[Clinical Study of miRNAs Derived from Serum Exosomes in Multiple Myeloma].

Objective: To investigate the expression level and prognostic value of miR-21, miR-18a, miR-146a, and Let-7b derived from serum exosomes in patients with multiple myeloma (MM).

Methods: Serum exosomes were extracted from 57 MM patients and 20 healthy persons using ExoQuick exosome precipitation solution kit, and the relative expression level of miR-21, miR-18a, miR-146a, and Let-7b derived from serum exosomes was measured by RT-qPCR. Correlations of the expression levels of all miRNAs mentioned above with routine laboratory parameters were analyzed by Spearman correlation analysis. The relationship between the expression level of miR-21, miR-18a, miR-146a, and Let-7b derived from serum exosomes and overall survival of patients with MM was analyzed using the Kaplan-Meier survival curve.

Results: The expression levels of miR-21, miR-18a, and Let-7b derived from serum exosomes in patients with MM were significantly lower than those in the normal control group (P<0.001), while the expression level of miR-146a between the two groups was not significantly different (P>0.05). The expression level of miR-21 was strongly negatively correlated with serum β-microglobulin concentration (r=-0.830), and weakly negatively correlated with serum creatinine, corrected serum calcium, and cystatin C (r=-0.488, -0.282, -0.627). The expression levels of Let-7b and miR-18a were also weakly negatively correlated with the corrected serum calcium, β-microglobulin, and cystatin C concentration (r=-0.305, -0.362, -0.461; -0.317, -0.542, -0.434). However, there was no significant correlation between the expression level of miR-146a and routine laboratory parameters in MM patients. The overall survival rate of MM patients with low expression level of miR-21, miR-18a, and Let-7b significantly decreased compared with high expression level group (P<0.05), however, the expression level of miR-146a was not related to the overall survival rate.

Conclusion: Aberrant low expression levels of miR-21, miR-18a, and Let-7b derived from serum exosomes exist in patients with MM, which are associated with a worse overall survival rate.