microRNA-762 promotes breast cancer cell proliferation and invasion by targeting IRF7 expression.

OBJECTIVES: miRNAs play crucial roles in human tumourigenesis. This study was performed to measure expression and function of miR-762 in breast cancer.

MATERIALS AND METHODS: Expression of miR-762 in breast tissues and cell lines (SK-BR-3, DA-MB-435s, MCF-7 and MDA-MB-231, HBL-100) was measured by using real-time RT-PCR. We restored expression of miR-762 in MCF-7 cells to measure its functional roles. Luciferase assays were performed to reveal the target gene of miR-762.

RESULTS: Expression of miR-762 was high in both breast cancer cell lines and specimens, and its overexpression increased breast cancer cell proliferation and invasion. Interferon regulatory factor 7 (IRF7) is a direct target of miR-762 and overexpression of miR-762 reduced expression of IRF7. Moreover, IRF7 was repressed, its levels inversely correlated to miR-762 expression. IRF7 rescued miR-762-induced cell invasion and proliferation.

CONCLUSIONS: These results demonstrate that miR-762 tumour effect was achieved by targeting IRF7 in human breast cancer specimens.