title: Involvement of Bcl-X(L) deamidation in E1A-mediated cisplatin sensitization of ovarian cancer cells.
abstract: The adenovirus E1A protein has been shown to be involved in the potentiation of apoptosis induced by chemotherapeutic agents, yet the molecular events of E1A-mediated apoptosis are not very clear. A recent report has suggested that deamidation of the Bcl-X(L) protein inhibits its antiapoptotic ability and leads to apoptosis induced by alkylating agents in Rb-deficient tumor cells. Since Rb is known to interact with E1A, which interrupts Rb's normal function, we examined Bcl-X(L) deamidation and cell death induced by cisplatin in E1A transfectants. We found that the E1A transfectants became sensitive to cisplatin-induced apoptosis compared to the parental cells, SKOV3.ip1. Our data show that cisplatin treatment induced the modification of Bcl-X(L) in the E1A transfectants in dosage and time-dependent manner. Furthermore, phosphatase treatment had no effect on the level of Bcl-X(L) modification, whereas alkaline lysis buffer appeared to induce the same modification of Bcl-X(L). Ectopic expression of the deamidated forms of Bcl- X(L) in SKOV3.ip1 cells revealed that the modification to the Bcl- X(L) protein molecules was deamidation. Expression of the E1A mutant (dl1108) which contains deletion at CR2 domain suppressed Bcl-X(L) deamidation and apoptosis induced by cisplatin. We also found that expression of the nondeamidated Bcl-X(L) protected E1A transfectants from apoptosis. These findings suggest that Bcl-X(L) deamidation contributes to E1A-mediated cisplatin sensitization in SKOV3.ip1 cells.
authors.affiliation: Institute of Biotechnology in Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: C-Y
authors.initials: CY
authors.lastname: Chang
authors.forename: Y-M
authors.initials: YM
authors.lastname: Lin
authors.forename: W-P
authors.initials: WP
authors.lastname: Lee
authors.forename: H-H
authors.initials: HH
authors.lastname: Hsu
authors.forename: E I T
authors.initials: EI
authors.lastname: Chen
mesh_terms: D017500:Adenovirus E1A Proteins / Q000235:genetics / Q000378:metabolism*; D000577:Amides / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002945:Cisplatin / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D016297:Mutagenesis, Site-Directed; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D016160:Retinoblastoma Protein / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured; D051020:bcl-X Protein / Q000378:metabolism*
chemical_list: D017500:Adenovirus E1A Proteins; D000577:Amides; D000970:Antineoplastic Agents; D061945:Caspase Inhibitors; D016160:Retinoblastoma Protein; D051020:bcl-X Protein; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D002945:Cisplatin