Treatment Of High-grade Serous Ovarian Cancer Research Articles

Integrated weighted gene co-expression network analysis reveals biomarkers associated with prognosis of high-grade serous ovarian cancer.

BackgroundOvarian cancer is the gynecologic tumor with the highest fatality rate, and high‐grade serous ovarian cancer (HGSOC) is the most common and malignant type of ovarian cancer. One important reason for the poor prognosis of HGSOC is the lack of effective diagnostic and prognostic biomarkers. New biomarkers are necessary for the improvement of treatment strategies and to ensure appropriate healthcare decisions.MethodsTo construct the co‐expression network of HGSOC samples, we applied weighted gene co‐expression network analysis (WGCNA) to assess the proteomic data obtained from the Clinical Proteomic Tumor Analysis Consortium (CPTAC), and module‐trait relationship was then analyzed and plotted in a heatmap to choose key module associated with HGSOC. Subsequently, hub genes with high connectivity in key module were identified by Cytoscape software. Furthermore, the biomarkers were selected through survival analysis, followed by evaluation using the relative operating characteristic (ROC) analysis.ResultsA total of 9 modules were identified by WGCNA, and module‐trait analysis revealed that the brown module was significantly associated with HGSOC (cor = 0.7). Ten hub genes with the highest connectivity were selected by protein‐protein interaction analysis. After survival and ROC analysis, ALB, APOB and SERPINA1 were suggested to be the biomarkers, and their protein levels were positively correlated with HGSOC prognosis.ConclusionWe conducted the first gene co‐expression analysis using proteomic data from HGSOC samples, and found that ALB, APOB and SERPINA1 had prognostic value, which might be applied for the treatment of HGSOC in the future.

Ovarian cancer recurrence: "is the definition of platinum resistance modified by PARP inhibitors and other intervening treatments?"

PolyADP ribose polymerase inhibitors (PARPi) have transformed the treatment of ovarian cancer. Particularly in high-grade serous ovarian cancer (HGSOC), a disease characterized by homologous recombination deficiency (HRD), PARPi have had a rapid and profound impact on the disease course, as well as biologic and biomarker definitions of HGSOC, thereby creating a paradigm shift in the approach to treatment. In this review, we discuss the role of PARPi in the maintenance treatment of HGSOC, its effect on platinum sensitivity, and cross-resistance between platinum and PARP inhibitors.

Proteomic Analysis Reveals Low-Dose PARP Inhibitor-Induced Differential Protein Expression in BRCA1-Mutated High-Grade Serous Ovarian Cancer Cells.

High-grade serous ovarian cancer (HGSOC) is the most common form of ovarian cancer diagnosed in patients worldwide. Patients with BRCA1/2-mutated HGSOC have benefited from targeted treatments such as poly(ADP-ribose) polymerase inhibitors (PARPi). Despite the initial success of PARPi-based ovarian cancer treatment regimens, approximately 70% of patients with ovarian cancer relapse and the 5-year survival rate remains at 30%. PARPi exhibit variable treatment efficacy and toxicity profiles. Furthermore, the off-target effects of PARP inhibition have not yet been fully elucidated, warranting further study of these classes of molecules in the context of HGSOC treatment. Highly reproducible quantitative mass spectrometry-based proteomic workflows have been developed for the analysis of tumor tissues and cell lines. To detect the off-target effects of PARP inhibition, we conducted a quantitative mass spectrometry-based proteomic analysis of a BRCA1-mutated HGSOC cell line treated with low doses of two PARPi, niraparib and rucaparib. Our goal was to identify PARPi-induced protein signaling pathway alterations toward a more comprehensive elucidation of the mechanism of action of PARPi beyond the DNA damage response pathway. A significant enrichment of nuclear and nucleoplasm proteins that are involved in protein binding was observed in the rucaparib-treated cells. Shared upregulated proteins between niraparib and rucaparib treatment demonstrated RNA II pol promoter-associated pathway enrichment in transcription regulation. Pathway enrichment analyses also revealed off-target effects in the Golgi apparatus and the ER. The results from our mass spectrometry-based proteomic analysis highlights notable off-target effects produced by low-dose treatment of BRCA1-mutated HGSOC cells treated with rucaparib or niraparib.

TTK inhibition increases cisplatin sensitivity in high-grade serous ovarian carcinoma through the mTOR/autophagy pathway

High-grade serous ovarian cancer (HGSOC) is the most lethal gynecological malignancy. However, the molecular mechanisms underlying HGSOC development, progression, chemotherapy insensitivity and resistance remain unclear. Two independent GEO datasets, including the gene expression profile of primary ovarian carcinoma and normal controls, were analyzed to identify genes related to HGSOC development and progression. A KEGG pathway analysis of the differentially expressed genes (DEGs) revealed that the cell cycle pathway was the most enriched pathway, among which TTK protein kinase (TTK) was the only gene with a clinical-grade inhibitor that has been investigated in a clinical trial but had not been studied in HGSOC. TTK was also upregulated in cisplatin-resistant ovarian cancer cells from two other datasets. TTK is a regulator of spindle assembly checkpoint signaling, playing an important role in cell cycle control and tumorigenesis in various cancers. However, the function and regulatory mechanism of TTK in HGSOC remain to be determined. In this study, we observed TTK upregulation in patients with HGSOC. High TTK expression was related to a poor prognosis. Genetic and pharmacological inhibition of TTK impeded the proliferation of ovarian cancer cells by disturbing cell cycle progression and increasing apoptosis. TTK silencing increased cisplatin sensitivity by activating the mammalian target of rapamycin (mTOR) complex to further suppress cisplatin-induced autophagy in vitro. In addition, the enhanced sensitivity was partially diminished by rapamycin-mediated inhibition of mTOR in TTK knockdown cells. Furthermore, TTK knockdown increased the toxicity of cisplatin in vivo by decreasing autophagy. These findings suggest that the administration of TTK inhibitors in combination with cisplatin may lead to improved response rates to cisplatin in patients with HGSOC presenting high TTK expression. In summary, our study may provide a theoretical foundation for using the combination therapy of cisplatin and TTK inhibitors as a treatment for HGSOC in the future.

Epigenetic Mechanisms and Therapeutic Targets in Chemoresistant High-Grade Serous Ovarian Cancer.

Simple SummaryHigh-grade serous ovarian cancer (HGSOC) is the most common ovarian cancer subtype. While 60–80% of HGSOC patients initially respond to treatment, the majority of patients will eventually become platinum resistant. Epigenetic modifications are mechanisms that alter the expression of a gene but do not change the DNA sequence itself. Several types of epigenetic modifications, including DNA methylation, histone deacetylation, and microRNA expression, have been implicated in the progression of HGSOC to chemoresistance. These modifications can be targeted by epigenetic modulating therapies to overcome chemoresistance. This review summarises the epigenetic modifications identified in chemoresistant HGSOC and clinical trials utilizing epigenetic therapies in HGSOC.High-grade serous ovarian cancer (HGSOC) is the most common ovarian cancer subtype, and the overall survival rate has not improved in the last three decades. Currently, most patients develop recurrent disease within 3 years and succumb to the disease within 5 years. This is an important area of research, as the major obstacle to the treatment of HGSOC is the development of resistance to platinum chemotherapy. The cause of chemoresistance is still largely unknown and may be due to epigenetics modifications that are driving HGSOC metastasis and treatment resistance. The identification of epigenetic changes in chemoresistant HGSOC enables the development of epigenetic modulating drugs that may be used to improve outcomes. Several epigenetic modulating drugs have displayed promise as drug targets for HGSOC, such as demethylating agents azacitidine and decitabine. Others, such as histone deacetylase inhibitors and miRNA-targeting therapies, demonstrated promising preclinical results but resulted in off-target side effects in clinical trials. This article reviews the epigenetic modifications identified in chemoresistant HGSOC and clinical trials utilizing epigenetic therapies in HGSOC.

Construction of a Macrophage Infiltration Regulatory Network and Related Prognostic Model of High-Grade Serous Ovarian Cancer

Background High-grade serous ovarian cancer (HGSOC) carries the highest mortality in the gynecological cancers; however, therapeutic outcomes have not significantly improved in recent decades. Macrophages play an essential role in the occurrence and development of ovarian cancer, so the mechanisms of macrophage infiltration should be elucidated. Method We downloaded transcriptome data of ovarian cancers from the Gene Expression Omnibus and The Cancer Genome Atlas. After rigorous screening, 1566 HGSOC were used for data analysis. CIBERSORT was used to estimate the level of macrophage infiltration and WGCNA was used to identify macrophage-related modules. We constructed a macrophage-related prognostic model using machine learning LASSO algorithm and verified it using multiple HGSOC cohorts. Results In the GPL570-OV cohort, high infiltration level of M1 macrophages was associated with a good outcome, while high infiltration level of M2 macrophages was associated with poor outcomes. We used WGCNA to select genes correlated with macrophage infiltration. These genes were used to construct protein-protein interaction maps of macrophage infiltration. IFL44L, RSAD2, IFIT3, MX1, IFIH1, IFI44, and ISG15 were the hub genes in the network. We then constructed a macrophage-related prognostic model composed of CD38, ACE2, BATF2, HLA-DOB, and WARS. The model had the ability to predict the overall survival rate of HGSOC patients in GPL570-OV, GPL6480-OV, TCGA-OV, GSE50088, and GSE26712. In exploring the immune microenvironment, we found that CD4 memory T cells and activated mast cells showed that the degree of infiltration was higher in the high-risk group, while M1 macrophages were the opposite, and HLA molecules were overexpressed in the high-risk group. Conclusion We constructed a macrophage infiltration-related protein interaction network that provides a basis for studying macrophages in HGSOC. Our macrophage-related prognostic model is robust and widely applicable. It predicts overall survival in HGSOC patients and may improve HGSOC treatment.

Classification of high-grade serous ovarian carcinoma by epithelial-to-mesenchymal transition signature and homologous recombination repair genes

<h3>Objectives:</h3> To investigate the molecular characteristics of high-grade serous ovarian cancer (HGSOC) through integrative analysis of whole exome sequencing (WES) and RNA sequencing (RNA-seq) data. <h3>Methods:</h3> We used blood samples and primary ovarian cancer tissues that were initially collected from HGSOC patients. Ten patients had germline mutations in either <i>BRCA1</i> or <i>BRCA2</i> gene, while 10 patients had wild-type <i>BRCA1/2</i> genes. We performed WES and RNA-seq on fresh frozen, chemotherapy naïve cancer tissues, and matched blood samples. Genomic and transcriptomic profiles were comprehensively compared between patients with germline <i>BRCA1/2</i> mutation and those with wild type <i>BRCA1/2.</i> <h3>Results:</h3> HGSOC samples initially divided into two groups by the presence of germline <i>BRCA1/2</i> mutations showed mutually exclusive mutational patterns. Implementation of RNA-seq and application of epithelial-to-mesenchymal transition index (EMT index) onto the HGSOC samples revealed that they can be divided into two subtypes; homologous recombination repair (HRR)-activated and mesenchymal. Patients with mesenchymal HGSOC, characterized by the activation of EMT transcriptional program, low genomic alteration, and diverse cell-type compositions, exhibited significantly worse overall survival than did those with HRR-activated HGSOC (<i>P</i>=0.002). By applying the EMT index to TCGA HGSOC data, patients with high EMT index (≥ the median) showed significantly worse overall survival than did those with low EMT index (< the median) (<i>P</i>=0.030). <h3>Conclusions:</h3> We identified the EMT index as a potential prognostic biomarker for HGSOC. Genes related to this index can be therapeutic targets for the treatment of HGSOC.

Abstract 1074: Improving efficacy of microtubule inhibitors in the treatment of high-grade serous ovarian cancer and ovarian carcinosarcoma

Abstract The high mortality (&amp;gt;80%) seen in high-grade serous ovarian cancer (HGSOC) highlights the unmet clinical need for treatments capable of producing long-term sustained responses. The related cancer, ovarian carcinosarcoma (OCS), has even poorer survival rates, which is due in part to being a rare cancer but also because of its unique phenotype. OCS are composed of both epithelial (carcinoma) and mesenchymal (sarcoma) components and molecular analysis has shown that most OCS are monoclonal and are derived from a common progenitor with sarcomatous transformation occurring by a stable epithelial-to-mesenchymal transition (EMT) process involving reprogramming of gene expression. Paclitaxel is an effective microtubule-stabilizing drug that is used in the treatment of HGSOC and OCS, however, resistance to platinum-taxane treatment usually occurs within 2-3 years and earlier in many OCS. We have been investigating the microtubule inhibitors, vinorelbine and eribulin, which each bind to distinct regions of microtubules and have a different mechanism of inhibition compared to paclitaxel. Eribulin has also been shown to reverse EMT, inducing vasculature remodeling and changes to the tumor-immune microenvironment. This dual activity of eribulin provides greater potential for improved efficacy in the clinic. Focusing on platinum resistant/refractory patient-derived xenografts (PDX) of HGSOC and OCS we assessed response to paclitaxel, vinorelbine and eribulin treatment and observed that around 50% of PDX were sensitive (HGSOC 8/13, 8/13 and 4/8 respectively; OCS 3/6 for all treatments). To deliver higher doses of drug to tumors but also limit toxicity, antibody-drug conjugates (ADCs) are being developed. MORAb-202 is an eribulin-anti-folate receptor alpha (FRα) ADC. It has been reported that 80-90% of HGSOC express FRα and in our HGSOC PDX cohort 14/15 (93%) were positive. However, only 1/5 (20%) OCS model showed any FRα and this was restricted to epithelial glandular structures, &amp;lt;5% of total area. We treated HGSOC and OCS PDX models with a single dose of MORAb-202, equivalent to a single ¼ dose of eribulin. Impressive sensitivity to MORAb-202 was observed in 2/3 HGSOC PDX, with the third model showing a response initially, then relapsing around 60 days post treatment. Two OCS PDX assessed were refractory to MORAb-202 due to insufficient FRα expression. These data provide validation that MORAb-202 is targeted to FRα-expressing tumors exclusively and in this preclinical setting is highly efficacious. This work was funded by Eisai Inc. Citation Format: Cassandra J. Vandenberg, Gwo-Yaw Ho, Ksenija Nesic, Elizabeth M. Swisher, Sean M. Grimmond, Matthew J. Wakefield, Holly E. Barker, David D. Bowtell, Clare L. Scott. Improving efficacy of microtubule inhibitors in the treatment of high-grade serous ovarian cancer and ovarian carcinosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1074.

The Effects of Chemotherapeutics on the Ovarian Cancer Microenvironment.

Simple SummaryCancer cells are the target of most approved therapies. A growing body of evidence suggests that these agents have important roles in modulating the biology of host cells and their interactions with cancer cells, including blood vessels, fibroblasts, immune and fat cells, among others. This review provides an overview of potential roles of commonly used therapeutics in the tumor microenvironment, with a focus on cancer-associated fibroblasts. This includes an emphasis on therapies commonly used for the treatment of high-grade serous ovarian cancers (e.g., platinum, taxanes, PARP inhibitors, and anti-angiogenic agents). In vitro, in vivo, and clinical studies are included, and perspectives offered on how to best interpret the influence of therapeutics on normal cells.High-grade serous ovarian cancer (HGSOC) is characterized by a complex and dynamic tumor microenvironment (TME) composed of cancer-associated fibroblasts (CAFs), immune cells, endothelial cells, and adipocytes. Although most approved therapies target cancer cells, a growing body of evidence suggests that chemotherapeutic agents have an important role in regulating the biology of the diverse cells that compose the TME. Understanding how non-transformed cells respond and adapt to established therapeutics is necessary to completely comprehend their action and develop novel therapeutics that interrupt undesired tumor–stroma interactions. Here, we review the effects of chemotherapeutic agents on normal cellular components of the host-derived TME focusing on CAFs. We concentrate on therapies used in the treatment of HGSOC and synthesize findings from studies focusing on other cancer types and benign tissues. Agents such as platinum derivatives, taxanes, and PARP inhibitors broadly affect the TME and promote or inhibit the pro-tumorigenic roles of CAFs by modifying the bidirectional cross-talk between tumor and stromal cells in the tumor organ. While most chemotherapy research focuses on cancer cells, these studies emphasize the need to consider all cell types within the tumor organ when evaluating chemotherapeutics.

Distinct T cell receptor repertoire diversity of clinically defined high-grade serous ovarian cancer treatment subgroups

SummaryIn patients with high-grade serous ovarian cancer (HGSC), it is unclear which genomic features are related to complete gross resection (R0), which is typically associated with better clinical outcomes, or response to neoadjuvant chemotherapy (NACT). In this study, we evaluated T cell receptor (TCR) repertoire diversity in primary and metastatic tumor samples (n = 90) from clinically well-annotated patients with HGSC who achieved R0 or received NACT with excellent or poor response based on a laparoscopic triage algorithm. TCR sequencing followed by an integrative analysis with comprehensive multi-omics data identified higher TCR diversity (e.g., higher number of unique productive sequences and less clonal relatedness) in the R0 than NACT groups. We found enrichment of specific TCRβ genes usage, distinct mutual exclusiveness and co-occurrence pattern of TCRβ genes among the groups. We also found significantly positive correlations between clonal relatedness and neoantigens, copy number variations, and mutation load in the groups.

Methylomic Signatures of High Grade Serous Ovarian Cancer

ABSTRACT High-grade serous ovarian cancer (HGSOC) harbours aberrant epigenetic features, including DNA methylation. In this study we delineate pathways and networks altered by DNA methylation and associated with HGSOC initiation and progression to a platinum-resistant state. By including tumours from patients who had been treated with the hypomethylating agent (HMA) guadecitabine, we also addressed the role of HMAs in treatment of HGSOC. Tumours from patients with primary (platinum-naïve) HGSOC (n = 20) were compared to patients with recurrent platinum-resistant HGSOC and enrolled in a recently completed clinical trial (NCT01696032). Human ovarian surface epithelial cells (HOSE; n = 5 samples) served as normal controls. Genome-wide methylation profiles were determined. DNA methyltransferase (DNMT) expression levels were examined by immunohistochemistry and correlated with clinical outcomes. Cancer-related and tumorigenesis networks were enriched among differentially methylated genes (DMGs) in primary OC vs. HOSE. When comparing platinum-resistant and primary tumours, 452 CpG island (CGI)-containing gene promoters acquired DNA methylation; of those loci, decreased (P < 0.01) methylation after HMA treatment was observed in 42% (n = 189 CGI). Stem cell pluripotency and cytokine networks were enriched in recurrent platinum-resistant OC tumours, while drug metabolism and transport-related networks were downregulated in tumours from HMA-treated patients compared to HOSE. Lower DNMT1 and 3B protein levels in pre-treatment tumours were associated with improved progression-free survival. The findings provide important insight into the DNA methylation landscape of HGSOC tumorigenesis, platinum resistance and epigenetic resensitization. Epigenetic reprogramming plays an important role in HGSOC aetiology and contributes to clinical outcomes.

ATM inhibition synergizes with fenofibrate in high grade serous ovarian cancer cells

While therapies targeting deficiencies in the homologous recombination (HR) pathway are emerging as the standard treatment for high grade serous ovarian cancer (HGSOC) patients, this strategy is limited to the ~50% of patients with a deficiency in this pathway. Therefore, patients with HR-proficient tumors are likely to be resistant to these therapies and require alternative strategies. We found that the HR gene Ataxia Telangiectasia Mutated (ATM) is wildtype and its activity is upregulated in HGSOC compared to normal fallopian tube tissue. Interestingly, multiple pathways related to metabolism are inversely correlated with ATM expression in HGSOC specimens, suggesting that combining ATM inhibition with metabolic drugs would be effective. Analysis of FDA-approved drugs from the Dependency Map demonstrated that ATM-low cells are more sensitive to fenofibrate, a PPARα agonist that affects multiple cellular metabolic pathways. Consistently, PPARα signaling is associated with ATM expression. We validated that combined inhibition of ATM and treatment with fenofibrate is synergistic in multiple HGSOC cell lines by inducing senescence. Together, our results suggest that metabolic changes induced by ATM inhibitors are a potential target for the treatment of HGSOC.

Prexasertib: an investigational checkpoint kinase inhibitor for the treatment of high-grade serous ovarian cancer

ABSTRACT Introduction Patients with high-grade serous ovarian cancer (HGSOC) have a poor prognosis, and current chemotherapy regimens for treating advanced disease are far from satisfactory. Prexasertib (LY2606368) is a novel checkpoint kinase inhibitor (CHK) under investigation for the treatment of HGSOC. Data from a recent phase II trial showed promising efficacy and safety results for treating wild-type BRCA HGSOC. Areas covered This article reviews the available data on the pharmacokinetics, pharmacodynamics, clinical efficacy, and safety of prexasertib in the treatment of HGSOC. Expert opinion Until now, prexasertib demonstrated clinical activity in phase I and II clinical trial for treating wild-type BRCA HGSOC, whereas its promising efficacy as monotherapy and combined with olaparib in BRCA-mutated HGSOC has been preliminary evidenced only in phase I studies. Compared to other drugs of the same class, prexasertib showed a better tolerability profile, causing moderate hematological toxicity. Further studies are needed to confirm efficacy and safety profiles of prexasertib in combined regimens. New early clinical trials may investigate prexasertib administered with programmed cell death ligand 1 (PD-L1) and PI3 K inhibitors due to the preclinical evidence of a synergic action.

Targeting DNA Repair in Ovarian Cancer Treatment Resistance

Most patients with advanced high-grade serous ovarian cancer (HGSOC) develop recurrent disease within 3 years and succumb to the disease within 5 years. Standard treatment for HGSOC is cytoreductive surgery followed by a combination of platinum (carboplatin or cisplatin) and taxol (paclitaxel) chemotherapies. Although initial recurrences are usually platinum-sensitive, patients eventually develop resistance to platinum-based chemotherapy. Accordingly, one of the major problems in the treatment of HGSOC and disease recurrence is the development of chemotherapy resistance. One of the causes of chemoresistance may be redundancies in the repair pathways involved in the response to DNA damage caused by chemotherapy. These pathways may be acting in parallel, where if the repair pathway that is responsible for triggering cell death after platinum chemotherapy therapy is deficient, an alternative repair pathway compensates and drives cancer cells to repair the damage, leading to chemotherapy resistance. In addition, if the repair pathways are epigenetically inactivated by DNA methylation, cell death may not be triggered, resulting in accumulation of mutations and DNA damage. There are novel and existing therapies that can drive DNA repair pathways towards sensitivity to platinum chemotherapy or targeted therapy, thus enabling treatment-resistant ovarian cancer to overcome chemotherapy resistance.

Identification of Hub Genes in High-Grade Serous Ovarian Cancer Using Weighted Gene Co-Expression Network Analysis.

BackgroundHigh-grade serous ovarian cancer (HGSOC) is the most malignant gynecologic tumor. This study reveals biomarkers related to HGSOC incidence and progression using the bioinformatics method.Material/MethodsFive gene expression profiles were downloaded from GEO. Differentially-expressed genes (DEGs) in HGSOC and normal ovarian tissue samples were screened using limma and the function of DEGs was annotated by KEGG and GO analysis using clusterProfiler. A co-expression network utilizing the WGCNA package was established to define several hub genes from the key module. Furthermore, survival analysis was performed, followed by expression validation with datasets from TCGA and GTEx. Finally, we used single-gene GSEA to detect the function of prognostic hub genes.ResultsOut of the 1874 DEGs detected from 114 HGSOC versus 49 normal tissue samples, 956 were upregulated and 919 were downregulated. The functional annotation indicated that upregulated DEGs were mostly enriched in cell cycle, whereas the downregulated DEGs were enriched in the MAPK or Ras signaling pathway. Two modules significantly associated with HGSOC were excavated through WGCNA. After survival analysis and expression validation of hub genes, we found that 2 upregulated genes (MAD2L1 and PKD2) and 3 downregulated genes (DOCK5, FANCD2 and TBRG1) were positively correlated with HGSOC prognosis. GSEA for single-hub genes revealed that MAD2L1 and PKD2 were associated with proliferation, while DOCK5, FANCD2, and TBRG1 were associated with immune response.ConclusionsWe found that FANCD2, PKD2, TBRG1, and DOCK5 had prognostic value and could be used as potential biomarkers for HGSOC treatment.

Abstract NT-104: SYNERGISTIC COMBINATION OF MORTALIN-TARGETING AND P53 REACTIVATOR DRUGS FOR OVARIAN CANCER

Abstract PURPOSE: TP53 gene missense mutations represent the most common genetic defect in fallopian tube (FT) lesions and high grade serous ovarian cancer (HGSOC) and cause of drug resistance. We hypothesized that drugs with complementary p53 protein-targeted mechanisms (SHetA2 drug release of p53 from mortalin binding, PRIMA-1MET drug reactivation of p53 transcription activity) synergistically kill ovarian cancer cells without harming normal cells. EXPERIMENTAL DESIGN: SHetA2-mediated cytoplasmic to nuclear/mitochondrial p53 translocation was studied in wildtype and mutant p53 ovarian cancer cell lines using Western blot analysis of subcellular-enriched fractions and fluorescent microscopic imaging of immunocytochemistry. Human FT epithelial cells (hFTSECs) were used as healthy controls. The p53 reactivator drugs PRIMA-1 and PRIMA-1MET were combined with SHetA2 to study drug interactions and mechanisms using Western blot, rtPCR, cytotoxicity, reactive oxygen species (ROS) and ATP assays. RESULTS: SHetA2 induced p53 nuclear and mitochondrial accumulation in ovarian cancer cell lines, but not in hFTSECs. Both mortalin and p53 expression altered SHetA2 cytotoxicity in ovarian cancer cells. Modest effects of PRIMA-1MET on cell lines inversely correlated with SLC7A11 expression, a known biomarker of PRIMA-1MET sensitivity. SHetA2 induced SLC7A11 in the presence of wildtype or missense mutant p53, but inhibited SLC7A11 in the absence of p53. SHetA2 and PRIMA-1MET were synergistic-to-strongly synergistic in ovarian cancer cells with mutant p53, synergistic with wildtype p53, additive with null p53 and antagonistic in hFTSECs. Elevated apoptosis, p53 transcription activity and ROS in combination with reduced ATP were associated with this mutant p53-dependent synergy. CONCLUSION: Altogether, our findings identified the SHetA2 and PRIMA-1MET combination as a promising new therapeutic strategy for the treatment of HGSOCs with missense mutant p53. GRANT SUPPORT: Supported by the US National Cancer Institute grant R01 CA196200 and Foundation for Women's Cancer- Ovarinnovate: Ovarcome Research Excellence Award. Citation Format: Satish Kumar Ramraj, Doris M. Benbrook. SYNERGISTIC COMBINATION OF MORTALIN-TARGETING AND P53 REACTIVATOR DRUGS FOR OVARIAN CANCER [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 NT-104.

Abstract AP12: FOXM1 INDUCES DNA REPLICATION STRESS AND PROMOTES GENOMIC INSTABILITY DOWNSTREAM OF CYCLIN E1 IN HIGH-GRADE SEROUS OVARIAN CANCER

Abstract PURPOSE: Genomic instability (GI) is a hallmark of high-grade serous ovarian cancer (HGSC), and induction of the FOXM1 transcription factor regulatory network is the second most frequent genetic alteration in HGSC. FOXM1 expression is associated with cancer GI, but the mechanistic link is unknown. DNA replication stress (DRS), which involves altered replication fork dynamics, is a key contributor to cancer GI. FOXM1 and cyclin E1 (CCNE1) are both expressed in STIC lesions in the fallopian tube epithelium (FTE), and CCNE1-CDK2 enhances FOXM1 transcriptional activity. Based on these observations, we hypothesized that: 1) FOXM1 is linked to cancer GI through the induction of DRS, and 2) FOXM1 promotes GI downstream of CCNE1, by promoting unscheduled M phase entry in cells that have not completed DNA synthesis. METHODS: We determined associations between FOXM1 and markers of DRS and GI in TCGA HGSC data. We overexpressed FOXM1c and a DNA binding domain mutant (DBD) in immortalized FTE cells and characterized the impact on DRS, DNA replication, and DNA damage. We determined the impact of CCNE1 on FOXM1 expression in immortalized FTE cells. We determined the combined effect of CCNE1 and FOXM1 on GI in FTE cells. RESULTS: FOXM1 was significantly associated with markers of DRS (CHK1-Ser345) and GI (fractional copy number altered genome (CNA)) in TCGA HGSC data. FOXM1 expression, but not its DBD mutant, induced biomarkers of DRS and DNA damage in hTERT/mutant Tp53 immortalized FTE cells. Unexpectedly, FOXM1c increased DNA replication fork rate in FTE cells. Increased fork rate is a novel and recently recognized cause of DRS. CCNE1 expression in FTE cells induced and activated FOXM1, promoting mitotic entry. FOXM1 and CCNE1 co-expression in FTE cells induced an expression signature of GI, and TCGA HGSC tumors with FOXM1 and CCNE1 co-expression showed significantly increased GI. CONCLUSIONS: We demonstrate that FOXM1 induces DRS and DNA damage in FTE cells, providing an explanation for the known link between FOXM1 and GI. Notably, FOXM1 induces a novel form of DRS involving increased replication fork rate. We show that CCNE1 activates FOXM1, which in turn promotes mitotic entry and GI. These data reveal a potentially major form of oncogenic collaboration in HGSC, and has implications for HGSC treatment approaches that promote DRS or inhibit the cellular DRS response. . Citation Format: Carter J Barger, Kajal Biswas, Linda Chee, Ronny Drapkin, Shyam Sharan, Adam R. Karpf. FOXM1 INDUCES DNA REPLICATION STRESS AND PROMOTES GENOMIC INSTABILITY DOWNSTREAM OF CYCLIN E1 IN HIGH-GRADE SEROUS OVARIAN CANCER [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 AP12.

Tumor cell‑fibroblast heterotypic aggregates inmalignant ascites of patients with ovarian cancer.

Ascitic multicellular aggregates (MCAs) promote peritoneal metastasis of ovarian cancer. The aim of the present study was to elucidate the role of cancer-associated fibroblasts (CAFs) in MCA formation and metastasis in patients with high-grade serous ovarian cancer (HGSOC). Immunohistochemistry was used to identify the cell phenotypes and the presence of CAFs in ascitic MCAs. The role of CAFs in tumor-cell MCA formation was assessed by co-culture in suspension. Primary ascitic tumor cells and omental CAFs were used to generate ex vivo MCAs in hanging drops, and the invasiveness of MCAs was evaluated by mesothelial clearance and adhesion assays in vitro and in vivo. MCAs containing CAFs and tumor cells were identified in the ascitic fluid. CAFs facilitated tumor cell aggregation and compaction to form MCAs, and enhanced the mesothelial clearance and adhesion abilities of tumor-cell MCAs. These findings suggest that ascitic CAFs promote peritoneal metastasis by forming heterotypic aggregates with tumor cells, and that they may serve as potential targets for the treatment of HGSOC.

Establishment of primary human epithelial ovarian cancer cells and their application to cytotoxicity assessment

Background: Ovarian carcinomas are highly metastatic tumors and the most lethal gynecological malignancies in the world. Treatment of human epithelial ovarian cancer (hEOC) is based on the combination of surgery and chemotherapy. The acquisition of resistance is a major obstacle to the clinical use of platinum drugs for 75% of high-grade serous ovarian cancer treatment. Hence, the urgent strategy is to develop platform to predict the resistance to targeted therapy after surgery and to screen the potential monotherapy, including platinum, in clinical treatment. Materials and Methods: Our laboratory tried to take advantage of ascites from hEOC patients to understand the mechanism of platinum-based resistance and screen the potential monotherapy choice via the primary culture strategy. We first established the culture conditions for ascites of the ovarian cancer patients. Results: We showed that we could culture these primary cells up to 13th generation. We further treated these primary cells with various steroid hormones for the epithelial-to-mesenchymal transient and regular monotherapy, including cisplatin, docetaxel, and doxorubicin, for the cytotoxicity. Finally, we also demonstrated the responsiveness of this monotherapy with antibodies against cell cycle, autophagy, or other survival-related factors. Conclusion: Our screening platform will provide us to further examine the resistance mechanism of any monotherapy in a different individual patient. We hope that our primary culture system used for standard monotherapy screening might provide the alert to drug resistance and the better combinatory therapy for personalized therapy.

Nucleotide excision repair protein ERCC1 and tumour-infiltrating lymphocytes are potential biomarkers of neoadjuvant platinum resistance in high grade serous ovarian cancer

ObjectiveERCC1 is a nucleotide excision repair protein that may have a role in drug resistance in high grade serous ovarian cancer (HGSOC). We hypothesized that ERCC1 expression and tumour infiltrating lymphocytes (TILS) are induced by chemotherapy in HGSOC, which may be prognostically useful. Methods115 HGSOC patients were used for this study. 92 (80%) of the tissue analysed had not been exposed to platinum chemotherapy. The remaining 20% (n = 23) of cases received combination or monotherapy with carboplatin before tissue was collected.Immunohistochemistry was used to score for ERCC1 expression and morphology to score for TILs. Correlation analysis of all clinical parameters, TILs and ERCC1 and Kaplan-Meier survival analysis was performed using the ERCC1 and TILs scoring parameters (0, 1, 2 or 3). ResultsERCC1 expression was 2-fold higher in the neoadjuvant chemotherapy group compared to the primary cytoreductive surgery group (p < 0.0001). The mean overall survival for the neoadjuvant group with high ERCC1 was 141.6 ± 20.2 months which was significantly longer than absent ERCC1 survival of 61 + 22.6 months (p = 0.028). ERCC1 score strongly correlated with TILs score across the whole cohort (0.349, p = 1.3 × 10−4) suggesting there is a relationship between ERCC1 expression and TILs, but this requires further investigation. ConclusionIn conclusion, ERCC1 was identified as a potential biomarker of platinum response overall survival in HGSOC undergoing neoadjuvant HGSOC treatment.