Functional analyses of microRNA-326 in breast cancer development

MicroRNA-326 (miR-326) was reported to be dysregulated and involved in the progression of multiple cancers. However, the clinical significance, biological role and underlying mechanism of miR-326 in the carcinogenesis of breast cancer are still unclear. In the present study, we showed that miR-326 was down-regulated in human breast cancer tissues and cell lines. Our results also revealed that miR-326 overexpression significantly suppressed breast cancer cell proliferation, migration and invasion, and induced cell cycle arrest at G(1)/G(0) phase. Furthermore, Sex determining region Y-box (SOX) protein 12 (SOX12), a known oncogene, was identified as a direct target of miR-326 by luciferase reporter assay. Moreover, miR-326 expression was inversely correlated with SOX12 mRNA expression levels in human breast cancer specimens. Overexpression of SOX12 partially rescued the inhibitory effect on cell proliferation, migration and invasion in breast cancer cells caused by miR-326 overexpression. These findings suggested that miR-326 might play a suppressive role in breast cancer, at least in part, by targeting SOX12, rendering miR-326 a promising therapeutic target for breast cancer.