title: Evidence that tumor necrosis factor-related apoptosis-inducing ligand induction by 5-Aza-2'-deoxycytidine sensitizes human breast cancer cells to adriamycin.
abstract: The DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (5-aza-CdR) inhibits DNA methyltransferase activity and sensitizes cancer cells to chemotherapy, but the mechanisms of its sensitization are not fully understood. Here, we show that 5-aza-CdR induces tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in the human breast cancer MDA-231 cells. Induction of TRAIL by 5-aza-CdR correlated with inactivation of Akt. Furthermore, we show that overexpression of the active form of Akt by adenovirus infection or inhibition of the Akt downstream target glycogen synthase kinase 3 by its pharmacologic inhibitors abolishes TRAIL induction by 5-aza-CdR. Importantly, we show that the combined treatment of breast cancer cells with 5-aza-CdR and Adriamycin significantly increases apoptotic cell death compared with the treatment with either agent alone. Moreover, the combined treatment activated both death receptor and mitochondrial apoptotic pathways, whereas Adriamycin alone activated only the mitochondrial pathway while 5-aza-CdR failed to activate either. More importantly, down-regulation of TRAIL by small interference RNA silencing decreased 5-aza-CdR-mediated Adriamycin-induced caspase activation and apoptosis, thus conferring Adriamycin resistance. Taken together, our results suggest that induction of TRAIL by 5-aza-CdR is critical for enhancing chemosensitivity of breast cancer cells to Adriamycin.
authors.affiliation: Program in Molecular Biology and Genetics, Department of Pathology, Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI 48201, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
authors.forename: Jun-Ying
authors.initials: JY
authors.lastname: Zhou
authors.forename: Michael A
authors.initials: MA
authors.lastname: Tainsky
authors.forename: Gen Sheng
authors.initials: GS
authors.lastname: Wu
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001374:Azacitidine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D000077209:Decitabine; D015536:Down-Regulation; D004317:Doxorubicin / Q000008:administration & dosage / Q000494:pharmacology*; D004357:Drug Synergism; D004789:Enzyme Activation; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases / Q000378:metabolism; D006801:Humans; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000096:biosynthesis* / Q000235:genetics; D014162:Transfection
chemical_list: D034741:RNA, Small Interfering; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D000077209:Decitabine; D004317:Doxorubicin; D051057:Proto-Oncogene Proteins c-akt; C110550:HDAC1 protein, human; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases; D001374:Azacitidine