Abstract: Objective:To investigate the clinical significance and biological function of microRNA(miR-106b) expression in retinoblastoma,and effects of miR-106b on the viability,proliferation and apoptosis of retinoblastoma cells.Methods:The expressions of miR-106b in 33 specimens of retinoblastoma tissue and precancerous tissues were detected using qRT-PCR,and the correlation of which with clinicopathologic feature was analyzed.The miR-106b mimics or inhibitors were transfected into the retinoblastoma cells.The viability,proliferation and apoptosis of retinoblastoma cells were detected using MTT,BrdU and flow cytometry,and the expression of Rb1 protein was detected using Western blot.Results:The expression of miR-106b in retinoblastoma tissue was significantly higher than that in precancerous tissue(P<0.01),which was not correlated with optic nerve infiltration(P<0.05).The expressions of miR-106b in retinoblastoma cells Y79 and HXO-Rb44 were significantly higher than that in normal retinal vascular endothelial cells ACBRI-181(P<0.01).MiR-106b inhibitor could obviously inhibit the expression of miR-106b in HXO-Rb44 cells(P<0.01),and significantly lead to the decreasing of cell viability,proliferation and increasing of percentage of cell apoptosis(P<0.05).The decreasing expression of miR-106b in HXO-Rb44 cells could significantly increase the Rb1 protein expression,and the increasing expression of miR-106b in Y79 cells could significantly decrease the Rb1 protein expression.Conclusions:The expression of miR-106b increases in retinoblastoma tissue,which is correlated with the adverse clinicopathological features of retinoblastoma.MiR-106b can strengthen the viability and proliferation,and reduce the apoptosis of retinoblastoma cells and the expression of Rb1 in retinoblastoma cells.MiR-106b may play a key role in the development and progression of retinoblastoma.