title: Transactivation of bad by vorinostat-induced acetylated p53 enhances doxorubicin-induced cytotoxicity in cervical cancer cells.
abstract: Vorinostat (VOR) has been reported to enhance the cytotoxic effects of doxorubicin (DOX) with fewer side effects because of the lower DOX dosage in breast cancer cells. In this study, we investigated the novel mechanism underlying the synergistic cytotoxic effects of VOR and DOX co-treatment in cervical cancer cells HeLa, CaSki and SiHa cells. Co-treatment with VOR and DOX at marginal doses led to the induction of apoptosis through caspase-3 activation, poly (ADP-ribose) polymerase cleavage and DNA micronuclei. Notably, the synergistic growth inhibition induced by the co-treatment was attributed to the upregulation of the pro-apoptotic protein Bad, as the silencing of Bad expression using small interfering RNA (siRNA) abolished the phenomenon. As siRNA against p53 did not result in an increase in acetylated p53 and the consequent upregulation of Bad, the observed Bad upregulation was mediated by acetylated p53. Moreover, a chromatin immunoprecipitation analysis showed that the co-treatment of HeLa cells with VOR and DOX increased the recruitment of acetylated p53 to the bad promoter, with consequent bad transactivation. Conversely, C33A cervical cancer cells containing mutant p53 co-treated with VOR and DOX did not exhibit Bad upregulation, acetylated p53 induction or consequent synergistic growth inhibition. Together, the synergistic growth inhibition of cervical cancer cell lines induced by co-treatment with VOR and DOX can be attributed to the upregulation of Bad, which is induced by acetylated p53. These results show for the first time that the acetylation of p53, rather than histones, is a mechanism for the synergistic growth inhibition induced by VOR and DOX co-treatments.
authors: Department of New Drug Discovery and Development, Chungnam National University, Daejeon, Republic of Korea.
authors: Sook-Jeong
authors: SJ
authors: Lee
authors: Department of Obstetrics and Gynecology, Inha University Hospital, Incheon, Republic of Korea.
authors: Sung-Ook
authors: SO
authors: Hwang
authors: Department of New Drug Discovery and Development, Chungnam National University, Daejeon, Republic of Korea.
authors: Eun Joo
authors: EJ
authors: Noh
authors: Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea.
authors: Dong-Uk
authors: DU
authors: Kim
authors: Department of New Drug Discovery and Development, Chungnam National University, Daejeon, Republic of Korea.
authors: Miyoung
authors: M
authors: Nam
authors: Department of Obstetrics and Gynecology, Asan Medical Center, Seoul, Republic of Korea.
authors: Jong Hyeok
authors: JH
authors: Kim
authors: Department of Obstetrics and Gynecology, Asan Medical Center, Seoul, Republic of Korea.
authors: Joo Hyun
authors: JH
authors: Nam
authors: Department of New Drug Discovery and Development, Chungnam National University, Daejeon, Republic of Korea.
authors: Kwang-Lae
authors: KL
authors: Hoe
mesh_terms: D000107:Acetylation; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002843:Chromatin / Q000378:metabolism; D004317:Doxorubicin / Q000494:pharmacology*; D004357:Drug Synergism; D005260:Female; D006367:HeLa Cells; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D015533:Transcriptional Activation; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D002583:Uterine Cervical Neoplasms / Q000378:metabolism; D000077337:Vorinostat; D051025:bcl-Associated Death Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; C494819:BAD protein, human; D002843:Chromatin; D006877:Hydroxamic Acids; D016159:Tumor Suppressor Protein p53; D051025:bcl-Associated Death Protein; D000077337:Vorinostat; D004317:Doxorubicin