MiR-146a-5p and miR-191-5p are the Candidates for Novel Diagnostic Markers of Ovarian Clear Cell Carcinoma

Background: Ovarian cancer is a malignant gynecologic disease rarely diagnosed in the early stages. Among ovarian cancers, clear cell carcinoma has a poor prognosis due to its malignant potential. MicroRNAs (miRNAs) regulate gene expression in cells by suppressing the translation of the target gene or by degrading the target mRNA. They are also secreted from the cells in the blood, binding to the proteins or included in extracellular vesicles lipids and assisting in cell-cell communication. Hence, the serum miRNAs can also be diagnostic biomarkers for ovarian cancer. This study investigated and identified specific miRNAs for ovarian cancer clear cell carcinoma and compared them to those of the ovarian endometrioma in healthy controlpatients. Results: CA125, an ovarian tumor marker, did not differ between ovarian clear cell carcinoma, endometriosis, and healthy controlsthe three groups. Four miRNAs (miR-146a-5p, miR-191-5p, miR-484, and miR-574-3p) were analyzed. The miR-146a-5p and miR-191-5p expression levels were significantly increased in the serum samples from the ovarian clear cell carcinoma subjects compared to the healthy controlscontrols, but not in the subjects with endometriosis (P < 0.05). Furthermore, the bioinformatics analysis showed that CCND2 and NOTCH2 were the candidate target genes of miR‑146a-5p and miR-191-5p.Conclusions: Our results showed that miR‑146a-5p and miR-191-5p might be useful as an early and non-invasive diagnostic tool in ovarian clear cell carcinoma. These miRNAs can help in distinguishing between ovarian clear cell carcinoma and ovarian endometrioma. To the best of our knowledge, no studies have screened any candidates specifically for clear cell carcinoma.