RNAi gene therapy of SiHa cells via targeting human TERT induces growth inhibition and enhances radiosensitivity.

Telomerase activity (TA) is reactivated in more than 90% of all human malignant tumors and normal somatic cells that lack TA. Thus, human TERT (hTERT) is a promising target in malignant tumor treatment. RNA interference is a powerful tool for gene silencing. In this study, we constructed siRNA#1-4 to knock down hTERT. All siRNAs were able to downregulate hTERT differently and we chose siRNA#3 (most effectively) in the following experiments. We studied the effects on cell proliferation, cell cycle, cell apoptosis and radiosensitivity using SiHa cells. Our results showed that siRNA#3 was able to silence hTERT gene effectively. The silencing of hTERT could induce immediate growth arrest, enhance the S phase in cell cycle study and lead to early apoptosis in human cervical cancer cells (SiHa). In clonogenic assays, we used multitarget-single hit and linear-quadratic models to assess the radiosensitivity after knockdown of hTERT. All results of parameters (D0, Dq, α, β) indicated that downregulation of hTERT enhanced radiosensitivity in SiHa cells.