The tubal epigenome - An emerging target for ovarian cancer

H2Bub1 loss is an early contributor to clear cell ovarian cancer progression

Epigenetic aberrations, including posttranslational modifications of core histones, are major contributors to cancer. Here, we define the status of histone H2B monoubiquitylation (H2Bub1) in clear cell ovarian carcinoma (CCOC), low-grade serous carcinoma, and endometrioid carcinomas. We report that clear cell carcinomas exhibited profound loss, with nearly all cases showing low or negative H2Bub1 expression. Moreover, we found that H2Bub1 loss occurred in endometriosis and atypical endometriosis, which are established precursors to CCOCs. To examine whether dysregulation of a specific E3 ligase contributes to the loss of H2Bub1, we explored expression of ring finger protein 40 (RNF40), ARID1A, and UBR7 in the same case cohort. Loss of RNF40 was significantly and profoundly correlated with loss of H2Bub1. Using genome-wide DNA methylation profiles of 230 patients with CCOC, we identified hypermethylation of RNF40 in CCOC as a likely mechanism underlying the loss of H2Bub1. Finally, we demonstrated that H2Bub1 depletion promoted cell proliferation and clonogenicity in an endometriosis cell line. Collectively, our results indicate that H2Bub1 plays a tumor-suppressive role in CCOCs and that its loss contributes to disease progression.

Rosline promotes p21 expression to inhibit ovarian cancer cell proliferation via p53-independent pathway

AIM

To investigate the effect of benzothiazole derivatives (Rosline) on ovarian cancer and the potential mechanism.

METHODS

Ovarian cancer tissues were collected clinically and immunohistochemistry was used to detect the expression of p53 and p21. Ovarian cancer cells were exposed to 0, 2.5, 5, 10 μmol/L Rosline for 24 h. 100 nmol/L Pifithrin-α pre-incubation was used to inhibit the transcriptional activity of p53. CCK-8 and BrdU assays were used to detect the effects of different concentrations of rosline on the proliferation and cell cycle of OVCAR420 and SKOV3 cells. Flow cytometry assay was used to detect cell cycle. The transcriptional and translational expression of p21 and p53 were detected by RT-qPCR and Western blot.

RESULTS

p21 was expressed in ovarian cancer tissues without p53 expression. Rosline inhibits the proliferation of ovarian cancer cells and blocks the cell cycle progression. Meanwhile, Rosline promotes p21 expression in ovarian cancer cells at both mRNA and protein levels, but with no significant effect on p53 expression. Besides, Rosline promotes p21 expression, inhibits cell proliferation, and blocks the cell cycle via the p53-independent pathway.

CONCLUSION

Rosline promoted p21 expression thereby inhibiting cell proliferation and blocks the cell cycle via p53-independent pathway.

Fallopian tube secreted protein affects ovarian metabolites in high grade serous ovarian cancer

High grade serous ovarian cancer (HGSOC), the most lethal histotype of ovarian cancer, frequently arises from fallopian tube epithelial cells (FTE). Once transformed, tumorigenic FTE often migrate specifically to the ovary, completing the crucial primary metastatic step and allowing the formation of the ovarian tumors after which HGSOC was originally named. As only the fimbriated distal ends of the fallopian tube that reside in close proximity to the ovary develop precursor lesions such as serous tubal intraepithelial carcinomas, this suggests that the process of transformation and primary metastasis to the ovary is impacted by the local microenvironment. We hypothesize that chemical cues, including small molecules and proteins, may help stimulate the migration of tumorigenic FTE to the ovary. However, the specific mediators of this process are still poorly understood, despite a recent growth in interest in the tumor microenvironment. Our previous work utilized imaging mass spectrometry (IMS) to identify the release of norepinephrine (NE) from the ovary in co-cultures of tumorigenic FTE cells with an ovarian explant. We predicted that tumorigenic FTE cells secreted a biomolecule, not produced or produced with low expression by non-tumorigenic cells, that stimulated the ovary to release NE. As such, we utilized an IMS mass-guided bioassay, using NE release as our biological marker, and bottom-up proteomics to demonstrate that a secreted protein, SPARC, is a factor produced by tumorigenic FTE responsible for enhancing release of ovarian NE and influencing primary metastasis of HGSOC. This discovery highlights the bidirectional interplay between different types of biomolecules in the fallopian tube and ovarian microenvironment and their combined roles in primary metastasis and disease progression.

Molecular mechanisms of platinum‑based chemotherapy resistance in ovarian cancer (Review)

Cisplatin is one of the most effective chemotherapy drugs for ovarian cancer, but resistance is common. The initial response to platinum‑based chemotherapy is as high as 80%, but in most advanced patients, final relapse and death are caused by acquired drug resistance. The development of resistance to therapy in ovarian cancer is a significant hindrance to therapeutic efficacy. The resistance of ovarian cancer cells to chemotherapeutic mechanisms is rather complex and includes multidrug resistance, DNA damage repair, cell metabolism, oxidative stress, cell cycle regulation, cancer stem cells, immunity, apoptotic pathways, autophagy and abnormal signaling pathways. The present review provided an update of recent developments in our understanding of the mechanisms of ovarian cancer platinum‑based chemotherapy resistance, discussed current and emerging approaches for targeting these patients and presented challenges associated with these approaches, with a focus on development and overcoming resistance.

Toward More Comprehensive Homologous Recombination Deficiency Assays in Ovarian Cancer, Part 1: Technical Considerations

Simple Summary

High-grade serous ovarian cancer (HGSOC) is the most frequent and lethal form of ovarian cancer and is associated with homologous recombination deficiency (HRD) in 50% of cases. This specific alteration is associated with sensitivity to PARP inhibitors (PARPis). Despite vast prognostic improvements due to PARPis, current molecular assays assessing HRD status suffer from several limitations, and there is an urgent need for a more accurate evaluation. In these companion reviews (Part 1: Technical considerations; Part 2: Medical perspectives), we develop an integrative review to provide physicians and researchers involved in HGSOC management with a holistic perspective, from translational research to clinical applications.

Abstract

High-grade serous ovarian cancer (HGSOC), the most frequent and lethal form of ovarian cancer, exhibits homologous recombination deficiency (HRD) in 50% of cases. In addition to mutations in BRCA1 and BRCA2, which are the best known thus far, defects can also be caused by diverse alterations to homologous recombination-related genes or epigenetic patterns. HRD leads to genomic instability (genomic scars) and is associated with PARP inhibitor (PARPi) sensitivity. HRD is currently assessed through BRCA1/2 analysis, which produces a genomic instability score (GIS). However, despite substantial clinical achievements, FDA-approved companion diagnostics (CDx) based on GISs have important limitations. Indeed, despite the use of GIS in clinical practice, the relevance of such assays remains controversial. Although international guidelines include companion diagnostics as part of HGSOC frontline management, they also underscore the need for more powerful and alternative approaches for assessing patient eligibility to PARP inhibitors. In these companion reviews, we review and present evidence to date regarding HRD definitions, achievements and limitations in HGSOC. Part 1 is dedicated to technical considerations and proposed perspectives that could lead to a more comprehensive and dynamic assessment of HR, while Part 2 provides a more integrated approach for clinicians.

Effects of trans-(±)-kusunokinin on chemosensitive and chemoresistant ovarian cancer cells

Ovarian cancer ranks eighth in cancer incidence and mortality among women worldwide. Cisplatin-based chemotherapy is commonly used for patients with ovarian cancer. However, the clinical efficacy of cisplatin is limited due to the occurrence of adverse side effects and development of cancer chemoresistance during treatment. Trans-(±)-kusunokinin has been previously reported to inhibit cell proliferation and induce cell apoptosis in various cancer cell types, including breast, colon and cholangiocarcinoma. However, the potential effects of (±)-kusunokinin on ovarian cancer remains unknown. In the present study, chemosensitive ovarian cancer cell line A2780 and chemoresistant ovarian cancer cell lines A2780cis, SKOV-3 and OVCAR-3 were treated with trans-(±)-kusunokinin to investigate its potential effects. MTT, colony formation, apoptosis and multi-caspase assays were used to determine cytotoxicity, the ability of single cells to form colonies, induction of apoptosis and multi-caspase activity, respectively. Moreover, western blot analysis was performed to determine the proteins level of topoisomerase II, cyclin D1, CDK1, Bax and p53-upregulated modulator of apoptosis (PUMA). The results demonstrated that trans-(±)-kusunokinin exhibited the strongest cytotoxicity against A2780cis cells with an IC₅₀ value of 3.4 µM whilst also reducing the colony formation of A2780 and A2780cis cells. Trans-(±)-kusunokinin also induced the cells to undergo apoptosis and increased multi-caspase activity in A2780 and A2780cis cells. This compound significantly downregulated topoisomerase II, cyclin D1 and CDK1 expression, but upregulated Bax and PUMA expression in both A2780 and A2780cis cells. In conclusion, trans-(±)-kusunokinin suppressed ovarian cancer cells through the inhibition of colony formation, cell proliferation and the induction of apoptosis. This pure compound could be a potential targeted therapy for ovarian cancer treatment in the future. However, studies in an animal model and clinical trial need to be performed to support the efficacy and safety of this new treatment.

A narrative review of the relationship between TGF-β signaling and gynecological malignant tumor

Objective

This paper reviews the association between transforming growth factor-β (TGF-β) and its receptor and tumor, focusing on gynecological malignant tumors. we hope to provide more methods to help increase the potential of TGF-β signaling targeted treatment of specific cancers.

Background

The occurrence of a malignant tumor is a complex process of multi-step, multi-gene regulation, and its progression is affected by various components of the tumor cells and/or tumor microenvironment. The occurrence of gynecological diseases not only affect women's health, but also bring some troubles to their normal life. Especially when gynecological malignant tumors occur, the situation is more serious, which will endanger the lives of patients. Due to differences in environmental and economic conditions, not all women have access to assistance and treatment specifically meeting their needs. TGF-β is a multi-potent growth factor that maintains homeostasis in mammals by inhibiting cell growth and promoting apoptosis in vivo. TGF-β signaling is fundamental to inflammatory disease and favors the emergence of tumors, and it also plays an important role in immunosuppression in the tumor microenvironment. In the early stages of the tumor, TGF-β acts as a tumor inhibitor, whereas in advanced tumors, mutations or deletion of the TGF-β signaling core component initiate neogenesis.

Methods

Literatures about TGF-β and gynecological malignant tumor were extensively reviewed to analyze and discuss.

Conclusions

We discussed the role of TGF-β signaling in different types of gynecological tumor cells, thus demonstrating that targeted TGF-β signaling may be an effective tumor treatment strategy.

Elevated LINC00909 Promotes Tumor Progression of Ovarian Cancer via Regulating the miR-23b-3p/MRC2 Axis

Ovarian cancer (OC), the third common gynecologic malignancy, contributes to the most cancer-caused mortality in women. However, 70% of patients with OC are diagnosed at an advanced stage, of which the 5-year survival is less than 30%. Long noncoding RNAs (long ncRNAs or lncRNA), a type of RNA with exceeding 200 nucleotides in length but no protein-coding capability, have been demonstrated to involve the pathogenesis of various cancers and show considerable potential in the diagnosis of OC. In this study, we found that the LINC00909 expression in tumor and serum specimens of OC patients was elevated, determined by real-time quantitative, and droplet digital PCR. In receiver operating characteristic (ROC) analysis, our results revealed that serum LINC00909 distinguished cancers from normal ovarian tissue with 87.8% of sensitivity and 69.6% of specificity (AUC, 81.2%) and distinguished serous ovarian cancer from normal ovarian tissue with 90.0% of sensitivity and 75.9% of specificity (AUC, 84.5%). Furthermore, we observed that the tumor and serum LINC00909 level was positively associated with the International Federation of Gynecology and Obstetrics (FIGO) stage and the Eastern Cooperative Oncology Group (ECOG) score (reflecting patients' performance status). Also, patients with low serum LINC00909 level showed a longer overall (hazard ratio, HR = 1.874, p = 0.0004) and progression-free (HR = 1.656, p = 0.0017) survival. Functional assays indicated that the elevation of LINC00909 expression contributes to cell proliferation, migration, and invasion capability of ovarian cancer cells. Besides, we demonstrated that LINC00909 functions as a competing endogenous RNA (ceRNA) of MRC2 mRNA by sponging miR-23-3p, and thereby promotes epithelial-to-mesenchymal transition (EMT) of ovarian cancer cells. Therefore, we highlight that the LINC00909/miR-23b-3p/MRC2 axis is implicated in the pathogenesis of ovarian cancer, and serum LINC00909 may be a promising biomarker for the diagnosis of OC.

FGFR3 phosphorylates EGFR to promote cisplatin-resistance in ovarian cancer

Ovarian cancer is a deadly gynecologic cancer, and the majority of patients with ovarian cancer experience relapse after traditional treatment. Cisplatin (DDP) is a common chemotherapeutic drug for ovarian cancer, but many patients acquire DDP-resistance after treatment with long-term chemotherapy. The mechanisms of drug-resistance in ovarian cancer are not clear, and we thus aim to investigate novel targets for DDP-resistant ovarian cancer. Differential analysis, KEGG pathway enrichment and protein interaction networks were employed to identify the key genes related to DDP-resistance in ovarian cancer. Subsequently, cell viability, apoptosis and migration were measured to assess the effect of fibroblast growth factor receptor 3 (FGFR3) on DDP-resistance. Further, Pearson correlation analysis and co-expression analysis were used to explore the downstream pathways of FGFR3, and the function of FGFR3 and its downstream targets were further demonstrated by in vitro and nude mice experiments. FGFR3 were expressed at high levels in DDP-resistant ovarian cancer cells. FGFR3 silencing suppressed the activation of PI3K/AKT pathway and impeded the drug-resistance and development of tumor cells. Afterwards, we found that FGFR3 was co-expressed with epidermal growth factor receptor (EGFR). FGFR3 overexpression elevated EGFR phosphorylation and activated PI3K/AKT signaling. Furthermore, in nude mice, silencing FGFR3 and inhibiting EGFR phosphorylation were observed to promote the therapeutic effect of DDP. In conclusion, FGFR3 overexpression enhances DDP-resistance of ovarian cancer by promoting EGFR phosphorylation and further activating PI3K/AKT pathway. This study may offer promising targets for DDP-resistant ovarian cancer.

The Cancer-Testis Long Non-coding RNA PCAT6 Facilitates the Malignant Phenotype of Ovarian Cancer by Sponging miR-143-3p

Background: It has been reported that long non-coding RNAs (lncRNAs) play critical roles in tumorigenesis. However, their roles in ovarian cancer (OC) remain to be elucidated. The aim of this study was to uncover the function and underlying mechanisms of PCAT6 in OC.

Methods: The expression pattern of PCAT6 in OC was analyzed in the GSE137238, GSE143897 and Gene Expression Profile Interactive Analysis (GEPIA) datasets. Kaplan–Meier Plotter online software was used for survival analysis. Loss-of-function assays and gain-of-function assays were used to assess the function of PCAT6 in OC development. Moreover, small-RNA sequencing, bioinformatic analysis, luciferase assays and rescue experiments were carried out to clarify the potential mechanism of PCAT6 in OC.

Results: PCAT6 expression was significantly increased in OC tissues and positively correlated with advanced stages and with poor overall survival, progression-free survival and post-progression survival. Knockdown of PCAT6 in A2780 and SKOV3 cells inhibited OC cell proliferation, migration and invasion. In contrast, Overexpression of PCAT6 exerted the opposite effects on OC cells. Notably, PCAT6 bound to miR-143-3p and affected the expression of transforming growth factor (TGF)-β-activated kinase 1 (TAK1). Subsequent rescue assays confirmed that upregulation of miR-143-3p decreased the PCAT6 overexpression-induced promotion of proliferation, migration and invasion. Moreover, downregulation of miR-143-3p reversed the PCAT6 knockdown-induced inhibition of proliferation, migration, and invasion.

Conclusions: Our findings demonstrate that PCAT6 plays an oncogenic role in OC and may be useful as a therapeutic target for OC.