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@#Human telomerase reverse transcriptase (hTERT) plays an important role in telomere restitution and gene regulation. Evidences suggest that hTERT is linked with the risk and progression of several types of malignancies. Detection of hTERT mRNA levels, as one of tumor markers, may reflect the tumor burden and the clinical status of the patient. Present paper emphasizes the potency of hTERT mRNA detection in serum as a sensitive tumor biomarker in different types of cancer. Detection of serum hTERT mRNA levels has been found highly sensitive and specific for varied cancers. A number of reports reflect its superiority to other conventional tumor markers including alfa-fetoprotein, EGFR, lens culinaris agglutinin-reactive AFP and Des-gamma carboxy prothrombin. Serum hTERT has been found linked with the risk and progression of different cancer types. hTERT levels in combination with other tumor markers may be used to improve cancer detection, tumor size and level of cancer progression.
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Objective To select an efficient method to inhibit telomerase activity, antisenseoligodeoxynucleotide and plasmid-vector mediated RNAi against hTERT were used to inhibit telomerase activity. The inhibiting effects of the two methods were compared. Methods Against hTERT mRNA, siRNA and oligodeoxynucleotide were designed and transfected into K562 cells by liposome. Effective and specific siRNA strands were selected and then plasmid was constructed and transfected into K562 cells; followed by analysis of the results. Results hTERT mRNA were detected after the three chemo-synthesized strands were transfected. It was found that si-hTERT-1 and si-hTERT-2 were effective, but si-hTERT-3 had no effect. The inhibiting effect of hTERT mRNA lasted only 48 h and disappeared at 72 h. Two siRNA strands were sieved and plasmids were constructed and transfected into K562 cells. In the P-1 group, hTERT mRNA was 0.39±0.13 at 48 h, 0.57±0.32 at 72 h. In the P-2 group, hTERTmRNA was 0.55±0.20 at 48 h, 0.88±0.23 at 72 h.In the P-1 group, the relative telomerase activity was 0.42±0.07 at 48 h, 0.31±0.08 at 72 h. In the P-2 group was 0.49±0.27 at 48 h, 0.39±0.03 at 72 h. The best concentration of siRNA was 100 μmol/L. The best concentration of ASODN was 0.6 μ mol/L. hTERTmRNA was 0.42±0.16 at 24 h, 0.71±0.18 at 48 h. Relative telomerase activity was 0.52±0.002 at 24 h, 0.482±0.018 at 48 h. Conclusion Both ASODN and RNAi targeting hTERT can inhibit the expression of hTERT mRNA, and then inhibit telomerase activity. The inhibiting effect is closely relative to the targeting site. The inhibiting effect of RNAi is better than that of ASODN. RNAi has better efficiency and lasts for a longer time. Plasmid mediated RNAi has better inhibiting effect than the chemo-synthesized siRNA.