Enhancement of 1,25-dihydroxyvitamin D_3 induced apoptosis through the down regulation of telomerase activity bytransfected antisense telomerase RNA into hepatocarcinoma cells

Objective To observe the effect of 1,25-dihydroxyvitamin D3(1,25-VD3) on hepatocarcinoma cell apoptosis after blocaking telomerase activity by antisense telomerase RNA.Methods The pBBS 212/hTR,antisense telomerase RNA gene expression vector was introduced into SMMC7721 cells with vitamin D receptor(VDR) by using lipofectin mediation.After the transfected cells were screened by hygromycin and cloned,divided into control group,drug group,transfected group and drug transfected group.The effects of antisense telomerase RNA on telomerase activity of SMMC7721 cells were observed by TRAP-PCR-ELISA,then the transfected cells were treated with 1,25-VD3.The terminal-deoxynucleotidyl transferase mediated nick end labeling(TUNEL) and electron microscope were adopted to detect the apoptosis in cells.Results The TRAP-PCR-ELISA showed the telomerase activity in transfected cells and control group was 0.686 and 1.685 respectively,suggested that antisense telomerase RNA had a significant inhibition effect on telomerase activity of SMMC7721 cells.The apoptosis rated of control group,drug group,transfected group and drug transfected group were 3.4 %,12.2 %,8.8 %,23.6 %,respectively.The statistically significant difference was found(P 0.01),and the apoptosis of SMMC7721 cells was further confirmed by ultrastructural examination.On the other hand,the apoptosis by 1,25-VD3-induced was significantly enhancement after inhibition the expression of telomerase activity in SMMC 7721 cells with transfected antisense telomerase RNA.Conclusion It is demonstrated that antisense telomerase RNA can decrease the telomerase activity of hepatocarcinoma cells,and that inhibition of telomerase activity could significant enhance the cell apoptosis and inhibit cell proliferation by 1,25-VD3-induced in hepatoca-rcinoma cells.