Here we report that 39-hydroxypterostilbene (HPSB), a natural pterostilbene analogue, was more potent than pterostilbene against the growth of human cancer cells (COLO 205, HCT-116, and HT-29) with measured IC50 values of 9.0, 40.2, and 70.9 mM, respectively. We found that HPSB effectively inhibited the growth of human colon cancer cells by inducing apoptosis and autophagy. Autophagy occurred at an early stage and was observed through the formation of acidic vesicular organelles and microtubule-associated protein 1 light chain 3-II production. At the molecular levels, the results from western blot analysis showed that HPSB significantly down-regulated phosphatidylinositol 3-kinase (PI3K)/Akt and mitogen-activated protein kinases (MAPKs) signalings including decreased the phosphorylation of mammalian target of rapamycin (mTOR). Significant therapeutic effects were demonstrated in vivo by treating nude mice bearing COLO 205 tumor xenografts with HPSB (10 mg/kg i.p.). These inhibitory effects were accompanied by mechanistic down-regulation of the protein levels of cyclooxygenase-2 (COX-2), matrix metallopeptidase-9 (MMP-9), vascular endothelial growth factor (VEGF), and cyclin D1, as well as by the induction of apoptosis in colon tumors. Our findings suggest that HPSB could serve as a novel promising agent for colon cancer treatment. This is an open-access article free of all copyright.
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