Expression Analysis and Epigenetics of MicroRNA-28-5p in Multiple Myeloma

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To investigate the expression, mechanism and methylation level of miR-28-5p in multiple myeloma (MM), so as to provide the expirement basis for searching new targeted therapy. RT-PCR was used to detect the expression levels of miR-28-5p and potential target CCND1 in CD138+ cells of the patients with MM and bone marrow mononuclear cells of patients with iron defficiency anemia(IDA) as control, Methylation-specific PCR(MSP) was used to detect methylation levels of CpG island in LPP/miR-28-5p promoter region and the correlation with other clinical indicators was analyzed. The 5-aza-2'-deoxycytidine (5-Aza-dC，DAC) was used to treat MM cell line U266; after drug treatment，MSP was used to analyze the methylation status of the CpG islands in LPP/miR-28-5p promoter; the qPCR was used to detect the expression levels of miR-28-5p，and the regulatory mechanism of miR-28-5p expression was explored furtherly. The methylation level of CpG island in LPP/miR-28-5p promoter region of MM patients was significantly higher than that of IDA patients. The relative expression level of miR-28-5p in MM patients was significantly lower than that of IDA patients. The relative expression level of miR-28-5p in newly diagnosed MM patients was higher than that in relapsed/progressive patients. The miR-28-5p target CCND1 was expressed at high levels in MM patients with LPP / miR-28-5p methylation, the expression level of miR-28-5p in MM patients correlated with β2-MG concentration. 5-aza-dc could significantly inhibit the growth of U266 cell line, arrest the cell cycle in G1 phase, inhibit the biosynthesis of cellular RNA and protein and promote cell apoptosis. At the same time, up-regulation of miR-28-5p expression was found. The expression of miR-28-5p in MM patients is regulated by methylation of CpG islands in the promoter region of the genome.miR-28-5p may act as a tumor suppressor gene, and its low expression may be involved in the occurrence and development of MM, suggesting that miR-28-5p may become a new target for the treatment of MM.