Exp Mol Med.  2014 Feb;46(2):e76. 10.1038/emm.2013.149.

Transactivation of bad by vorinostat-induced acetylated p53 enhances doxorubicin-induced cytotoxicity in cervical cancer cells

• Lee SJ
• Hwang SO
• Noh EJ
• Kim DU
• Nam M
• Kim JH
• Nam JH
• Hoe KL

• KMID: 2155341
• DOI: http://doi.org/10.1038/emm.2013.149

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.

Keyword

bad; cervical cancer cell; doxorubicin; p53 acetylation; vorinostat

MeSH Terms

Acetylation
Antineoplastic Agents/*pharmacology
Apoptosis/drug effects
Cell Survival/drug effects
Chromatin/metabolism
Doxorubicin/*pharmacology
Drug Synergism
Female
HeLa Cells
Humans
Hydroxamic Acids/*pharmacology
Transcriptional Activation
Tumor Suppressor Protein p53/genetics/*metabolism
Uterine Cervical Neoplasms/metabolism
bcl-Associated Death Protein/genetics/*metabolism
Antineoplastic Agents
Chromatin
Doxorubicin
Hydroxamic Acids
Tumor Suppressor Protein p53
bcl-Associated Death Protein