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

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).

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.

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 β₂-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, β₂-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.

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.