Sensitization for Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand-Induced Apoptosis by the Chemopreventive Agent Resveratrol
Survivin is a member of the inhibitor of apoptosis proteins that is expressed at high levels in most human cancers and may facilitate evasion from apoptosis and aberrant mitotic progression. Naturally occurring dietary compounds such as resveratrol have gained considerable attention as cancer chemopreventive agents. Here, we discovered a novel function of the chemopreventive agent resveratrol: resveratrol is a potent sensitizer of tumor cells for tumor necrosis factor-related apoptosis-inducing
... apoptosis-inducing ligand (TRAIL)-induced apoptosis through p53-independent induction of p21 and p21-mediated cell cycle arrest associated with survivin depletion. Concomitant analysis of cell cycle, survivin expression, and apoptosis revealed that resveratrol-induced G 1 arrest was associated with downregulation of survivin expression and sensitization for TRAIL-induced apoptosis. Accordingly, G 1 arrest using the cell cycle inhibitor mimosine or induced by p21 overexpression reduced survivin expression and sensitized cells for TRAIL treatment. Likewise, resveratrol-mediated cell cycle arrest followed by survivin depletion and sensitization for TRAIL was impaired in p21-deficient cells. Also, down-regulation of survivin using survivin antisense oligonucleotides sensitized cells for TRAIL-induced apoptosis. Importantly, resveratrol sensitized various tumor cell lines, but not normal human fibroblasts, for apoptosis induced by death receptor ligation or anticancer drugs. Thus, this combined sensitizer (resveratrol)/ inducer (e.g., TRAIL) strategy may be a novel approach to enhance the efficacy of TRAIL-based therapies in a variety of human cancers. MATERIALS AND METHODS Cell Culture. Neuroblastoma (SHEP, GIMEN, and LAN5), medulloblastoma (PSFK), glioblastoma (U373MG and A172), melanoma (SK-Mel and Colo38), pancreatic carcinoma (MiaPaCa2), prostate carcinoma (LNCaP), or breast carcinoma (MCF7) were maintained in RPMI 1640 (Life Technologies, Inc., Eggenstein, Germany) as described previously (8) . p53ϩ/ϩ, p53Ϫ/Ϫ, p21ϩ/ϩ, or p21Ϫ/Ϫ HCT116 colon carcinoma cells (kindly provided by Dr. B. Vogelstein; Baltimore, MD) were maintained in McCoy's 5A medium supplemented with 10% heat-inactivated FCS, 10 mM HEPES (Biochrom, Berlin, Germany), and 2 mM L-glutamine (Biochrom). Human fibroblasts (PromoCell, Heidelberg, Germany) were maintained according to the manufacturer's instructions. Cells (0.5 ϫ 10 5 cells/ml) were cultured in 96-, 24-, or 6-well plates or in 75-cm 2 flasks (Falcon, Heidelberg, Germany).