The rs78378222 prevalence and the copy loss of the protective allele A in the tumor tissue of diffuse large B-cell lymphoma

Background

Rare single nucleotide polymorphisms (SNPs) are likely to be a crucial genetic factor for human diseases, including cancer. rs78378222 is rare SNP in 3′-untranslated region (UTR) of TP53 gene leading to disturbance of 3′-end mRNA processing. The frequency of rs78378222 varies in several studied populations. The meta-analysis of 34 genome-wide association studies indicated that rs78378222 was significantly associated with an increased risk of cancer overall. Bioinformatic analysis indicates that somatic loss of the protective A allele of rs78378222 occurs in the tumor tissue of some malignant. The goal of the current study is to document the rs78378222 prevalence and evaluate the copy loss status of the protective allele A in the tumor tissue of patients with diffuse large B-cell lymphoma (DLBCL).

Methods

Total DNA was isolated from FFPE-samples and peripheral blood of patients with DLBCL and comparable in age and sex controls. rs78378222 genotyping was performed by the PCR-RFLP method using restriction endonuclease HindIII. Direct Sanger’s sequencing was used to confirm the presence of C allele of the rs78378222. The search for TP53 gene mutations was carried out by Sanger’s direct sequencing method, according to the IARC protocol.

Results

The result of genotyping of 136 DNA samples from DLBCL tumor tissue suggested that frequency of the rs78378222 was 11/136 (8.1%). Rare allele C frequency was 11/272 (4.2%). A total of 5/11 DLBCL rs78378222 heterozygous samples had the heterozygosity loss in the TP53 gene. Only one of these cases was combined with TP53 gene mutations which have proven oncogenic potential—p.Arg196Gln, other four cases have not mutations in the coding regions of gene.

Conclusions

At the stages of DLBCL initiation or progression a loss of the protective allele A of rs78378222 occurs. Further efforts are needed to study possible molecular mechanisms underlying somatic alterations in DLBCL in this region of the TP53 3′-UTR as well as functional studies to illustrate how the presents of rs78378222 may affect tumor progression of lymphoma.

Two Functional TP53 Genetic Variants and Predisposition to Keloid Scarring in Caucasians

Introduction

Keloid is defined as a benign proliferative scar that grows beyond the confines of the original insult to the skin, invading into adjacent normal tissue. The pathogenesis of keloid is complex, and many evidences suggest the influence of genetic factors, among them the polymorphisms of the TP53 gene encoding tumor protein p53.

Objective

To investigate the association of rs1042522 (c.215G>C, p.Arg72Pro) and rs17878362 (16-bp insertion/duplication in intron 3) variants, two most frequently analyzed TP53 functional polymorphisms and the risk of keloid in Polish patients.

Materials and Methods

The rs1042522 and rs17878362 polymorphisms were identified by sequencing genomic DNA extracted from peripheral blood leukocytes of 86 keloid patients and from cordial blood leukocytes of 100 newborn infants consisting control group.

Results

The rs1042522 and rs17878362 TP53 genotype distributions both in keloid patients and in the control group conformed to the expected Hardy–Weinberg equilibrium. No significant differences in the distribution of rs1042522 and rs17878362 TP53 alleles or genotypes have been found between keloid patients and newborn controls. There is tight, but not complete, linkage disequilibrium between rs1042522 and rs17878362 TP53 polymorphisms (D′ = 0.667, r = 0.448, and p=0). No significant differences in the distribution of rs1042522 and rs17878362 TP53 haplotypes or diplotypes have been found between keloid patients and newborn controls.

Conclusions

Our results suggest the lack of association of rs1042522 and rs17878362 TP53 polymorphisms and their haplotypes or diplotypes with the susceptibility to keloid scarring in Polish patients.