Abstract LB-50: Identification and functional analysis of p53MRA as a novel p53 target gene.

Abstract

Abstract Identification and characterization of p53-target genes are critical step for the understanding of tumor suppression mechanisms. So far, we have isolated a number of p53 target genes such as p53AIP1, p53R2, p53RDL1, XEDAR and PADI4, and revealed molecular mechanisms by which p53 regulate human carcinogenesis. Here we identified p53MRA (p53-inducible mitochondrial regulator of apoptosis) as a novel p53 target gene that play an important role in an apoptotic pathway through a cDNA microarray analysis using mRNAs isolated from U373MG cells ectopically expressed p53. p53MRA mRNA and protein expression was remarkably induced by ectopic expression of p53 but not by that of LacZ. We also found that adriamycin treatment remarkably induced p53MRA expression in HCT116 colorectal cancer cells in a p53 dependent manner. Subsequently, we surveyed the genomic sequence of the p53MRA gene and found putative p53-binding region within the first intron. Luciferase assay using reporter vector containing this putative p53-binding region revealed that co-transfection of wild-type p53 expressing plasmid enhanced the luciferase activity more than 10-fold. On the other hand, substitution of nucleotides within putative p53-binding region completely diminished the luciferase activity, indicating that p53 regulates p53MRA expression through this p53-binding region. To further investigate the role of p53MRA on tumor cell growth, we treated HCT116 cells with adriamycin 36h after transfection with sip53MRA or siEGFP. As a result, treatment with sip53MRA remarkably increased cell viability to the extent similar to that with sip53. Taken together, p53MRA is novel p53 target gene which plays an important role in the p53-mediated apoptotic pathway. Citation Format: Yuki Funauchi, Chizu Tanikawa, Paulisally Hau Yi Lo, Yusuke Nakamura, Koichi Matsuda. Identification and functional analysis of p53MRA as a novel p53 target gene. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-50. doi:10.1158/1538-7445.AM2013-LB-50