title: Compound C sensitizes Caki renal cancer cells to TRAIL-induced apoptosis through reactive oxygen species-mediated down-regulation of c-FLIPL and Mcl-1.
abstract: The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), either alone or in combination with other anticancer drugs, is considered as a new strategy for anticancer therapy. Compound C, a cell-permeable pyrrazolopyrimidine derivative, acts as a potent, selective, reversible ATP-competitive inhibitor of AMP-activated protein kinase (AMPK). In this study, we show that compound C sensitizes Caki human renal cancer cells, but not normal human skin fibroblast cells (HSF) and human mesangial cells, to TRAIL-mediated apoptosis. However, AMPK siRNA failed to affect TRAIL-mediated apoptosis in Caki cells and transduction of dominant negative AMPK rather attenuated TRAIL-induced apoptosis, indicating that the effect of compound C on sensitization of TRAIL-induced apoptosis is independent of AMPK activity. Interestingly, we found that down-regulation of c-FLIP(L) and Mcl-1 contributes to compound C-enhanced TRAIL-induced apoptosis. Reduced expression of c-FLIP(L) and Mcl-1 were caused by the decreased protein stability of c-FLIP(L) and Mcl-1, but not by their transcriptional control, in compound C-treated cells. Pretreatment with N-acetyl-L-cysteine (NAC) significantly inhibited the cell death induced by the combined treatment with compound C and TRAIL as well as recovered the expression levels of c-FLIP(L) and Mcl-1 down-regulated by the combinatory treatment with compound C plus TRAIL, suggesting that compound C-stimulated TRAIL-induced apoptosis appears to be dependent on the generation of reactive oxygen species for down-regulation of c-FLIP(L) and Mcl-1. Taken together, the present study demonstrates that compound C enhances TRAIL-induced apoptosis in human renal cancer cells by ROS-mediated c-FLIP(L) and Mcl-1 down-regulation.
authors.affiliation: Department of Immunology, School of Medicine, Keimyung University, 2800 Dalgubeoldaero, Dalseo-Gu, Daegu, 704-701, South Korea.
authors.forename: Ji Hoon
authors.initials: JH
authors.lastname: Jang
authors.forename: Tae Jin
authors.initials: TJ
authors.lastname: Lee
authors.forename: Eun Sun
authors.initials: ES
authors.lastname: Yang
authors.forename: Do Sik
authors.initials: do S
authors.lastname: Min
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Kim
authors.forename: Sang Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Yung Hyun
authors.initials: YH
authors.lastname: Choi
authors.forename: Jong-Wook
authors.initials: JW
authors.lastname: Park
authors.forename: Kyeong Sook
authors.initials: KS
authors.lastname: Choi
authors.forename: Taeg Kyu
authors.initials: TK
authors.lastname: Kwon
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000235:genetics / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D005434:Flow Cytometry; D006801:Humans; D007680:Kidney Neoplasms / Q000378:metabolism / Q000473:pathology*; D050527:Mesangial Cells / Q000378:metabolism / Q000473:pathology; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D011720:Pyrazoles / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000235:genetics / Q000378:metabolism*
chemical_list: D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D019253:Proto-Oncogene Proteins c-bcl-2; D011720:Pyrazoles; D011743:Pyrimidines; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; C516138:dorsomorphin; D055372:AMP-Activated Protein Kinases