Abstract 5508: Histone modifications affect differential regulation of TGF-beta-induced Nox4 by p53

Abstract

Abstract Recent studies suggest p53 plays an important role in TGF-β-mediated cell signaling and migration. Previously, we showed wild-type (WT) and mutant (mt) forms of p53 differentially regulate reactive oxygen species (ROS) generation by NADPH oxidase-4 (NOX4). We found that WT-p53 suppresses TGF-β-induced NOX4, ROS production, and cell migration, whereas tumor-associated p53-mt proteins enhance NOX4 expression and cell migration by TGF-β/SMAD3-dependent mechanisms. In this study, we utilized The Cancer Genome Atlas (TCGA) to perform statistical analysis on gene expression data from primary tumor samples and found a correlation between tumors with p53 “hotspot” mutations and increased NOX4 mRNA expression. Furthermore, we examined the basis of human NOX4 promoter regulation by p53 and SMAD3. By deletion analysis of the NOX4 promoter, we found two critical SMAD3 binding elements (SBE) are also required for p53-dependent promoter activity. Conversely, promoter activity was abolished by dose-dependent heterologous expression of p53-WT. Moreover, expression of active SMAD3 resulted in robust NOX4 promoter activity, which was abolished when co-expressed with p53-WT. Chromatin immunoprecipitation (ChIP) analysis revealed SMAD3 and p53-WT or p53-mt were associated with specific SBEs and p53 response elements (p53-RE) in a TGF-β-dependent manner. Interestingly, the repressive effect by p53- WT on NOX4 was relieved upon treatment with histone deacetylase (HDAC) inhibitors or mutation of the transactivation domain. Overexpression of p300, a known p53-mt-binding transcriptional co-regulator and histone acetyltranserfase (HAT), enhanced p53-mt-mediated NOX4 promoter activity, whereas the HAT-inactive p300-mt reduced promoter activity. Furthermore, overexpression of p53-mt augmented TGF-β-mediated acetylation of histones associated with the NOX4 promoter. Finally, scratch wound assays demonstrated NOX4 and p300 promote TGF-β/mutant p53-mediated cell migration. Collectively, these data and provide new insight on TGF-β/SMAD3 and mutant p53-mediated NOX4 induction involving epigenetic control of NOX4 in tumor cell migration. Citation Format: Howard E. Boudreau, Wei Feng MA, Agnieszka Korzeniowska, Jonathan J. Park, Thomas L. Leto. Histone modifications affect differential regulation of TGF-beta-induced Nox4 by p53 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5508. doi:10.1158/1538-7445.AM2017-5508