Project description:To identify mutant p53 gain-of-function, primary murine osteosarcomas expressing p53 heterozygous mutants were compared to p53 heterozygous tumors. Transcriptomes regulated by different p53 hotspots were used to identify their mechanisms of action. Validation was done in cell line expressing mutant p53, to confirm its binding to transcription factors Stat3 and Egr1.
Project description:We investigated the genomewide binding pattern of prevalent p53 gain-of-function (GOF) mutants by ChIP-seq, in a panel of breast cancer cell lines. We assessed the genomewide changes of H3K4me3 upon GOF p53 knockdown in MDA-MB-468 breast cancer cells bearing the p53 R273H mutation.
Project description:We investigated the genomewide binding pattern of prevalent p53 gain-of-function (GOF) mutants by ChIP-seq, in a panel of breast cancer cell lines. We assessed the genomewide changes of H3K4me3 upon GOF p53 knockdown in MDA-MB-468 breast cancer cells bearing the p53 R273H mutation. This study uses ChIP-seq of H3K4me3 and histone H3 in wild-type or p53 R172H knock-in MEFs. Additionally, this study examines the transcriptome of wild-type or p53 R172H knock-in MEFs using polyA+ RNA-seq.
Project description:Mutant p53 proteins, resulting from the missense mutations of the TP53 tumor suppressor gene, possess gain-of-function activities and are among the most robust oncoproteins in human tumors. They are potentially important therapeutic targets. No studies to date have distinguished common, therapeutically relevant mutant p53 gain-of-function effects from effects specific to different mutant variants and cell backgrounds. here we perform the analysis of transcriptomes,rRegardless of the cell background, of different mutant p53s.
Project description:Mutant p53 proteins, resulting from the missense mutations of the TP53 tumor suppressor gene, possess gain-of-function activities and are among the most robust oncoproteins in human tumors. They are potentially important therapeutic targets. No studies to date have distinguished common, therapeutically relevant mutant p53 gain-of-function effects from effects specific to different mutant variants and cell backgrounds. here we performed RNA-seq analysisin MDA-MB-231 (R280K) upon silencing TP53 or the control siRNA.
Project description:Mutant p53 proteins, resulting from the missense mutations of the TP53 tumor suppressor gene, possess gain-of-function activities and are among the most robust oncoproteins in human tumors. They are potentially important therapeutic targets. To complement our mutant p53 transcriptomic studies we have performed ChIP-seq analysis in MDA-MB-231 (R280K) using the mouse anti-p53 DO1 antibody or control mouse IgG versus the input material.
Project description:TP53 (p53) is the most commonly mutated gene in human cancers, and p53 missense mutations are present in more than 40% of all human tumors. Most p53 mutations are located within the DNA binding domain, including hotspot mutations R175H, R248W, and R273H. To elucidate the precise mechanism by which p53 missense mutants execute their gain-of-functions (GOFs) in vivo, we used a proteomic screen to identify any protein that recognizes the p53 DNA-binding domain (DBD) in a manner dependent on its mutation status. To do so, we first purified the potential binding proteins associated with the p53 DBD through multi-step affinity chromatography from a SFB-p53 H1299 stable cell line. The affinity-purified SFB-p53 interacting proteins were detected by liquid chromatography mass spectrometry/mass spectrometry (LC–MS/MS) and revealed a few cellular proteins that have been reported to interact with the DNA binding domain of p53, such as TP53BP1, USP28, and Sirt1. Interestingly, we also identified many new interacting proteins from the same complex.
Project description:The TP53 gene is frequently mutated in human cancer. Research has focused predominantly on six major “hotspot” codons, accounting for only ~30% of cancer-associated p53 mutations. To comprehensively characterize the consequences of the p53 mutation spectrum, we created a synthetically designed library and measured the functional impact of ~10,000 DNA-binding domain (DBD) p53 variants in human cells in culture and in vivo. Our results highlight the differential outcome of distinct p53 mutations in human patients and elucidate the selective pressure driving p53 conservation throughout evolution. Furthermore, while loss of anti-proliferative functionality largely correlates with the occurrence of cancer-associated p53 mutations, we observe that selective gain-of-function may further favor particular mutants in vivo. Finally, when combined with additional acquired p53 mutations, seemingly neutral TP53 SNPs may modulate phenotypic outcome and presumably tumor progression.
Project description:TMPRSS2-ERG fusion is the most common genetic alteration in prostate cancer (PCa) and TP53 is the most frequently mutated gene in human cancers. However, their precise roles in PCa pathogenesis remain elusive. Here we showed that TMPRSS2-ERG fusion co-occurred with TP53 deletion/mutation in PCa patient specimens. ERG overexpression and Trp53 knockout/R172H mutant knockin induced pyrimidine synthesis gene (PSG) expression and prostate tumorigenesis in mice. Gain-of-function p53 mutants bound to the CTNNB1 promoter and upregulated β-Catenin. Overexpressed ERG and β-Catenin co-occupied PSG loci and mediated PSG expression, and high PSG expression associated with increased β-Catenin level and poor overall survival of PCa patients. β-Catenin inhibition by proteolysis-targeting chimeras (PROTACs) of its co-activator CBP and partner proteins LEF1/TCFs blocked ERG/p53-mutant PCa growth. Our study identifies CTNNB1 as a transcriptional target of p53 GOF-mutants, and reveals a druggable dependency on β-Catenin and pyrimidine synthesis in p53-mutated cancers with or without TMPRSS2-ERG fusion.
Project description:Mutant p53 proteins, resulting form frequent TP53 tumor suppressor missense mutations, possess gain-of-function activities and are among the most widespread and robust oncoproteins in human tumors. They are potentially important but understudied therapeutic targets. No studies to date have distinguished common, therapeutically relevant mutant p53 gain-of-function effects, from effects specific to different mutant variants and cell backgrounds. Here we identify 26S proteasome machinery as the common downstream effector controlled by mutant p53s in Triple Negative Breast Cancer (TNBC - aggressive carcinomas with TP53 as the most frequently mutated locus) and conserved in other human cancers. We have identified this pathway using a combination of single-model, multi-method vertical analysis (whole cell proteome, RNA sequencing an ChIP sequencing) and multi-cell line, horizontal analysis of transcriptiomes. We found that different missense mutant p53s regardless of the cell background transcriptionaly activate whole 26S proteasome machinery. Proteasome activity is significantly increased in p53 mutant versus wild-type or knockdown/null status - in cellular and mouse models as well as in human breast tumors. Increased proteasome activity leads to inhibition of tumor suppressive pathways. The control of mutant p53 over proteasome transcription and activity results in the increased resistance to proteasome inhibitors. By combining the mutant p53 targeting agents and proteasome inhibitor we were able to overcome the “bounce-back” proteasome inhibitor resistance mechanism in mutant p53 bearing TNBC cells and xenografts in vivo.