Silencing of MGMT with small interference RNA reversed resistance in human RCTIN-resistant glioma cell lines

Background Our previous study had cloned two glioma cell lines SWOZ1 and SWOZ2 isolated from parental gliomacell line SW038. The 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) resistance of SWOZ1 was higher than that of SWOZ2.Since O~6-methylguanine-DNA methyltransferase (MGMT) was thought to be closely related to BCNU resistance in glioma,this study aimed to explore the function of MGMT in glioma resistant to BCNU.Methods A BCNU resistant glioma cell line SWOZ2-BCNU was established. The expression of MGMT was detected inSWOZ1, SWOZ2 and SWOZ2-BCNU. Small interferencing RNA targeting MGMT was used to silence the expression ofMGMT in resistant cell lines SWOZ1 and SWOZ2-BCNU. The cytotoxicity of BCNU to these cells was measured usingthe cell counting kit-8 assay. Statistical analysis was carried out by one-way analysis of variance in statistical packageSPSS 13.0.Results The resistance of SWOZ1 and SWOZ2-BCNU against BCNU was 4.9-fold and 5.3-fold higher than that ofSWOZ2. The results of quantitative RT-PCR and Western blotting confirmed that MGMT was both significantly increasedin SWOZ1 and SWOZ2-BCNU compared to SOWZ2. After transfection with small interferencing RNA targeting MGMT, adecreased level of MGMT mRNA expression in SWOZ1 and SWOZ2-BCNU for more than 75% compared to negativecontrol was found and confirmed by Western blotting. As a result, the resistance against BCNU was reversed for about50% both in the BCNU-resistant cell lines SWOZ1 and SWOZ2-BCNU.Conclusions Silencing MGMT with specific small interferencing RNA can reverse the BCNU resistant phenotype inthese glioma cell lines. MGMT may play an important role both in intrinsic and acquired BCNU-resistance in glioma.