Recently miR-15a-5p, miR-20a-5p and miR-33b-3p were found to be abnormally expressed in multiple myeloma (MM) patients. However, the significance of these microRNAs in MM pathogenesis remains poorly understood. Therefore the aim of the current study was to make an integrated bioinformatics analysis of miR-15a-5p, miR-20a-5p and miR-33b-3p to identify the biological processes in MM pathogenesis.

The Steven K. Thompson equation and a-priori power analysis was conducted to determine the minimum sample size required. Forty patients with newly diagnosed MM and staged by the International Staging System (ISS) and 20 healthy bone marrow donors were included in our study. The baseline bone marrow miR-15a-5p, miR-20a-5p and miR-33b-3p expression levels were evaluated by RTqPCR technique. Moreover, EGR2 expression level was evaluated by using immunohistochemistry. A bioinformatics analysis for miR-15a-5p, miR-20a-5p, miR-33b-3p and EGR2 was done by using miRNet and miRDB (for target genes prediction), GO analysis and KEGG analysis (for biological processes identification) and STRING database (for PPI network).

The target genes of miR-15a-5p, miR-20a-5p and miR-33b-3p were retrieved then GO analysis was done which showed that the pathway with many shared target genes was MAPK signaling pathway that involved in the cell cycle control. The baseline bone marrow miR-15a-5p, miR-20a-5p& miR-33b-3p expression levels were significantly decreased (0.29 ± 0.04, p < 0.001;0.42 ± 0.06, p < 0.001;0.51 ± 0.07, p = 0.02 fold-change relative to controls) in MM patients when compared to controls (1.04 ± 0.11,1.02 ± 0.07&1.05 ± 0.11;respectively) while EGR2 protein was significantly increased in MM patients when compared to controls. Results obtained from ROC curve revealed that miR-15a-5p + miR-20a-5p + miR-33b-3p panel (AUC = 0.98, 100%sensitivity, 85%specificity, p < 0.001) and EGR2 protein expression (AUC = 0.986, 97.5%sensitivity, 90%specificity, p < 0.001) were the best ones as diagnostic biomarkers could differentiate MM disease. By using Kaplan − Meier survival test, the mean (95%CI) for OS was 24.08 (21.58–29.88) months throughout the 32-month follow-up period for MM patients, our results indicated that patients with lower expression levels of miR-15a-5p, miR-20a-5p&miR-33b-3p and higher expression level of EGR2 protein had poorer prognosis and possessing a shorter OS. The logistic regression analysis indicates that miR-15a-5p, miR-20a-5p, and miR-33b-3p are risk factors for the development of MM (OR = 9.36,2.56,4.76; 95% CI 4.02–21.28,1.28–5.32,2.43–9.16; p < 0.001, p = 0.016, p < 0.001;respectively).

Finally miR-15a-5p, miR-20a-5p, and miR-33b-3p may have roles in MM pathogenesis through cell cycle control.