1. ¹Department of Microbiology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan, China
2. ²Institute of Chengdu Biological Products, Chengdu, Sichuan, China

Correspondence: Professor M Li, Department of Microbiology, West China School of Preclinical and Forensic Medicine, Sichuan University, 17# South of Renming Road, Chengdu, Sichuan 610041, China. E-mail: zxllmyus@yahoo.com

Received 19 October 2006; Revised 1 March 2007; Accepted 11 March 2007; Published online 20 April 2007.

Abstract

Small interfering RNA (siRNA) has become a powerful tool for selectively silencing gene expression in cultured mammalian cells. In this study, a 67-bp oligonucleotide encoding human telomerase RNA (hTR) was introduced into pSIREN, a shuttle vector for construction of recombinant adenovirus. Then the U6-RNA promoter and siRNA-encoding insert were cut out from the pSIREN and subcloned into pAdeno-X to construct the plasmid pAd-hTR. After the pAd-hTR was transfected into a mammalian cell line HEK-293, adenovirus carrying the hTR-targeting siRNA (Ad-hTR-siRNA) was obtained. We performed a series of experiments to demonstrate silencing of the telomerase mediated by Ad-hTR-siRNA in HeLa cells. Compared with control virus (Ad-NT-siRNA), Ad-hTR-siRNA significantly reduced both hTR mRNA level (by 70.21%) and telomerase activity (by 58.87%) in HeLa cells. Moreover, it induced apoptosis in HeLa cells. Treatment of subcutaneous tumor xenografted with Ad-hTR-siRNA could slow down tumor growth, at least partially due to the induction of apoptosis (P<0.05) in vivo. Taken together, our results demonstrated efficient and specific knockdown of telomerase in HeLa cell line by the hTR siRNA, and indicated the prospect of applying this siRNA expressing recombinant adenovirus system in cancer gene therapy.