Use of RNA-Seq and a Transgenic Mouse Model to Identify Genes Which May Contribute to Mutant p53-Driven Prostate Cancer Initiation.

We previously demonstrated that the Trp53-R270H mutation can drive prostate cancer (CaP) initiation using the FVB.129S4 (Trp53 tm3Tyj/wt ); FVB.129S (Nkx3-1 tm3(cre)Mmswt ) genetically engineered mouse model (GEM). We now validate this finding in a different model (B6.129S4- Trp53 tm3.1Tyj /J mice) and use RNA-sequencing (RNA-Seq) to identify genes which may contribute to Trp53 R270H -mediated prostate carcinogenesis. Wildtype ( Trp53 WT/WT ), heterozygous ( Trp53 R270H/WT ), and homozygous mice ( Trp53 R270H/R270H ) were exposed to 5 Gy irradiation to activate and stabilize p53, and thereby enhance our ability to identify differences in transcriptional activity between the three groups of mice. Mouse prostates were harvested 6 h post-irradiation and processed for histological/immunohistochemistry (IHC) analysis or were snap-frozen for RNA extraction and transcriptome profiling. IHC analyses determined that presence of the Trp53-R270H mutation impacts apoptosis (lower caspase 3 activity) but not cell proliferation (Ki67). RNA-Seq analysis identified 1378 differentially expressed genes, including wildtype p53 target genes (E.g., Cdkn1a , Bax , Bcl2 , Kras , Mdm2 ), p53 gain-of-function (GOF)-related genes ( Mgmt, Id4 ), and CaP-related genes ( Cav-1, Raf1, Kras ). Further understanding the mechanisms which contribute to prostate carcinogenesis could allow for the development of improved preventive methods, diagnostics, and treatments for CaP.