Withaferin A sensitizes TRAIL-induced apoptosis through reactive oxygen species-mediated up-regulation of death receptor 5 and down-regulation of c-FLIP.
Withaferin A (Wit A) has reportedly shown cytotoxicity in a variety of tumor cell lines. Here, we show that cotreatment with subtoxic doses of Wit A and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in human renal cancer cells, Caki cells, but not in human normal mesangial cells. Moreover, the combined treatment with Wit A and TRAIL dramatically induces apoptosis in various cancer cell types, suggesting that this combined treatment might offer an attractive strategy for safely treating human cancers. Treatment of Caki cells with Wit A up-regulated death receptor 5 (DR5) in a C/EBP homologous protein (CHOP)-dependent manner. Interestingly, a Wit A-induced increase in ROS levels preceded the up-regulation of CHOP and DR5. The involvement of ROS in CHOP-mediated DR5 up-regulation was confirmed by the result that pretreatment with an antioxidant, NAC or catalase, inhibited Wit A-induced up-regulation of both CHOP and DR5. We also found that Wit A treatment down-regulated c-FLIP via NF-kappaB-mediated transcriptional control as well as ROS signaling pathways. Taken together, our results show that DR5 up-regulation and c-FLIP down-regulation contribute to the sensitizing effect of Wit A on TRAIL-mediated apoptosis in cancer cells.
Department of Immunology, School of Medicine, Keimyung University, 194 Dong San-Dong Jung-Gu, Taegu 700-712, South Korea.
Tae-Jin
TJ
Lee
Hee Jung
HJ
Um
Do Sik
do S
Min
Jong-Wook
JW
Park
Kyeong Sook
KS
Choi
Taeg Kyu
TK
Kwon
D017209:Apoptosis / Q000187:drug effects*; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000187:drug effects* / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D004875:Ergosterol / Q000031:analogs & derivatives* / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000187:drug effects* / Q000378:metabolism; D012680:Sensitivity and Specificity; D015398:Signal Transduction / Q000187:drug effects; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000187:drug effects; D054358:Withanolides
D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D016328:NF-kappa B; D017382:Reactive Oxygen Species; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D053221:TNF-Related Apoptosis-Inducing Ligand; D054358:Withanolides; C009684:withaferin A; D004875:Ergosterol