Diminished miR-613 expression as a novel prognostic biomarker for human ovarian cancer.

OBJECTIVE miR-613 may suppress ovarian cancer development and progression. We wished to assess the potential prognostic value of miR-613 expression analysis in ovarian cancer. PATIENTS AND METHODS A total of 236 pairs of human ovarian cancer and matched normal tissue specimens were collected. Resected tissue specimens were obtained during the operation and were snap-frozen in liquid nitrogen for subsequent RNA extraction. Total RNA was extracted from tissue specimens, and miR-613 expression was quantified using TaqMan qPCR. The miR-613 expression was normalized to expression of U6 as an internal standard. RESULTS miR-613 expression in ovarian cancer tissue specimens was significantly (p < 0.001) lower than that in matched normal adjacent tissue specimens. Furthermore, within ovarian cancer tissue specimens, 114 specimens exhibited lower levels of miR-613 ("low expression" group), whereas 122 specimens showed higher levels of this miR ("high expression" group). Low expression of miR-613 showed significant associations with the FIGO stage (p < 0.001), tumour grade (p < 0.001), and lymph node metastases (p < 0.001). Furthermore, low miR-613 expression was associated with lower progression-free and overall survival (respectively, p < 0.01 and < 0.0001). Finally, the multivariate analysis using the Cox proportional hazards model showed that miR-613 expression levels, FIGO stage, and lymph node metastases were independently associated with progression-free and overall survival in patients with ovarian cancer. CONCLUSIONS miR-613 expression levels are low in ovarian cancer tissue and correlate with progression-free and overall survival. Thus, miR-613 may be useful as a prognostic marker in ovarian cancer.