MicroRNAs in Diffuse Large B-Cell Lymphoma (DLBCL): Biomarkers with Prognostic Potential

<b>Background/Objectives</b>: The heterogeneity of diffuse large B-cell lymphoma (DLBCL) based on differences in both genetic and epigenetic factors contributes to the dynamics of tumor growth and efficacy of cytoreductive therapy, as well as considerably affecting disease prognosis. This study aimed to detect microRNAs (miRNAs) capable of improving prognostic accuracy in DLBCL patients. <b>Methods</b>: We performed miRNA sequencing in bone marrow (BM) samples collected from DLBCL patients. Next, the expression levels of miRNAs in lymph node (LN) samples (<i>n</i> = 43) and BM samples (<i>n</i> = 70) were analyzed by real-time RT-PCR in the group of DLBCL patients. <b>Results</b>: It was found that the expression levels of miRNA-10b, -100, -125a, -125b, -126, -143, -23a and let-7a were statistically significantly reduced in the group of DLBCL patients who had a poor prognosis compared to DLBCL patients with a favorable prognosis (<i>p</i> < 0.05). Kaplan-Meier survival analysis demonstrated that the upregulated expression of miRNA-23a, miRNA-125a, and miRNA-100 was associated with better overall survival in DLBCL patients. A statistically significant elevation in the expression levels of miRNA-151a, miRNA-148b and miRNA-192 in the BM samples was observed for DLBCL patients both with and without BM involvement compared to BM samples from non-cancerous blood disease (NCBD) patients (<i>p</i> < 0.05). Statistically significant upregulation of <i>PD-L1</i>, <i>TIMP1</i>, <i>TOP2A</i>, and <i>TP53</i> was observed in BM samples from DLBCL patients with and without BM involvement in comparison with BM samples from NCBD patients (<i>p</i> < 0.05). <b>Conclusions</b>: miRNA-23a, miRNA-125a, and miRNA-100 were shown to be potential prognostically significant biomarkers in DLBCL patients. Changes in expression levels of miRNA-151a, miRNA-148b, miRNA-192, <i>PD-L1</i>, <i>TIMP1</i>, <i>TOP2A</i>, and <i>TP53</i> reflect alterations in the BM without morphological or immunophenotypic signs of a DLBCL-related BM pathology.