Interaction between ZBP-89 and p53 mutants and its contribution to effects of HDACi on hepatocellular carcinoma

Abstract

ZBP-89, a zinc finger transcription factor, participates in histone deacetylases inhibitors (HDACi)-mediated growth arrest and apoptosis in cancer cells. p53 mutants may interact with ZBP-89 that transcriptionally regulates p21Waf1 (p21). However, this interaction and its consequence in cancer treatments are poorly understood. In this study, we demonstrate that ZBP-89 is essentially required in HDACi-mediated p21 upregulation in hepetocellular carcinoma (HCC). Overexpression of ZBP-89 protein enhanced the lethal effectiveness of Trichostatin A (TSA). p53 mutant p53G245D, but not p53R249S, directly bound to ZBP-89 and prevented its translocation from cytoplasm to nucleus. Furthermore, p53G245D was shown to have a similar pattern of subcellular localization to ZBP-89 in tissues of HCC patients in Hong Kong. Functionally, the cytoplasmic accumulation of ZBP-89 by p53G245D significantly abrogated the induction of p21 caused by sodium butyrate (NaB) treatment and protected cells from TSA-induced death. The activations of several apoptotic proteins, such as Bid and PARP, were involved in p53G245D-mediated protection. Moreover, the resistance to HDACi in p53G245D-expressing cells was reversed by overexpression of ZBP-89. Taken together, these data suggest a potential mechanism via which mutant p53 enables tumor cells to resist chemotherapy and, therefore, establish a plausible link between mutant p53 binding to ZBP-89 and a decreased chemosensitivity of HCC cells. © 2012 Landes Bioscience.