miR-21 enhances resistance of glioma cells to carmustine by down-re-gulating PTEN

AIM:To explore the function of miR-21 in human glioma cells resistant to carmustine[1,3-bis(2-chloroethyl)-1-nitrosourea,BCNU] and to elucidate its related mechanism.METHODS: SWOZ2 cells were transfected with miR-21 mimics(SWOZ2-miR-21 mimics) or miRNA mimics negative control(control group) by the method of jetPRIME.The real-time fluorescence quantitative PCR was used to detect and compare the levels of miR-21 expression between BCNU-resistant cell line SWOZ2-BCNU and BCNU-sensitive cell line SWOZ2,or between SWOZ2-miR-21 mimic group and control group.The drug sensitivity of these cells to BCNU was determined by CCK-8 assay.The protein expression of phosphatase and tensin homology deleted on chromosome 10(PTEN),phosphorylated protein kinase B(p-Akt) and P-glycoprotein(P-gp) in these cells were also detected by Western blotting.RESULTS: The expression level of miR-21 was remarkably higher in SWOZ2-BCNU cells than that in SWOZ2 cells.The expression level of miR-21 was significantly higher in SWOZ2-miR-21 mimics group than that in control group.The half-maximal inhibitory concentration(IC50) of BCNU was obviously higher for SWOZ2-BCNU cells than that for SWOZ2 cells.The IC50 of BCNU was markedly higher in SWOZ2-miR-21 mimics group than that in control group.PTEN protein expression was remarkably lower,but p-Akt and P-gp protein expression levels were markedly higher in SWOZ2-BCNU cells than those in SWOZ2 cells.The protein level of PTEN was significantly lower,but the protein levels of p-Akt or P-gp were distinctly higher in SWOZ2-miR-21 mimics group than those in control group.CONCLUSION: miR-21 enhances the resistance of human glioma cells to BCNU by down-regulating the expression of PTEN protein.