Objective: To investigate relationship of miRNA-132, miRNA-256, miRNA-143 and miRNA-145 level with antophagy and apoptosis of multiple mgeloma cells.
Methods: Human myeloma cell line U266 and normal CD138+ plasma cells were selected and used for study and detection, the 45 cases of MM were enrolled in MM group, and 40 normal persons were sellectod in control group. The expression of miRNA-132, miRNA-125b, miRNA-143 and miRNA-145 were measured by using qPCR, the expressions of autophagy-related protein (LC3-Ⅱ, LC3-Ⅰ, P62, beclin-1) and apoptosis-related molecules (cleaved-Caspase3, cleaved-Caspase7, BCL-2, BAX) were measured by using Western blot, respectively. The rate of apoptosis was measured by using flow cytometry. The correlation of miRNA expression level with clinical-related indexes including M protein, hemoglobin, β2-MG, lactate dehydrogenase, albumin, creatinine and serum calcium was analyzed.
Results: Compared with normal plasma cells, the expression of miRNA-132 and miRNA-125b in myeloma cells increased significantly (P<0.05), and the expression of miRNA-143 and miRNA-145 decreased significantly (P<0.05), but the expression of LC3-Ⅱ/LC3-Ⅰ and Beclin-1 increased significantly (P<0.05). The expression of P62. BAX, cleaved-Caspase3 and cleaved-Caspase7 decreased significantly (P<0.05), the BCL-2 expression increased significantly (P<0.05), but the rate of apoptosis decreased (P<0.05). After transfection with miRNA-125b mimic or miRNA-143 inhibitor by using the cationic liposomes, the LC3-Ⅱ /LC3-Ⅰ of normal plasma cells increased significantly (P<0.05), the expression of Beclin-1 significantly increased (P<0.05), the expression of P62 decreased significantly (P<0.05), and the apoptosis rate decreased (P<0.05). However, the apoptosis rate was not significantly changed after addition of the autophagic inhibitor 3-MA in the reaction system(P>0.05). The expressions of miRNA-132, miRNA-125b, miRNA-143 and miRNA-145 were significantly different between DS and ISS staging group, also between the patients with abnormal and normal chromosome karyotype (P<0.05). The miRNA-125b and miRNA-143 significantly correlated with the levels of β2-MG, albumin and hemoglobin (P<0.05).
Conclusion: The expressions of miRNA-132, miRNA-125b, miRNA-143 and miRNA-145 in patients with multiple myeloma closely relate with the clinical characteristics. Both over-expression of miRNA-125b and down-expression of miRNA-143 inhibit the apoptosis of myeloma cells by up-regulation of autophagy.