miR-146a (miR-146a-5p) has been reported to be aberrantly expressed in different types of cancers, the current knowledge about the role of miR-146a in prostate cancer is still limited.

The expression levels of miR-146a in cell lines and tissues were measured by qRT-PCR and in situ hybridization. Effects of miR-146a on cell growth and migration were evaluated by colony formation assay and RTCA assay, respectively. The dual luciferase assay was used to examine the binding between miR-146a and the 3'UTR of potential targets.

We found that enforced over-expression of miR-146a in prostate cancer cells suppressed whereas knockdown of miR-146a increased anchorage-independent growth, migration, and invasion. Mechanistic studies revealed that miR-146a repressed the expression of Rac1 through binding to its 3'UTR. Consistently, knockdown of Rac1 phenocopied the anti-migration effect of overexpressing miR-146a, and knockdown of Rac1 in miR-146a-silencing cells antagonized the increase in cell motility induced by silencing miR-146a. Furthermore, miR-146a was found to be inversely correlated with Rac1 in human prostate cancer tissues.

Our data suggest that miR-146a plays a suppressive role in prostate cancer through down-regulation of Rac1. The miR-146a/Rac1 signaling axis may be a potential therapeutic target to prevent prostate cancer progression. Prostate © 2014 Wiley Periodicals, Inc.