Circulating epithelial-mesenchymal transition-associated miRNAs are promising biomarkers in ovarian cancer.

Ovarian cancer is the fifth most common cause of cancer death among women that is mostly due to the difficulty of early diagnosis. Circulating miRNAs proved to be reliable biomarkers in various cancers. We screened 9 miRNAs, which are involved in epithelial-mesenchymal transition, in the plasma samples of patients with malignant (n = 28) or non-malignant (n = 12) ovarian tumors and disease-free healthy volunteers (n = 60) by qRT-PCR. The expression levels of miR200a, miR200b, miR200c, miR141, miR429, miR203a, miR34b (p < 0.001) and miR34a (p < 0.01) were significantly higher in the malignant samples than in healthy controls. MiR203a, miR141 (p < 0.01), miR200a and miR429 (p < 0.05) levels were also higher in malignant compared to non-malignant samples. ROC-AUC was the highest in the case of miR200c: 0.861 (95%CI = 0.776-0.947). Spearman's rank correlation analysis revealed positive correlation between the plasma levels of the studied miRNAs that was the highest between miR200b and miR200c (rs = 0.774; p < 0.001). Target analysis also suggested tight interaction between these miRNAs in the regulation of cancer development. The agreement of diagnostic tests based on miRNA levels and the standard CA125 or HE4 was weak according to Cohen's kappa values. We conclude that miR200 family members, miR34b and miR203a might be promising complementary biomarkers in ovarian cancer.