Effect of specific hTERT RNA interference on biological characteristics of colon carcinoma in vivo and in vitro

AIM:To investigate the effect of specific hTERT RNA interference on biological characteristics of colon carcinoma in vivo and in vitro.METHODS: A small interference RNA(siRNA) targeting to hTERT mRNA(pU6-hTERT-siRNA) was constructed.The siRNA was transfected into LoVo colon cancer cells in vivo and in vitro with LipofectamineTM2000.The groups of non-specific siRNA(pU6-hTERT) and non-treatment were designed as negative control and blank control,respectively.The cell growth in vitro was detected by MTT method.The effect of pU6-hTERT-siRNA on xenografts in nude mice was observed by determining the tumor size.The mRNA expression of hTERT in vitro and in vivo was detected by FQ-PCR quantitatively.The protein level of hTERT was determined by Western blotting.RESULTS: The inhibition rate of cell growth in vitro 72 h after transfection with recombinant plasmids containing hTERT-target sequences was 42.1%,significantly higher than that in control group(3.2%,P0.01).The size of xenografts in pU6-hTERT-siRNA group was(85.9±18.7)mm3,significantly smaller than that in control group [(157.4±55.6)mm3] and blank group [(155.2±54.2)mm3],P0.01.The mRNA expression and the protein level of hTERT were both specifically inhibited by pU6-hTERT-siRNAs in LoVo colon cancer cells and xenografts(P0.01).No difference between control group and blank group was observed(P0.05).CONCLUSION: hTERT expression in LoVo colon cancer cells is inhibited significantly in vivo and in vitro by using plasmid-based siRNA.Down-regulation of hTERT expression distinctly inhibits the growth of LoVo colon cancer cells in vitro or subcutaneously transplanted in athymic mice.