LAUSR

BACKGROUND AND AIMS Cilostazol, beyond its antiplatelet effect, is also capable of promoting vascular smooth muscle cell (VSMC) differentiation. The aim of this study was to explore the potential role of PTEN, known to associate with VSMC differentiation, and its related microRNA (miRNA) in cilostazol-dependent effects. METHODS AND RESULTS Microarray analysis in balloon-injured rat carotid arteries comparing with and without balloon injury revealed that miR-132 was differentially expressed. Bioinformatic analysis predicts PTEN as a novel target of miR-132. Western blot and quantitative real-time reverse transcription-polymerase chain reaction along with in situ hybridization documented that cilostazol treatment enhanced PTEN and reduced miR-132 expression in the neointima of balloon-injured arteries. Treatment of cultured rat VSMCs with cilostazol resulted in the up-regulation of PTEN mRNA and the down-regulation of miR-132, supporting an in vitro relevance. Co-transfection experiments showed that transfection of miR-132 mimic into VSMCs suppressed PTEN 3'UTR activities, further reflecting that PTEN is the direct target of miR-132. Over-expression of miR-132 in VSMCs led to an attenuation of cilostazol-induced PTEN and its downstream VSMC differentiation marker (calponin) expression, confirming the critical role of miR-132 in VSMC differentiation. Transient transfection studies demonstrated that cilostazol reduced the activity of miR-132 promoter, which was mediated via cyclic AMP response element-binding protein. Notably, the use of lentivirus to over-express miR-132 in the neointima of balloon-injured arteries could reverse the effect of cilostazol in vivo. CONCLUSIONS These results suggest that miR-132 by targeting PTEN may be an important regulator in mediating cilostazol actions on VSMC differentiation.