title: Lipoxygenase inhibitor MK886 potentiates TRAIL-induced apoptosis through CHOP- and p38 MAPK-mediated up-regulation of death receptor 5 in malignant glioma.
abstract: Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) triggers specific apoptosis in tumor cells and is one of the most promising candidates for cancer gene therapy. However, resistance to TRAIL is one of the main impediments to use of TRAIL in cancer treatment. We showed previously that the lipoxygenase inhibitor MK886 in combination with TRAIL exhibits enhanced antitumor activities compared with each agent alone in human glioma cells. In this study, we elucidated the molecular mechanisms responsible for MK886-mediated sensitization to TRAIL-induced apoptosis. We found that MK886 sensitized glioma cells to TRAIL-induced apoptosis by upregulating the death receptor 5 (DR5) and that specific knockdown of DR5 attenuated cell death. The mechanisms underlying this sensitization involved activation of the MK886-induced p38 mitogen-activated protein kinase (MAPK) pathway and subsequent DR5 overexpression. However, treatment with a specific inhibitor or gene silencing of p38 MAPK abolished both the DR5 induction and the increase in apoptosis caused by TRAIL. Taken together, our findings indicate that the increased expression of DR5 in a p38 MAPK-dependent manner plays an important role in the sensitization of MK886 to TRAIL-induced apoptosis.
authors.affiliation: Department of Biomedical Science, College of Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Republic of Korea.
authors.forename: Ji Sun
authors.initials: JS
authors.lastname: Woo
authors.forename: Seong Muk
authors.initials: SM
authors.lastname: Kim
authors.forename: Chang Hyun
authors.initials: CH
authors.lastname: Jeong
authors.forename: Chung Heon
authors.initials: CH
authors.lastname: Ryu
authors.forename: Sin-Soo
authors.initials: SS
authors.lastname: Jeun
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004357:Drug Synergism; D055785:Gene Knockdown Techniques; D005910:Glioma / Q000378:metabolism*; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology*; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000096:biosynthesis*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*; D051742:Transcription Factor CHOP / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D002722:Chlorobenzenes
chemical_list: D007211:Indoles; D016859:Lipoxygenase Inhibitors; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D053221:TNF-Related Apoptosis-Inducing Ligand; D051742:Transcription Factor CHOP; D048051:p38 Mitogen-Activated Protein Kinases; C497249:DDIT3 protein, human; C060893:MK-886; D002722:Chlorobenzenes