Methylation of P53-responsive oncosuppressive microRNA genes in hemoblastosis

The purpose of the study was to present up-to-date data on the frequency and significance of a number of p53-responsive oncosuppressive microRNAs genes methylation in malignant neoplasms of the blood system. Material and Methods. The search for available literary sources published in the PubMed and RISC databases was carried out. A total of 399 articles were found, of which 62 were included in this review. Results. The p53 protein regulates a whole class of microRNAs - highly conserved small RNA molecules that affect gene expression mainly by suppressing translation. МicroRNAs play an important role in all cellular processes and can have both oncosuppressive and pro-oncogenic properties. Impaired expression of p53-activated oncosuppressive microRNAs in various tumors may be associated with specific epigenetic mechanisms (DNA methylation and histone deacetylation). The review examines the molecular and genetic characteristics of oncosuppressive microRNAs functioning in normal hematopoiesis, the violation of expression of which is shown in the development of hemoblastoses, namely: miR-34a, miR-34b/c, miR-145, miR-143 and miR-203. It is known that the transcription of the genes of these microRNAs is carried out and regulated from their own promoters. The latest published research results on the diagnostic, prognostic and clinical significance of gene methylation of the microRNAs under consideration in malignant neoplasms of the blood system are presented. According to literature data, common targets for miR-34a, miR-34b/c, miR-145, miR-143 and miR-203 microRNAs are mRNAs of a number of pro-oncogenes, namely: transcription factor C-MYC, positive cell cycle regulators at the G1/S transition point of CDK4, CDK6 and CYCLIN-D1 phases, anti-apoptotic proteins MDM2, MDM4, BCL2 and MCL1, as well as DNMT3A and DNMT3B methyltransferases and other molecules. In this regard, it should be noted that there are positive feedbacks between p53 and microRNAs activated by it, as well as negative feedbacks between p53-responsive microRNAs and C-MYC and DNA methyltransferases. Conclusion. Thus, the data presented in the review clarify the current understanding of the work of the regulatory network of the p53 protein and the microRNAs activated by it, and also emphasize the functional association of p53-responsive microRNAs.