Transcriptome alterations in prostates from Trp53 R270H mutant mice following irradiation

Our group previously demonstrated that the Trp53 R270H mutation can drive prostate cancer (CaP) initiation in a genetically engineered mouse model (FVB.129S4(Trp53tm3Tyj/wt);FVB.129S(Nkx3-1tm3(cre)Mmswt)). The objective of the current study was to identify molecules that may facilitate Trp53 R270H-mediated prostate carcinogenesis. Mice that harbor a Trp53 R270H germline mutation (B6.129S4-Trp53tm3.1Tyj/J) were used for the current study. Wildtype (Trp53WT/WT), heterozygous (Trp53R270H/WT), and homozygous mice (Trp53R270H/R270H) were exposed to 5 Gy radiation to activate and stabilize p53 and thereby enhance our ability to identify differences in transcriptional activity between the 3 groups of mice. Mouse prostates were harvested 6 hours post-irradiation and either processed for histological/immunohistochemistry (IHC) analysis or snap-frozen for RNA extraction and transcriptome profiling with RNA-Sequencing (RNA-Seq) analysis. IHC was used to assess cell proliferation (Ki67) and apoptosis (activated caspase 3). PIN lesions were observed in heterozygous and homozygous mice as early as 3 months, thereby validating our prior finding that the Trp53 R270H mutation can drive CaP initiation. RNA-Seq analysis identified 1,378 differentially expressed genes, including multiple wildtype p53 target genes (E.g. Cdkn1a, Bax, Bcl2, Kras, Mdm2), p53 gain-of-function (GOF) genes (Mgmt, Id4), and CaP-related genes (Cav-1, Raf1, Kras). Our combined data validate a role for the Trp53 R270H mutation in CaP initiation, and identify molecules that may contribute to Trp53 R270H-mediated prostate carcinogenesis. The study consisted of 3 groups of mice with duplicate sampels in each. Mice that were homozygous (Trp53+/+) for wild type Trp53 served as the control group. The experimental groups consisted of mice that were heterozygous (Trp53R270H/+) or homozygous (Trp53R270H/R270H) for the Trp53 R270H mutation. At ~3 months of age, mice were exposed to 5 Gy whole body irradiation. Mouse prostates were harvested 6 hours post-irradiation and snap-frozen for subsequent RNA extraction and transcriptome profiling with RNA-Sequencing (RNA-Seq) analysis.