title: Nutlin-3, a small-molecule MDM2 inhibitor, sensitizes Caki cells to TRAIL-induced apoptosis through p53-mediated PUMA upregulation and ROS-mediated DR5 upregulation.
abstract: Nutlin-3 is a novel small-molecule antagonist of the human homolog of mouse double minute (MDM2) that binds MDM2 in the p53-binding pocket and activates the p53 signaling pathway. In this study, we show that nutlin-3 sensitizes Caki human renal cancer cells, but not normal human skin fibroblast (HSF) cells or human mesangial cells, to TRAIL-mediated apoptosis. Combined treatment with nutlin-3 and TRAIL markedly induces apoptosis in HCT116 cells (p53 wild type), but not in HCT116 p53-/- cells, suggesting that p53 is critical for the sensitizing effect of nutlin-3 on TRAIL-induced apoptosis. Pretreatment with N-acetylcysteine (NAC) significantly inhibited nutlin-3-induced DR5 upregulation and cell death induced by the combined treatment with nutlin-3 and TRAIL, suggesting that reactive oxygen species (ROS) mediate nutlin-3-induced DR5 upregulation, which contributes toward TRAIL-mediated apoptosis. However, the upregulation of the p53-mediated protein p53 upregulated modulator of apoptosis (PUMA) by nutlin-3 is likely to be ROS independent because antioxidants failed to block PUMA upregulation. Interestingly, a combined treatment with NAC and PUMA small interfering RNAs significantly blocks nutlin-3-induced and TRAIL-induced apoptosis. Therefore, the present study shows that nutlin-3 enhances TRAIL-induced apoptosis in human renal cancer cells by ROS-mediated or p53-mediated DR5 upregulation and p53-induced PUMA upregulation. These results may offer a novel therapeutic approach to TRAIL-based cancer therapy.
authors.affiliation: Department of Immunology, School of Medicine, Keimyung University, Daegu 704-701, South Korea.
authors.forename: Eun Jung
authors.initials: EJ
authors.lastname: Park
authors.forename: Kyeong Sook
authors.initials: KS
authors.lastname: Choi
authors.forename: Young Hyun
authors.initials: YH
authors.lastname: Yoo
authors.forename: Taeg Kyu
authors.initials: TK
authors.lastname: Kwon
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D016158:Genes, p53; D045325:HCT116 Cells / Q000187:drug effects; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D007680:Kidney Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D010879:Piperazines / Q000494:pharmacology*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051736:Proto-Oncogene Proteins c-mdm2 / Q000037:antagonists & inhibitors*; D017382:Reactive Oxygen Species / Q000378:metabolism; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D051017:Apoptosis Regulatory Proteins; C438378:BBC3 protein, human; D007093:Imidazoles; D010879:Piperazines; D011518:Proto-Oncogene Proteins; D017382:Reactive Oxygen Species; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D053221:TNF-Related Apoptosis-Inducing Ligand; C482205:nutlin 3; D051736:Proto-Oncogene Proteins c-mdm2; D000111:Acetylcysteine