title: Absence of death receptor translocation into lipid rafts in acquired             TRAIL-resistant NSCLC cells.
abstract: Resistance to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a major limitation for its clinical use. The mechanisms of TRAIL resistance have been mostly studied in the context of cell lines that are intrinsically resistant to TRAIL. However, little is known about the molecular alterations that contribute to the development of acquired resistance during treatment with TRAIL. In this study, we established H460R, an isogenic cell line with acquired TRAIL resistance, from the TRAIL‑sensitive human lung cancer cell line H460 to investigate the mechanisms of acquired resistance. The acquired TRAIL‑resistant H460R cells remained sensitive to cisplatin. The mRNA and protein expression levels of death receptor 4 (DR4) and death receptor 5 (DR5) were not altered in either of the TRAIL-treated cell lines. Nevertheless, tests in which the DR4 or DR5 gene was overexpressed or silenced suggest that death receptor expression is necessary but not sufficient for TRAIL‑induced apoptosis. Compared with parental TRAIL-sensitive H460 cells, H460R cells showed a decreased TRAIL-induced translocation of DR4/DR5 into lipid rafts. Further studies showed that nystatin partially prevented lipid raft aggregation and DR4 and DR5 clustering and reduced apoptosis in H460 cells again. Analysis of apoptotic molecules showed that more pro-caspase-8, FADD, caspase-3 and Bid, but less cFLIP in H460 cells than in H460R cells. Our findings suggest that the lack of death receptor redistribution negatively impacts DISC assembly in lipid rafts, which at least partially leads to the development of acquired resistance to TRAIL in H460R cells.
authors.affiliation: Department of Radiation and Medical Oncology, Zhongnan Hospital,                     Wuhan University, Wuhan 430071, P.R. China.
authors.forename: Wen
authors.initials: W
authors.lastname: Ouyang
authors.forename: Chunxu
authors.initials: C
authors.lastname: Yang
authors.forename: Simin
authors.initials: S
authors.lastname: Zhang
authors.forename: Yu
authors.initials: Y
authors.lastname: Liu
authors.forename: Bo
authors.initials: B
authors.lastname: Yang
authors.forename: Junhong
authors.initials: J
authors.lastname: Zhang
authors.forename: Fuxiang
authors.initials: F
authors.lastname: Zhou
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Zhou
authors.forename: Conghua
authors.initials: C
authors.lastname: Xie
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology; D053418:Death Domain Receptor Signaling Adaptor Proteins / Q000378:metabolism; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D021962:Membrane Microdomains / Q000378:metabolism; D009761:Nystatin / Q000494:pharmacology; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism*; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000235:genetics* / Q000378:metabolism; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism*
chemical_list: D053418:Death Domain Receptor Signaling Adaptor Proteins; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D011994:Recombinant Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C105190:TNFRSF10A protein, human; C505653:TNFSF10 protein, human; D009761:Nystatin; D002945:Cisplatin