomal RNA genes from Mallomonas papillosa Harris et Bradley (Synurophyceae) and Tribonema aequale Pascher (Xanthophyceae) were sequenced and compared to those of other eukaryotes. Mallomonas is closely related to Ochromonas (Chrysophyceae) and supports the general hypothesis of a close phylogenetic relationship between the Synurophyceae and Chrysophyceae. Tribonema is specifically related to Costaria costata (C. A. Agardh) Saunders (Phaeophyceae) demonstrating an unexpected phylogenetic relationship between the Xanthophyceae and Phaeophyceae. Distance and parsimony analysis place these four chromophyte genera in a complex evolutionary assemblage that includes the Bacillariophyceae and Oomycetes but excludes the Dinophyceae. The close relationship between the chromophyte algae and the Oomycete fungi supports the hypothesis that protists with tripartite hairs form a natural assemblage.

Our understanding of the tumor microenvironment continues to evolve and allows for the identification of biomarkers that should detect the presence of early stage malignancies. Recent advances in computational analysis and biomedical technologies have come together to elucidate signatures associated with cancer and that are capable of identifying unique tumor-specific proteins. Within the tumor microenvironment, we continue to characterize the proteophysiology of the different steps associated with tumor progression. The urgent need for biomarkers accurately detecting early-stage epithelial ovarian cancer has prompted us, and others, to engage in a search for specific peptide signatures that may discriminate transformed cells from those of the normal ovarian microenvironment. This endeavor also provides new insights into the biology of the disease, which may not only be applicable to detection but may also help to initiate new therapies and optimize patient care.

Late stage ovarian cancer is characterized by disseminated intraperitoneal metastasis as secondary lesions anchor in the type I and III collagen-rich submesothelial matrix. Ovarian carcinoma cells preferentially adhere to interstitial collagen, and collagen-induced integrin clustering up-regulates the expression of the transmembrane collagenase membrane type 1 matrix metalloproteinase (MT1-MMP). Collagenolytic activity is important in intraperitoneal metastasis, potentiating invasion through the mesothelial cell layer and colonization of the submesothelial collagen-rich matrix. The objective of this study was to elucidate a potential mechanistic link between collagen adhesion and MT1-MMP expression. Our results indicate that culturing cells on three-dimensional collagen gels, but not thin layer collagen or synthetic three-dimensional hydrogels, results in rapid induction of the transcription factor EGR1. Integrin signaling through a SRC kinase-dependent pathway is necessary for EGR1 induction. Silencing of EGR1 expression using small interfering RNA abrogated collagen-induced MT1-MMP expression and inhibited cellular invasion of three-dimensional collagen gels. These data support a model for intraperitoneal metastasis wherein collagen adhesion and clustering of collagen binding integrins activates integrin-mediated signaling via SRC kinases to induce expression of EGR1, resulting in transcriptional activation of the MT1-MMP promoter and subsequent MT1-MMP-catalyzed collagen invasion. This model highlights the role of unique interactions between ovarian carcinoma cells and interstitial collagens in the ovarian tumor microenvironment in inducing gene expression changes that potentiate intraperitoneal metastatic progression.

The tumor microenvironment plays an important role equal to the tumor cell population in the progression of cancer. Consisting of stromal fibroblasts, inflammatory cells, components of the vasculature, normal epithelia, and extracellular matrix, the surrounding environment interacts or "cross-talks" with tumor cells through the release of growth factors, cytokines, proteases, and other bioactive molecules. Tumor growth, formation of new vascular networks, evasion of the host immune system, and invasion and metastasis are processes that co-evolve and become finely optimized and regulated within the tumor microenvironment. However, relatively recent reports on three areas of study have come together to add new levels of complexity to the tumor microenvironment. These include ectodomain shedding of proteins, shedding of membrane-derived vesicles, and novel roles for phospholipids. These dynamic changes that take place in the tumor microenvironment provide new avenues for study and for the early detection of cancer, whereas proteomic technologies provide the means to detect these unique proteins and lipids. Here we review the evolving concepts of the tumor microenvironment that, together with advances in proteomic technologies, hold the promise to facilitate the detection of early-stage cancer.

Activation of matrix metalloproteinase 2 (MMP-2) has been shown to play a significant role in the behavior of cancer cells, affecting both migration and invasion. The activation process requires multimolecular complex formation involving pro-MMP-2, membrane type 1-MMP (MT1-MMP), and tissue inhibitor of metalloproteinases-2 (TIMP-2). Because calcium is an important regulator of keratinocyte function, we evaluated the effect of calcium on MMP regulation in an oral squamous cell carcinoma line (SCC25). Increasing extracellular calcium (0.09-1.2 mm) resulted in a dose-dependent increase in MT1-MMP-dependent pro-MMP-2 activation. Despite the requirement for MT1-MMP in the activation process, no changes in MT1-MMP expression, cell surface localization, or endocytosis were apparent. However, increased generation of the catalytically inactive 43-kDa MT1-MMP autolysis product and decline in the TIMP-2 levels in conditioned media were observed. The decrease in TIMP-2 levels in the conditioned media was prevented by a broad spectrum MMP inhibitor, suggesting that calcium promotes recruitment of TIMP-2 to MT1-MMP on the cell surface. Despite the decline in soluble TIMP-2, no accumulation of TIMP-2 in cell lysates was seen. Blocking TIMP-2 degradation with bafilomycin A1 significantly increased cell-associated TIMP-2 levels in the presence of high calcium. These data suggest that the decline in TIMP-2 is because of increased calcium-mediated MT1-MMP-dependent degradation of TIMP-2. In functional studies, increasing calcium enhanced MMP-dependent cellular migration on laminin-5-rich matrix using an in vitro colony dispersion assay. Taken together, these results suggest that changes in extracellular calcium can regulate post-translational MMP dynamics and thus affect the cellular behavior of oral squamous cell carcinoma.

Triple Negative Breast cancer (TNBC) is an aggressive subtype of breast cancer associated with early recurrence and poor prognosis. The treatment options are limited due to lack of expression of common drug targets: estrogen receptor (ER), Progesterone receptor (PR) and Epidermal growth factor receptor 2 (Her2). Epigenetic programs can generate aberrant transcription contributing to TNBC progression; however the dynamic and reversible nature of epigenetic changes offers the possibility to reprogram cancer cells to re-express targets that can render TNBC sensitive to targeted therapies like tamoxifen. Envisioning such ‘epidrugs’, we previously published that targeting PAH2 domain of the master transcriptional scaffold Sin3 by stable expression of 13-mer peptide corresponding to a specific motif called SID (mSin3A interaction domain) disrupts its interaction with a small group of SID-containing transcription factors. This interference reverts the expression of important breast cancer-associated genes and impairs tumor growth in vivo. We have now extended our study towards the evaluation of a cell penetrating SID peptide (pSID) in in vitro and in vivo models to establish parameters for the design of targeted epigenetic therapy for TNBC. pSID co-localizes with Sin3A and interference with PAH2-mediated Sin3A functions by pSID is shown by disruption of Sin3A-MAD1 interactions in Co-IP and Duo-Link assays. pSID treatment in MDA-MB 231 cells results in functional re-expression of CDH1 and ER along with increased H3K4 and decreased H3K27 methylation on their promoters. We also show reduction in the tumorsphere formation by pSID-pretreated MDA-MB-231 cells indicating possible epigenetic reprogramming of tumor initiating stem cells towards a differentiated phenotype. Support to this hypothesis is added by the 50% reduction in tumor growth and re-expression of CDH1 observed in FVB mice injected with pSID-pretreated MMTV-myc cells. Moreover, microarray expression analysis indicates pSID-induced EMT reversal, increased cell adhesion and reduced cell migration. Intriguingly, upon further dissection of the mechanism of epigenetic regulation by pSID we show dissociation of two important chromatin readers/modifiers from the Sin3 complex: histone H3K4Me3/2 demethylase JARID1B and H3K4Me0 binding PHD-like domain containing protein PF1; both with significantly correlated overexpression in invasive breast carcinoma. We also observe loss of recruitment of JARID1B but not Sin3A from the CDH1 promoter. Currently studies are underway to understand the cooperative role between JARID1B and PF1 in potentiating the aberrant transcription regulation by Sin3 at important breast cancer-associated promoters that can be selectively reprogrammed by SID decoys. We believe this selectivity can limit the otherwise adverse affects that may be observed by the use of generic HDAC inhibitors and demethylating agents. Citation Format: Rossitza Christova, Kevin Petrie, Nidhi Bansal, Boris Leibovitch, Louise Howell, Veronica Gil, Ming-Ming Zhou, Edgardo Ariztia, Eduardo Farias, Arthur Zelent, Samuel Waxman. Targeted PF1, JARID1B inhibition induces epigenetic reprogramming in triple negative breast cancer. [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 411. doi:10.1158/1538-7445.AM2014-411

The Sin3 A/B adapter proteins function as structural scaffolds for repressor/activator complexes that regulate transcription through the specific association with histone modifying enzymes and a number of transcription factors. Sin3 contains four paired amphipathic α-helices (PAH domains). We have reported earlier that targeted disruption of the PAH2 domain with a SID (Sin3 Interaction Domain) peptide decoy in triple negative (TN) breast cancer cells leads to cytoskeletal reorganization, loss of anchorage independent growth and 3D invasive morphology and decreased cell adhesion and invasion. There is epigenetic reprogramming of silenced genes such as CDH1, ESR1 and RARA which are re-expressed and together contribute to a SID decoy induced switch from basal to a more differentiated luminal phenotype (Farias, et. al., PNAS, 2010, 107:11811-6). Computerized screening coupled with such assays as Duolink, GST pull downs and mammalian two hybrid identified small molecule inhibitors (SMI) that mimic the effects of the SID decoy peptide. SMI inhibit cellular invasion at nanomolar range and in in vivo mouse myc TN breast cancer prolong latency, decrease local invasion and metastasis. Tumors recovered showed evidence of re-expression of E-cadherin and estrogen receptor. Early effects of SID decoy in TN breast cancer cells include inhibition of invasion that is associated with a significant decrease in Src phosphorylation within 2-4hr of treatment. Recovery of phosphorylation after SID decoy washout is coupled with recovered invasion at 24hr. These effects occurred prior to measurable increase in E-cadherin expression, suggesting a non-transcriptional effect. In Drosophila larval breast cancer models with activated Src/Ras, overexpression of SID inhibited (60%) tumor growth in the eye imaginal disc, and was eradicated by the addition of a MEK inhibitor (AZD-6244), indicating a strong synergy between SID and AZD-6244. In the adult fly SID expression greatly inhibited RetMEN2B induced eye tumors (90%). These data demonstrate that SID decoys have a potential to be effective agents in the treatment of TN breast cancer by promoting basal phenotype reversal, inhibiting invasion and metastasis, and could be synergistic with specific inhibitors of signal transduction targets. Moreover, SID decoys can overcome profound oncogenic stimulus such as Ras, Src and Ret suggesting that they have a potential greater role than just in the treatment of TN breast cancer. 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 1826. doi:1538-7445.AM2012-1826

Sendai virus P/C mRNA, human erythrocyte membrane protein 4.1 mRNA and PDGF-B chain mRNA were used to test whether translation initiation from non-AUG codons in COS1 cells was mRNA species dependent. Site-directed mutants of the authentic translation start sites of these mRNAs to alternate start codons showed that while P/C mRNA is capable of initiating translation from non-AUG start sites the other two mRNAs are not. Our study shows that translation initiation from non-AUG codons is mRNA species dependent and suggests that higher order structure of an mRNA determines the non-AUG translation start site.

Our recent work in understanding silenced retinoic acid response genes in breast cancer led us to explore the role of transcription repressor complexes in gene silencing in breast cancer. To this end we constructed a set of tagged vectors that contain a specific MAD1 motif called SID (mSin3A interaction domain), which binds with high affinity to block the function of the Sin3. Sin3A/B serve as multisubunit co-repressor scaffold protein that regulate gene transcription by recruiting histone deacetylase and histone demethylase activities to sequence-specific transcriptional repressors which are aberrant in breast cancer. The PAH2 domain of Sin3A/B binds with high affinity to a small number of transcription factors, and offers a more specific epigenetic target which contributes to the development of breast cancer. PAH-2 domain a specific component of a transcriptional repressor complex that plays an important role in modulating a small number of transcription factors containing the Sin3 PAH-2 interaction domain (SID). Here we demonstrated that in both human and mouse breast cancer cells, the targeted disruption of Sin3 function by introduction with their partners by the expression of SID transcript or peptide decoy interfered with PAH2 binding to SID-containing partner proteins as measured by co-immunoprecipitation and mammalian two-hybrid assays, reverteds the silencing of several genes involved in cell growth and differentiation. We observed that the SID decoy induced clear signs of differentiation in both human and mouse breast cancer cellsIn particular, the which include theSID decoys led to acinar morphogenesis in 3D cultures, increased adherence to collagen type-IV and laminin, reduced invasive phenotype and impaired tumor growth in vivo (>75%). This was associated with epigenetic reprogramming characterized by a marked increase in H3K4 2/3 methylation and a modest increase in H3 acetylation in the promoter region, promoter DNA demethylation and re-expression of the important breast cancer-associated silenced genes encoding E-cadherin, and, estrogen receptor α (ERα) and retinoic acid receptor β (RARβ)and impairment in tumor growth in vivo. There was increased expression of E-cadherin, CRBP1 and p27 known RAR response genes. The re-expression of ERα and RARβ in the “triple negative” MDA-MB-231 breast cancer cell line is functional since there was significant growth inhibition by tamoxifen after stimulation with 17b-estradiol and RAR activation by atRA and AM580. Therefore, the development of small molecules that mimic the 13 amino acid SID peptide and block interactions between PAH2 and SID-containing proteins This offers a new novel approach for treating this type of breast cancer and may also provide wider therapeutic implicationstriple negative breast cancer cells. 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 572.

Sequence comparisons of small subunit ribosomal RNA coding regions from 12 chlorophylls a + c-containing algae were used to infer phylogenetic relationships within the Chromophyta. Three chromophyte lines of descent, delineated by the Bacillariophyceae, the Phaeophyceae/Xanthophyceae, and the Chrysophyceae/Eustigmatophyceae/Synurophyceae are members of a complex evolutionary assemblage, which also includes representatives of the Oomycota ("lower" fungi). Maximum parsimony and distance matrix methods demonstrate a common evolutionary history for these lineages but their relative branching order could not be determined. Other algal species with chlorophylls a + c, including dinoflagellates and prymnesiophytes, are not members of this complex assemblage. Dinoflagellates are specifically related to apicomplexans and ciliates, and the prymnesiophyte, Emiliania huxleyi, represents an independent photosynthetic lineage that separated from other eukaryotes during the nearly simultaneous divergence of plants, animals, fungi, and a number of other protist lineages. The small subunit rRNA phylogenies of chromophytes/oomycetes were compared to those derived from comparisons of ultrastructural characters. Only tubular, tripartite mastigonemes (flagellar hairs) characterized all studied taxa of chromophytes/oomycetes as a monophyletic assemblage.

Sarcocystis muris is a coccidium with a two-host life cycle involving the domestic cat and the mouse, Mus musculus. S. muris and Theileria annulata belong to the phylum Apicomplexa, but the latter organism is a tick-borne protozoon in the subclass Piroplasmea and causes tropical theileriosis in cattle. The small-subunit ribosomal RNA (16S-like rRNA) coding regions of these organisms as well as that of the free living dinoflagellate Crypthecodinium cohnii were amplified using polymerase chain reaction techniques and compared to 16S-like rRNA sequences from other eukaryotes. The 16S-like rRNA genes of S. muris and T. annulata are more similar to each other than either is to Plasmodium falciparum, the cause of malignant tertian malaria of humans or Plasmodium berghei, the agent of the commonly studied malaria of rodents. Evolutionary trees inferred from the rRNA sequence similarities support a close phylogenetic relationship between the Apicomplexa and Dinoflagellata as represented by Prorocentrum micans and C. cohnii. Apparently members of these related phyla arose from an ancestral stock that gave rise to the ciliated protozoa.

16047 Background: Matrix metalloproteinases (MMPs) are responsible for the breakdown of extracellular matrix components, and are important in the metastatic phenotype. HEC-1A is an endometrial cancer cell line, derived from a moderately-differentiated tumor. These cells do not produce MMP-2, an important mediator of invasive behavior. We sought to: evaluate if HEC-1A cells have the capacity to activate proMMP-2 if given the proenzyme exogenously; and determine if the addition of lysophosphatidic acid (LPA), a known activator of MMPs in other cancers, would further enhance this conversion. Methods: HEC-1A cells were maintained per known protocols. Conditioned media from HT1080 chondrosarcoma cells, a source of proMMP-2, was added to HEC-1A cells. Cells were also treated with 0.1, 1.0 and 10uM LPA. Conditioned media from the cells was analyzed for the presence of MMP-2 and its proenzyme utilizing gelatin zymography. Cellular invasion through collagen matrix was quantified using a modified Boyden chamber assay. Migration was evaluated using a wound healing assay with quantification of wound closure at 48 hours. Proliferation was assessed following cell culture for 48 hours using an MTS tetrazolium salt/phenazine methosulfate assay. Results: HEC-1A cells activated exogenous proMMP-2 to MMP-2, as confirmed by gelatin zymography. This occurred in both the presence and absence of LPA. Invasion of HEC-1A cells treated with proMMP-2 was significantly increased as compared to controls (p < .001). LPA increased invasion in cells with and without exogenous proMMP-2, with the most invasive cells being those treated with both LPA and exogenous proMMP-2. The addition of both exogenous MMP-2 and LPA significantly increased cellular migration as quantified using the wound healing assay (p < .001). Cellular proliferation was significantly increased with LPA vs. controls. The addition of proMMP-2 did not lead to a significant difference in proliferation. Conclusions: HEC-1A cells can convert exogenous proMMP-2 to its active form, and in doing so exhibit a more invasive phenotype. LPA serves to further increase these behaviors. This may reflect the tumor microenvironment, with endometrial cancer cells responding to bioactive lipids and proenzymes secreted by the surrounding stroma. No significant financial relationships to disclose.