Abstract

Epithelial ovarian cancer (EOC) is the leading cause of death among gynecologic malignancies. Despite great efforts to improve early detection and optimize chemotherapeutic regimens, the 5-year survival rate is only 30% for patients presenting with late-stage ovarian cancer. The high mortality of this disease is due to late diagnosis in over 70% of ovarian cancer cases. A class of small noncoding RNAs, or microRNAs, was found to regulate gene expression at the post-transcriptional level. Some, but not all, of the data indicated that the miR-200 family was dysregulated in a variety of malignancies. In this study, we demonstrated that miR-200a and E-cadherin were significantly upregulated in EOC compared to benign epithelial ovarian cysts and normal ovarian tissues. However, further stratification of the subject indicated that the expression levels of miR-200a were significantly downregulated in late-stage (FIGO III+V) and grade 3 groups compared with early stage (FIGO I+II) and grade 1 to 2 groups. Similarly, relatively low levels of miR-200a were observed in the lymph compared to the node-negative group. E-cadherin expression was found to be absent in normal ovarian tissue and was frequently expressed in benign epithelial ovarian cysts, with absence or low levels observed in late-stage ovarian cancers. There was a significantly positive correlation between miR-200a and E-cadherin in EOC. The biphasic expression pattern suggested that miR-200a levels may serve as novel biomarkers for the early detection of EOC, and miR-200a and E-cadherin are candidate targets for the development of new treatment modalities against ovarian cancer.

Keywords: Epithelial ovarian cancer, microRNA, miR-200a, E-cadherin.