title: Mitotic arrest deficient 2 expression induces chemosensitization to a DNA-damaging agent, cisplatin, in nasopharyngeal carcinoma cells.
abstract: Recently, mitotic arrest deficient 2 (MAD2)-mediated spindle checkpoint is shown to induce mitotic arrest in response to DNA damage, indicating overlapping roles of the spindle checkpoint and DNA damage checkpoint. In this study, we investigated if MAD2 played a part in cellular sensitivity to DNA-damaging agents, especially cisplatin, and whether it was regulated through mitotic checkpoint. Using nine nasopharyngeal carcinoma (NPC) cell lines, we found that decreased MAD2 expression was correlated with cellular resistance to cisplatin compared with the cell lines with high levels of MAD2. Exogenous MAD2 expression in NPC cells also conferred sensitivity to DNA-damaging agents especially cisplatin but not other anticancer drugs with different mechanisms of action. The increased cisplatin sensitivity in MAD2 transfectants was associated with mitotic arrest and activation of apoptosis pathway evidenced by the increased mitotic index and apoptosis rate as well as decreased Bcl-2 and Bax ratio and expression of cleaved poly(ADP-ribose) polymerase and caspase 3. Our results indicate that the MAD2-induced chemosensitization to cisplatin in NPC cells is mediated through the induction of mitotic arrest, which in turn activates the apoptosis pathway. Our evidence further confirms the previous hypothesis that spindle checkpoint plays an important part in DNA damage-induced cell cycle arrest and suggests a novel role of MAD2 in cellular sensitivity to cisplatin.
authors.affiliation: Department of Anatomy, Faculty of Medicine, University of Hong Kong, Hong Kong, China.
authors.forename: Hiu Wing
authors.initials: HW
authors.lastname: Cheung
authors.forename: Dong-Yan
authors.initials: DY
authors.lastname: Jin
authors.forename: Ming-Tat
authors.initials: MT
authors.lastname: Ling
authors.forename: Yong Chuan
authors.initials: YC
authors.lastname: Wong
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Sai Wah
authors.initials: SW
authors.lastname: Tsao
authors.forename: Xianghong
authors.initials: X
authors.lastname: Wang
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D001578:Benzopyrans / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D018797:Cell Cycle Proteins; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology*; D004249:DNA Damage; D004441:Ecdysterone / Q000031:analogs & derivatives* / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D064246:Mad2 Proteins; D008938:Mitosis / Q000187:drug effects / Q000502:physiology; D009303:Nasopharyngeal Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009570:Nitriles / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors; D012097:Repressor Proteins
chemical_list: D000970:Antineoplastic Agents; D001578:Benzopyrans; D002135:Calcium-Binding Proteins; D061945:Caspase Inhibitors; D018797:Cell Cycle Proteins; D004791:Enzyme Inhibitors; C577697:MAD2L1 protein, human; D064246:Mad2 Proteins; D009570:Nitriles; D019253:Proto-Oncogene Proteins c-bcl-2; D012097:Repressor Proteins; C456800:ethyl 2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate; D004441:Ecdysterone; C008999:ponasterone A; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D002945:Cisplatin