Betulinic Acid Inhibits High Glucose-Induced Vascular Smooth Muscle Cells Proliferation and Migration

The proliferation of vascular smooth muscle cells may perform a crucial role in the pathogenesis of diabetic vascular disease. The principal objective of this study was to determine the effects of betulinic acid (BA) on human aortic smooth muscle cell (HASMC) proliferation induced by high glucose (HG). In this study, [H-3]-thymidine incorporation under 25 mM HG was accelerated significantly as compared with 5.5 mM glucose, and this increase was inhibited significantly by BA treatment. We utilized Western blotting analysis to evaluate the effects of BA on cell-cycle regulatory proteins. HG induced the expression of cyclins/CDKs and reduced the expression of p21(waf1/cip1)/p27(kip1). However, BA also attenuated the expression of HG-induced cell-cycle regulatory proteins. The results of gelatin zymography demonstrated that the HG-treated HASMC secreted gelatinases, probably including MMP-2/-9, which may be involved in the invasion and migration of HASMC. Additionally, BA suppressed the protein and mRNA expression levels of MMP-2/-9 in a dose-dependent manner. BA inhibited the production of HG-induced hydrogen peroxide (H2O2) and the formation of DCF-sensitive intracellular reactive oxygen species (ROS). Further, BA suppressed the nuclear translocation and phosphorylation of I kappa B-alpha of NF-kappa B under HG conditions. Our results showed that BA exerts multiple effects on HG-induced HASMC proliferation and migration, including the inhibition of both MMP-2 and MMP-9 transcription, protein activity, and the downregulation of ROS/NF-kappa B signaling, thereby suggesting that BA may be a possible therapeutic approach to the inhibition of diabetic vascular disease. J. Cell. Biochem. 111: 1501-1511, 2010. (C) 2010 Wiley-Liss, Inc.