Salusin-α Inhibits Proliferation and Migration of Vascular Smooth Muscle Cell via Akt/mTOR Signaling

Background/Aims: The proliferation and migration of vascular smooth muscle cells (VSMCs) are key steps in the progression of atherosclerosis. The aim of the present study was to investigate the potential roles of salusin-α in the functions of VSMCs during the development of atherosclerosis. Methods: In vivo, the effects of salusin-α on atherogenesis were examined in rabbits fed a cholesterol diet. The aortas were en face stained with Sudan IV to evaluate the gross atherosclerotic lesion size. The cellular components of atherosclerotic plaques were analyzed by immunohistochemical methods. In vitro, Cell Counting Kit-8 and wound-healing assays were used to assess the effects of salusin-α on VSMC proliferation and migration. In addition, western blotting was used to evaluate the total and phosphorylated levels of Akt (also known as protein kinase B) and mammalian target of rapamycin (mTOR) in VSMCs. Results: Salusin-α infusion significantly reduced the aortic lesion areas of atherosclerosis, with a 39% reduction in the aortic arch, a 71% reduction in the thoracic aorta, and a 71% reduction in the abdominal aorta; plasma lipid levels were unaffected. Immunohistochemical staining showed that salusin-α decreased both macrophage- and VSMC-positively stained areas in atherosclerotic lesions by 54% and 69%, cell proliferative activity in the intima and media of arteriosclerotic lesions, and matrix metalloproteinase 2 (MMP-2) and MMP-9 expression in plaques. Studies using cultured VSMCs showed that salusin-α decreased VSMC migration and proliferation via reduced phosphorylation of Akt and mTOR. Conclusion: Our data indicate that salusin-α suppresses the development of atherosclerosis by inhibiting VSMC proliferation and migration through the Akt/mTOR pathway.