TELOMERASE ACTIVITY IN HEAD AND NECK SQUAMOUS-CELL CARCINOMA AND ADJACENT TISSUES

The primary function of telomerase is the synthesis of telomeric DNA, which is the main pathway by which telomere length is maintained in th e human germline and stem cells. Activation of telomerase is associate d with elongation of telomeres and cell immortalization. Recently, tel omerase activity has been detected in tissues from many human cancers but not in the majority of normal tissues, suggesting that telomere st abilization and telomerase activation may play a role in tumorigenesis . To explore telomerase activity in head and neck neoplastic and prene oplastic tissues, we studied 16 head and neck squamous cell carcinoma (HNSCC) cell Lines and 60 specimens from 29 patients with HNSCC for te lomerase activity. We precisely compared telomerase activity with hist ological features in adjacent tissue sections. We detected telomerase activity in 16 of 16 (100%) HNSCC cell lines, 26 of 29 (90%) invasive tumors, 7 of 7 (100%) dysplastic lesions, and 5 of 5 (100%) hyperplast ic lesions, whereas 0 of 17 normal tissues or 2 hyperkeratotic lesions had detectable telomerase activity. Our data indicate that activation of telomerase activity is frequent in HNSCC and may occur early in th e tumorigenesis process. The reactivation of telomerase may be a usefu l marker for cancer risk assessment in the oral cavity.