title: Hypermethylation of the death-associated protein kinase promoter attenuates the sensitivity to TRAIL-induced apoptosis in human non-small cell lung cancer cells.
abstract: Death-associated protein (DAP) kinase plays an important role in IFN-gamma, tumor necrosis factor (TNF)-alpha, or Fas-ligand induced apoptosis. TNF-related apoptosis-inducing ligand (TRAIL) is a member of the TNF ligand family and can induce caspase-dependent apoptosis in cancer cells while sparing most of the normal cells. However, some of the cancer cell lines are insensitive to TRAIL, and such resistance cannot be explained by the dysfunction of TRAIL receptors or their known downstream targets. We reported previously that DAP kinase promoter is frequently methylated in non-small cell lung cancer (NSCLC), and such methylation is associated with a poor clinical outcome. To determine whether DAP kinase promoter methylation contributes to TRAIL resistance in NSCLC cells, we measured DAP kinase promoter methylation and its gene expression status in 11 NSCLC cell lines and correlated the methylation/expression status with the sensitivity of cells to TRAIL. Of the 11 cell lines, 1 had a completely methylated DAP kinase promoter and no detectable DAP kinase expression, 4 exhibited partial promoter methylation and substantially decreased gene expression, and the other 6 cell lines showed no methylation in the promoter and normal DAP kinase expression. Therefore, the amount of DAP kinase expression amount was negatively correlated to its promoter methylation (r = -0.77; P = 0.003). Interestingly, the cell lines without the DAP kinase promoter methylation underwent substantial apoptosis even in the low doses of TRAIL, whereas those with DAP kinase promoter methylation were resistant to the treatment. The resistance to TRAIL was reciprocally correlated to DAP kinase expression in 10 of the 11 cell lines at 10 ng/mL concentration (r = 0.91; P = 0.001). We treated cells resistant to TRAIL with 5-aza-2'-deoxycytidine, a demethylating reagent, and found that these cells expressed DAP kinase and became sensitive to TRAIL. These results suggest that DAP kinase is involved in TRAIL-mediated cell apoptosis and that a demethylating agent may have a role in enhancing TRAIL-mediated apoptosis in some NSCLC cells by reactivation of DAP kinase.
authors.affiliation: Molecular Biology Laboratory, Department of Thoracic/Head and Neck Medical Oncology, University of Texas MD Anderson Cancer Center, Unit 432, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
authors.forename: Ximing
authors.initials: X
authors.lastname: Tang
authors.forename: Weiguo
authors.initials: W
authors.lastname: Wu
authors.forename: Shi-Yong
authors.initials: SY
authors.lastname: Sun
authors.forename: Ignacio I
authors.initials: II
authors.lastname: Wistuba
authors.forename: Waun Ki
authors.initials: WK
authors.lastname: Hong
authors.forename: Li
authors.initials: L
authors.lastname: Mao
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000096:biosynthesis / Q000378:metabolism; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics* / Q000473:pathology*; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D004396:Coloring Agents / Q000494:pharmacology; D053938:DNA Fragmentation; D019175:DNA Methylation; D018076:DNA, Complementary / Q000378:metabolism; D064550:Death-Associated Protein Kinases; D000077209:Decitabine; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm; D053222:Fas Ligand Protein; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008175:Lung Neoplasms / Q000235:genetics* / Q000473:pathology*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053221:TNF-Related Apoptosis-Inducing Ligand; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D013997:Time Factors; D016896:Treatment Outcome; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D000964:Antimetabolites, Antineoplastic; D051017:Apoptosis Regulatory Proteins; D004396:Coloring Agents; D018076:DNA, Complementary; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C105190:TNFRSF10A protein, human; C505653:TNFSF10 protein, human; D013778:Tetrazolium Salts; D013844:Thiazoles; D014409:Tumor Necrosis Factor-alpha; D000077209:Decitabine; D064550:Death-Associated Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C022616:thiazolyl blue; D001374:Azacitidine