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Transcriptome alterations in prostates from Trp53 R270H mutant mice following irradiation

ABSTRACT: 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.

ORGANISM(S): Mus musculus

PROVIDER: GSE130440 | GEO | 2022/03/02

REPOSITORIES: GEO

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Project description:We treated the following 3 groups of 8-16 week old mice with tamoxifen: 1) CDX2P-CreERT2, Apc flox/+, Kras LSL-G12D/+, Trp53 flox/flox mice (n=6); 2) CDX2P-CreERT2, Apc flox/+, Kras LSL-G12D/+,Trp53 R270H/flox mice (n=6); 3) Wild-type control mice (n=3). The CDX2P-CreERT2 transgene expresses a tamoxifen (TAM)-regulated Cre protein (CreERT2) under control of human CDX2 regulatory sequences, allowing for TAM-inducible targeting of flox alleles in adult mouse terminal ileum, cecum, and colon epithelium. Treating the mice having CDX2P-CreERT2 transgene with tamoxifen permits the Cre recombinase to enter the cell nucleus and recombine the floxed alleles for Apc, Kras, and Trp53, resulting in deletion mutations in Apc and Trp53, and an activating, oncogenic mutation in Kras (G12D mutation). The Trp53 R270H allele carries a constitutive R270H mutation, which is the mouse equivalent of human TP53 R273H mutation. Laser capture microdissection was used to obtain adenocarcinoma tissue samples from the first two groups of mice and normal tissue from control mice. RNA was purified and targets for Affymetrix arrays were synthesized from the mRNAs. We used Affymetrix Mouse Gene 2.1 ST plate arrays, which hold 41345 probe-sets, but we largely analyzed just those 24562 probe-sets that were mapped to Entrez gene IDs. Raw data was processed with the Robust Multi-array Average algorithm (RMA). Data is log2-transformed transcript abundance estimates. We fit a one-way ANOVA model to the 3 groups of samples. We supply a supplementary excel workbook that holds the same data as the data matrix file for those 24562 probe-sets, but also holds the probe-set annotation at the time we analyzed the data, and some simple statistical calculations, which selects subsets of the probe-sets as differentially expressed between pairs of groups. It also shows data and analysis from a separate experiment of RNA purified from organoids cultured from samples from 3 groups of mice similar to those here, as well as an extra group of mice with CDX2P-CreERT2 Apc flox/flox genotype. It also joins a statistical summary of differences between 9 human tumors with TP53 missense mutations at codon 273 and 36 tumors with TP53 null mutations assayed with RNA-seq by the TCGA project. A separate supplementary file of the TCGA data is also provided. Consumers should consider obtaining more up-to-date probe-set annotation for the array platform.

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Transcriptome alterations in prostates from Trp53 R270H mutant mice following irradiation

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