The Biphasic Expression Pattern of miR-200a and E-cadherin in Epithelial Ovarian Cancer and its Correlation with Clinicopathological Features

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.