Intronic TP53 Polymorphisms Are Associated with Increased Δ133TP53 Transcript, Immune Infiltration and Cancer Risk

SIMPLE SUMMARY: We investigated the influence of genetic variants, called single nucleotide polymorphisms (SNP) in the TP53 tumour suppressor gene, on cancer risk, clinical features and TP53 isoform levels. These SNPs were significantly over-represented in cohorts of mixed cancers versus controls, suggesting they confer increased cancer risk. Heterozygosity at rs1042522(GC) and either of the two SNPs rs9895829(TC) and rs2909430(AG) confer up to a 5-fold greater risk of developing cancer. The SNP combinations were associated with high Δ133TP53 and TP53β messenger RNA levels, elevated infiltrating immune cells and shorter patient survival for glioblastoma and prostate cancer. The data suggest that ∆133p53β protein levels are increased by the SNPs resulting in increased inflammation which contributes to more aggressive cancers. ABSTRACT: We investigated the influence of selected TP53 SNPs in exon 4 and intron 4 on cancer risk, clinicopathological features and expression of TP53 isoforms. The intron 4 SNPs were significantly over-represented in cohorts of mixed cancers compared to three ethnically matched controls, suggesting they confer increased cancer risk. Further analysis showed that heterozygosity at rs1042522(GC) and either of the two intronic SNPs rs9895829(TC) and rs2909430(AG) confer a 2.34–5.35-fold greater risk of developing cancer. These SNP combinations were found to be associated with shorter patient survival for glioblastoma and prostate cancer. Additionally, these SNPs were associated with tumor-promoting inflammation as evidenced by high levels of infiltrating immune cells and expression of the Δ133TP53 and TP53β transcripts. We propose that these SNP combinations allow increased expression of the Δ133p53 isoforms to promote the recruitment of immune cells that create an immunosuppressive environment leading to cancer progression.