Mulberry polyphenols induce cell cycle arrest of vascular smooth muscle cells by inducing NO production and activating AMPK and p53

• Mulberry polyphenols inhibit VSMCs proliferation via arresting the progression of G0/G1 cell cycle.
• Mulberry polyphenols enhance NO production and iNOS expression in A7r5 cells.
• Mulberry polyphenols activate AMPK and p53.

Proliferation/migration of vascular smooth muscle cells (VSMCs) plays vital roles in the pathogenesis of atherosclerosis and restenosis after percutaneous coronary intervention. Water extracts from mulberry fruit can inhibit VSMCs proliferation and migration and thereby atherosclerosis. In the present study, our aim was to identify the functional polyphenols in mulberry polyphenol extracts (MPEs) and confirm their effects on atherosclerosis and its underlying mechanisms. Western blot analysis of the impact of MPEs on inducible nitric oxide synthase (iNOS), adenosine 5′-monophosphate-activated protein kinase (AMPK), and proteins related to cell cycle progression showed that 1) MPEs initially activate iNOS to increase NO release, thereby activating (in succession) AMPK, p53, p21, and p-Rb, which eventually results in cell cycle arrest of VSMCs and 2) inhibitors of iNOS, AMPK, and p53 blunt or reverse the induction of cell cycle arrest. Thus, MPEs inhibit atherosclerosis through inducing NO production and AMPK/p53 activation and thereby cell cycle arrest of VSMCs.