Resveratrol causes WAF-l/p21-mediated G(1)-phase arrest of cell cycle and induction of apoptosis in human epidermoid carcinoma A431 cells

Resveratrol (trans-3,4',5,-trihydroxystilbene), a phytoalexin found in grap es, nuts, fruits, and red wine, is a potent antioxidant with cancer-prevent ive properties, The mechanism by which resveratrol imparts cancer chemoprev entive effects is not clearly defined, Here, we demonstrate that resveratro l, via modulations in cyclin-dependent kinase (cdk) inhibitor-cyclin-cdk ma chinery, results in a G(1)-phase arrest of the cell cycle followed by apopt osis of human epidermoid carcinoma (A431) cells. Resveratrol treatment (1-5 0 muM for 24 h) of A431 cells resulted in a dose-dependent (a) inhibition o f cell growth as shown by 3-(4,5-dimethylthiazol-2-yl)-2,-5-diphenyltetrazo lium bromide assay, (6) G,phase arrest of the cell cycle as shown by DNA ce ll cycle analysis, and (c) induction of apoptosis as assessed by ELISA, The immunoblot analysis revealed that resveratrol treatment causes a dose- and time-dependent (a) induction of WAF1/p21; (b) decrease in the protein expr essions of cyclin D1, cyclin D2, and cyclin E; and (c) decrease in the prot ein expressions of cdk2, cdk4, and cdk6, Resveratrol treatment was also fou nd to result in a dose- and time-dependent decrease in kinase activities as sociated with all of the cdks examined. Taken together, our study suggests that resveratrol treatment of the cells causes an induction of WAF1/p21 tha t inhibits cyclin D1/D2-cdk6, cyclin D1/D2-cdk4, and cyclin E-cdk2 complexe s, thereby imposing an artificial checkpoint at the G(1)-->S transition of the cell cycle. This series of events results in a G(1)-phase arrest of the cell cycle, which is an irreversible process that ultimately results in th e apoptotic death of cancer cells. To our knowledge, this is the first syst ematic study showing the involvement of each component of cdk inhihitor-cyc lin-cdk machinery during cell cycle arrest and apoptosis of cancer cells by resveratrol.