Role In Development Of Ovarian Cancer Research Articles

MATN2 overexpression suppresses tumor growth in ovarian cancer via PTEN/PI3K/AKT pathway.

The incidence rate of developing ovarian cancer decreases over the years; however, mortality ranks top among malignancies of women, mainly metastasis through local invasion. Matrilin-2 (MATN2) is a member of the matrilin family that plays an important role in many cancers. However, its relationship with ovarian cancer remains unknown. Our study aimed to explore the function and possible mechanism of MATN2 in ovarian cancer. Human ovarian cancer tissue microarrays were used to detect the MATN2 expression in different types of ovarian cancer using immunohistochemistry (IHC). CCK-8, wound scratch healing assay, transwell assay, and flow cytometry were used to detect cell mobility. Gene and protein expression were detected using quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting. MATN2 interacts with phosphatase, and the tensin homolog (PTEN) deleted on chromosome 10 was analyzed using TCGA database and co-immunoprecipitation (Co-IP). In vivo experiments were conducted using BALB/c nude mice, and tumor volume and weight were recorded. Tumor growth was determined using hematoxylin and eosin (H&E) and IHC staining. MATN2 was significantly downregulated in ovarian cancer cells. The SKOV3 and A2780 cell mobility was significantly inhibited by MATN2 overexpression, while the cell apoptosis rate was significantly increased. MATN2 overexpression decreased transplanted tumor size in vivo. These results were reversed by inhibiting MATN2. Furthermore, we found that PTEN closely interacted with MATN2 using bioinformatics and Co-IP. MATN2 overexpression significantly inhibited the PI3K/AKT pathway, however, PTEN suppression reversed this effect of MATN2 overexpression. These results indicated that MATN2 may play a critical role in ovarian cancer development by inhibiting cells proliferation and migration. The mechanism was related to interacting with PTEN, thus inhibiting downstream effectors in the PI3K/AKT pathway, which may be a novel target for treating ovarian cancer.

Exploring the Relationship between Ovarian Cancer and Genital Microbiota: A Systematic Review and Meta-Analysis.

Ovarian cancer (OC) remains a significant health challenge globally, with high mortality rates despite advancements in treatment. Emerging research suggests a potential link between OC development and genital dysbiosis, implicating alterations in the microbiome composition as a contributing factor. To investigate this correlation, a meta-analysis was conducted following PRISMA and MOOSE guidelines, involving eight studies encompassing 3504 patients. Studies investigating the role of upper and inferior genital tract dysbiosis were included, with particular reference to HPV infection and/or history of pelvic inflammatory disease. The analysis revealed no significant difference in genital dysbiosis prevalence between OC patients and healthy controls. Although previous literature suggests associations between dysbiosis and gynecologic cancers, such as cervical and endometrial cancers, the findings regarding OC are inconclusive. Methodological variations and environmental factors may contribute to these discrepancies, underscoring the need for standardized methodologies and larger-scale studies. Despite the limitations, understanding the microbiome's role in OC development holds promise for informing preventive and therapeutic strategies. A holistic approach to patient care, incorporating microbiome monitoring and personalized interventions, may offer insights into mitigating OC risk and improving treatment outcomes. Further research with robust methodologies is warranted to elucidate the complex interplay between dysbiosis and OC, potentially paving the way for novel preventive and therapeutic approaches.

Abstract 3040: Tumor-specific super-enhancer drives overexpression of EVI1 in ovarian cancer

Abstract Epithelial ovarian cancer (OC) is typically diagnosed at a late stage and, despite treatment with cytoreductive surgery and chemotherapy, 70-80% of patients relapse and eventually die due to the disease. Major challenges to improve patient outcomes are to overcome therapy resistance and to individually tailor therapy. Uncovering the molecular drivers of OC, especially in the most common subgroup high-grade serous (HGS), will help develop novel therapeutic strategies to meet these challenges. Using the Cancer Genome Atlas (TCGA) data, we observed that a locus in 3q26.2, near the EVI1 oncogene, was the most significantly amplified region in HGS OC, occurring in more than 80% of those tumors. We validated these findings in an OC dataset from the Hartwig Medical Foundation and in OC cell lines from the DepMap database. Furthermore, HGS OC had the highest mean copy number of the 3q26.2 locus co-occurring with high mean EVI1 expression among all tumor entities in the pan-cancer TCGA dataset. These EVI1 expression levels are significantly higher than in normal fallopian tube, from which HGS OC most likely arises. EVI1 overexpression promotes leukemogenesis in 3q26-rearranged acute myeloid leukemia (AML), as a result of chromosomal translocations that enable hijacking of hyperactive enhancers. Here, we hypothesize that EVI1 also plays a crucial role in OC development, but that its aberrant expression in this disease is driven by the amplification of yet undiscovered regulatory elements near EVI1. We showed that EVI1-positive OC cell lines, of which the majority are HGS, are EVI1-dependent and harbor a ~200 kb amplified region near EVI1. This region interacts with the EVI1 promoter (4C-Seq), is characterized by open chromatin (ATAC-Seq), and shows high levels of H3K27 acetylation (H3K27ac ChIP-Seq), suggesting the presence of an active enhancer. Furthermore, based upon H3K27ac signal, we identified within this region a super-enhancer of approximately 65 kb. In OC cell lines without detectable EVI1 levels or cell lines from other cancer subtypes, such as breast and colon cancer, this location had no active enhancer and did not loop to the EVI1 promoter. Altogether, these data point to the generation of a hyperactive super-enhancer driving EVI1 overexpression in OC. These findings emphasize the importance of epigenetic control in the regulation of EVI1 expression, as previously shown in 3q26-rearranged AML. Since OC tumor cell lines are strongly dependent on EVI1, interference with this super-enhancer, leading to loss of EVI1 expression, could be exploited to inhibit tumor growth. For this purpose, we generated GFP-tagged EVI1 cell line models (e.g. SKOV3), which will be used to discover small molecules to target the activity of this super-enhancer. In conclusion, we discovered a new mechanism of enhancer-mediated overexpression of the EVI1 oncogene as a molecular driver in ovarian cancer, with possible implications for therapy. Citation Format: Leonie Smeenk, Sabrina Kruse, Roger Mulet-Lazaro, Ingrid Boere, John Martens, Stefan Gröschel, Claudia Scholl, Stefan Fröhling, Ruud Delwel. Tumor-specific super-enhancer drives overexpression of EVI1 in 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 3040.

Integrating cell cycle score for precise risk stratification in ovarian cancer.

Background: Ovarian cancer (OC) is a highly heterogeneous disease, of which the mesenchymal subtype has the worst prognosis, is the most aggressive, and has the highest drug resistance. The cell cycle pathway plays a vital role in ovarian cancer development and progression. We aimed to screen the key cell cycle genes that regulated the mesenchymal subtype and construct a robust signature for ovarian cancer risk stratification. Methods: Network inference was conducted by integrating the differentially expressed cell cycle signature genes and target genes between the mesenchymal and non-mesenchymal subtypes of ovarian cancer and identifying the dominant cell cycle signature genes. Results: Network analysis revealed that two cell cycle signature genes (POLA2 and KIF20B) predominantly regulated the mesenchymal modalities of OC and used to construct a prognostic model, termed the Cell Cycle Prognostic Signature of Ovarian Cancer (CCPOC). The CCPOC-high patients showed an unfavorable prognosis in the GSE26712 cohort, consistent with the results in the seven public validation cohorts and one independent internal cohort (BL-OC cohort, qRT-PCR, n = 51). Functional analysis, drug-sensitive analysis, and survival analysis showed that CCPOC-low patients were related to strengthened tumor immunogenicity and sensitive to the anti-PD-1/PD-L1 response rate in pan-cancer (r = −0.47, OC excluded), which indicated that CCPOC-low patients may be more sensitive to anti-PD-1/PD-L1. Conclusion: We constructed and validated a subtype-specific, cell cycle-based prognostic signature for ovarian cancer, which has great potential for predicting the response of anti-PD-1/PD-L1.

PIK3R3, a regulatory subunit of PI3K, modulates ovarian cancer stem cells and ovarian cancer development and progression by integrative analysis

BackgroundOvarian cancer is the most lethal gynecologic disease and is one of the most commonly diagnosed cancers among women worldwide. The phosphatidylinositol 3-kinase (PI3K) family plays an important regulatory role in various cancer signaling pathways, including those involved in ovarian cancer development; however, its exact function remains to be fully understood. We conducted this study to understand the role of P13K in the molecular mechanisms underlying ovarian cancer development.MethodsTo determine the differential gene expression of phosphoinositide-3-kinase regulatory subunit 3 (PIK3R3), a regulatory subunit of PI3K, in normal, tumor, and metastatic ovary tissues, TNM plotter analysis was performed. The microarray dataset GSE53759 was downloaded from Gene Expression Omnibus. ROC plotter analysis was conducted to understand the potential of PIK3R3 as a predictive marker for effectiveness of therapy in ovarian cancer. muTarget was used to identify mutations that alter PIK3R3 expression in ovarian cancer. To determine the interacting partners for PIK3R3 in ovarian tissues, the interactome-atlas tool was used. The Kyoto encyclopedia of genes and genomes (KEGG) analysis was conducted to identify the pathways in which these interacting partners were primarily enriched.ResultsPIK3R3 was overexpressed in ovarian and metastatic tumors. Elevated PIK3R3 levels were observed in ovarian cancer stem cells, wherein inhibiting PIK3R3 expression significantly reduced the size of ovarian cancer spheroids. Treatment of ovarian cancer stem cells with PF-04691502 (10 μM), an inhibitor of both PI3K and mTOR kinases, also reduced the size of spheroids and the level of OCT4. PIK3R3 was highly expressed in ovarian cancer with several somatic mutations and was predicted better outcomes in patients undergoing Avastin® chemotherapy using bioinformatic tool. Protein interaction analysis showed that PIK3R3 interacts with 157 genes, including GRB2, EGFR, ERBB3, PTK2, HCK, IGF1R, YES1, and PIK3CA, in the ovary. KEGG enrichment analysis revealed that the interacting partners of PIK3R3 are involved in the ErbB signaling pathway, proteoglycans in cancer, FoxO, prolactin, chemokine, and insulin signaling pathways.ConclusionsPIK3R3 plays a pivotal role in ovarian cancer development and is therefore a potential candidate for developing novel therapeutic approaches.

Aryl hydrocarbon Receptor (AhR) Promotes Cell Growth, Induces Stemness Like Characteristics and Metastasis in Ovarian Cancer Cells via Activation of Akt, β‐Catenin and EMT

BackgroundOvarian cancer is the most lethal form of all gynecological malignancies with highpitched tumor relapse and chemoresistance. Cancer stem cells (CSCs), a small sub population of cancer cells driving tumor initiation, progression, and metastasis, are known to be a major contributor of therapy resistance. Recent studies have depicted a link between CSC development and exposure to environmental pollutants like 2,3,7,8‐Tetrachlorodibenzo‐p‐dioxin (TCDD). Reports suggest that one of the major pathways that mediate the metabolism of these environmental chemicals is the aryl hydrocarbon receptor (AhR) pathway, whose role in several CSCs is lately demonstrated. However, its role in ovarian cancer development and chemoresistance remains uninvestigated. We hypothesize that AhR and its regulatory genes CYP1A1 and CYP1B1 are involved in the ovarian cancer progression and chemoresistance. The objectives of the present study were a) to examine the role and involvement of AhR in ovarian cancer progression and chemoresistance and b) to explore the underlying mechanisms.MethodsTo test our hypothesis, seven ovarian cancer cell lines; A2780, A2780cis (cisplatin resistant), OVCAR‐3, SKOV‐3, CAOV‐3, and SW‐626 were utilized in this study. Ovarian cancer cells were treated for 24 h with a potent AhR activator, tetrachlorodibenzo‐p‐dioxin (TCDD, 10 nM), thereafter protein expression of AhR, CYP1A1, CYP1B1, pro‐ and anti‐apoptotic, and stemness markers were determined by immunoblotting.Resultsour study showed that SKOV‐3 cells showed highest basal expression of AhR, whereas A2780cis and A2780 expressed the highest basal expression of CYP1A1 and CYP1B1 proteins, respectively. At the inducible levels, treatment of selected cells (OVCAR‐3, SKOV‐3 and A2780) with TCDD significantly induced the protein level of AhR, CYP1A1 in OVCAR‐3 and SKOV‐3, and CYP1B1 in only SKOV‐3 and A2780 cells. To investigate the mechanism involved, we utilized A2780 cells as a model to explore the effect of TCDD on pro‐ and anti‐apototic, Epithelial to Mesenchymal Transition (EMT), and stemness markers. Our results showed that activation of AhR by TCDD in A2780 cells induced phosphorylation of Akt protein with a concomitant increase in the expression of anti‐apoptotic proteins BCL‐2, BCL‐xl and MCL‐1. In addition, a significant increase of aldehyde dehydrogenase (ALDH1), a functional CSC‐specific marker exhibiting important role in cancer progression and chemoresistance was also observed. This effect was also associated with an accumulation of βCatenin, a Wnt transcription factor. Moreover, we found a decrease in E‐cadherin, an epithelial marker, followed by a concurrent increase in Vimentin, a mesenchymal marker, upon AhR activation, confirming the induction of EMT.ConclusionThe results from our study indicate that AhR regulates ovarian cancer progression, exerts stemness characteristics and induces metastasis via activation of Akt, Wnt/β‐Catenin and EMT. This study provides a better understanding of the regulation of ovarian cancer cells in relation to AhR that could help in devising novel therapeutics for better management of ovarian cancer and prevention.

Collagen I dysregulation is pivotal for ovarian cancer progression

As a principal matrisomal protein, collagen is involved in the regulation of the structural framework of extracellular matrix (ECM) and therefore is potentially crucial in determining the biophysical character of the ECM. It has been suggested that collagen architecture plays a role in ovarian cancer development, progression and therapeutic responses which led us to examine the collagen morphology in normal and cancerous ovarian tissue. Also, the behaviour of ovarian cancer cells cultured in four qualitatively different collagen gels was investigated.The results here provide evidence that collagen I morphology in the cancerous ovary is distinct from that in the normal ovary. Tumour-associated collagen I showed streams or channels of thick elongated collagen I fibrils. Moreover, fibril alignment was significantly more prevalent in endometrioid and clear cell cancers than other ovarian cancer subtypes. In this work, for the first-time collagen I architecture profiling (CAP) was introduced using histochemical staining, which distinguished between the collagen I morphologies of ovarian cancer subtypes. Immunohistochemical examination of ovarian normal and cancerous tissues also supported the notion that focal adhesion and Rho signalling are upregulated in ovarian cancers, especially in the high-grade serous tumours, as indicated by higher expression of p-FAK and p190RhoGEF. The results also support the concept that collagen I architecture, which might be collagen I concentration-dependent, influences proliferation in ovarian cancer cells. The study provides evidence that modification of collagen I architecture integrity is associated with ovarian cancer development and therapeutic responses.

Bisphenol A induces ovarian cancer cell proliferation and metastasis through estrogen receptor-α pathways.

Bisphenol A (BPA) is a widely used raw material that can be detected both in the environment and in the human body. Due to its estrogen-like effects, wide concerns have been raised about the potential role of BPA in the initiation and development of hormone-dependent cancers. Ovarian cancer is the most common reproductive system cancer and has a high mortality rate in women. Despite recent investigations into BPA's carcinogenic effects, studies on its role in ovarian cancer development remain limited. In this study, we aimed to assess the effect of BPA at various environmentally relevant concentrations on proliferation and metastasis of ovarian cancer cells. We discovered that BPA can stimulate proliferation of OVCAR-3 ovarian cancer cells after exposure for up to 5 days. Strikingly, BPA enhanced ovarian cancer cell migration, invasion, and adhesion (to vascular endothelial cells) through upregulation of matrix metalloproteinase-2 (MMP-2), MMP-9, and intercellular cell adhesion molecule-1 (IMAC-1). The stimulatory effects of BPA on cancer cell proliferation and metastasis were reversed by treatment with an ERα inhibitor, but not by treatment with an ERβ inhibitor. Together, these results suggest that BPA induces proliferation and metastasis of ovarian cancer cells through ERα signaling pathways. This study provides new insights into the carcinogenic effects of BPA with regard to ovarian cancer.

Text Analytics and Mixed Feature Extraction in Ovarian Cancer Clinical and Genetic Data

Developments of richer integrative analysis methods for oncological studies are needed for efficiently leveraging the amount of clinical and genetic data available to provide the clinicians with better information. However, analyses of this nature often require mixing data of different types, which are not immediate to address jointly with classical methods. In this work, our aim is to find relationships between clinical and genetic features of different types (metric, categorical, and text) and the ovarian cancer (OC) disease progression. To this end, we first propose a univariate statistical method for text type applying bootstrap resampling to Bag of Words and Latent Dirichlet Allocation in order to include as features the free-text fields of the health recordings. Secondly, we extend bootstrap resampling for metric and categorical feature extraction with Principal Component Analysis (PCA) and Multiple Correspondence Analysis (MCA), respectively. We subsequently formulate a novel and integrative method for jointly considering metric, categorical, and text features. Results obtained in text analysis indicate individual differences in some words between two OC patients groups categorised according to their sensitivity to platinum drugs. These results indicate separability between both groups for text features. Also, regarding the multivariate analysis, clinical data results showed separability patterns for the three methods analysed according to the platinum-sensitivity degree. The use of these analytical tools in our OC cohort has allowed us to demonstrate their strengths by confirming the predictive and prognostic role of widely-known clinical and genetic variables (BRCA status, value of adjuvant therapy and optimal resection, or family history) and demonstrating significant associations in other variables whose role in OC development has been studied to a lesser extent (such as PMS1, GPC3, and SLX4 genes). These results highlight the value of implementing these approaches for the identification of novel biomarkers in the context of OC.

Cyclooxygenase-2 promotes ovarian cancer cell migration and cisplatin resistance via regulating epithelial mesenchymal transition.

Drug-resistance and metastasis are major reasons for the high mortality of ovarian cancer (OC) patients. Cyclooxygenase-2 (COX-2) plays a critical role in OC development. This study was designed to evaluate the effects of COX-2 on migration and cisplatin (cis-dichloro diammine platinum, CDDP) resistance of OC cells and explore its related mechanisms. Cell counting kit-8 (CCK-8) assay was used to detect the cytotoxicity effects of celecoxib (CXB) and CDDP on SKOV3 and ES2 cells. The effect of COX-2 on migration was evaluated via the healing test. Western blot and real-time quantitative polymerase chain reaction (qPCR) were used to analyze E-cadherin, vimentin, Snail, and Slug levels. COX-2 promoted drug-resistance and cell migration. CXB inhibited these effects. The combination of CDDP and CXB increased tumor cell sensitivity, reduced the amount of CDDP required, and shortened treatment administration time. COX-2 upregulation increased the expression of Snail and Slug, resulting in E-cadherin expression downregulation and vimentin upregulation. COX-2 promotes cancer cell migration and CDDP resistance and may serve as a potential target for curing OC.

SIRT5 Promotes Cisplatin Resistance in Ovarian Cancer by Suppressing DNA Damage in a ROS-Dependent Manner via Regulation of the Nrf2/HO-1 Pathway.

Sirtuin 5 (SIRT5), a mitochondrial class III NAD-dependent deacetylase, plays controversial roles in tumorigenesis and chemoresistance. Accordingly, its role in ovarian cancer development and drug resistance is not fully understood. Here, we demonstrate that SIRT5 is increased in ovarian cancer tissues compared to its expression in normal tissues and this predicts a poor response to chemotherapy. SIRT5 levels were also found to be higher in cisplatin-resistant SKOV-3 and CAOV-3 ovarian cancer cells than in cisplatin-sensitive A2780 cells. Furthermore, this protein was revealed to facilitate ovarian cancer cell growth and cisplatin-resistance in vitro. Mechanistically, we show that SIRT5 contributes to cisplatin resistance in ovarian cancer by suppressing cisplatin-induced DNA damage in a reactive oxygen species (ROS)-dependent manner via regulation of the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase 1 (HO-1) pathway.

TRIM52 plays an oncogenic role in ovarian cancer associated with NF-kB pathway

Emerging evidence suggests that the members of the tripartite motif (TRIM) family play a crucial role in cancer development and progression. The purpose of the study was to explore TRIM52's role in tumorigenesis and its potential molecular mechanism in ovarian cancer. The study demonstrated that knockdown of TRIM52 in SKOV3 and CAOV3 cells inhibited ovarian cancer cell invasion, migration, and proliferation, and induced cell apoptosis. On the contrary, overexpression of TRIM52 in HO8910 cells showed contrary results. Further, overexpression of TRIM52 enhanced the expression of phosphorylated IKKβ and IKBα proteins and nuclear protein P65, which implied the activation of NF-kB signal pathway. Knockdown of TRIM52 downregulated the mRNA and protein levels of NF-kB signal downstream effectors of the NF-kB pathway, including MMP9, Bcl2, IL8, and TNFα, but upregulated caspase-3 expression. These results suggested that activation of the NF-kB pathway is involved in TRIM52-mediated regulation in ovarian cancer. The nude mice study further confirmed that knockdown of TRIM52 blocked tumor growth, inhibited cell proliferation, and promoted cell apoptosis. Our data strongly suggested that TRIM52 plays an oncogenic role in ovarian cancer development associated with the NF-kB signal pathway and may be a potential target for cancer therapy.

Abstract B50: YAP induces development of mesenchymal subtype of high-grade serous ovarian cancer from granulosa cells

Abstract The Hippo pathway plays critical roles in both organ development and tumorigenesis. Our previous studies demonstrated that Yes-Associated Protein 1 (YAP), a transcription coactivator and the major effector of the Hippo pathway, plays a critical role in ovarian cancer development. The present study investigates the role of the Hippo/YAP signaling pathway in the tumorigenesis of ovarian granulosa cells. Fluorescent and chromogenic immunohistochemistry were used to examine YAP expression in human and mouse ovaries. Western blot and qRT-PCR were used to determine protein and mRNA expression. Retrovirus-based YAP expressing constructs and YAP siRNAs were utilized to manipulate YAP levels in primary or immortalized human granulosa cells. A new three-dimensional hanging-drop culture system was used to mimic the growth of granulosa cells in vivo. The soft agar assay and xenograft mouse models were employed to investigate the role of YAP in transformation and tumorigenesis of granulosa cells. Immunohistochemical analyses showed that the active form of YAP (nuclear YAP) was expressed in proliferative granulosa cells in human and mouse ovaries, whereas the inactive form of YAP (cytoplasmic YAP) was detected predominantly in terminally differentiated luteal cells, indicating that YAP activity may be involved in the regulation of granulosa cell proliferation and differentiation. Overexpression of wild-type or constitutively active YAP compromised the expression of genes required for steroidogenesis and induced de-differentiation of differentiated granulosa cells. Ectopic expression of the constitutively active form of YAP in less-differentiated human granulosa cells derived from growing follicles induced tumors in a xenograft mouse model. Intriguingly, we found that these tumors resembled human high-grade serous ovarian cancer (HGSOC) morphologically, histologically, and genetically. The tumors were accompanied by accumulation of large amount of ascites in the peritoneal cavity. Highly proliferative and aggressive tumor cells invaded into omentum, visceral fat tissue, diaphragm, pancreas, liver, and gastrointestinal system. Deletion of the BRCA1 gene in these tumor cells promoted tumor progression and significantly reduced survival rate. Interestingly, these tumors have high expression of N-cadherin but very low expression of CA125 and E-cadherin, which are molecular characteristics of a recently identified mesenchymal subtype of HGSOC. Studies from The Cancer Genome Atlas and the Australian Ovarian Cancer Study Group indicate that the mesenchymal subtype of HGSOC has the poorest prognosis among all subtypes of ovarian cancers. In conclusion, results from this study indicate that YAP plays a critical role in regulating granulosa cell proliferation and differentiation. Overactivation of YAP can result in de-differentiation and reprogramming of ovarian granulosa cells, leading to development of mesenchymal subtype of HGSOC. Our results identify early-stage granulosa cells as a cell of origin of newly identified mesenchymal type of HGSOC. Citation Format: Xiangmin Lv, Chunbo He, Cong Huang, Guohua Hua, Bowen Ma, Xingcheng Chen, Jin Zhou, Zhengfeng Wang, Jixin Dong, Bo R. Rueda, John S. Davis, Cheng Wang. YAP induces development of mesenchymal subtype of high-grade serous ovarian cancer from granulosa cells. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr B50.

Histone Methyltransferase EZH2: A Therapeutic Target for Ovarian Cancer.

Ovarian cancer is the fifth leading cause of cancer-related deaths in females in the United States. There were an estimated 22,440 new cases and 14,080 deaths due to ovarian cancer in 2017. Most patients present with advanced-stage disease, revealing the urgent need for new therapeutic strategies targeting pathways of tumorigenesis and chemotherapy resistance. While multiple genomic changes contribute to the progression of this aggressive disease, it has become increasingly evident that epigenetic events play a pivotal role in ovarian cancer development. One of the well-studied epigenetic modifiers, the histone methyltransferase EZH2, is a member of polycomb repressive complex 2 (PRC2) and is commonly involved in transcriptional repression. EZH2 is the enzymatic catalytic subunit of the PRC2 complex that can alter gene expression by trimethylating lysine 27 on histone 3 (H3K27). In ovarian cancer, EZH2 is commonly overexpressed and therefore potentially serves as an effective therapeutic target. Multiple small-molecule inhibitors are being developed to target EZH2, which are now in clinical trials. Thus, in this review, we highlight the progress made in EZH2-related research in ovarian cancer and discuss the potential utility of targeting EZH2 with available small-molecule inhibitors for ovarian cancer. Mol Cancer Ther; 17(3); 591-602. ©2018 AACR.

MicroRNA-595 sensitizes ovarian cancer cells to cisplatin by targeting ABCB1.

Ovarian cancer is among the leading cause of cancer-related deaths in females. In this study, we demonstrated that miR-595 expression was downregulated in the ovarian cancer tissues and cell lines. miR-595 expression was lower in the lymph node metastases tissues than in the primary ovarian cancer tissues and normal tissues. Furthermore, miR-595 overexpression suppressed the ovarian cancer cell proliferation, colony formation and invasion and promoted the sensitivity of ovarian cancer cell to cisplatin. We identified ABCB1 as a direct target gene of miR-595 in the ovarian cancer cell. ABCB1 expression was upregulated in the ovarian cancer tissues and cell lines. Morevoer, the expression level of ABCB1 was inversely correlated with miR-595 in the ovarian cancer tissues. In addition, overexpression of ABCB1 decreased the miR-595-overexpressing HO8910PM and SKOV-3 cell sensitivity to cisplatin. Ectopic expression of ABCB1 promoted the miR-595-overexpressing HO8910PM and SKOV-3 cell proliferation, colony formation and invasion. These data suggested that miR-595 acted a tumor suppressor role in ovarian cancer development and increased the sensitivity of ovarian cancer to cisplatin.

PFTK1 regulates cell proliferation, migration and invasion in epithelial ovarian cancer

PFTK1, also named Cyclin-Dependent Kinase 14 (CDK14), is a member of the cell division cycle 2 (CDC2)-related protein kinase family. It is a serine/threonine-protein kinase involved in the regulation of cell cycle progression and cell proliferation. In this study, we investigated the role of PFTK1 in epithelial ovarian cancer (EOC) development. The expression of PFTK1 was detected by Western blot and immunohistochemistry staining, both of which demonstrated that PFTK1 was overexpressed in EOC tissues and cells. Statistical analysis showed the expression of PFTK1 was associated with multiple clinicopathological factors, including tumor grade, FIGO stage, lymph node metastatis, Ki-67 expression and predicted a poor prognosis of EOC patients. With in vitro studies we found that PFTK1 expression was decreased in serum-starved ovarian cancer cells, and progressively increased after serum-re-feeding. Knocking PFTK1 down by small interfering RNA (siRNA) significantly inhibited ovarian cancer cell proliferation, migration and invasion. Taken together, our study suggested that PFTK1 played an important role in ovarian cancer development.

Prognostic value and characterization of the ovarian cancer-specific antigen CA166-9.

COC166-9 is an ovarian cancer-specific monoclonal antibody, and COC166-9-based immunotherapy has been shown to possess killing effects against ovarian cancer cells in vitro and in vivo. However the antigen recognized by COC166-9 (COC166-9-Ag, CA166-9) has not been identified and the clinical significance of CA166-9 expression remains unknown. We found that CA166-9 was positive in 53.1% of ovarian cancer tissues. Expression of CA166-9 was strongly correlated with the cancer recurrence (P<0.001). Patients with positive CA166-9 had substantially shorter overall survival (P=0.026) and disease-free survival (P=0.002). CA166-9 was also shown to be an independent predictive factor for overall survival (HR=2.454, P=0.016) and disease-free survival (HR=2.331, P=0.021). We identified CA166-9 as human immunoglobulin γ-1 heavy chain constant region (IGHG1). Purified IGHG1 promoted proliferation, migration, and invasion of CA166-9-negative ovarian cancer HOC1A cells, whereas it had minimal effects on the phenotypes of CA166-9-positive ovarian cancer CAOV-3 cells. In addition, overexpression of IGHG1 enhanced migration of ovarian cancer cells. On the contrary, COC166-9 inhibited proliferation, migration, and invasion of CAOV-3 cells, but had no effects on HOC1A cells. Therefore, IGHG1 similarly to CA166-9, could play an important role in ovarian cancer development and may serve as a potential prognostic marker and a therapeutical target for ovarian cancer.

A mathematical model of bimodal epigenetic control of miR-193a in ovarian cancer stem cells.

Accumulating data indicate that cancer stem cells contribute to tumor chemoresistance and their persistence alters clinical outcome. Our previous study has shown that ovarian cancer may be initiated by ovarian cancer initiating cells (OCIC) characterized by surface antigen CD44 and c-KIT (CD117). It has been experimentally demonstrated that a microRNA, namely miR-193a, targets c-KIT mRNA for degradation and could play a crucial role in ovarian cancer development. How miR-193a is regulated is poorly understood and the emerging picture is complex. To unravel this complexity, we propose a mathematical model to explore how estrogen-mediated up-regulation of another target of miR-193a, namely E2F6, can attenuate the function of miR-193a in two ways, one through a competition of E2F6 and c-KIT transcripts for miR-193a, and second by binding of E2F6 protein, in association with a polycomb complex, to the promoter of miR-193a to down-regulate its transcription. Our model predicts that this bimodal control increases the expression of c-KIT and that the second mode of epigenetic regulation is required to generate a switching behavior in c-KIT and E2F6 expressions. Additional analysis of the TCGA ovarian cancer dataset demonstrates that ovarian cancer patients with low expression of EZH2, a polycomb-group family protein, show positive correlation between E2F6 and c-KIT. We conjecture that a simultaneous EZH2 inhibition and anti-estrogen therapy can constitute an effective combined therapeutic strategy against ovarian cancer.

The non-canonical Wnt ligand, Wnt5a, is upregulated and associated with epithelial to mesenchymal transition in epithelial ovarian cancer

ObjectiveAberrant Wnt signalling has previously been associated with gynaecological cancers, and the aim of this study was to investigate the expression of Wnt5a in epithelial ovarian cancer, and clarify its role in activating or inhibiting β-catenin dependent and independent Wnt signalling pathways. MethodWnt5a expression was investigated in a large cohort of epithelial ovarian cancer patient samples using immunohistochemistry and correlated with clinicopathological variables. Wnt5a function was investigated in vitro in ovarian cell lines. ResultsWnt5a expression was found to be upregulated in all major subtypes (serous, endometrioid, clear cell and mucinous) of epithelial ovarian cancer compared to borderline tumours and benign controls. Treatment of ovarian surface epithelial cells with recombinant Wnt5a decreased cell adhesion and was associated with increased epithelial to mesenchymal transition (EMT). In addition, downstream targets of β-catenin dependent Wnt signalling were inhibited, and β-catenin independent targets increased following Wnt5a upregulation. Knockdown of Wnt5a in ovarian cancer cells was associated with a mesenchymal to epithelial transition (MET), but had no significant effect on cell migration or proliferation. ConclusionThis study adds to the increasing evidence that Wnt signalling may play an important role in ovarian cancer development. Utilising an unparalleled large cohort of 623 patients, Wnt5a protein expression was shown to be significantly higher in ovarian cancer patients when compared to benign and borderline ovarian tumours and healthy control patients. In addition, we have utilised in vitro models to show for the first time in ovarian cancer that Wnt5a driven non-canonical pathways can alter epithelial to mesenchymal transition (EMT).

Abstract 3557: The aging suppressor hormone Klotho inhibits ovarian cancer cell proliferation by down-regulation of the estrogen receptor.

Abstract Klotho is a 1012 amino acid (aa) long transmembranal protein, which can be cleaved, shed and act as a circulating hormone. Klotho contains two regions named KL1 and KL2, each about 500aa long. Klotho deficient mice present a syndrome of early aging, while overexpression of klotho extends lifespan. Klotho is an essential co-factor for the activity of FGF23 and thus serves as a major regulator of phosphate homeostasis. Klotho is also a potent inhibitor of the insulin growth factor (IGF)-1 pathway. We have identified klotho as a tumor suppressor in breast and pancreatic cancer. Recently, klotho activity as a tumor suppressor was observed also in melanoma and in cervix, lung, colon and gastric cancers. As klotho is expressed in the normal ovary, we undertook to study the expression and activity of klotho in ovarian cancer. We first analyzed klotho expression, using quantitative RT-PCR and Western blotting, in 18 ovarian cancer cell lines and noted high levels of klotho mRNA and protein in only three lines. We next used immunohistochemistry analysis to study klotho expression in a tissue array containing 277 primary and recurrent ovarian, fallopian and primary peritoneal cancers, along with 22 normal and benign tumor samples. While high klotho expression was noted in all normal samples, reduced expression was noted in 30% of the tumors. Reduced expression was not associated with histology, tumor location or stage. Overexpression of either full length klotho or KL1 reduced clonal growth of OvCa432, SKOV3 and ES2 ovarian cancer cell lines by 80%, 60%, and 0%, respectively. Klotho inhibits the IGF-1 pathway in pancreatic and breast cancer cells. As the IGF-1 pathway plays an important role in ovarian cancer development, we studied the effect of klotho on this pathway in ovarian cancer cell lines. Klotho inhibited IGF-1-mediated AKT activation, and to a lesser degree ERK1/2 phosphorylation, in SKOV3 and OvCa432 cells. Interestingly, ES2 cells did not respond to IGF-1. Estrogen receptor (ER)α and progesterone receptor (PR) have a significant role in ovarian cancer development. ERα is expressed in a majority of ovarian cancers, while PR is less abundant, and its expression is a marker for better prognosis. We found that klotho reduces ERα expression and activity in SKOV3 and OvCa432. Interestingly, klotho elevated PR-A isoform expression in these cell lines. In conclusion, unlike in breast and pancreas cancer, where klotho was identified as a potent tumor suppressor in most cancer subtypes, and the IGF-1 pathway was inhibited in a wide array of cell lines, in the ovary, klotho plays a role in a smaller subset of tumors. The characteristics of this group have not been identified yet. However, it appears that ERα inhibition and PR-A up-regulation may play a role in mediating klotho activities in this subset. Citation Format: Irina Lojkin, Omer Schwartzman, Tami Rubinek, Ido Wolf. The aging suppressor hormone Klotho inhibits ovarian cancer cell proliferation by down-regulation of the estrogen receptor. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3557. doi:10.1158/1538-7445.AM2013-3557