Changes in non-coding sequences of the TP53 gene in diffuse large B-cell lymphoma

Background. Currently, in-depth analysis of the results of sequencing outside the coding sequences of the TP53 gene is absent, the number and functional effects of aberrations detected in them are underestimated. The purpose of this study was to identify changes in non-coding regions of TP53 in tumor tissue of diffuse large B-cell lymphoma (DLBCL) and to predict the possible consequences of these changes. Material and methods. Genomic DNA was isolated from paraffin blocks of biopsies of tumor lymph nodes and extranodal lesions of 92 patients with DLBCL. The nucleotide sequence of the coding region of TP53 (exons 5-10) and adjacent introns, as well as the fragment of the 3'-UTR gene sequence containing the polyadenylation signal, was determined by direct capillary sequencing by Sanger method. Theoretical prediction of possible consequences of detected intron mutations was carried out using the program NetGene2. Results. In tumor material from 74 patients with DLBCL, 12 types of mutations in intron sites were identified: g.7675266A>G, g.7675010C>A, g.7674988A>G, g.7674326C>G, g.7674153C>G, g.7673691G>T, g.7673681T>C, g.7673664T>C and g.7673523A>G. The mutation I g.7674326C>G, which has proven biological significance from in vivo experiments, according to The Human Cancer Mutation Database refers to changes that affect splicing. According to the prognosis of NetGene2, from intron replacements revealed by us in the group of patients, g.7675010C>A leads to the formation of an additional acceptor site for splicing, which may result in the incorporation of a part of the intron 5 into the mRNA sequence. In 5/9 cases of detection of rs78378222 in samples of tumor tissue of DLBCL, a homozygous minor genotype C/C was determined, which indicated the loss of heterozygosity in this locus, which contributes to a significant increase in malignant cell potential. Conclusions. Thus, the data obtained by us testify to the functional selection at the stages of the tumor progression of DLBCL changes not only in the coding but also introns and 3'-UTR TP53 gene.