A Pilot Study of Circulating MicroRNA-125b as a Diagnostic and Prognostic Biomarker for Epithelial Ovarian Cancer

OBJECTIVE: Early diagnosis of epithelial ovarian cancer is critical for patient survival. The objective of this pilot study is to identify a circulating micro (mi)RNA as a potential biomarker for epithelial ovarian cancer. METHODS: A total of 135 epithelial ovarian cancer patients and 54 benign ovarian tumor patients were recruited for this study. Using customized TaqMan low density miRNA arrays, we first screened expression levels of 48 miRNAs in sera from 18 epithelial ovarian cancer patients and 16 benign ovarian tumor patients. The most significantly and differentially expressed miRNA was then further examined in all serum samples using real-time polymerase chain reaction. Its expression was further analyzed in relationship with clinicopathological factors and patient survival. RESULTS: Array screening data showed that expression levels of serum miRNA-20a, miRNA-125b, miRNA-126, miRNA-355, and let-7c were significantly different between malignant and benign ovarian tumor patients. Subsequent real-time polymerase chain reaction results showed that serum miRNA-125b levels were significantly higher in epithelial ovarian cancer patients compared to benign controls. Moreover, serum miRNA-125b levels were significantly higher in ovarian cancer patients in early stages I and II, and in patients having no residual tumor following surgery, but were not associated with differentiation and histological types of ovarian cancer. Notably, the higher level of miR-125b was significantly positively correlated with progression-free survival (P = 0.035) and marginally, with overall survival (P = 0.069). CONCLUSIONS: miRNA-125b plays an important role in the pathogenesis and progression of epithelial ovarian cancer. Circulating miRNA-125b has the potential to become a novel biomarker for early diagnosis and prognosis prediction of epithelial ovarian cancer.