title: Akt-mediated eminent expression of c-FLIP and Mcl-1 confers acquired resistance to TRAIL-induced cytotoxicity to lung cancer cells.
abstract: Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potential anticancer agent due to its selectivity in killing transformed cells. However, TRAIL can also stimulate the proliferation and metastasis of TRAIL-resistant cancer cells. Thus, acquired TRAIL resistance during TRAIL therapy would shift the patient's treatment from beneficial to detrimental. In this study, we focused on the acquired TRAIL resistance mechanism and showed that the elevated expression of the antiapoptotic factor cellular FLICE-like inhibitory protein (c-FLIP) and the prosurvival Bcl-2 family member myeloid cell leukemia-1 (Mcl-1) underlie the main mechanism of this type of TRAIL resistance in lung cancer cells. Chronic exposure to TRAIL resulted in lung cancer cell resistance to TRAIL-induced cytotoxicity, and this resistance was associated with the increase in the cellular levels of c-FLIP(L) and Mcl-1(L). Overexpresssion of c-FLIP(L) suppressed recruitment of caspase-8 to the death-inducing signaling complex, whereas increased Mcl-1(L) expression blunted the mitochondrial apoptosis pathway. The elevation of c-FLIP(L) and Mcl-1(L) expression was due to Akt-mediated stabilization of these proteins in TRAIL-resistant cells. Importantly, suppressing c-FLIP(L) and Mcl-1(L) expression by RNA interference collectively alleviated acquired TRAIL resistance. Taken together, these results identify c-FLIP(L) and Mcl-1(L) as the major determinants of acquired TRAIL resistance and could be molecular targets for improving the therapeutic value of TRAIL against lung cancer.
authors.affiliation: Molecular Biology and Lung Cancer Program, Lovelace Respiratory Research Institute, 2425 Ridgecrest Drive Southeast, Albuquerque, NM 87108, USA.
authors.forename: Xia
authors.initials: X
authors.lastname: Wang
authors.forename: Wenshu
authors.initials: W
authors.lastname: Chen
authors.forename: Weihua
authors.initials: W
authors.lastname: Zeng
authors.forename: Lang
authors.initials: L
authors.lastname: Bai
authors.forename: Yohannes
authors.initials: Y
authors.lastname: Tesfaigzi
authors.forename: Steven A
authors.initials: SA
authors.lastname: Belinsky
authors.forename: Yong
authors.initials: Y
authors.lastname: Lin
mesh_terms: D000970:Antineoplastic Agents / Q000378:metabolism / Q000627:therapeutic use / Q000633:toxicity*; D017209:Apoptosis; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000235:genetics / Q000378:metabolism*; D053181:Caspase 8 / Q000378:metabolism; D016923:Cell Death; D045744:Cell Line, Tumor; D053418:Death Domain Receptor Signaling Adaptor Proteins / Q000378:metabolism; D019008:Drug Resistance, Neoplasm; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000378:metabolism*; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism / Q000633:toxicity*
chemical_list: D000970:Antineoplastic Agents; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D053418:Death Domain Receptor Signaling Adaptor Proteins; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D019253:Proto-Oncogene Proteins c-bcl-2; D053221:TNF-Related Apoptosis-Inducing Ligand; D051057:Proto-Oncogene Proteins c-akt; D053181:Caspase 8