Treatment of transplanted tumor from colotectal cancer in nude mice by RNA interference silencing human telomerase reverse transcriptase gene

Objective To study the effect of short hairpin RNA (shRNA) fragment of human telomerase reverse transcriptase (pGPU6/GFP/Neo-hTERT shRNA) on the growth of transplanted tumors of colorectal carcinoma in nude mice in vivo.Methods Human colorectal carcinoma cell line 5 × 107 SW480 cells were inoculated into nude mice to establish the solid tumor model.The tumor models were randomly divided into the following 3 groups,8 nude mice each group.The experimental group was injected with hTERT-shRNA plasmid (20 μg) intratumoraly.NC-shRNA group (20 μg) and NS group (100 μl) served as negative group and blank group,respectively.The tumor growth was observed,and the cuve of tumor growth was drawn.The collected tumor specimens were examined,and the expression of hTERT mRNA and protein was detected.Telomerase activity and cell apoptosis were assayed.Results The transplanted tumor in experimental group grew more slowly than negative control and blank control groups.The relative expression of hTERT mRNA in experimental group was 0.388 ± 0.093 and the average gray value of hTERT protein was 171.42 ± 30.94,which were significantly lower than in control groups (P ＜ 0.05,P ＜0.01,respectively).The activity of telomerase (A450-A630) in experimental group (0.484 ± 0.359) was markedly lower than in control groups (P ＜ 0.05,P ＜0.01,respectively).The proportion of apoptotic cells in experimental group (36.30 ± 5.05) ％ was higher than in control groups (P ＜ 0.01).Conclusion The shRNA fragment of hTERT gene can partly inhibit the growth of SW480 transplantrf tumor in nude mice probably by suppressing hTERT mRNA and protein expression and the activity of telomerase,as well as inducing apoptosis of SW480 cells. Key words: RNA interference;  Telomerase reverse transcriptase;  Transplanted tumor