Methods: hTERT-over expressed or hTERT-down regulated immortalized oral keratinocytes were established by transfection of plpc-hTERT or TERT shRNA, respectively. Over expression and down regulation of hTERT were confirmed by RT-PCR, western blotting and TRAP assay. As functional studies for the role of hTERT in oral carcinogenesis, MTT, Flow cytometry, apoptosis assay, transinvasion assay and in vivo study were performed.
Results: The hTERT-transfection effectively upregulated the mRNA and protein levels of hTERT, and increased the telomerase activity. The hTERT-shRNA also effectively knocked downed the mRNA and protein levels of hTERT and reduced the telomerase activity. hTERT overexpression leads to enhance cell proliferation and invasion in immortalized oral keratinocytes. On the contrary, hTERT-shRNA suppression leads to inhibition of proliferation, inducing apoptotic activity in immortal cells and oral squamous carcinoma cells.
Conclusion: Our results suggest that hTERT would have casual effects on tumorigenesis, independent of telomere-extension activity.
Acknowledgment: This work was supported by Priority Research Centers Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2009-0094028) and 2009-0078630