Overlapping region of p53/wrap53 transcripts: mutational analysis and sequence similarity with microRNA-4732-5p.

BACKGROUND Although the majority of investigations concerned with TP53 and its protein have focused on coding regions, recently a set of studies highlighted significant roles of regulatory elements located in p53 mRNA, especially 5 ? UTR. The wrap53α transcript is one of those that acts as a natural antisense agent, forming RNA-RNA hybrids with p53 mRNA and protecting it from degradation. MATERIALS AND METHODS In this study, we focused on the mutation status of exon 1α of the WRAP53 gene (according to exon 1 of p53) in 160 breast tumor tissue samples and conducted a bioinformatics search for probable miRNA binding site in the p53/wrap53 overlapping region. Mutations were detected, using single stranded conformation polymorphism (SSCP) and sequencing. We applied the miRBase database for prediction of miRNAs which target overlapping region of p53/wrap53 transcripts. RESULTS Our results showed all samples to have wild type alleles in exon 1 of TP53 gene. We could detect a novel and unreported intronic mutation (IVS1+ +56, G>C) outside overlapping regions of p53/wrap53 genes in breast cancer tissues and also predict the presence of a binding site for miR-4732-5p in the 5' UTR of Wrap53 mRNA. CONCLUSIONS From our findings we propose designing further studies focused on overexpression of miRNA-4732-5p and introducing different mutations in the overlapping region of wrap53 and p53 genes in order to study their effects on p53 and its δN isoform (δ40p53) expression. The results may provide new pieces in the p53 targeting puzzle for cancer therapy.