Оценка метилирования генов MIR-143 и MIR-145 в лимфоузлах больных диффузной В-крупноклеточной лимфомой

Abstract

Introduction. The expression of miR-143 and miR-145 oncosuppressive microRNAs is observed in all types of normal tissues studied and, according to numerous studies, it is lost in malignant neoplasms. A decrease in the expression of these microRNAs in diffuse large B-cell lymphoma (DLBCL) is described, the mechanisms of which require additional study. Aim. To evaluate the methylation of MIR-143 and MIR-145 genes in the lymph node tissue of patients with DLBCL and lymph nodes of patients with reactive follicular hyperplasia. Materials and methods. The study included biopsies of 14 formalin-fixed and paraffinized tumor lymph nodes of patients with DLBCL and 11 lymph nodes of patients with reactive lymphadenopathy. The methylation status of the MIR-145 gene in samples was determined by the method of methyl-specific polymerase chain reaction. Direct bisulfite sequencing based on the Sanger method was used to quantify the methylation of the MIR-143 gene. Results. It was found that all the studied samples, both reactive and tumor, had methylation of the MIR-145 gene. A similar level of methylation of CpG dinucleotides of the MIR-143 gene was registered in all samples of reactive lymph node tissue, whereas tumor samples showed greater heterogeneity. In the samples of DLBCL, namely a non-germinal B cell phenotype, the average level of methylation of the studied fragment of the MIR-143 gene sequence was significantly lower, than in the samples of reactive lymph nodes (p = 0.026). Conclusion. The methylation of MIR-143 and MIR-145 genes detected in the lymph nodes of patients with DLBCL is not tumor-specific. The complex cellular composition of the analyzed samples, as well as the different density of microvessels, may explain the differences in the level of MIR-143 methylation in the tissue of reactive and tumor lymph nodes.