title: Bim directly antagonizes Bcl-xl in doxorubicin-induced prostate cancer cell apoptosis independently of p53.
abstract: Doxorubicin and other anthracycline compounds exert their anti-cancer effects by causing DNA damage and initiating cell cycle arrest in cancer cells, followed by apoptosis. DNA damage generally activates a p53-mediated pathway to initiate apoptosis by increasing the level of the BH3-only protein, Puma. However, p53-mediated apoptosis in response to DNA damage has not yet been validated in prostate cancers. In the current study, we used LNCaP and PC3 prostate cancer cells, representing wild type p53 and a p53-null model, to determine if DNA damage activates p53-mediated apoptosis in prostate cancers. Our results revealed that PC3 cells were 4 to 8-fold less sensitive than LNCaP cells to doxorubicin-inuced apoptosis. We proved that the differential response of LNCaP and PC3 to doxorubicin was p53-independent by introducing wild-type or dominant negative p53 into PC3 or LNCaP cells, respectively. By comparing several apoptosis-related proteins in both cell lines, we found that Bcl-xl proteins were much more abundant in PC3 cells than in LNCaP cells. We further demonstrated that Bcl-xl protects LNCaP and PC3 cells from doxorubicin-induced apoptosis by using ABT-263, an inhibitor of Bcl-xl, as a single agent or in combination with doxorubicin to treat LNCaP or PC3 cells. Bcl-xl rather than p53, likely contributes to the differential response of LNCaP and PC3 to doxorubicin in apoptosis. Finally, co-immunoprecipitation and siRNA analysis revealed that a BH3-only protein, Bim, is involved in doxorubicin-induced apoptosis by directly counteracting Bcl-xl.
authors.affiliation: a Department of Biotechnology , Kaohsiung Medical University , Kaohsiung , Taiwan.
authors.forename: Min-Chi
authors.initials: MC
authors.lastname: Yang
authors.affiliation: a Department of Biotechnology , Kaohsiung Medical University , Kaohsiung , Taiwan.
authors.forename: Ru-Wei
authors.initials: RW
authors.lastname: Lin
authors.affiliation: a Department of Biotechnology , Kaohsiung Medical University , Kaohsiung , Taiwan.
authors.forename: Shih-Bo
authors.initials: SB
authors.lastname: Huang
authors.affiliation: a Department of Biotechnology , Kaohsiung Medical University , Kaohsiung , Taiwan.
authors.forename: Shin-Yuan
authors.initials: SY
authors.lastname: Huang
authors.affiliation: a Department of Biotechnology , Kaohsiung Medical University , Kaohsiung , Taiwan.
authors.forename: Wen-Jie
authors.initials: WJ
authors.lastname: Chen
authors.affiliation: b Hsueh-Shih Clinic , Taichung , Taiwan.
authors.forename: Shiaw
authors.initials: S
authors.lastname: Wang
authors.affiliation: c Department of Biochemistry & Graduate Institute of Medicine, Medical University , Kaohsiung , Taiwan.
authors.forename: Yi-Ren
authors.initials: YR
authors.lastname: Hong
authors.affiliation: a Department of Biotechnology , Kaohsiung Medical University , Kaohsiung , Taiwan.
authors.forename: Chihuei
authors.initials: C
authors.lastname: Wang
mesh_terms: D000814:Aniline Compounds / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D000072224:Bcl-2-Like Protein 11 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects; D004317:Doxorubicin / Q000494:pharmacology*; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D008297:Male; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D051020:bcl-X Protein / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D000814:Aniline Compounds; D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; C438378:BBC3 protein, human; D000072224:Bcl-2-Like Protein 11; D050759:Cyclin-Dependent Kinase Inhibitor p21; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D013449:Sulfonamides; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D051020:bcl-X Protein; D004317:Doxorubicin; C528561:navitoclax
keywords: Bcl-xl; Bim; LNCaP; PC3; apoptosis; doxorubicin; p53