Synthesized small interfering RNA inhibits the expression of DNA methyltransferase 1 in salivary adenoid cystic carcinoma

Objective To select the effective siRNA which could inhibit the expression of DNA methyltransferase 1(DNMT-1)in adenoid cystic carcinoma(ACC)and discuss the time-,and dose- dependant effect of RNA interference(RNAi).Methods Four pairs of siRNA were designed,synthesized and transfeeted through oligofectamine reagent into ACC cell lines ACC-2,ACC-3 and ACC-M.24,48 and 72 h after transfection,total RNA and protein were harvested respectively,mRNA and protein expression level of DNMT-1 were detected by real time PCR,RT-PCR and Western blot,and then the effective siRNA was subsequently selected.ACC-3 as also transfected by different concentration of siRNA and the dose- dependant effect of RNAi was discussed.Cy~3 labelled GAPDH siRNA was used as a positive control. Results Two of 4 pairs of siRNA inhibited the mRNA expression of DNMT-1 in three ACC cell lines and the expression of DNMT-I was downregulated by 67%,86%,92% and 76%,76%,86% respectively. The gene inhibition was detected at 24 h or 48 h after transfection,maintained only 1-2 days and showed direct relationship to the concentration of siRNA.The change of protein expression level of DNMT-1 was consistent to the changes of mRNA.Conclusions The effective siRNA which could inhibited the expression of DNMT-1 of ACC were achieved.The inhibition effect of RNAi was time-dependant and dose-dependent.