title: Inactivation of human MAD2B in nasopharyngeal carcinoma cells leads to chemosensitization to DNA-damaging agents.
abstract: Rev7p has been suggested to play an important role in regulating DNA damage response in yeast, and recently, the human homologue (i.e., MAD2B) has been identified, which shares significant homology to the mitotic checkpoint protein MAD2. In this study, we investigated whether MAD2B played a key role in cellular sensitivity to DNA-damaging anticancer drugs by suppressing its expression using RNA interference in nasopharyngeal carcinoma cells. Using colony formation assay, we found that suppression of MAD2B conferred hypersensitivity to a range of DNA-damaging agents, especially DNA cross-linkers, such as cisplatin, and gamma-irradiation. This effect was associated with reduced frequencies of spontaneous and drug-induced mutations, elevated phosphorylation of histone H2AX, and markedly increased chromosomal aberrations in response to DNA damage. In addition, there was also a significant decrease in cisplatin-induced sister chromatid exchange rate, a marker for homologous recombination-mediated post-replication repair in MAD2B-depleted cells. These results indicate that MAD2B may be a key factor in regulating cellular response to DNA damage in cancer cells. Our findings reveal a novel strategy for cancer therapy, in which cancer cells are sensitized to DNA-damaging anticancer drugs through inactivation of the MAD2B gene.
authors.affiliation: Department of Anatomy, Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: Hiu Wing
authors.initials: HW
authors.lastname: Cheung
authors.forename: Abel C S
authors.initials: AC
authors.lastname: Chun
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Wen
authors.initials: W
authors.lastname: Deng
authors.forename: Liang
authors.initials: L
authors.lastname: Hu
authors.forename: Xin-Yuan
authors.initials: XY
authors.lastname: Guan
authors.forename: John M
authors.initials: JM
authors.lastname: Nicholls
authors.forename: Ming-Tat
authors.initials: MT
authors.lastname: Ling
authors.forename: Yong
authors.initials: Y
authors.lastname: Chuan Wong
authors.forename: Sai Wah
authors.initials: SW
authors.lastname: Tsao
authors.forename: Dong-Yan
authors.initials: DY
authors.lastname: Jin
authors.forename: Xianghong
authors.initials: X
authors.lastname: Wang
mesh_terms: D045744:Cell Line, Tumor; D002842:Chromatids / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D015536:Down-Regulation; D019008:Drug Resistance, Neoplasm; D006657:Histones / Q000378:metabolism; D006801:Humans; D064246:Mad2 Proteins; D008938:Mitosis; D009303:Nasopharyngeal Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011506:Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D014162:Transfection
chemical_list: C468783:H2AX protein, human; D006657:Histones; C120552:MAD2L2 protein, human; D064246:Mad2 Proteins; D011506:Proteins