Human Cancer Biology MicroRNA-200a Promotes Anoikis Resistance and Metastasis by Targeting YAP1 in Human Breast Cancer

Purpose:Theprocess ofmetastases involves the dissociation of cells from theprimary tumor, penetration into the basement membrane, invasion, and exiting from the vasculature to seed and colonize distant tissues. miR-200a is involved in this multistep metastatic cascade. This study aimed to test the hypothesis that miR-200a promotes metastasis through increased anoikis resistance in breast cancer. Experimental Design: Breast cancer cells transfected withmimic or inhibitor formiR-200a were assayed for anoikis in vitro. miR-200a expression was assessed by quantitative real-time PCR (qRT-PCR). Luciferase assays, colony formation assays, and animal studies were conducted to identify the targets of miR-200a and the mechanism by which it promotes anoikis resistance. Results: We found that overexpression of miR-200a promotes whereas inhibition of miR-200a suppresses anoikis resistance in breast cancer cells. We identified Yes-associated protein 1 (YAP1) as a novel target ofmiR-200a.Our data showed that targeting of YAP1 bymiR-200a resulted in decreased expression of proapoptotic proteins, which leads to anoikis resistance. Overexpression ofmiR-200a protected tumor cells fromanoikis andpromotedmetastases in vivo. Furthermore, knockdownof YAP1phenocopied the effects of miR-200a overexpression, whereas restoration of YAP1 in miR-200a overexpressed breast cancer cells reversed the effects ofmiR-200a on anoikis andmetastasis. Remarkably, we found that YAP1 expressionwas inversely correlatedwithmiR-200a expression in breast cancer clinical specimens, andmiR-200a expression was associated with distant metastasis in patients with breast cancer. Conclusions: Our data suggest that miR-200a functions as anoikis suppressor and contributes to metastasis in breast cancer. Clin Cancer Res; 19(6); 1389–99. 2013 AACR.