Pterostilbene, a natural small-molecular compound, promotes cytoprotective macroautophagy in vascular endothelial cells

Chemical modulators of macroautophagy (herein referred to as autophagy) have aroused widespread interest among biologists and clinical physicians because of their potential for disease therapy. Pterostilbene (PT), a natural small-molecular compound, has been demonstrated to inhibit oxidized low-density lipoprotein (oxLDL)-induced apoptosis in vascular endothelial cells (VECs). The aim of the present study was to investigate whether and how PT could induce VEC autophagy. PT at 0.5 or 1 mu M could effectively induce autophagosome formation in human umbilical vein VECs (HUVECs). PT promoted autophagy via a rapid elevation in intracellular calcium ([Ca2+](i)) concentration and subsequent AMP-activated protein kinase alpha 1 subunit (AMPK alpha 1) activation, which in turn inhibited mammalian target of rapamycin, a potent inhibitor of autophagy. PT-induced AMPK alpha 1 activation and autophagy were refractory to the depletion of serine/threonine kinase 11 but depended on calcium/calmodulin-dependent protein kinase-beta activation. Interestingly, PT stimulated cytoprotective autophagy so as to aid in the removal of accumulated toxic oxLDL and inhibit apoptosis in HUVECs. Our study provides a potent small molecule enhancer of autophagy and a novel useful tool in exploring the molecular mechanisms for crosstalk between apoptosis and autophagy. PT could serve as a potential lead compound for developing a class of autophagy regulator as autophagy-related diseases therapy. (C) 2013 Elsevier Inc. All rights reserved.