Etiology Of Epithelial Ovarian Cancer Research Articles

Abstract 5606: The role of KMT2C in the homologous recombination repair in epithelial ovarian cancer

Abstract Background: Epithelial ovarian cancer (EOC) with homologous recombination (HR) deficiency is susceptible to PARP inhibitor therapy due to synthetic lethality. Identification of the patient population for PARP inhibitor therapy is imperative to reduce recurrence of EOC and improve the survival outcomes of patients. Current biomarkers for PARP inhibitor therapy consist of an array of genes involved in the HR repair pathway in EOC, including BRCA1, BRCA2 and PALB2. Through TCGA analysis, we found that the lysine (K)-specific methyltransferase 2C (KMT2C) gene is mutated in 10.3% of all EOC patients and considerably enriched in BRCA1 mutated EOC patients. However, the role of KMT2C in HR repair and PARP inhibitor sensitivity of EOC remains largely undefined. Methods: BRCA2-mutated PEO1 and BRCA2-wild type PEO1-NR cells were transfected with KMT2C siRNA and assayed for KMT2C protein expression by western blotting. DR-GFP (HR) and EJ5-GFP (NHEJ)-SKOV3 cell lines were co-transfected with the ISceI-expressing plasmid pCBA-ISceI and KMT2C siRNA. GFP-positive cells were analyzed by flow cytometry. SKOV3 cells were transfected with KMT2C siRNA and the expression of BRCA2 and Rad51 mRNA was determined using quantitative RT-PCR analysis. Results: siRNA-mediated knockdown of KMT2C resulted in marked down-regulation of KMT2C protein in PEO1 and PEO1-NR cells. KMT2C knockdown caused a significant decrease in ISceI-induced HR activity in DR-GFP-SKOV3 cells (p < 0.05). In contrast, KMT2C knockdown had no effects on ISceI-induced NHEJ activity in EJ5-GFP-SKOV3 cells. As a control, Rad51 knockdown caused complete suppression of HR activity and had no effects on NHEJ activity. Furthermore, quantitative RT-PCR analysis of key HR genes showed that KMT2C knockdown resulted in a moderate but significant down-regulation of BRCA2 (p < 0.05) and Rad51 (p < 0.01) expression in SKOV3 cells. Conclusion: Our results suggest that KMT2C partakes in the HR repair pathway in EOC. However, the contribution of KMT2C to HR activity is not rate-limiting. Based on the known function of KMT2C in histone modification, we speculate that KMT2C serves to positively regulate the transcription of HR genes and therefore promote HR activity. Future investigation into the exact roles of KMT2C in HR repair, etiology of EOC, and diagnostic biomarkers for the PARP inhibitor sensitivity of EOC is warranted. Citation Format: Mirielle C. Ma, Z. Ping Lin, Elena S. Ratner. The role of KMT2C in the homologous recombination repair in epithelial ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5606.

TIPE2 acts as a tumor suppressor and correlates with tumor microenvironment immunity in epithelial ovarian cancer.

Epithelial ovarian cancer (EOC) is one of the deadliest gynecologic cancers. The etiology of EOC has still not been elucidated thoroughly. Tumor necrosis factor-α-induced protein 8-like2 (TNFAIP8L2, TIPE2), an important regulator of inflammation and immune homeostasis, plays a critical role in the progression of various cancers. This study aims to investigate the role of TIPE2 in EOC. Expression of TIPE2 protein and mRNA in EOC tissues and cell lines was examined using Western blot and quantitative real-time PCR (qRT-PCR). The functions of TIPE2 in EOC were investigated by cell proliferation assay, colony assay, transwell assay, and apoptosis analysis in vitro. To further investigate the regulatory mechanisms of TIPE2 in EOC, RNA-seq and western blot were performed. Finally, the CIBERSORT algorithm and databases including Tumor Immune Single-cell Hub (TISCH), Tumor Immune Estimation Resource (TIMER), Tumor-Immune System Interaction (TISIDB), and The Gene Expression Profiling Interactive Analysis (GEPIA) were used to elucidate its potential role in regulating tumor immune infiltration in the tumor microenvironment (TME). TIPE2 expression was shown to be considerably lower in both EOC samples and cell lines. Overexpression of TIPE2 suppressed EOC cell proliferation, colony formation, and motility in vitro. Mechanistically, TIPE2 suppressed EOC by blocking the PI3K/Akt signaling pathway, according to bioinformatics analysis and western blot in TIPE2 overexpression EOC cell lines, and the anti-oncogenic potentials of TIPE2 in EOC cells could be partially abrogated by the PI3K agonist, 740Y-P. Finally, TIPE2 expression was positively associated with various immune cells and possibly involved in the regulation of macrophage polarization in ovarian cancer. We detail the regulatory mechanism of TIPE2 in EOC carcinogenesis, as well as how it correlates with immune infiltration, emphasizing its potential as a therapeutic target in ovarian cancer.

Genetically predicted circulating protein biomarkers and ovarian cancer risk

ObjectiveMost women with epithelial ovarian cancer (EOC) are diagnosed after the disease has metastasized and survival in this group remains poor. Circulating proteins associated with the risk of developing EOC have the potential to serve as biomarkers for early detection and diagnosis. We integrated large-scale genomic and proteomic data to identify novel plasma proteins associated with EOC risk. MethodsWe used the germline genetic variants most strongly associated (P <1.5 × 10−11) with plasma levels of 1329 proteins in 3301 healthy individuals from the INTERVAL study to predict circulating levels of these proteins in 22,406 EOC cases and 40,941 controls from the Ovarian Cancer Association Consortium (OCAC). Association testing was performed by weighting the beta coefficients and standard errors for EOC risk from the OCAC study by the inverse of the beta coefficients from INTERVAL. ResultsWe identified 26 proteins whose genetically predicted circulating levels were associated with EOC risk at false discovery rate < 0.05. The 26 proteins included MFAP2, SEMG2, DLK1, and NTNG1 and a group of 22 proteins whose plasma levels were predicted by variants at chromosome 9q34.2. All 26 protein association signals identified were driven by association with the high-grade serous histotype that comprised 58% of the EOC cases in OCAC. Regional genomic plots confirmed overlap of the genetic association signal underlying both plasma protein level and EOC risk for the 26 proteins. Pathway analysis identified enrichment of seven biological pathways among the 26 proteins (Padjusted <0.05), highlighting roles for Focal Adhesion-PI3K-Akt-mTOR and Notch signaling. ConclusionThe identified proteins further illuminate the etiology of EOC and represent promising new EOC biomarkers for targeted validation by studies involving direct measurement of plasma proteins in EOC patient cohorts.

LY75 Suppression in Mesenchymal Epithelial Ovarian Cancer Cells Generates a Stable Hybrid EOC Cellular Phenotype, Associated with Enhanced Tumor Initiation, Spreading and Resistance to Treatment in Orthotopic Xenograft Mouse Model.

The implications of the epithelial–mesenchymal transition (EMT) mechanisms in the initiation and progression of epithelial ovarian cancer (EOC) remain poorly understood. We have previously shown that suppression of the antigen receptor LY75 directs mesenchymal–epithelial transition (MET) in EOC cell lines with the mesenchymal phenotype, associated with the loss of Wnt/β-catenin signaling activity. In the present study, we used the LY75-mediated modulation of EMT in EOC cells as a model in order to investigate in vivo the specific role of EOC cells, with an epithelial (E), mesenchymal (M) or mixed epithelial plus mesenchymal (E+M) phenotype, in EOC initiation, dissemination and treatment response, following intra-bursal (IB) injections of SKOV3-M (control), SKOV3-E (Ly75KD) and a mixed population of SKOV3-E+M cells, into severe combined immunodeficiency (SCID) mice. We found that the IB-injected SKOV3-E cells displayed considerably higher metastatic potential and resistance to treatment as compared to the SKOV3-M cells, due to the acquisition of a Ly75KD-mediated hybrid phenotype and stemness characteristics. We also confirmed in vivo that the LY75 depletion directs suppression of the Wnt/β-catenin pathway in EOC cells, suggestive of a protective role of this pathway in EOC etiology. Moreover, our data raise concerns regarding the use of LY75-targeted vaccines for dendritic-cell EOC immunotherapy, due to the possible occurrence of undesirable side effects.

High Resolution Based Quantitative Determination of Methylation Status of CDH1 and VIM Gene in Epithelial Ovarian Cancer.

Background:DNA promoter methylation is widely explored epigenetic phenomena, known to effect gene expression and further perturbation in cellular homeostasis. Myriad of studies have leveraged promoter methylation and its potential as biomarker for various types of cancer. Aim of present study is to investigate promoter methylation of CDH1 and VIM gene and etiology of epithelial ovarian cancer (EOC). Methods:Most of previous studies were qualitative; we have quantitatively assessed methylation levels in 50 EOC cases and control each through high recognition melt (HRM) technique. Results:At 10 % cutoff for CDH1 94% of EOC cases were found to be methylated with mean methylation of 45±13.8, whereas for control mean methylation was found to be 7.3±3.7 amongst 16 % methylation positive control samples. For VIM methylation was detected in 96% of cases with mean of 50.44±11.7 in EOC and in 12% methylation positive samples for control mean methylation was 6.24±4.3. Conclusion:In short HRM based DNA methylation can serve as a robust and sensitive diagnostic method for promoter methylation detection and as a biomarker for early epithelial ovarian cancer detection.

Polymorphism of xenobiotic metabolizing gene and susceptibility of epithelial ovarian cancer with reference to organochlorine pesticides exposure.

The transformation of ovarian surface epithelial cells, stromal cells, sex cord, or germ cells initiates ovarian malignancy. Epithelial ovarian cancer (EOC) is clinically silent with vague, non-specific symptomatology and is generally diagnosed at an advanced stage, resulting in a high mortality rate. The known main etiological factors are: age at menarche and menopause (early menarche or late menopause), use of oral contraception (estrogen and/or progesterone), family history, genetic factors, inflammation, occupational and environmental exposure. The study is intended to assess the association between blood organochlorine pesticide (OCP) levels and polymorphic status of phase I and phase II metabolizing enzymes (CYP1A1, GSTM1, and GSTT1) in the pathogenesis of epithelial ovarian cancer. The study included 200 subjects in total, of which 100 were epithelial ovarian cancer cases and 100 were controls. Estimation of blood organochlorine pesticide levels was carried out using gas chromatography and significantly high levels of beta-hexachlorocyclohexane (β-HCH), endosulfan-I, endosulfan-II, dichlorodiphenyltrichloroethane (pʹpʹ-DDT), dichlorodiphenyldichloroethylene (pʹpʹ-DDE) were observed in cases as compared to controls ( P-value = 0.029, 0.042, 0.044, 0.039 and 0.037 respectively). For studying the polymorphism of CYP1A1, GSTM1/T1, PCR-RFLP, AS-PCR and multiplexing were performed and the frequency of null deletion of GSTM1/T1 was significantly higher in epithelial ovarian cancer cases. Regression model testing was also performed to check the interactive effect of organochlorine pesticide levels and polymorphic variant of genes keeping CA-125 as the dependent variable and observed a statistically significant role of genotypic/environmental interaction in epithelial ovarian cancer cases in the North Indian population. Impact statement Among pervasive environmental toxins, OCPs are one of the largest and most hazardous classes of contaminants in use around the world. Because these compounds possess the estrogen mimicking properties, the accumulation of these compounds in the human body may be a risk for several hormone-dependent diseases. EOC is hormonally dependent cancer and the mortality rate due to this disease is increasingly prevalent, and it has become imperative to explore the role of OCPs in the disease pathogenesis. The present study highlights the significant association of high OCPs level in the disease pathogenesis. It is also observed that the polymorphism in xenobiotic metabolism enzymes alters the predisposition of OCPs. The synergistic effect of gene polymorphism (CYP1A1, GSTM1, and GSTT1) and non-occupational exposure to OCPs was also assessed considering CA125 level as dependent variable with the risk of EOC and concluded that there exist a potential role of genotypic/environmental interaction in the etiology of EOC.

Abstract 606: Circulating proteins associated with ovarian cancer risk and survival are enriched for immune-related pathways

Abstract Most women with epithelial ovarian cancer (EOC) are diagnosed after the disease has metastasized and five-year survival rates in this group continue to remain very poor. Circulating proteins may illuminate EOC etiology and have the potential to serve as biomarkers for early detection and diagnosis. We performed a two-sample Mendelian randomization (MR) study with circulating protein levels as exposures and susceptibility to EOC and its histological subtypes as outcomes. We used previously identified quantitative trait loci (QTLs) robustly associated with plasma levels of 1,478 proteins as genetic instruments and corresponding summary genetic association statistics for these instruments derived from 22,406 EOC cases and 40,941 controls. Among proteins that had only a single QTL variant available as a genetic instrument, we identified 12 proteins whose circulating levels were associated with overall EOC risk at a False Discovery Rate (FDR) of &amp;lt; 0.1. For nine of the 12 proteins, the association was driven by variants near ABO, which is both a genome-wide significant high grade serous histotype risk locus and a hub QTL for several proteins. Three of these 12 proteins and their QTLs were, however, not linked to the ABO locus and included the products of the NOTCH signaling genes MFAP2 and DLK1. Among proteins that had multiple QTL variants available for the creation of more robust multi-variant genetic instruments, we identified 33 protein level-EOC risk associations at FDR &amp;lt; 0.1. Once again, we observed that the majority of associations (19/33) were driven by variants at the ABO locus. Nine of the 14 remaining associations were for overall and high grade serous EOC risk and included predominantly immune system proteins: ARTS1 (HLA class I), CPNE1 (involved in innate immunity), Macrophage mannose receptor (HLA class I), DQA2 (HLA class II), RGAP1 (innate immunity), Cathepsin H (innate immunity), and FCG2B (the low affinity receptor for the Fc region of immunoglobulin gamma). We observed one mucinous histotype-specific association (complement C4) and two clear cell histotype-specific associations (KI2S2 and PSG4). KI2S2 is a Killer cell immunoglobulin-like receptor expressed by natural killer cells and PSG4 is a member of the carcinoembryonic antigen gene family that also includes the gene encoding the tumor marker for colorectal cancer. Finally, we also performed two-sample MR analyses using survival as the outcome and identified two proteins whose plasma levels were associated with overall EOC survival at FDR &amp;lt; 0.1: SULT1E, a phenol sulfotransferase that conjugates sulfates to estrogens, and MA2B2. Thus, we identified circulating proteins that are candidate biomarkers for EOC risk and survival. They represent promising starting points for follow-up studies and the measurement of plasma levels of these proteins in EOC cohorts is required to validate these associations. Citation Format: Daniel P. Considine. Circulating proteins associated with ovarian cancer risk and survival are enriched for immune-related pathways [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 606.

The polypeptide GALNT6 Displays Redundant Functions upon Suppression of its Closest Homolog GALNT3 in Mediating Aberrant O-Glycosylation, Associated with Ovarian Cancer Progression.

Epithelial ovarian cancer (EOC) represents the most lethal gynecologic malignancy; a better understanding of the molecular mechanisms associated with EOC etiology could substantially improve EOC management. Aberrant O-glycosylation in cancer is attributed to alteration of N-acetylgalactosaminyltransferases (GalNAc-Ts). Reports suggest a genetic and functional redundancy between GalNAc-Ts, and our previous data are indicative of an induction of GALNT6 expression upon GALNT3 suppression in EOC cells. We performed single GALNT3 and double GALNT3/T6 suppression in EOC cells, using a combination of the CRISPR-Cas9 system and shRNA-mediated gene silencing. The effect of single GALNT3 and double GALNT3/T6 inhibition was monitored both in vitro (on EOC cells roliferation, migration, and invasion) and in vivo (on tumor formation and survival of experimental animals). We confirmed that GALNT3 gene ablation leads to strong and rather compensatory GALNT6 upregulation in EOC cells. Moreover, double GALNT3/T6 suppression was significantly associated with stronger inhibitory effects on EOC cell proliferation, migration, and invasion, and accordingly displayed a significant increase in animal survival rates compared with GALNT3-ablated and control (Ctrl) EOC cells. Our data suggest a possible functional redundancy of GalNAc-Ts (GALNT3 and T6) in EOC, with the perspective of using both these enzymes as novel EOC biomarkers and/or therapeutic targets.

When Is "Type I" Ovarian Cancer Not "Type I"? Indications of an Out-Dated Dichotomy.

The dualistic classification of epithelial ovarian cancer (EOC) into “type I” and “type II” is widely applied in the research setting; it is used as a convenient way of conceptualizing different mechanisms of tumorigenesis. However, this classification conflicts with recent molecular insights of the etiology of EOC. Molecular and cell of origin studies indicate that while type II tumors could be classed together, type I tumors are not homogenous, even within the histological types, and can have poor clinical outcomes. Type II high grade serous carcinoma and type I low grade serous carcinomas best fit the description of the dualistic model, with different precursors, and distinct molecular profiles. However, endometriosis-associated cancers should be considered a separate group, without assuming an indolent course or type I genetic profiles. Furthermore, the very clear differences between mucinous ovarian carcinomas and other type I tumors, including an uncertain origin, and heterogeneous mutational spectrum and clinical behavior, indicate a non-type I classification for this entity. The impression that only type II carcinomas are aggressive, have poor prognosis, and carry TP53 mutations is an unhelpful misinterpretation of the dualistic classification. In this review, we revisit the history of EOC classification, and discuss the misunderstanding of the dualistic model by comparing the clinical and molecular heterogeneity of EOC types. We also emphasize that all EOC research, both basic and clinical, should consider the subtypes as different diseases beyond the type I/type II model, and base novel therapies on the molecular characteristics of each tumor.

Delineating Potential Transcriptomic Association with Organochlorine Pesticides in the Etiology of Epithelial Ovarian Cancer.

Background:Recent studies have shown that there is an increased risk of Epithelial Ovarian Cancer (EOC) with Organochlorine Pesticides (OCPs). However, the alteration in the gene expression profile has not been explored so far. The goal of the present study is to understand the probable molecular mechanism of OCPs toxicity towards discovery of dysregulation of signaling pathway associated with differential gene expression and candidate transcriptomic set of markers in the pathophysiology of EOC in OCPs exposed population.Methods:The OCP levels were estimated by gas chromatography and whole genome differential expression study was carried out using expression microarray and candidate genes were validated using Real time RT-PCR.Results:Significant level of OCP residues such as β-hexachlorocyclohexane (β-HCH), Heptachlor, Heptachlor epoxide B (HTEB), dichlorodiphenyldichloroethylene (p’p’-DDE) and endosulfan-I was found between healthy and EOC patients. The transcriptome profile of several genes revealed regulation of various important cellular processes such as metabolism, inflammation, cytoskeleton dysregulation of TGF and WNT pathway in EOC cases with high OCPs.Conclusion:This study provides the first evidence showing that differentially expressed genes and dysregulation of signaling pathways might be associated with significant level of OCPs exposure in ovary tissue of epithelial ovarian cancer patients. Moreover, significant correlation of these genes with OCPs revealed that OCPs exposure played vital role in dysregulation of related pathways in the etiology of EOC

Androgens Are Differentially Associated with Ovarian Cancer Subtypes in the Ovarian Cancer Cohort Consortium.

Invasive epithelial ovarian cancer (EOC) is the most lethal gynecologic malignancy. The etiology of EOC remains elusive; however, experimental and epidemiologic data suggest a role for hormone-related exposures in ovarian carcinogenesis and risk factor differences by histologic phenotypes and developmental pathways. Research on prediagnosis androgen concentrations and EOC risk has yielded inconclusive results, and analyses incorporating EOC subtypes are sparse. We conducted a pooled analysis of 7 nested case-control studies in the Ovarian Cancer Cohort Consortium to investigate the association between pre-diagnosis circulating androgens [testosterone, free testosterone, androstenedione, dehydroepiandrosterone sulfate (DHEAS)], sex hormone binding globulin (SHBG), and EOC risk by tumor characteristics (i.e., histology, grade, and stage). The final study population included 1,331 EOC cases and 3,017 matched controls. Multivariable conditional logistic regression was used to assess risk associations in pooled individual data. Testosterone was positively associated with EOC risk (all subtypes combined, ORlog2 = 1.12; 95% confidence interval 1.02-1.24); other endogenous androgens and SHBG were not associated with overall risk. Higher concentrations of testosterone and androstenedione associated with an increased risk in endometrioid and mucinous tumors [e.g., testosterone, endometrioid tumors, ORlog2 = 1.40 (1.03-1.91)], but not serous or clear cell. An inverse association was observed between androstenedione and high grade serous tumors [ORlog2 = 0.76 (0.60-0.96)]. Our analyses provide further evidence for a role of hormone-related pathways in EOC risk, with differences in associations between androgens and histologic subtypes of EOC. Cancer Res; 77(14); 3951-60. ©2017 AACR.

Lifetime number of ovulatory cycles and epithelial ovarian cancer risk in African American women.

Incessant ovulation has been consistently linked to epithelial ovarian cancer (EOC). Although reproductive characteristics differ substantially by race, the association between incessant ovulation and EOC has been evaluated only in populations of predominantly white women. In the present study, we examined the association between lifetime number of ovulatory cycles (LOCs) and EOC risk among African American (AA) women. We used data from 534 cases and 722 controls enrolled in the African American Cancer Epidemiology Study. LOCs were determined using the standard method, with modifications to include episodes of irregular or missed periods. Multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between LOCs and EOC risk overall and by age, while adjusting for appropriate confounders. The mean number of LOCs was 378.2 ± 105.8 for cases and 346.4 ± 117.3 for controls. Women in the highest tertile of LOCs had 59% higher odds of EOC compared to women in the lowest tertile (OR = 1.59; 95% CI = 1.15-2.20). When examining this relationship by age, the positive association with EOC was stronger among women <50years of age (OR for highest vs. lowest tertile = 2.61; 95% CI = 1.15-5.94), followed by women aged 50-60years (OR = 2.27; 95% CI = 1.30-3.94). Yet, no association was present among women aged >60years (OR = 0.79; 95% CI = 0.45-1.40). In a population of AA women, we observed a positive association between LOCs and EOC risk, providing further support for the hypothesis that incessant ovulation contributes to the etiology of EOC.

Association of a common variant of SYNPO2 gene with increased risk of serous epithelial ovarian cancer.

In China, the majority of ovarian cancer patients (80%-90%) are women who are diagnosed with epithelial ovarian cancer. The SYNPO2 gene has recently been reported to be associated with epithelial ovarian cancer in Europeans. To investigate the association of common variants of SYNPO2 gene with epithelial ovarian cancer in Han Chinese individuals, we designed a case-control study with 719 epithelial ovarian cancer patients and 1568 unrelated healthy controls of Han Chinese descent. A total of 49 tagging single-nucleotide polymorphisms were genotyped; single-single-nucleotide polymorphism association, imputation, and haplotypic association analyses were performed. The single-nucleotide polymorphism rs17329882 was found to be strongly associated with serous epithelial ovarian cancer and with ages ≤49 years, consistent with the pre-menopausal status of analyzed epithelial ovarian cancer cases. Odds ratios and 95% confidence intervals provided evidence of the risk effects of the C allele of the single-nucleotide polymorphism on epithelial ovarian cancer. Imputation analyses also confirmed the results with a similar pattern. Additionally, haplotype analyses indicated that the haplotype block that contained rs17329882 was significantly associated with epithelial ovarian cancer risk, specifically with the serous epithelial ovarian cancer subtype. In conclusion, our results show that SYNPO2 gene plays an important role in the etiology of epithelial ovarian cancer, suggesting that this gene may be a potential genetic modifier for developing epithelial ovarian cancer.

Genetically-defined ovarian cancer mouse models.

Epithelial ovarian cancer (EOC), the deadliest of gynaecological cancers, is a disease that remains difficult to detect early and treat efficiently. A significant challenge for researchers in the field is that the aetiology of EOC and the molecular pathways important for its development are poorly understood. Moreover, precursor lesions have not been readily identifiable, making the mechanisms of EOC progression difficult to delineate. In order to address these issues, several genetically-defined ovarian mouse models have been generated in the past 15 years. However, because of the recent suggestion that most EOCs may not originate from the ovarian surface 'epithelium', but from other tissues of the female genital tract, some models may need to be re-evaluated within this new paradigm. In this review, we examine several genetically-defined EOC models and discuss how the new paradigm may explain some of the features of these models. A better understanding of the strengths and limitations of the current EOC mouse models will undoubtedly allow us to utilize these tools to better understand the biology of the disease and develop new approaches for EOC prevention, detection, and treatment.

Association of organochlorine pesticides and risk of epithelial ovarian cancer: A case control study

Background/aimsOrganochlorine pesticides (OCPs) belongs to the class of hydrocarbons characterize by its cyclic structure. Due to their persistence nature OCP gets accumulated in the food chain and cause possible adverse health effects specifically various hormone mediated disorders. Ovarian cancer is also one of the hormone dependant cancer and begins with the transformation of cells that comprises the ovaries including surface epithelial, germ cells, etc. It has been suggested that endocrine disruption, exposure to xenobiotic and subsequent oxidative stress may antedate ovarian cancer and contribute to its pathogenesis. However, no report regarding any association of OCP level with etiology of epithelial ovarian cancer is so far available among North Indian population. MethodsA total of 120 subjects were included in this case control study, consisting of 60 histological proven cases of epithelial ovarian cancer and 60 controls subjects. Quantification of OCP levels was done by Perkin Elmer Gas Chromatograph (GC) equipped with 63Ni selective Electron Capture Detector. ResultsLevels of β-HCH, endosulfan I, p'p'-DDT, p'p'-DDE and heptachlor were found significantly high in cases of epithelial ovarian cancer as compare to control. A significant association was also observed between higher levels of β-HCH and heptachlor and EOC with odds ratio of 2.76 and 2.97 respectively. ConclusionResults indicate the plausible role of OCPs with the pathogenesis of epithelial ovarian cancer among north Indian population. Moreover, it is one of the first report suggesting significant level of heptachlor among north Indian women population with epithelial ovarian cancer.

Role of aberrant glycosylation in ovarian cancer dissemination

Epithelial ovarian cancer (EOC) is the most lethal gynecologic malignancy, and understanding the molecular changes associated with EOC etiology could lead to the identification of novel targets for more effective therapeutic interventions. Glycosylation represents a post-translational modification (PTM) of proteins playing a major role in various cellular functions. Moreover, glycosylation participates in major pathobiological events during tumor progression, as aberrant expression of glycan structures has been shown to contribute in alterations of specific cellular onco-phenotypes, including tumor cell proliferation, migration and invasion. This review aims to describe what is currently known about aberrant glycosylation in EOC, and more specifically, the contribution of aberrant O-linked glycosylation in EOC progression. We also discuss our findings about the altered GALNT3 overexpression in EOC and its involvement in disease dissemination through aberrant mucin O-glycosylation, as well as the potential to exploit the role of GALNT3 in understanding the general mechanisms of abnormal glycosylation implicated in EOC spreading. Further analyses in cancer glycobiology could significantly enhance our understanding of the molecular mechanisms of cancer progression, including EOC dissemination, and could lead to the identification of novel biomarkers/therapeutic targets for better management of this deadly disease. Biomedical Reviews 2014; 25: 83-92.

Abstract 260: Integrative genomic analysis identifies epigenetic marks that mediate genetic risk for epithelial ovarian cancer

Abstract Both genetic and epigenetic factors influence the development and progression of epithelial ovarian cancer (EOC). However, there is an incomplete understanding of the interrelationship between these factors and whether they interact to impact disease risk. Given that the development of ovarian cancer is complex, we aimed to identify DNA methylation marks that are candidates for mediating ovarian cancer genetic risk. We used 214 cases and 214 age-matched controls from the Mayo Clinic Ovarian Cancer Study. Pretreatment, blood-derived DNA was profiled for genome-wide methylation (Illumina Infinium HumanMethylation27 BeadArray) and single nucleotide polymorphisms (SNPs, Illumina Infinium HD Human610-Quad BeadArray). We employed a three-step filtering procedure, followed by the Causal Inference Test (CIT), to distinguish CpG sites that mediate genetic risk, from those that are consequential or independently acted on by genotype. Controlling for the estimated distribution of immune cells and other key covariates, we identified 1,993 out of 25,926 (7.7%) CpGs that were significantly differentially methylated between cases and controls (FDR, q &amp;lt; 0.05). The relationship between methylation and case-control status among these 1,993 CpGs was found to be highly consistent with the results of an independent study. Implementation of the CIT test revealed 13 CpG/SNP pairs, comprising 13 unique CpGs and 17 unique SNPs, which represent potential methylation-mediated relationships between genotype and EOC risk. These findings provide additional insight into EOC etiology and may serve as novel biomarkers for EOC susceptibility. Citation Format: Devin C. Koestler, Prabhakar Chalise, Mine S. Cicek, Julie M. Cunningham, Sebastian Armasu, Melissa C. Larson, Jeremy Chien, Matthew Block, Kimberly R. Kalli, Thomas A. Sellers, Ellen L. Goode, Brooke L. Fridley. Integrative genomic analysis identifies epigenetic marks that mediate genetic risk for epithelial ovarian 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 260. doi:10.1158/1538-7445.AM2014-260

Integrative genomic analysis identifies epigenetic marks that mediate genetic risk for epithelial ovarian cancer

BackgroundBoth genetic and epigenetic factors influence the development and progression of epithelial ovarian cancer (EOC). However, there is an incomplete understanding of the interrelationship between these factors and the extent to which they interact to impact disease risk. In the present study, we aimed to gain insight into this relationship by identifying DNA methylation marks that are candidate mediators of ovarian cancer genetic risk.MethodsWe used 214 cases and 214 age-matched controls from the Mayo Clinic Ovarian Cancer Study. Pretreatment, blood-derived DNA was profiled for genome-wide methylation (Illumina Infinium HumanMethylation27 BeadArray) and single nucleotide polymorphisms (SNPs, Illumina Infinium HD Human610-Quad BeadArray). The Causal Inference Test (CIT) was implemented to distinguish CpG sites that mediate genetic risk, from those that are consequential or independently acted on by genotype.ResultsControlling for the estimated distribution of immune cells and other key covariates, our initial epigenome-wide association analysis revealed 1,993 significantly differentially methylated CpGs that between cases and controls (FDR, q < 0.05). The relationship between methylation and case-control status for these 1,993 CpGs was found to be highly consistent with the results of previously published, independent study that consisted of peripheral blood DNA methylation signatures in 131 pretreatment cases and 274 controls. Implementation of the CIT test revealed 17 CpG/SNP pairs, comprising 13 unique CpGs and 17 unique SNPs, which represent potential methylation-mediated relationships between genotype and EOC risk. Of these 13 CpGs, several are associated with immune related genes and genes that have been previously shown to exhibit altered expression in the context of cancer.ConclusionsThese findings provide additional insight into EOC etiology and may serve as novel biomarkers for EOC susceptibility.

Abstract B2: Sex steroid hormones and epithelial ovarian cancer: A nested case-control study in two maternity cohorts

Abstract Sex steroid hormones are thought to be involved in the etiology of epithelial ovarian cancer (EOC). At present, only the association of prediagnostic endogenous androgen concentrations with risk of EOC has been investigated and the results were unremarkable. The relatively small number of cases included in the previous studies precluded analyses by histological subtypes, despite growing evidence that the associations of risk factors differ by histological subtype and invasiveness of EOC. We nested a case-control study within the Finnish Maternity Cohort and the Northern Sweden Maternity Cohort. Study subjects were selected among cohort members with singleton pregnancies, who donated a blood sample during the first trimester of a pregnancy leading to childbirth, and who were free of invasive cancer (except for non-melanoma skin cancer) and/or borderline ovarian cancer up to the relevant index date. Through linkages with the nationwide cancer registries, we identified 1,052 EOC cases among cohort members diagnosed after blood collection and before March 2011. The sample from the pregnancy that led to the birth of the last child before diagnosis was selected for the study. Up to three controls were matched to each case by cohort, age at and date of blood donation as well as parity at the index pregnancy and cancer diagnosis (n=2,692). Concentrations of progesterone, 17-hydroxyprogesterone (17-OHP), androgens (testosterone and androstenedione), and estradiol were measured by high-performance liquid chromatography tandem mass spectrometry. Odds ratios (OR) and 95% confidence intervals [CI] across tertiles of hormone concentrations were estimated by conditional logistic regression and adjusted for gestational age at blood donation (except for androgens), maternal age at first birth, smoking and family history of breast and/or ovarian cancer. The majority of the cases were diagnosed with invasive EOC (n=642, 61%). Of these, 283 (44%) were serous, 150 (23%) mucinous, and 128 (20%) endometrioid or clear cell. Among the borderline tumors (n=410, 39%), 194 (47%) were serous and 206 (50%) mucinous. Median age at EOC diagnosis was 44 years and on average 12 years elapsed between blood donation and diagnosis. Associations of hormones with EOC differed by tumor histology and invasiveness. None of the hormones were associated with risk of invasive serous tumors. For borderline serous tumors, we observed positive associations with testosterone (1.85 [1.16-2.95]) and 17-OHP (1.75 [1.06-2.89]) comparing extreme tertiles of hormone concentrations. Risk of both invasive and borderline mucinous tumors significantly increased with androgen concentrations (about 75% risk increase in the top tertiles of each hormone for each subtype). Risk of endometrioid and clear cell tumors increased with rising estradiol concentrations (2.33 [0.95-5.72], ptrend=0.07). Similar associations were observed in subgroup analyses by time between blood donation and cancer diagnosis or ages at diagnosis or blood donation. In this large prospective study elevated early pregnancy androgen concentrations were associated with risk of borderline serous, and borderline and invasive mucinous EOC, whereas elevated estradiol concentrations were associated with risk of endometrioid and clear cell EOC. These results support a role of sex steroid hormones in the etiology of EOC arising in the ovaries. In contrast, sex steroid concentrations were not related to invasive serous tumors, which are presumed to originate in the fallopian tubes. First trimester progesterone concentrations were not associated with maternal risk of EOC, but it would be of interest to explore if the peak concentrations during the third trimester are etiologically important. Citation Format: Helena Schock, Eva Lundin, Anne Zeleniuch-Jacquotte, Kjell Grankvist, Hans-Åke Lakso, Eero Pukkala, Matti Lehtinen, Paolo Toniolo, Heljä-Marja Surcel, Annekatrin Lukanova. Sex steroid hormones and epithelial ovarian cancer: A nested case-control study in two maternity cohorts. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr B2.

Abstract 4729: Pathway and gene set analyses for epithelial ovarian cancer (EOC) genome-wide association study (GWAS)

Abstract The etiology of ovarian cancer is poorly understood but there is clearly a heritable component. Efforts to identify susceptibility alleles rarely consider interactions among alleles or their joint effects because it quickly becomes computationally intractable. In this study, we sought to identify multi-SNP effects jointly with a pathway-based analysis (GSEA-SNP) of 1,952 EOC cases and 2,042 frequency-matched controls genotyped with the Illumina 610K array. All subjects were self-reported non-Hispanic non-Jewish Caucasians, with SNP and sample call rates &amp;gt; 95%. Subjects with ambiguous gender, unresolved identical genotypes and &amp;lt; 80% European ancestry were excluded. SNPs with MAF &amp;lt; 1% were excluded. Missing genotypes were inferred using Mach based on the HapMap CEU population. SNPs not within introns were annotated to genes within 100 bp. We retrieved the following databases of gene sets (GSs) from a compiled database, MsigDB: human chromosome and cytogenetic band, chemical and genetic perturbations, canonical pathways, microRNA binding targets, transcription factor targets (TFT), cancer gene neighborhood (CGN), Cancer modules and Gene Ontology. The GSEA-SNP approach calculates and rank orders the trend statistic for association between each SNP and EOC risk. The Enrichment Score (ES) estimates the overrepresentation of top-ranked SNPs for each GS; the statistical significance was estimated using 10,000 permutations. The ES was normalized according to the size of GS to yield Normalized Enrichment Score (NES). The false discovery (FDR) rate was estimated using NES to adjust for multiple hypothesis testing. A total of 5181 gene-sets were included in the analysis. When controlling the FDR at 15%, 14 of the GSs were highly enriched with association signals, including two chromosomal regions, 8q13 (p = 0.0055, FDR = 0.15) and 6p24 (p = 0.0012, FDR = 0.08). BIOCARTA_LYM_PATHWAY, a pathway related to cell adhesion and diapedesis of lymphocytes, was also significant (p = 0.0002, FDR = 0.12). A TFT GS, composed of genes with promoter regions around transcription start sites containing the motif GGCNRNWCTTYS, was associated with risk (p = 0.0004, FDR = 0.08). Currently, no known transcription factors bind to this computationally predicted motif. Molecular function of double stranded RNA binding was also enriched (p = 0.005, FDR = 0.10). The remaining enriched sets were CGN sets, for which the neighborhoods around the cancer genes were originally defined using correlation of gene expression from 4 large data sets of various cancer types. The enriched CGN included: CD48 (p = 0.011), CD53 (p = 0.009), CD97 (p = 0.011), INPP5D (p = 0.010), PTPN6 (p = 0.008), VAV1 (p = 0.011), ITGAL (p = 0.012), PTPRC (p = 0.012), and STAT6 (p = 0.010). In summary, these analyses detected biologically plausible GSs related to etiology of EOC, highlighting SNPs in core enrichment groups that were not identified using individual SNP tests. 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 4729. doi:10.1158/1538-7445.AM2011-4729