Availability of Circulating MicroRNAs as a Biomarker for Early Diagnosis of Diffuse Large B-Cell Lymphoma

Abstract Background: MicroRNA (miRNA) regulates post-transcriptional gene expression through binding to complementary sites of target messenger RNA, including that from oncogenes or tumor suppressor genes. This study planned to pursue the possibility that circulating miRNA could be used for the early diagnosis of diffuse large B-cell lymphoma (DLBCL). Materials and Methods: Expression levels of miRNA obtained from serum, exosome-enriched serum, and formalin-fixed paraffinembedded (FFPE) tissue were evaluated. Samples were collected from patients with newly diagnosed DLBCL (n = 33) or healthy volunteers (n = 22). Based on the results of previous reports, ten miRNAs were selected and expression levels were analyzed by the quantitative real-time PCR. Results: The expression levels of hsa-miR-15a-3p, hsa-miR-21-5p, hsa-miR-181a-5p, and hsa-miR-210-5p differed significantly between DLBCL patients and controls in serum and/or exosomeenriched serum, but not in FFPE tissue. In contrast, expression levels of hsa-miR-155-5p in FFPE tissue were significantly higher in DLBCL patients, as previously reported. Conclusion: We confirmed that some miRNAs were differentially expressed in serum from DLBCL patients as previously reported. Measurement of these miRNA in exosome-enriched serum did not improve the accuracy in the differential diagnosis of DLBCL. In addition, these miRNAs seem to be produced outside of lymphoma tissue. * Corresponding author. K. Inada et al. 4