FHIT-targeting miR-92a regulates proliferation and apoptosis of lymphoma cells: a mechanistic study

Objective To determine the mechanism by which fragile histidine triad (FHIT) targeting microRNA-92a (miR-92a) in regulates proliferation and apoptosis of lymphoma cells. Methods Lymphoma cells were subject to different transfections. miR-92a inhibitor group, NC- inhibitor group, miR-92a inhibitor+si-FHIT group, and miR-92a inhibitor+si-NC group were transfected with miR-92a inhibitor, inhibitor control, co-transfected with miR-92a inhibitor and FHIT small interference RNA (siRNA) , or with miR-92a inhibitor and siRNA control, respectively. Real-time quantitative PCR was used to determine the expression level of lymphoma cells miR-92a in miR-92a inhibitor group and NC-inhibitor group. The proliferation of cells in each group was examined by CCK-8 assay. The apoptosis of cells in each group was examined by flow cytometry. Bax and Bcl-2 protein levels in each group were measured by Western blotting. Bioinformatics software predicted that there were targeted binding loci between miR-92a and FHIT, and the luciferase reporting system was used to identify the target genes. Results Compared with NC-inhibitor group, the expression level of lymphoma cells miR-92a (0.43±0.05 vs 1.01±0.08, P<0.001) and cell proliferation rate (0.27±0.03 vs 0.42±0.06, P=0.018) in miR-92a inhibitor group significantly decreased, whereas the cell apoptosis rate [ (14.75±1.26) % vs (3.38±0.36) %, P<0.001], and protein expression levels of Bax (0.56±0.08 vs 0.30±0.05, P=0.009) and FHIT (0.42±0.05 vs 0.27±0.07) increased. The protein expression level of Bcl-2 in the miR-92a inhibitor decreased compared with that in NC-inhibitor group (0.57±0.07 vs 0.94±0.10, t=5.250, P=0.006) . Target gene prediction and identification results indicated that FHIT was a target gene of miR-92a. Compared with miR-92a inhibitor+si-NC group, the proliferation rate of lymphoma cells in miR-92a inhibitor+si-FHIT group increased (0.38±0.04 vs 0.28±0.02, P=0.018) , the apoptosis rate reduced [ (7.15±0.74) % vs (13.84±1.78) %, P=0.004], the protein expression level of Bax decreased (0.30±0.04 vs 0.54±0.06, P=0.005) , and the protein expression level of Bcl-2increased (0.88±0.09 vs 0.48±0.0, P=0.003) . Conclusion Down-regulation of miR-92a promotes expression of miR-92a-targeted FHIT expression, thereby inhibiting lymphoma cell proliferation and inducing cell apoptosis. Key words: Lymphoma; miR-92a; Fragile histidine triad (FHIT) gene; Apoptosis; Proliferation