Telomerase activity in head and neck tumors after introduction of wild-type p53, p21, p16, and E2F-1 genes by means of recombinant adenovirus.

ABSTRACT

BACKGROUND: Telomerase (reverse transcriptase) has been shown to play a role in the process of cellular immortalization. METHODS: Telomerase activity was determined in 11 head and neck squamous cell carcinoma (SCCHN) cell lines. The effects of wild-type p16, p21, E2F-1, and p53 genes on telomerase activity were examined by introducing the wild-type genes into two SCCHN cell lines by means of a recombinant adenovirus. RESULTS: We found elevated telomerase activity in 10 of the 11 SCCHN cell lines tested. When we infected Tu-138 and Tu-167 cell lines with wild-type p16, p21, E2F-1, and p53 genes, we found that p16 had little effect on telomerase activity. Both E2F-1 and p53 were known to induce apoptosis in SCCHN cell lines. Significantly reduced telomerase activity by p53 in both cell lines and E2F-1 in Tu-167 cells was in agreement with suppression of cell growth. Overexpression of p21 also exhibited reduction in telomerase activity. CONCLUSIONS: We conclude from this study that overexpression of E2F-1 and p53 can reverse telomerase activity in SCCHN cell lines and that telomerase activity may be involved in cancer cell immortalization.