This study shows that microRNA-320 (miR-320) is associated with many important cell functions, including cell differentiation, proliferation, migration, and apoptosis. However, the role of miR-320 in vascular smooth muscle cells (VSMCs) and proliferative vascular diseases is still completely unclear. In our study, we found that the expression of miR-320 in human VSMCs after PDGF stimulation was significantly down-regulated in time- and dose-dependent manner. Function analyses identified that miR-320 could inhibit the proliferation and migration of VSMCs in both basal and PDGF-stimulated conditions. Furthermore, Neuropilin 1 (NRP1) was demonstrated as a direct target of miR-320 in Luciferase reporter assays and miR-320 overexpression inhibited the expression of NRP1 with or without PDGF treatment. Finally, miR-320 was markedly decreased in mice carotid arteries after ligated injury, while the restoration of miR-320 via Ad-miR-320 attenuated neointimal hyperplasia by declining the NRP1 expression. The results confirmed that miR-320 regulated proliferation and migration of VSMCs and neointimal formation by targeting NRP1. These novel findings implied that the regulation of NRP1 expression by miR-320 has important significance in the early diagnosis and treatment of proliferation vascular diseases.
Keywords: miR-320; migration; neointimal formation; proliferation; vascular smooth muscle cell.