Circular RNAs in Epithelial Ovarian Cancer: From Biomarkers to Therapeutic Targets

SIMPLE SUMMARY: Epithelial ovarian cancer (EOC) is the deadliest cancer in the female reproductive system. Currently, there are no effective early detection methods for this disease, and the treatments for advanced stages of EOC have a low success rate. Circular RNAs (circRNAs) are noncoding RNAs generated from the “back-splicing” of precursor messenger RNAs. Recent studies have shown that many circRNAs are aberrantly expressed in tumor tissues and/or plasma of EOC patients, and they regulate EOC cell activity and tumor growth. In this review, we provide an overview of EOC and circRNA biology. We then summarize circRNAs that are dysregulated and exert tumor-promoting or tumor-suppressive effects in EOC. We also discuss the possibility of using circRNAs as diagnostic/prognostic markers and therapeutic targets. ABSTRACT: Epithelial ovarian cancer (EOC) is the most lethal gynecological cancer, and more than 70% of patients are diagnosed at advanced stages. Despite the application of surgery and chemotherapy, the prognosis remains poor due to the high relapse rate. It is urgent to identify novel biomarkers and develop novel therapeutic strategies for EOC. Circular RNAs (circRNAs) are a class of noncoding RNAs generated from the “back-splicing” of precursor mRNA. CircRNAs exert their functions via several mechanisms, including acting as miRNA sponges, interacting with proteins, regulating transcription, and encoding functional proteins. Recent studies have identified many circRNAs that are dysregulated in EOC and may be used as diagnostic and prognostic markers. Increasing evidence has revealed that circRNAs play a critical role in ovarian cancer progression by regulating various cellular processes, including proliferation, apoptosis, metastasis, and chemosensitivity. The circRNA-based therapy may be a novel strategy that is worth exploring in the future. Here, we provide an overview of EOC and circRNA biogenesis and functions. We then discuss the dysregulations of circRNAs in EOC and the possibility of using them as diagnostic/prognostic markers. We also summarize the role of circRNAs in regulating ovarian cancer development and speculate their potential as therapeutic targets.