Testosterone suppresses rat vascular smooth muscle cell phenotypic transition and proliferation

Objective To investigate the inhibitory effect of testosterone on oxidized low-density lipoproteins(ox-LDL)-stimulated phenotypic transition and proliferation of vascular smooth muscle cells(VSMCs)in vitro, and to explore its possible mechanisms. Methods Rat VSMCs cultured in vitro were divided into control group, ox-LDL group(50 μg/ml ox-LDL), fetal bovine serum(FBS)group(10% FBS), and testosterone groups(5×10-8 or 5×10-7mol/L testosterone plus 50 μg/ml ox-LDL). The effect of testosterone on ox-LDL-induced proliferation of VSMCs was explored by WST-1 assay. The cell cycle distribution was determined using flow cytometry. Western blotting was used to detect the expressions of mitofusin2(Mfn2), phosphorylated extracellular signal-regulated kinases 1/2(p-ERK1/2), proliferating cell nuclear antigen(PCNA), α-smooth muscle actin(α-SMA), and osteopontin(OPN). Results Compared with control group, the proliferation of VSMCs was promoted by ox-LDL, the number of VSMCs decreased in G0/G1 phase and increased in S phase significantly, the expression levels of Mfn2 and α-SMA were significantly reduced, and the expression levels of p-ERK1/2, PCNA, and OPN were significantly raised in ox-LDL group. Compared with ox-LDL group, the proliferation of VSMCs was inhibited, the number of VSMCs increased in G0/G1 phase and decreased in S phase in two testosterone groups, along with the increased expressions of Mfn2 and α-SMA, and the descended expressions of p-ERK1/2, PCNA, and OPN. Conclusions Testosterone inhibits phenotypic transition and proliferation of VSMCs induced by ox-LDL in vitro, which may be related to the up-regulated expression of Mfn 2 and the suppression of ERK1/2 pathway.(Chin J Endocrinol Metab, 2015, 31: 806-809) Key words: Testosterone; Vascular smooth muscle cell; Mitofusin2; Phenotype; Proliferation