Endoplasmic reticulum stress mediates withaferin A-induced apoptosis in human renal carcinoma cells.
The accumulation of misfolded proteins in the lumen of the endoplasmic reticulum (ER) results in cellular stress that initiates a specialized response designated as the unfolded protein response. ER stress has been implicated in a variety of common diseases, such as diabetes, ischemia and neurodegenerative disorders. Withaferin A, a major chemical constituent of Withania somnifera, has been reported to inhibit tumor cell growth. We show that withaferin A induced a dose-dependent apoptotic cell death in several types of human cancer cells, as measured by FACS analysis and PARP cleavage. Treatment of Caki cells with withaferin A induced a number of signature ER stress markers, including phosphorylation of eukaryotic initiation factor-2α (eIF-2 α), ER stress-specific XBP1 splicing, and up-regulation of glucose-regulated protein (GRP)-78. In addition, withaferin A caused up-regulation of CAAT/enhancer-binding protein-homologous protein (CHOP), suggesting the induction of ER stress. Pretreatment with N-acetyl cysteine (NAC) significantly inhibited withaferin A-mediated ER stress proteins and cell death, suggesting that reactive oxygen species (ROS) mediate withaferin A-induced ER stress. Furthermore, CHOP siRNA or inhibition of caspase-4 activity attenuated withaferin A-induced apoptosis. Taken together, the present study provides strong evidence supporting an important role of the ER stress response in mediating withaferin A-induced apoptosis.
Department of Immunology, School of Medicine, Keimyung University, 2800 Dalgubeoldaero, Dalseo-Gu, Daegu 704-701, South Korea.
Min Jung
MJ
Choi
Eun Jung
EJ
Park
Kyoung Jin
KJ
Min
Jong-Wook
JW
Park
Taeg Kyu
TK
Kwon
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002292:Carcinoma, Renal Cell / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D002467:Cell Nucleus; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004354:Drug Screening Assays, Antitumor; D018870:Endoplasmic Reticulum, Rough / Q000187:drug effects* / Q000378:metabolism; D020868:Gene Silencing; D019073:HT29 Cells; D006801:Humans; D007680:Kidney Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D018384:Oxidative Stress / Q000187:drug effects*; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D000071701:Regulatory Factor X Transcription Factors; D051742:Transcription Factor CHOP / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D054358:Withanolides / Q000494:pharmacology*; D000071717:X-Box Binding Protein 1
D000970:Antineoplastic Agents; C497249:DDIT3 protein, human; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D054358:Withanolides; D000071717:X-Box Binding Protein 1; C000605543:XBP1 protein, human; D051742:Transcription Factor CHOP; C009684:withaferin A