by E. Voropaeva | T. Pospelova | O. Berezina | M. Churkina | A. Gurazheva | V. Maksimov | Institute of Therapy and Preventive Medicine — branch of ICG SB RAS | Novosibirsk State Medical University | Novosibirsk State Medical University | Novosibirsk State Medical University | Institute of Therapy and Preventive Medicine — branch of ICG SB RAS | Institute of Therapy and Preventive Medicine — branch of ICG SB RAS
Motivation and Aim: The aim of our study was to identify the frequency, specificity and clinical significance of MIR-34B/C, MIR-34A, MIR-203 and MIR-129-2 genes methylation in Diffuse Large B-cell Lymphoma (DLBCL).
Material and methods: DNA was extracted from primary FFPE-samples and treated to convert unmethylated cytosine to uracil. Methylation status was analyzed by methyl-specific PCR and methyl-sensitive HRM in 73 tumor samples and 11 samples with reactive polyclonal B-cell proliferation. We evaluated the combined methylation of genes in pairs using the one-sided Fisher exact criterion (p-value) and multiple testing corrections with Benjamin-Hochberg procedure (q-value).
Results: Methylation of MIR-129-2, MIR-203, MIR-34A and MIR34B/C in tumor samples occurred with a frequency of 67%, 66%, 27% and 62%, respectively. Methylation of the analyzed genes in the tissue of reactive lymph nodes was not detected. Combined methylation of MIR-203, MIR-129-2 and MIR-34B/C genes (p=0.013, q=0.020), as well as pairs of MIR-34B/C and MIR-34A genes (p=0.010, q=0.029) has been shown. An assessment of the relationship between studied microRNA genes methylation and clinical and laboratory features of the disease showed that 18/20 (90%) patients in the subgroup with the MIR-34A gene methylation had a high and intermediate/high risk according to International Prognostic Index against 26/53 (49.1%, p=0.002) in the subgroup of patients without this gene methylation. Methylation of MIR-34A was associated with reduced frequency of remission (p=0.060) and decreased overall survival (p=0.162). Methylation of MIR-34B/C (p=0.026) and MIR-203 (p=0.011) was associated with Ki-67 expression level of more than 45%.
Conclusions: Tumor-specific methylation of gene promoters can serve as a significant mechanism for reducing the miR-34B/C, miR-34A, miR-203 and miR-129 expression in DLBCL. MIR-34A gene methylation is helpful in prognosis and targeted therapy strategy development of DLBCL.
Funding: This work was supported by grant of Russian Science Foundation № 22-25-00222.
BGRS Voropaeva et al.