Search

Invasion is a hallmark feature of endometrial pathologies, including myometrial invasion of endometrial cancer and invasion of distal sites during endometriosis. Mutations in the chromatin remodeling protein ARID1A have been observed at high rates in endometrial cancer and endometriosis. ARID1A loss, in combination with phosphoinositide 3-kinase (PI3K) pathway activation, has been shown to induce invasion phenotypes in the endometrial epithelium. Using bioinformatic approaches, we identified histone acetyltransferase (HAT) protein P300 as potential co-regulator of ARID1A-deficient gene expression programs. Knockdown of P300 prevented invasive phenotypes in a genetically engineered mouse model and human endometrial epithelial cells through induction of apoptosis, indicating a synthetic-lethal relationship between ARID1A and P300 in the endometrial epithelium. Using the novel HAT inhibitor, A-485, we identified P300 HAT activity as the mechanism by which P300 promotes invasive phenotypes. A-485 treatment rescued invasion in vitro at concentrations which had no effect on cell viability in adherent culture, but induced anoikis in suspension culture. Using an RNA-seq approach, we identified cell adhesion and migration pathways as being regulated by ARID1A knockdown and P300 co-knockdown or A-485 co-treatment. Among genes in these pathways, we identified SERPINE1 as an essential component of P300-dependent invasive processes. SERPINE1 is overexpressed following ARID1A loss in mouse and human models, and SERPINE1 knockdown rescued invasive phenotypes following ARID1A loss. By chromatin immunoprecipitation, we identified a role for P300-dependent acetylation of histone 3 lysine 27 (H3K27ac) at the SERPINE1 super-enhancer. The novel P300 bromodomain inhibitor CCS1477 also rescues invasion and SERPINE1 expression following ARID1A loss, suggesting a role for bromodomain inhibition as a modulator of P300 H3K27ac deposition. These studies suggest the therapeutic utility of P300 inhibition to induce anoikis in mutant endometrium which has detached from the basement membrane, thereby preventing invasion. Citation Format: Mike R. Wilson, Jake J. Reske, Ronald L. Chandler. Inhibition of P300 histone acetyltransferase activity rescues invasive phenotypes of ARID1A-deficient endometrial epithelium [abstract]. In: Proceedings of the AACR Virtual Special Conference: Endometrial Cancer: New Biology Driving Research and Treatment; 2020 Nov 9-10. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(3_Suppl):Abstract nr PO048.

Inheritance of a deleterious mutation in the BRCA1/2 genes increases the risk of the disease by up to 40%. The origin of the disease is still debated; however considerable evidence suggests the fallopian tube as the primary site of disease origin. The fallopian tube epithelium changes morphologically and genomically with the ovulatory cycle. To further understand the transcriptomic profile of the fallopian tube epithelium amongst patients with and without a BRCA mutation who have undergone prophylactic surgery, samples with clinically annotated ovulatory cycle status were analyzed by next-generation sequencing (RNA-Seq). The results from this study will provide an understanding of the origins of the disease and how new therapeutic and preventative interventions can be applied early in the development of the disease. METHODS: In total a cohort of 68 archival formalin fixed paraffin embedded (FFPE) fallopian tube -fimbria was amassed: FTE-BRCA1 (n=32), FTE-BRCA2 (n=4), chemonaive HGSC-BRCA1 (n=9), FTE-nonBRCA (n=26). The pre-menopausal fallopian tube specimens were sub-divided by ovulatory cycle: normal-Follicular, normal-Luteal, BRCA-Follicular, BRCA-Luteal. The majority of the FTE specimen were obtained from pre-menopausal women (post-menopausal n=2). Laser capture microdissection was performed on the distal end of the fallopian tubes – the fimbria. Six-twelve, 10um FFPE sections were cut and stained with hematoxylin prior to LCM. RNA was extracted using the Roche High Pure FFPE Micro Kit and samples were processed using Illumina Tru-Seq Stranded Total RNA Kit with RiboGold ready and sequenced on the Illumina Hi-seq 2000 V3. Raw results, in FASTQ format, were then processed through the RNA sequencing pipeline to generate results including gene expression data. RESULTS: Gene expression differences between carriers and non-carriers (FTE-BRCA1/2 and FTE-nonBRCA) revealed genes involved in metabolic pathways namely: oxidative phosphorylation, mitochondrial functions, glycolysis/gluconeogenesis and glycan biosynthesis and metabolism: UGT2A1, ST6GALNNAC6, Complex 1 (ND1, ND2, ND4, NDL4, ND5), ATP6/ATP8, and COX1-3. A comparison between the tumor and fimbria cases showed increased activity in the HMGBI Signaling (increase in HAT1, KAT2B, LIF, JAK3 and PIK3CA and decrease in RAP1A/B, ATM and HMGB1). CONCLUSION: These results highlight BRCA1/2 distinct unique preneoplastic processes not previously identified. The fallopian tube epithelial in the fimbria in BRCA1 and BRCA2 mutation carriers have increased metabolic activity, indicated by their gene expression profiles. HGSC developed BRCA1 germline mutation carriers have an increased histone acetyltransferase activity shown to be involved in BRCA mediated DNA damage repair. Further analysis is required to understand how the ovulatory cycle influences the fallopian tube epithelium transcriptome, but preliminary results suggest that pathways altered include: metabolic pathways, apoptosis pathways, p53 pathways and mismatch repair pathways. These results support previous findings in addition to providing new insight into the early development of the disease. Citation Format: Ramlogan Sowamber, Leah Dodds, Anca Milea, Iru Paudel, Michael Considine, Leslie Cope, Patricia A Shaw and Sophia HL George. RNA-SEQUENCING OF FALLOPIAN TUBE – FIMBRIA AND HGSC FROM BRCA MUTATION CARRIERS [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr DP-005.

Histone acetylation plays an important role in regulating the chromatin structure and is tightly regulated by two classes of enzyme, histone acetyltransferases (HAT) and histone deacetylases (HDAC). Deregulated HAT and HDAC activity plays a role in the development of a range of cancers. Consequently, inhibitors of these enzymes have potential as anticancer agents. Several HDAC inhibitors have been described; however, few inhibitors of HATs have been disclosed. Following a FlashPlate high-throughput screen, we identified a series of isothiazolone-based HAT inhibitors. Thirty-five N-substituted analogues inhibited both p300/cyclic AMP–responsive element binding protein–binding protein–associated factor (PCAF) and p300 (1 to >50 μmol/L, respectively) and the growth of a panel of human tumor cell lines (50% growth inhibition, 0.8 to >50 μmol/L). CCT077791 and CCT077792 decreased cellular acetylation in a time-dependent manner (2–48 hours of exposure) and a concentration-dependent manner (one to five times, 72 hours, 50% growth inhibition) in HCT116 and HT29 human colon tumor cell lines. CCT077791 reduced total acetylation of histones H3 and H4, levels of specific acetylated lysine marks, and acetylation of α-tubulin. Four and 24 hours of exposure to the compounds produced the same extent of growth inhibition as 72 hours of continuous exposure, suggesting that growth arrest was an early event. Chemical reactivity of these compounds, as measured by covalent protein binding and loss of HAT inhibition in the presence of DTT, indicated that reaction with thiol groups might be important in their mechanism of action. As one of the first series of small-molecule inhibitors of HAT activity, further analogue synthesis is being pursued to examine the potential scope for reducing chemical reactivity while maintaining HAT inhibition.

Prostate cancer is the most frequent non–skin cancer in men. Although the mechanisms involved in the progression of prostate cancer are not entirely understood, androgen receptor has been shown to play an important role. Androgen receptor is expressed in both early and late-stage prostate cancer. Also, androgen-regulated pathways are thought to be active as evidenced by elevated levels of prostate-specific antigen (PSA). In addition, several androgen receptor coactivators and cytokines are involved in prostate cancer progression. In this regard, we have shown previously that the coactivator p300 plays a major role in the androgen-independent activation of PSA by interleukin 6 (IL-6), a cytokine involved in late-stage prostate cancer. In this study, we investigated the role of p300 and its homologue CREB-binding protein in prostate cancer cells treated chronically with IL-6. We found that p300 but not CREB-binding protein induced activation of PSA in these cells and that the histone acetyltransferase activity of p300 was critical. This effect was independent of the presence of androgens or antiandrogens. Moreover, we found markedly reduced levels of androgen receptor in these cells and p300 transfection did not affect those levels, suggesting that the p300 effect on PSA could be bypassing the androgen receptor. Transfection with exogenous androgen receptor showed minimal response of PSA to androgens but higher response to p300. We found similar effects of p300 on the androgen response element III, which mediates the androgen receptor–dependent activation of PSA. Finally, we showed that p300 alone regulates expression of the endogenous PSA gene in the IL-6–treated cells. These findings reveal a new insight in the progression of prostate cancer, suggesting that coactivators, such as p300, play more important roles in late-stage prostate cancer, and could regulate androgen-dependent genes in the absence or with very low levels of androgen receptor.

Chromosomal rearrangements of the Mixed-Lineage Leukemia (MLL) gene are found in 5-10% of all patients with acute leukemia and associated with a poor prognosis. MLL-rearrangements are more frequently present in pediatric and infant patients where AF9 is one of the most common fusion partners. In order to identify novel druggable targets in MLL-AF9 rearranged leukemia, we conducted a chromatin regulator focused RNAi screen in murine MLL-AF9 leukemia cells and found hairpins targeting (K)Lysine Acetyltransferase 8 (Kat8, also known as Mof) and the previously identified target Bromodomain Containing 4 (Brd4), to be the most potent suppressors of cell growth. MOF is a histone 4 lysine 16 (H4K16) acetyltransferase and member of the MYST family of histone acetyltransferases (HATs). MOF has been shown to be crucial for murine embryogenesis and is a cell-type dependent regulator of chromatin state and various cellular processes such as T-cell differentiation, DNA damage response and cell cycle progression. Using a conditional murine Mof knockout system, we studied the role of MOF in MLL-AF9 leukemogenesis in detail. In vitro inactivation of Mof in MLL-AF9 transformed mouse hematopoietic stem and progenitor cells led to impaired colony-forming capacity. The specificity of this phenotype was shown by expression of exogenous full-length Mof, which fully rescued transformed cells from the dramatic phenotype. Inactivation of Mof in vivo, lead to reduced tumor burden and prolonged survival of mice bearing MLL-AF9 leukemia cells. RNA sequencing data comparing MLL-AF9 cells with homozygous Mof loss to a wild type control, showed a significant enrichment of genes within the apoptosis (NES 1.98, FDR-q These results indicate that MOF HAT activity is required for MLL-AF9 leukemia maintenance. Our data further suggest that MOF HAT activity may be a good target for new small molecule inhibitor development for the treatment of patients with MLL-AF9 rearranged leukemia. Citation Format: Daria G. Valerio, Haiming Xu, Chun-Wei Chen, Takayuki Hoshii, Meghan Eisold, Christopher Delaney, Monica Cusan, Aniruddha J. Deshpande, Chun-Hao Huang, Amaia Lujambio, George Zheng, Tej K. Pandita, Scott W. Lowe, Scott A. Armstrong. Histone acetyltransferase activity of MOF is required for MLL-AF9 leukemogenesis. [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 2694.

Background: Patients with advanced carcinoma of unknown primary (CUP) have limited effective therapeutic options given the challenges of phenotypic and genotypic diversity. To identify future novel therapeutic strategies we conduct an ongoing exploratory analysis of next-generation sequencing (NGS) of relapsed, refractory CUP. Methods: We identified CUP patients referred to our phase I clinic with adequate FFPE sections from archival tissue for a targeted CLIA-certified NGS assay (Foundation One, MA). Over 2000 exons of 186 cancer-related genes plus over 30 introns from 14 genes often rearranged in cancer were fully sequenced for point mutations, insertions/deletions, copy number alterations (CNAs) and select gene fusions. Results: Of 19 patients seen (10 male, 9 female; median age at diagnosis 49 years), 17 demonstrated genomic alterations (median 3 aberrations/tumor, range 0 - 10); two patients had no reportable genomic alterations. Of the 71 detected aberrations, 17 (24%) have been implicated in impaired cell cycle regulation and arrest; specifically in genes which encode the cyclin-dependent kinases (CDK12 Q570*, CDKN2A/B loss, CDKN2A p16INK4a loss and p14ARF exon 2-3 loss) or their associated proteins including amplification of CCND1 and CCNE1 (n = 3). Of these 8 patients with impaired cell cycle regulation, 5 (63%) demonstrated concurrent mutations associated with epigenetic deregulation and impaired DNA methylation, most commonly ARID1A Y1211fs*5 and S1929fs*25, which encodes the AT-rich interactive domain-containing protein 1A, Arid1a, a member of the SWI/SNF chromatin remodeling complex); other mutations observed are CREBBP S893L (encoding a ubiquitously expressed transcriptional coregulatory protein controlling chromatin remodeling via its histone acetyltransferase activity); MLL2 R4904* (encoding an H3K4-specific histone methyltransferase) and KDM6A S466* (encoding the histone H3 lysine 27 demethylase UTX). Overall 5 of 19 (26%) patients with advanced relapsed CUP demonstrated a profile of aberrations that concurrently impact cell cycle arrest and epigenetic regulation. Conclusion: Through NGS-based molecular profiling, we can a subset of patients with advanced carcinoma of unknown primary with coexisting mutations leading to impaired cell cycle arrest and epigenetic deregulation, highlighting a therapeutic combination with a cell cycle inhibitor (such as Cdk4/6 inhibitors currently in clinical trial) and histone deacetylase inhibitors. Note: This abstract was not presented at the meeting. Citation Format: Ishwaria M. Subbiah, Gauri Varadhachary, Apostolia M. Tsimberidou, Jennifer J. Wheler, Vivek Subbiah, Filip Janku, Sinchita Roy Chowdhuri, Ralph Zinner, David S. Hong. Impaired cell cycle arrest with concurrent epigenetic deregulation identified through next generation sequencing in patients with advanced carcinoma of unknown primary: Implications for personalized medicine. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 604. doi:10.1158/1538-7445.AM2015-604

The cell surface heparan sulfate proteoglycan syndecan-1 (CD138) is expressed by myeloma tumor cells, is proteolytically shed from the cell surface and accumulates in the serum. High levels of serum syndecan-1 are an independent indicator of poor prognosis. Our lab has demonstrated that shed syndecan-1 drives myeloma tumor progression in vivo, but the mechanism(s) mediating this are not fully understood. The role of heparan sulfate proteoglycans on the cell surface and in the extracellular matrix has been extensively studied, but their presence and function within the nucleus is often overlooked. However, recent findings indicate that nuclear heparan sulfate has important regulatory functions. Based on preliminary findings, we hypothesized that shed syndecan-1 binds to the tumor cell surface and translocates to the nucleus where it regulates gene expression thereby promoting aggressive tumor behavior. We utilized murine myeloma cells which were grown in the presence of medium containing human shed syndecan-1. Strikingly, the shed syndecan-1 was rapidly taken up by these cells and translocated to the nucleus. Additionally, exogenous human shed syndecan-1 added to murine stromal cells also bound to the cell surface and translocated to the nucleus. This is the first demonstration that shed proteoglycans can translocate to the nucleus of cells. When stromal cells were grown in the presence of tumor-derived shed syndecan-1, acetylated histone H3 was decreased. Additionally, tumor cells engineered to express high levels of shed SDC1 have a 58% reduction in histone acetyltransferase activity. This may be due to syndecan-1 directly binding to p300/CBP-associated factor, a HAT enzyme. Moreover, HGF bound to shed syndecan-1 was shuttled to the nucleus of myeloma cells as a complex. Shed syndecan-1 and HGF translocation to the nucleus is dependent on intact heparan sulfate chains present on the syndecan-1 core protein. These data reveal a novel mechanism of tumor-host crosstalk whereby syndecan-1, shed by tumor cells, alters histone acetyltransferase activity and shuttles heparin-binding factors to the nucleus to reprogram cells and alter gene expression. Therapeutic regulation of syndecan-1 shedding, its binding to the cell surface or translocation to the nucleus represent novel strategies to control the progression of myeloma and other cancers. Citation Format: Mark Stewart, Vishnu Ramani, Ralph Sanderson. Shed syndecan-1 downregulates histone acetyltransferase activity and shuttles HGF to the nucleus of tumor and host cells. [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 1156. doi:10.1158/1538-7445.AM2014-1156

Non-small-cell lung cancer (NSCLC) represents approximately 80% of all types of lung cancer, and the dismal 5-year survival rate of about 14% has shown no improvement over the past three decades. Histone deacetylases (HDACs) regulate many biologic processes, including cell cycle progression and cell differentiation. Among HDACs, class I HDACs are frequently overexpressed in various human cancers and this overexpression correlates with drug resistance and poor prognosis. Thus, class I HDACs have been considered as potential therapeutic targets for the treatment of cancers. Here, we report the chemotherapeutic effect of honokiol, a phytochemical from Magnolia plant, on NSCLC cells and the molecular mechanisms underlying these effects using in vitro and in vivo models. Treatment of NSCLC cells (A549, H1299, H460 and H226) with honokiol (20, 40 and 60 μM) inhibited histone deacetylase (HDAC) activity, reduced the levels of class I HDAC proteins and enhanced histone acetyltransferase activity in a dose-dependent manner. These effects of honokiol were associated with a significant reduction in the viability of NSCLC cells. Concomitant treatment of cells with a proteasome inhibitor, MG132, prevented honokiol-induced degradation of class I HDACs, suggesting that honokiol reduced the levels of HDACs in NSCLC cells through proteasomal degradation. Valproic acid, an inhibitor of HDACs, exhibited a similar pattern of reduced viability and induction of death of NSCLC cells. Treatment of A549 and H1299 cells with honokiol resulted in an increase in G1 phase arrest, and a decrease in the levels of cyclin D1, D2, and cyclin dependent kinases. Further, administration of honokiol by oral gavage (100 mg/kg body weight of mice) significantly inhibited the growth of s.c. A549 and H1299 tumor xenografts in athymic nude mice, which was associated with the induction of apoptotic cell death and marked inhibition of class I HDACs proteins and HDAC activity in the tumor xenograft tissues. Together, our study provides new insights and previously unrecognized role of class I HDACs in the chemotherapeutic effects of honokiol on lung cancer cells. These new insights into the epigenetic mechanism of action of honokiol may contribute to the chemoprevention or treatment of lung cancer and may have important implications for epigenetic therapy. Key words: Apoptotic index, cell cycle, histone, histone deacetylase, histone acetyl transferase, honokiol, non-small cell lung cancer Citation Format: Tripti Singh, Ram Prasad, Santosh K. Katiyar. Inhibition of class I histone deacetylases in non-small cell lung cancer cells by honokiol leads to suppression of cancer cell proliferation and induction of cell death in vitro and in vivo models. [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 3672. doi:10.1158/1538-7445.AM2013-3672

Aurora B (AurB) is a mitotic checkpoint kinase that plays a pivotal role in the cell cycle, ensuring correct chromosome segregation and normal progression through mitosis. Tumor suppressor p53 is a genome guardian and an important negative regulator of the cell cycle. Although overexpression of AurB and loss or degradation of p53 have been described in many types of human cancers, it is not known whether AurB and p53 are coordinately regulated during the cell cycle. Recently has been shown that NIR, which is a transcriptional co-repressor of histone acetyltransferase activity, interact with and suppress p53 via interaction with AurB. Our results show that AurB directly interacts with p53 in a NIR-independent matter. To prove direct molecular interaction between AurB and p53 in whole cells, we employed the method of bimolecular fluorescent complementation (BiFC). AurB-p53 interaction occurs at the nucleus in interphase and at the centromeres in prometaphase of mitosis. We observed that AurB-p53 interaction co-localized with Survivin and CENP-A, suggesting that AurB and p53 interact at the centromeres. Our results also show that Aurora B phosphorylates p53 to accelerate p53's degradation through the polyubiquitination-proteasome pathway, thus functionally suppressing the expression of p53 target genes involved in cell cycle inhibition and apoptosis. Inhibition of Aurora B in cancer cells with wild-type p53 increased p53 protein level and expression of p53 target genes to inhibit tumor growth. Together, these results give a new insight of a novel mechanism of p53 inactivation during the cell cycle and imply that oncogenic hyperactivation or overexpression of AurB may compromise p53's tumor suppressor function. 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 LB-283. doi:1538-7445.AM2012-LB-283

A20 Epidemiologic observations have implicated chronic excess ethanol consumption as a risk factor for various cancers including colon cancer. Recent epigenetic studies demonstrated that ethanol causes selective acetylation of histone H3 at lysine 9 (H3K9) in the liver, lung, spleen and testes, indicating that ethanol may inhibit histone deacetylase activity, or enhance histone acetyltransferase activity in those tissues. We therefore investigated the effect of ethanol on histone H3 modifications in colonic epithelial cells. NCM460, human colonic epithelial cells were incubated with 100mM of ethanol for 24, 48, or 72 hr and then the acetylation and methylation states of histone H3K9 were measured by immunoblot analysis using site-specific antibodies. We found that ethanol decreased acetylation of histone H3K9 in a time-dependent manner (71, 21, 17%, respectively, P Citation Information: Cancer Prev Res 2008;1(7 Suppl):A20.