Ovarian Tumor Samples Research Articles

Functional Interrogation of Enhancer Connectome Prioritizes Candidate Target Genes at Ovarian Cancer Susceptibility Loci.

Identifying causal regulatory variants and their target genes from the majority of non-coding disease-associated genetic loci is the main challenge in post-Genome-Wide Association Studies (GWAS) functional studies. Although chromosome conformation capture (3C) and its derivative technologies have been successfully applied to nominate putative causal genes for non-coding variants, many GWAS target genes have not been identified yet. This study generated a high-resolution contact map from epithelial ovarian cancer (EOC) cells with two H3K27ac-HiChIP libraries and analyzed the underlying gene networks for 15 risk loci identified from the largest EOC GWAS. By combinatory analysis of 4,021 fine-mapped credible variants of EOC GWAS and high-resolution contact map, we obtained 162 target genes that mainly enriched in cancer related pathways. Compared with GTEx eQTL genes in ovarian tissue and annotated proximal genes, 132 HiChIP targets were first identified for EOC causal variants. More than half of the credible variants (CVs) involved interactions that were over 185 kb in distance, indicating that long-range transcriptional regulation is an important mechanism for the function of GWAS variants in EOC. We also found that many HiChIP gene targets showed significantly differential expressions between normal ovarian and EOC tumor samples. We validated one of these targets by manipulating the rs9303542 located region with CRISPR-Cas9 deletion and dCas9-VP64 activation experiments and found altered expression of HOXB7 and HOXB8 at 17q21.32. This study presents a systematic analysis to identify putative target genes for causal variants of EOC, providing an in-depth investigation of the mechanisms of non-coding regulatory variants in the etiology and pathogenesis of ovarian cancer.

Oncogenic B-Myb Is Associated With Deregulation of the DREAM-Mediated Cell Cycle Gene Expression Program in High Grade Serous Ovarian Carcinoma Clinical Tumor Samples.

Cell cycle control drives cancer progression and treatment response in high grade serous ovarian carcinoma (HGSOC). MYBL2 (encoding B-Myb), an oncogene with prognostic significance in several cancers, is highly expressed in most HGSOC cases; however, the clinical significance of B-Myb in this disease has not been well-characterized. B-Myb is associated with cell proliferation through formation of the MMB (Myb and MuvB core) protein complex required for transcription of mitotic genes. High B-Myb expression disrupts the formation of another transcriptional cell cycle regulatory complex involving the MuvB core, DREAM (DP, RB-like, E2F, and MuvB), in human cell lines. DREAM coordinates cell cycle dependent gene expression by repressing over 800 cell cycle genes in G0/G1. Here, we take a bioinformatics approach to further evaluate the effect of B-Myb expression on DREAM target genes in HGSOC and validate our cellular model with clinical specimens. We show that MYBL2 is highly expressed in HGSOC and correlates with expression of DREAM and MMB target genes in both The Cancer Genome Atlas (TCGA) as well as independent analyses of HGSOC primary tumors (N = 52). High B-Myb expression was also associated with poor overall survival in the TCGA cohort and analysis by a DREAM target gene expression signature yielded a negative impact on survival. Together, our data support the conclusion that high expression of MYBL2 is associated with deregulation of DREAM/MMB-mediated cell cycle gene expression programs in HGSOC and may serve as a prognostic factor independent of its cell cycle role. This provides rationale for further, larger scale studies aimed to determine the clinical predictive value of the B-Myb gene expression signature for treatment response as well as patient outcomes.

Long non‑coding RNA ASAP1‑IT1 suppresses ovarian cancer progression by regulating Hippo/YAP signaling.

Long non‑coding RNAs (lncRNAs) are a class of non‑protein coding transcripts that are involved in the regulation of gene expression in mammalian cells. Transcriptional co‑activator Yes associated protein 1 (YAP1) plays a key role in the progression of ovarian cancer. However, the regulation of Hippo/YAP signaling in ovarian cancer remains elusive. In the present study, the expression levels of lncRNA ASAP1‑IT1 were investigated. The analysis indicated that lncRNA ASAP1‑IT1 expression was downregulated in ovarian tumor samples and ovarian cancer cells. The overexpression of ASAP1‑IT1 inhibited ovarian cancer cell proliferation and induced cell apoptosis. Bioinformatics analysis predicted that miR‑2278, a previously reported upregulated miRNA in ovarian tumors, may bind to ASAP1‑IT1. Dual luciferase assay confirmed the direct regulatory association between ASAP1‑IT1 and miR‑2278. In addition, the data demonstrated that large tumor suppressor 2 (LATS2) was a target gene of miR‑2278, whose expression was upregulated by ASAP1‑IT1 in ovarian cancer cells. By regulating the expression of LATS2, ASAP1‑IT1 induced the downregulation of YAP1 expression in ovarian cancer cells. Moreover, the silencing of LATS2 attenuated the inhibition of cell proliferation and the apoptosis induced by ASAP1‑IT1 overexpression in ovarian cancer cells. The association among the expression levels of ASAP1‑IT1, miR‑2278 and LATS2 was observed in specimens obtained from patients with ovarian cancer. Taken together, the data presented herein demonstrate that ASAP1‑IT1 functions as a potential tumor suppressor lncRNA by upregulating LATS2 expression in ovarian cancer.

Systematically Characterizing A-to-I RNA Editing Neoantigens in Cancer.

A-to-I RNA editing can contribute to the transcriptomic and proteomic diversity of many diseases including cancer. It has been reported that peptides generated from RNA editing could be naturally presented by human leukocyte antigen (HLA) molecules and elicit CD8+ T cell activation. However, a systematical characterization of A-to-I RNA editing neoantigens in cancer is still lacking. Here, an integrated RNA-editing based neoantigen identification pipeline PREP (Prioritizing of RNA Editing-based Peptides) was presented. A comprehensive RNA editing neoantigen profile analysis on 12 cancer types from The Cancer Genome Atlas (TCGA) cohorts was performed. PREP was also applied to 14 ovarian tumor samples and two clinical melanoma cohorts treated with immunotherapy. We finally proposed an RNA editing neoantigen immunogenicity score scheme, i.e. REscore, which takes RNA editing level and infiltrating immune cell population into consideration. We reported variant peptide from protein IFI30 in breast cancer which was confirmed expressed and presented in two samples with mass spectrometry data support. We showed that RNA editing neoantigen could be identified from RNA-seq data and could be validated with mass spectrometry data in ovarian tumor samples. Furthermore, we characterized the RNA editing neoantigen profile of clinical melanoma cohorts treated with immunotherapy. Finally, REscore showed significant associations with improved overall survival in melanoma cohorts treated with immunotherapy. These findings provided novel insights of cancer biomarker and enhance our understanding of neoantigen derived from A-to-I RNA editing as well as more types of candidates for personalized cancer vaccines design in the context of cancer immunotherapy.

The Capacity of the Ovarian Cancer Tumor Microenvironment to Integrate Inflammation Signaling Conveys a Shorter Disease-free Interval.

Ovarian cancer has one of the highest deaths to incidence ratios across all cancers. Initial chemotherapy is effective, but most patients develop chemoresistant disease. Mechanisms driving clinical chemo-response or -resistance are not well-understood. However, achieving optimal surgical cytoreduction improves survival, and cytoreduction is improved by neoadjuvant chemotherapy (NACT). NACT offers a window to profile pre- versus post-NACT tumors, which we used to identify chemotherapy-induced changes to the tumor microenvironment. We obtained matched pre- and post-NACT archival tumor tissues from patients with high-grade serous ovarian cancer (patient, n = 6). We measured mRNA levels of 770 genes (756 genes/14 housekeeping genes, NanoString Technologies), and performed reverse phase protein array (RPPA) on a subset of matched tumors. We examined cytokine levels in pre-NACT ascites samples (n = 39) by ELISAs. A tissue microarray with 128 annotated ovarian tumors expanded the transcriptional, RPPA, and cytokine data by multispectral IHC. The most upregulated gene post-NACT was IL6 (16.79-fold). RPPA data were concordant with mRNA, consistent with elevated immune infiltration. Elevated IL6 in pre-NACT ascites specimens correlated with a shorter time to recurrence. Integrating NanoString (n = 12), RPPA (n = 4), and cytokine (n = 39) studies identified an activated inflammatory signaling network and induced IL6 and IER3 (immediate early response 3) post-NACT, associated with poor chemo-response and time to recurrence. Multiomics profiling of ovarian tumor samples pre- and post-NACT provides unique insight into chemo-induced changes to the tumor microenvironment. We identified a novel IL6/IER3 signaling axis that may drive chemoresistance and disease recurrence.

Identification of three molecular subtypes based on immune infiltration in ovarian cancer and its prognostic value.

Background: Increasing studies suggest that tumor immune infiltration is a relative factor of prognosis in ovarian cancer (OvCa). The present study explored the composition of tumor-infiltrating immune cells (TIICs) in OvCa using CIBERSORT algorithm and further assessed their values for prognosis and therapeutic strategies by molecular subtypes.Methods: Publicly available databases including The Cancer Genome Atlas (TCGA) and GTEx were searched. Ovarian tumor samples were available from TCGA, and normal ovarian samples were obtained from the GTEx dataset. The relative proportions of immune cell profiling in OvCa and normal samples were evaluated by CIBERSORT algorithm. Association between each immune cell subtype and survival was inferred by the fractions of 22 immune cell types. “CancerSubtypes” R-package was employed to identify the three types of molecular classification and analyze the functional enrichment in each subclass. Response to immunotherapy and anticancer drug targets was predicted via TIDE algorithm and GDSC dataset.Results: Substantial variation reflecting individual difference was identified between cancer and normal tissues in the immune infiltration profiles. T cells CD4 memory activated, macrophages M1 were associated with improved overall survival (OS) as evaluated by univariate Cox regression and multivariate Cox. Three subtypes were identified by ´CancerSubtypes’ R-package and every sub-cluster possessed specific immune cell characterization. Meanwhile, Cluster II exhibited poor prognosis and sensitive response to immunotherapy.Conclusions: The cellular component of immune infiltration shows remarkable variation in OvCa. Profiling of immune infiltration is useful in prediction of prognosis of OvCa. The results from profiling might be considered in therapeutic modulation.

Expression of p52, a non-canonical NF-kappaB transcription factor, is associated with poor ovarian cancer prognosis

BackgroundThe canonical and non-canonical nuclear factor-kappaB (NF-κB) signaling pathways have key roles in cancer, but studies have previously evaluated only the association of canonical transcription factors and ovarian cancer survival. Although a number of in vitro and in vivo studies have demonstrated mechanisms by which non-canonical NF-κB signaling potentially contributes to ovarian cancer progression, a prognostic association has yet to be shown in the clinical context.MethodsWe assayed p65 and p52 (major components of the canonical and non-canonical NF-κB pathways) by immunohistochemistry in epithelial ovarian tumor samples; nuclear and cytoplasmic staining were semi-quantified by H-scores and dichotomized at median values. Associations of p65 and p52 with progression-free survival (PFS) and overall survival (OS) were quantified by Hazard Ratios (HR) from proportional-hazards regression.ResultsAmong 196 cases, median p52 and p65 H-scores were higher in high-grade serous cancers. Multivariable regression models indicated that higher p52 was associated with higher hazards of disease progression (cytoplasmic HR: 1.54; nuclear HR: 1.67) and death (cytoplasmic HR: 1.53; nuclear HR: 1.49), while higher nuclear p65 was associated with only a higher hazard of disease progression (HR: 1.40) in unadjusted models. When cytoplasmic and nuclear staining were combined, p52 remained significantly associated with increased hazards of disease progression (HR: 1.91, p = 0.004) and death (HR: 1.70, p = 0.021), even after adjustment for p65 and in analyses among only high-grade serous tumors.ConclusionsThis is the first study to demonstrate that p52, a major component of non-canonical NF-κB signaling, may be an independent prognostic factor for epithelial ovarian cancer, particularly high-grade serous ovarian cancer. Approaches to inhibit non-canonical NF-κB signaling should be explored as novel ovarian cancer therapies are needed.

Characterizing the Tumor Microenvironment of Metastatic Ovarian Cancer by Single Cell Transcriptomics

Epithelial ovarian cancer is a highly heterogenous, metastatic and lethal disease. The presence of CD8+ T cells within ovarian tumors is positively associated with overall patient survival. Determining if a patient has T cells that respond to immunotherapies, their characteristics and how they can be manipulated to target cancer cells is an area of intense investigation in cancer therapy. This study determines the cellular composition and the transcriptional state of immune cells in solid metastatic ovarian cancer tumor samples from patients using single cell RNA sequencing (scRNA-seq). Hierarchical clustering stratified our patient samples into 2 main groups: 1) a high T cell infiltration (high Tinf ) group and 2) a low T cell infiltration (low Tinf) group. To assess the immune response in these patient samples, we performed an unsupervised clustering of the T cell population in each group. The T cell population clustered into 4 and 3 subpopulations in the high Tinf and low Tinf group respectively. A granulysin-expressing T cell cluster was identified and unique to the High Tinf group. Interestingly, although both groups had resident memory CD8+ T (CD8+ Trm) cells, only the CD8+ Trm cells in the high Tinf group expressed TOX , a recently described transcription factor that confers longevity to T cells within immunosuppressive environments such as cancer. Along with TOX+ CD8+ Trm cells, we found a unique plasmablast cluster and an IRF8+ macrophage cluster unique to the high Tinf group. Our comprehensive scRNA-seq study provides important insights in elucidating the immune response within ovarian tumors.

The expression of Fibulin-3 in ovarian cancer and its relationship with prognosis.

BackgroundDespite the significant advancements made in the treatment of ovarian cancer (OC), poor prognosis remains a major concern because this disease is frequently diagnosed at an advanced stage. Tumor recurrence and metastasis have been implicated in the poor clinical outcomes of OC. Although Fibulin-3 has been shown to be closely related to the development of various tumors, its relationship with OC has not been widely examined. Hence, this study was conducted to investigate the expression of Fibulin-3 in epithelial ovarian cancer (EOC), determine its relationship with EOC prognosis, and correlate its expression with that of the epithelial-mesenchymal transition markers (Snail, E-cadherin, and N-cadherin).MethodsImmunohistochemistry analysis was performed to detect the expression of Fibulin-3 protein in 84 OC samples, 10 benign ovarian tumor samples, and eight borderline ovarian tumor samples.ResultsThe positive rates of Fibulin-3 protein expression in OC, benign ovarian tumors, and borderline ovarian tumors were 45.24%, 20%, and 0%, respectively, showing significant differences (P<0.05). Fibulin-3 expression was found to be correlated with the FIGO stage of EOC, with tumors in higher stages (FIGO III + IV) showing higher expression. Additionally, at the protein level, Fibulin-3 was negatively correlated with E-cadherin protein (r=–0.252, P<0.05), and positively correlated with Snail and N-cadherin protein (r=0.644, 0.451, P<0.01).Overexpression of Fibulin-3 and the FIGO stage (III + IV) were related to the poor prognosis of patients (P<0.05). High expression of Fibulin-3 was an independent prognostic factor of EOC (P<0.05) The survival curve analysis showed that patients overexpressing Fibulin-3 had significantly shorter survival than those with low expression (P<0.05).ConclusionsIncreased expression of Fibulin-3 was found to be related to the invasion, metastasis, and prognosis of ovarian tumors, suggesting that it is an important indicator for evaluating the clinical prognosis of patients with EOC.

Abstract 5255: The SAGE Direct TestTM: A reliable way of functional profiling to predict the most effective treatment for cancer patients

Abstract Cancer is a genetic disease with increasing heterogeneity during disease progression. However, despite the widespread use of genomic testing, a recent publication estimated that only 5% of cancer patients in the US benefit from genome-driven targeted therapies, largely because “actionable mutations” are rare.[1] Thus, SageMedic has developed the SAGE Direct Test™, leading the next generation of functional precision medicine to accurately predict the most effective treatment for virtually all cancer patients without limitations of genomic sequencing or having to identify a specific pathway. Our SAGE Direct Test™ consists of four critical steps, i.e., tissue processing, creation of 3D microtumors, live/dead cell imaging, and metabolic profiling. Using our proprietary technology, we can create hundreds of 3D microtumors from a core needle biopsy sample that recapitulate the in vivo tumor heterogeneity and microenvironment of the tumor biopsy. After these microtumors have been treated with a panel of drugs, we quantify the number of live and dead cells in those microtumors using our proprietary technology and scalable automatic stage confocal imaging (Molecular Devices). The advantage of our SAGE Direct Platform™ is the ability to multiplex our image-based results with the metabolic profile of our 3D microtumors, which cross validates our image-based readout. Our SAGE Direct Test™ has been optimized with ATCC cell lines and further validated with patient-derived tumor cells from lung, ovarian, and colon cancer tumor samples. Validation of high-quality confocal imaging samples followed by quantitative metabolic analysis suggests accurate quantification of viable cells, as reflected in a positive correlation between imaging quantitation and metabolic analysis (correlation coefficient r=0.84, p&amp;lt;0.01). In summary, SageMedic has developed the SAGE Direct Test™, a simple, highly sensitive, robust, and straightforward functional profiling assay with significant clinical relevance, as it can model the natural physiological conditions of tumors. [1] Marquart et al. Estimation of the Percentage of US Patients With Cancer Who Benefit From Genome-Driven Oncology. JAMA Oncology 2018 Aug 1;4(8):1093-1098 Citation Format: Dhruva Mishra, Jennifer Moy, Chris Apfel. The SAGE Direct TestTM: A reliable way of functional profiling to predict the most effective treatment for cancer patients [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5255.

MiR-5193, regulated by FUT1, suppresses proliferation and migration of ovarian cancer cells by targeting TRIM11

Ovarian cancer is the most lethal gynecological malignancy worldwide. A better understanding of the pathogenesis of ovarian cancer may help to improve the overall survival. Our previous studies have demonstrated that alpha-(1,2)-fucosyltransferase 1 (FUT1) is an oncogenic glycogene in ovarian cancer. However, the underlying mechanism is not fully clarified. In this study, we identified a microRNA as an important downstream regulator for the carcinogenic effect of FUT1 in ovarian cancer. miR-5193 was found down-regulated in ovarian cancer cells, FUT1-overexpression ovarian cancer cells and ovarian tumor samples. MTT, flow cytometry and Transwell assays demonstrated that miR-5193 inhibited the proliferation and migration, and induced the cell cycle arrest and apoptosis of ovarian cancer cells. Real-time PCR and western blot assays showed that miR-5193 downregulated the expression of TRIM11 and upregulated the expression of p53 and p21. Dual luciferase reporter assay indicated that TRIM11 was a direct target of miR‑5193. Rescue experiments confirmed that miR-5193 functioned in ovarian cancer cells by directly targeting TRIM11. Moreover, transfection with miR-5193 mimic in FUT1-overexpression ovarian cancer cells reversed the carcinogenic effect of FUT1. Taken together, our results suggest that miR-5193 is an essential suppressor of human ovarian cancer development, and is an important downstream regulator regarding the carcinogenesis of FUT1 in ovarian cancer.

FAT4 silencing promotes epithelial-to-mesenchymal transition and invasion via regulation of YAP and \u03b2-catenin activity in ovarian cancer

BackgroundThe adhesion molecule, FAT4, has a tumor suppressor function with a critical role in the epithelial-to-mesenchymal-transition (EMT) and anti-malignant growth in several cancers. No study has investigated yet its role in epithelial ovarian cancer (EOC) progression. In the present study, we examined the role of FAT4 in proliferation and metastasis, and its mechanisms of interaction in these processes.MethodsWe have performed cell viability, colony formation, and invasion assays in ovarian cancer cells treated with siRNA to knockdown FAT4 gene expression. The regulatory effects of FAT4 on proteins involved in apoptotic, Wnt, Hippo, and retinoblastoma signaling pathways were evaluated by Western blotting following FAT4 repression. Also, 426 ovarian tumor samples and 88 non-tumor samples from the Gene Expression Profiling Interactive Analysis (GEPIA) database were analyzed for the expression of FAT4. Pearson’s correlation was performed to determine the correlation between FAT4 and the E2F5, cyclin D1, cdk4, and caspase 9 expressions.ResultsLower expression of FAT4 was observed in ovarian cancer cell lines and human samples as compared to non-malignant tissues. This down-regulation seems to enhance cell viability, invasion, and colony formation. Silencing FAT4 resulted in the upregulation of E2F5, vimentin, YAP, β-catenin, cyclin D1, cdk4, and Bcl2, and in the downregulation of GSK-3-β, and caspase 9 when compared to control. Furthermore, regulatory effects of FAT4 on the EMT and aggressive phenotype seem to occur through Hippo, Wnt, and cell cycle pathways.ConclusionFAT4 downregulation promotes increased growth and invasion through the activation of Hippo and Wnt-β-catenin pathways.

Abstract B022: PARP1 complex composition as a predictor of response to PARP inhibitors in BRCA-linked ovarian carcinoma

Abstract Background: About 40-50% of epithelial ovarian cancers (EOC) show defects in DNA repair by homologous recombination (HR), which are mostly associated with BRCA1/2 loss-of-function mutations. The PARP inhibitors (PARPis) olaparib, niraparib and rucaparib were recently approved for treatment of ovarian cancer patients with platinum-sensitivity and recurrent ovarian cancer who carry inactivating BRCA1/2 mutations. These targeted drugs produce significant response rates ranging from 40-60% in patients with BRCA-linked advanced EOCs, but resistance is a continuing challenge. Whereas several studies have reported various mechanisms of acquired resistance to PARPis, the mechanisms of primary resistance are still poorly understood. Our goal is to develop predictors of PARPi response and to identify new targets for combination therapy to overcome primary resistance. We apply a novel integrated proteomics approach to develop mechanism-based biomarkers of response or primary resistance and to identify new therapeutic targets for rational combination approaches that can overcome resistance to single agent PARPi therapy. Methods: Primary patient-derived EOC cell lines and an isogenic EOC cell line pair with BRCA1 deletion and reconstituted with ectopic BRCA1 was used. Primary cell lines were genomically characterized by BROCA next generation sequencing. The effects of the FDA approved PARPis olaparib, rucaparib, and niraparib on BRCA1-null and BRCA1-reconstituted EOC cell lines regarding short- and long-term cell viability were determined by CellTiterGlo and crystal violet assays. Chemical and phosphoproteomics approach was used to identify the components of PARP1-based multiprotein complexes as well as protein post-translational modifications in the DNA damage signaling network in BRCA1/2-linked EOC cells. Specific PARP1-engaged protein complexes were further determined by immunoblotting. Frozen BRCA1-proficient and deficient ovarian cancer patient tumor samples collected at the time of debulking were also characterized by chemical proteomics. Results: Cell viability and clonogenic assays confirmed the expected correlation between PARPi response and BRCA1/2 status. Chemical proteomics with rucaparib and olaparib detected important elements of DNA damage repair, as components of PARP1 protein complexes, which are differentially represented in EOC cells that are sensitive to PARPi treatment compared to cells that show primary resistance to PARPi. In addition, phosphoproteomics analysis further identified significant and actionable changes in the DNA damage response signaling network in these cells. Most interestingly, these PARP1 protein complex differences are also observed in PARPi drug pulldowns (olaparib and rucaparib) from BRCA1-proficient compared to BRCA1-deficient tumor samples. Conclusion: Ovarian cancers that do not respond to PARPi displayed significant changes in PARPi-engaged protein complexes as well as protein modifications. We expect to identify new potential targets for combination therapy BRCA-linked EOC by further validation of our data. Citation Format: Ou Deng, Sweta Dash, Thales Nepomuceno, Ming D Han, Bin Fang, Doug Marchion, Alvaro N Monteiro, Uwe Rix. PARP1 complex composition as a predictor of response to PARP inhibitors in BRCA-linked ovarian carcinoma [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr B022. doi:10.1158/1535-7163.TARG-19-B022

DNA damage measurements within tissue samples with Repair Assisted Damage Detection (RADD).

Exposures to genotoxic carcinogens and reactive species result in strand breaks and a spectrum of covalent modifications to DNA that can induce mutations and contribute to the initiation and progression of cancer. Measurements of DNA damage within tissue or tumor samples can serve as a biomarker for exposures or assess changes in DNA repair capacity relevant in cancer development and treatment. Numerous methods to characterize DNA damage exist. However, these methods are primarily applicable to isolated DNA or cultured cells, often require a substantial amount of material, and may be limited to the detection and quantification of only a handful of DNA adducts. Here, we used the Repair Assisted Damage Detection (RADD) assay to detect and excise DNA adducts using a cocktail of DNA repair enzymes, then the damage site within the genome are tagged for detection using a modified nucleotide. We previously demonstrated the RADD assay can detect lesions within isolated DNA and fixed cells, and now RADD can be used to detect DNA adducts and DNA strand breaks in formalin-fixed paraffin-embedded (FFPE) tissue samples. We verified the ability of the RADD assay to detect DNA damage in tissue by exogenously inducing DNA damage with X-rays and restriction enzymes. We also showed that RADD can be multiplexed with antibodies to detect cell cycle markers or other proteins of interest. Finally, we showed that RADD can detect DNA damage within clinically relevant ovarian tumor samples. RADD is a flexible and easy-to-use assay that allows relative damage levels to be determined within FFPE samples and allows the heterogeneity of DNA adducts and strand breaks within clinically relevant samples to be measured.

1009P - Incidence of tumour BRCA1/2 variants in relapsed, platinum-sensitive ovarian, fallopian tube and primary peritoneal cancer

BackgroundRandomised phase 3 trials have demonstrated that poly (ADP-ribose) polymerase (PARP) inhibitors significantly improve progression-free survival in BRCA-mutant high-grade serous and endometrioid ovarian carcinoma. Consequently, the demand for germline and tumour BRCA1/2testing has increased significantly throughout the UK. We report results from a tumour BRCA1/2testing service available to cancer centres across England, Wales and Northern Ireland from July 2017 to February 2019. MethodsDNA extracted from formalin fixed, paraffin-embedded tumour samples underwent next generation sequencing for BRCA1/2 variants. Eligibility criteria included relapsed, platinum-sensitive ovarian, fallopian tube or primary peritoneal cancer with germline BRCA1/2wild-type or unknown germline. Patients also had to have received ≥2 prior lines of platinum-based chemotherapy. A confirmatory histopathology report was requested as part of the tumour BRCA1/2testing service. ResultsTwo hundred and ninety-three histologically-confirmed high-grade serous and/or endometrioid ovarian cancer tumour samples underwent tumour BRCA1/2testing. The prevalence of pathogenic (class 5) or likely pathogenic (class 4) variants was 17.7% (52/293). The germline BRCA1/2was wild-type for 185/293 (63.1%) of patients, with the remaining 36.9% (108/293) with germline BRCA1/2unknown. There were at least 36 (12.3%) pathogenic/likely pathogenic somatic BRCA1/2variants detected. The allele fraction for somatic BRCA1/2pathogenic variants ranged from 0.06 to 0.98, with 50% (18/36) reported with an allele fraction of≥0.5 (50%), in keeping with putative biallelic loss-of-function. ConclusionsProspective evaluation of paired germline and tumour BRCA1/2testing in all women who are diagnosed with platinum-sensitive high-grade serous and/or endometrioid ovarian cancer in the UK is now required to validate these findings. Legal entity responsible for the studyAstraZeneca. FundingAstraZeneca. DisclosureAll authors have declared no conflicts of interest.

Abstract 3809: Modulation of MRP1 activity reverses chemotherapy resistance in adult cancer cells

Abstract Multidrug resistance protein 1 (MRP1) is an ATP-dependent efflux pump that extrudes chemotherapeutic drugs from cancer cells, preventing their intracellular accumulation and thus their efficacy. MRP1 also regulates intracellular levels of glutathione (GSH), an antioxidant that when elevated in cancer provides resistance against chemotherapy- and radiotherapy-induced oxidative damage. The different binding sites for drugs and GSH on MRP1 has allowed the development of small molecule MRP1 modulators that block chemotherapy efflux whilst simultaneously enhancing GSH efflux to deplete GSH. As no therapeutic options are available to combat MRP1-mediated multidrug resistance, we have been investigating MRP1 modulators for their efficacy in sensitizing MRP1-expressing cancers to treatment. MRP1 immunohistochemistry staining in ovarian and non-small cell lung cancer (NSCLC) patient samples was assessed to determine the frequency of high MRP1 expression. High MRP1 staining was frequently observed in the subcellular compartment (37%, 47%) and, to a lesser extent, plasma membrane (7%, 16%) in ovarian and NSCLC patient tumour samples respectively. In NSCLC, subcellular MRP1 was associated with poorer overall survival in late stage disease (p=0.0095) and membrane MRP1 with poorer disease-free survival in Stage 4 cancer (p=0.01449). Analysis for ovarian cancer is ongoing. As MRP1 is therefore an attractive target for inhibition, we used membrane vesicle uptake assays to compare the ability of modulators to inhibit [3H]-labelled MRP1 substrate transport. 7-(difluoromethyl)-N-4-morpholinyl-5-phenylpyrazolo[1,5-a]pyrimidine-3-carboxamide (7914321) was identified as an analogue of the MRP1 inhibitor Reversan with improved potency. Interestingly, this inhibition was GSH dependent. Exploring further this relationship with GSH, the high MRP1-expressing A549 lung and SKOV3 ovarian cancer cell lines were treated with 7914321 alone or in combination with the GSH synthesis inhibitor buthionine sulfoximine (BSO), then GSH levels were determined by glutathione recycling assay. 7914321 stimulated GSH efflux in both cell lines in an MRP1-dependent manner and strongly synergised with BSO to cause near complete GSH depletion. To determine the potential of this synergistic GSH depletion to chemosensitize cells, the viability of A549 and SKOV3 cells treated with chemotherapy, 7914321, and BSO was assessed by clonogenic and resazurin-based cytotoxicity assays. 7914321/BSO significantly diminished clonogenicity in high but not low MRP1-expressing cells, and further sensitized cancer cell lines to MRP1-substrate chemotherapeutics compared to the single agents. Together, these findings provide preliminary evidence that 7914321 is a potent MRP1 modulator whose dual effects on MRP1 place it in a unique position to potentially enhance the therapeutic window to treat chemoresistant MRP1-overexpressing cancers. Citation Format: Kimberley M. Hanssen, Christine C. Gana, Madeleine S. Wheatley, Denise M. Yu, Claudia L. Flemming, Richard Young, Gavin M. Wright, Gwenaelle Conseil, Catherine J. Kennedy, Anna deFazio, Ben Solomon, Susan P. Cole, Murray D. Norris, Michelle Haber, Jamie I. Fletcher. Modulation of MRP1 activity reverses chemotherapy resistance in adult cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3809.

Ddx4+ Oogonial Stem Cells in Postmenopausal Women's Ovaries: A Controversial, Undefined Role.

Recent studies support the existence of oogonial stem cells (OSCs) in the ovarian cortex of different mammals, including women.These cells are characterized by small size, membrane expression of DEAD(Asp-Glu-Ala-Asp)-box polypeptide-4 (Ddx4), and stemness properties (such as self-renewal and clonal expansion) as well as the ability to differentiate in vitro into oocyte-like cells. However, the discovery of OSCs contrasts with the popular theory that there is a numerically defined oocyte pool for female fertility which undergoes exhaustion with menopause. Indeed, in the ovarian cortex of postmenopausal women OSCs have been detected that possess both viability and capability to differentiate into oocytes, which is similar to those observed in younger patients. The pathophysiological role of this cell population in aged women is still debated since OSCs, under appropriate stimuli, differentiate into somatic cells, and the occurrence of Ddx4+ cells in ovarian tumor samples also suggests their potential involvement in carcinogenesis. Although further investigation into these observations is needed to clarify OSC function in ovary physiology, clinical investigators and researchers studying female infertility are presently focusing on OSCs as a novel opportunity to restore ovarian reserve in both young women undergoing early ovarian failure and cancer survivors experiencing iatrogenic menopause.

The expression of Platelet-derived Growth factor receptors (PDGFRs) and their correlation with overall survival of patients with ovarian cancer.

The main aim of the study was to investigate the expression of Platelet-Derived Growth Factor Receptors alpha (PDGFR-alpha) and beta (PDGFR-beta) in malignant and benign ovarian tumors. We performed an analysis of the correlation of PDGFRs expression and stage of the disease, tumor grade and histopathological type of epithelial ovarian cancer (EOC). Additionally, we evaluated patient prognosis according to PDGFR expression. Our study group was composed of 52 samples of EOCs, 35 samples of benign ovarian tumors (BOTs), and 21 samples of unchanged ovaries (UOs). The samples were collected from patients who had been operated on in the Division of Gynecological Surgery of the Poznan University of Medical Sciences. PDGFR-alpha was found to be expressed more frequently in cancer cells of EOCs, when compared with tumor cells of BOTs and epithelium of UOs. On the other hand, PDGFR-alpha receptors were present less frequently in the stroma of EOCs, when compared with the stroma of BOTs and UOs. Comparing the studied groups, there were no statistically significant differences in the expression of PDGFR-beta. The expression of both PDGFRs was not related to the FIGO stage, grade or histopathological type of EOCs. The expression of the PDGFR-beta receptor in cancer cells was associated with an improved overall survival among patients with EOCs. Patient prognosis was not affected by either PDGFR-alpha expres- sion or by PDGFR-beta tumor stroma expression. The expression of PDGFR-alpha is significantly different when comparing EOCs, BOTs and UOs. However, the prognosis of EOC only seems to be affected by PDGFR-beta expression in cancer cells.

Cancer stem cell-related marker NANOG expression in ovarian serous tumors using Western blotting and immunohistochemistry: comparison of two techniques

Purpose of Investigation: The objective of the study was to evaluate cancer stem cell-related marker NANOG expression in ovarian serous tumors using Western blotting (WB) and to compare WB results to immunohistochemical (IHC) results of NANOG expression in the same tumors. Materials and Methods: Of the 37 ovarian tumor samples obtained intraoperatively, diagnosis of ovarian serous tumors was established histopathologically in 17 cases. WB and IHC for NANOG was performed on the parallel portions of the same ovarian tumors in the latter cases. The IHC staining samples were made up of a NANOG positive and a NANOG-negative group. Pursuant to summation of signal intensity and positive cell occurrence, the authors additionally divided the NANOG-positive group into three subgroups. Correlation coefficient between NANOG WB and NANOG IHC results was calculated. Results: NANOG measured by means of WB was significantly higher in the IHC determined NANOG-positive group than in the NANOG-negative group (p = 0.003). Comparison of the amount of NANOG measured by WB and IHC scores of individual cases revealed substantial dispersion of WB results among the NANOG subgroups; the dispersion was largest when NANOG was IHC only slightly-positive. In the NANOG moderate- and strongly-positive subgroups, WB values were higher and more homogenously arranged. In all IHC determined NANOG-negative cases NANOG WB values were low, with low value variability among tumor samples. However, correlation between NANOG WB results and NANOG IHC scoring subgroups revealed statistical significance (r = 0.73, p = 0.001). Conclusion: By means of WB and IHC the authors demonstrated NANOG to be a potential marker of ovarian high-grade serous carcinoma. Further research on the correlation between NANOG WB expression and clinical parameters is needed.

Overexpression of HER2/HER3 and clinical feature of ovarian cancer.

ObjectivesHuman epidermal growth factor receptor-2 (HER2) and 3 (HER3) belong to the epidermal growth factor receptor (EGFR) family of transmembrane receptor tyrosine kinases. In this study, we assessed HER2/HER3 expression levels in specimens of epithelial ovarian cancer and determined their correlation with clinical features of ovarian cancer.MethodsTissue microarrays (TMAs) were prepared from paraffin blocks of 105 ovarian tumour samples. HER2, HER3, PI3K, Akt, p-Akt, mTOR, p-mTOR, S6, and p-S6 expression levels were investigated using immunohistochemistry (IHC). HER2 and HER3 amplifications were determined using in situ hybridization (ISH). The correlation between HER2/3 expression and disease outcome of the patients including surgical outcome, progression-free survival (PFS) and overall survival (OS) was analysed.ResultsHER2 positivity was 3.8% by IHC and 5.7% by ISH, whereas that of HER3 was 12.4% and 8.6%, respectively. HER2 status by either IHC or ISH was not related to PFS (p=0.128, 0.168, respectively) and OS (p=0.245, 0.164, respectively). However, the HER3 status determined using fluorescence ISH was associated with poor PFS (p=0.035 on log rank test), which was a significant risk factor even after adjusting other possible risk factors in multivariate analysis (hazard ratio=2.377 [1.18–7.49], p=0.021). Expressions of Akt, p-mTOR, and S6 were also related with poor progression (p=0.008, 0.049, 0.014, respectively).ConclusionHER3 is possibly an independent marker for poor prognosis in individuals with ovarian cancer, as the HER3 signalling pathway is distinct from that of HER2. The possibility of targeted therapy for patients with HER3 alteration in ovarian cancer should be evaluated.