Effects of interference of DNA methyltransferases in re-expression of cancer/testis antigens in hepatocellular carcinoma cells / 解放军医学杂志

ABSTRACT

Objective To explore the effects and the underlying mechanisms of inhibiting three kinds of DNA methyltransferases(DNMT1,DNMT3a and DNMT3b) on the re-expression of cancer/testis antigen(CTA) in hepatic cells.Methods Transient transfection of HepG2 cells with siRNA was targeted against DNMT1,DNMT3a and DNMT3b(DNMT1+3a+3b),DNMT1 and DNMT3a(DNMT1+3a),DNMT1 and DNMT3b(DNMT1+3b),DNMT3a and DNMT3b(DNMT3a+3b),respectively.The other batch of cells was treated with 5'-aza-deoxycytidine(5-aza-dC) as positive control.Real-time PCR and Western blotting were used to detect the expressions of DNMTs and CTAsm,and the promoter methylation of partial CTA genes was detected with methylation specific PCR(MSP).Results Expressions of DNMT1,DNMT3a and DNMT3b declined significantly after siRNA interference in HepG2 cells.Two CTAs,CT10 and SSX1,re-expressed in the cells transfected by DNMT1+3a and DNMT1+3b.MAGE1 and MAGE3 were equally expressed in all cells despite been transfected or not.Demethylation occurred in the promoter region of CT10,while the promoter region of MAGE1 was in a state of unmethylation.Conclusions In HepG2 cells,CTA promoter can be demethylated via interference of DNMTs,which may lead to the re-expression of CTA that was originally unexpressed due to methylation.