MicroRNAs (
miRNAs) function as genetic modulators that regulate gene expression and are involved in a wide range of
biological roles, including
tumor cell migration and invasion. In the present study, we demonstrated that the migration and invasion activity in MDA-MB-231
breast cancer cells could be directly influenced by altering miR-146a expression. The expression of RhoA and miR-146a in the
breast cancer cells showed an inverse correlation. Upregulation of miR-146a in the MDA-MB‑231
breast cancer cells by transfection of miR-146a mimics resulted in decreased
RhoA protein levels. Conversely, downregulation of miR-146a by transfection of miR-146a inhibitor resulted in increased
RhoA protein levels. To confirm the fact that RhoA is a potential target of miR-146a,
luciferase reporter containing the RhoA
3' untranslated region (
3'UTR) was constructed. The results demonstrated that the
luciferase reporter activity was reduced after overexpression of miR-146a. Moreover, the
luciferase reporter which was constructed with the RhoA
3'UTR mutant did not show significantly altered
luciferase reporter activity. Furthermore,
after treatment with the RhoA inhibitor exoenzyme C3
transferase protein, the migratory capacity of the MDA-MB-231 cells was not significantly altered even though the amount of miR-146a was changed. Our results indicate that miR-146a functions as a
tumor suppressor in
breast cancer cells. Downregulation of the expression of miR-146a increased the migration of MDA-MB-231 cells, due to the upregulation of RhoA expression.