title: Antipsychotic agent thioridazine sensitizes renal carcinoma Caki cells to TRAIL-induced apoptosis through reactive oxygen species-mediated inhibition of Akt signaling and downregulation of Mcl-1 and c-FLIP(L).
abstract: Thioridazine has been known as an antipsychotic agent, but it also has anticancer activity. However, the effect of thioridazine on tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) sensitization has not yet been studied. Here, we investigated the ability of thioridazine to sensitize TRAIL-mediated apoptosis. Combined treatment with thioridazine and TRAIL markedly induced apoptosis in various human carcinoma cells, including renal carcinoma (Caki, ACHN, and A498), breast carcinoma (MDA-MB231), and glioma (U251MG) cells, but not in normal mouse kidney cells (TMCK-1) and human normal mesangial cells. We found that thioridazine downregulated c-FLIP(L) and Mcl-1 expression at the post-translational level via an increase in proteasome activity. The overexpression of c-FLIP(L) and Mcl-1 overcame thioridazine plus TRAIL-induced apoptosis. We further observed that thioridazine inhibited the Akt signaling pathway. In contrast, although other phosphatidylinositol-3-kinase/Akt inhibitors (LY294002 and wortmannin) sensitized TRAIL-mediated apoptosis, c-FLIP(L) and Mcl-1 expressions were not altered. Furthermore, thioridazine increased the production of reactive oxygen species (ROS) in Caki cells, and ROS scavengers (N-acetylcysteine, glutathione ethyl ester, and trolox) inhibited thioridazine plus TRAIL-induced apoptosis, as well as Akt inhibition and the downregulation of c-FLIP(L) and Mcl-1. Collectively, our study demonstrates that thioridazine enhances TRAIL-mediated apoptosis via the ROS-mediated inhibition of Akt signaling and the downregulation of c-FLIP(L) and Mcl-1 at the post-translational level.
authors.affiliation: Department of Immunology, School of Medicine, Keimyung University, Daegu 704-701, South Korea.
authors.forename: K-j
authors.initials: KJ
authors.lastname: Min
authors.affiliation: Department of Immunology, School of Medicine, Keimyung University, Daegu 704-701, South Korea.
authors.forename: B R
authors.initials: BR
authors.lastname: Seo
authors.affiliation: Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 700-412, South Korea.
authors.forename: Y C
authors.initials: YC
authors.lastname: Bae
authors.affiliation: Department of Anatomy and Cell Biology and Mitochondria Hub Regulation Center, Dong-A University College of Medicine, Busan 602-714, South Korea.
authors.forename: Y H
authors.initials: YH
authors.lastname: Yoo
authors.affiliation: Department of Immunology, School of Medicine, Keimyung University, Daegu 704-701, South Korea.
authors.forename: T K
authors.initials: TK
authors.lastname: Kwon
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology; D014150:Antipsychotic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D001932:Brain Neoplasms / Q000201:enzymology / Q000473:pathology; D001943:Breast Neoplasms / Q000201:enzymology / Q000473:pathology; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D005910:Glioma / Q000201:enzymology / Q000473:pathology; D006801:Humans; D007680:Kidney Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D051379:Mice; D064549:Myeloid Cell Leukemia Sequence 1 Protein / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology; D013881:Thioridazine / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection
chemical_list: D000975:Antioxidants; D014150:Antipsychotic Agents; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; C579095:MCL1 protein, human; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D047428:Protein Kinase Inhibitors; D017382:Reactive Oxygen Species; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D051057:Proto-Oncogene Proteins c-akt; D013881:Thioridazine