Effects of miR-32 targeting PTEN on proliferation and apoptosis of myeloma cells.

OBJECTIVE: To explore the effects of micro ribonucleic acid (miR)-32 on the proliferation and apoptosis of myeloma cells, and to verify whether it exerts its function by targeting phosphatase and tensin homolog deleted on chromosome ten (PTEN). PATIENTS AND METHODS: The differentially expressed miRNAs were screened in healthy people and myeloma patients. The myeloma U266 cells transfected with negative control (NC) were used as control group, those transfected with miR-32 inhibitor as transfection group, and those transfected with miR-32 inhibitor and treated with PTEN inhibitor SF1670 as the transfection + inhibitor group. Then, the cell proliferation and apoptosis in each group were detected using the 5-Ethynyl-2'-deoxyuridine (EdU) kit and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay, respectively. Finally, the expressions of apoptosis-related proteins B-cell lymphoma-2 (Bcl-2), Bcl-2 homologous antagonist/killer (Bak), caspase-9, and survivin were detected. RESULTS: The expressions of some miRNAs and genes in myeloma patients were significantly different from those in healthy people. In myeloma patients, miR-32, miR-126, miR-123, and miR-183 were significantly highly expressed, while miR-5, miR-76, and miR-50 were remarkably lowly expressed. After myeloma U266 cells were transfected with the miR-32 inhibitor, the expression of miR-32 markedly declined. In addition, the mRNA expression of PTEN in myeloma cells rose after transfection with the miR-32 inhibitor, and declined after addition of the PTEN inhibitor SF1670, which were consistent with the results of Western blotting. Besides, the proliferation ability of myeloma cells was evidently weakened after transfection with the miR-32 inhibitor, while it was restored to a certain extent after addition of the PTEN inhibitor SF1670. Moreover, the number of apoptotic myeloma cells was remarkably larger after transfection with the miR-32 inhibitor, while it was remarkably smaller after addition of the PTEN inhibitor SF1670. The expressions of pro-apoptotic proteins Bak and caspase-9 in myeloma cells were significantly increased after transfection with the miR-32 inhibitor (p<0.05), and significantly decreased after addition of the PTEN inhibitor SF1670, while the expressions of anti-apoptotic proteins Bcl-2 and survivin were opposite to those of Bak and caspase-9. CONCLUSIONS: MiR-32 targeting PTEN will have certain effects on the proliferation and apoptosis of myeloma cells.