MicroRNA-29b inhibits human vascular smooth muscle cell proliferation via targeting the TGF-β/Smad3 signaling pathway

Intracranial aneurysms (IAs) are bulges of blood vessels in the cerebral area. The development and progression of IAs are associated with the proliferation of vascular smooth muscle cells (VSMCs) during phenotypic modulation under environmental cues. MicroRNA-29b (miR-29b) has been studied extensively and demonstrated to reduce cell proliferation in various diseases by binding to the 3'-untranslated region (3'-UTR) of a variety of target messenger RNAs (mRNAs), thereby inhibiting their translation. The present study aimed to investigate the role of miR-29b on the proliferation of VSMCs and human umbilical artery smooth muscle cells. The results indicated that the overexpression of miR-29b reduced cell migration and proliferation. Western blotting results indicated that this effect may be attributed to the attenuation of a signaling pathway involving transforming growth factor beta (TGF-beta) and Smad3 proteins. Luciferase assay confirmed the binding of miR-29b to TGF-beta 1 and the knockdown of TGF-beta 1 reduced miR-29b inhibitor-induced cell migration. The present study indicates that miR-29b downregulates the expression of TGF-beta 1 by targeting the 3'-UTR of its mRNA and modulates cell migration and proliferation via the TGF-beta 1/Smad3 signaling pathway.