Carcinoma and Adjacent Tissues Telomerase Activity in Head and Neck Squamous Cell

The primary function of telomerase is the synthesis of telomeric DNA, which is the main pathway by which telomere length is maintained in the human germline and stem cells. Activation of telomerase is associated with elongation of telomeres and cell immortalization. Recently, telomerase activity has been detected in tissues from many human cancers but not in the majorityof normaltissues,suggestingthat telomerestabilizationand telomerase activation may play a role in tumorigenesis. To explore telom erase activity in head and neck neoplastic and preneoplastic tissues, we studied 16 head and neck squamouscell carcinoma(HNSCC)cell lines and 60 specimens from 29 patients with HNSCC for telomerase activity. We precisely compared telomerase activity with histological 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%) hyperplastic lesions, whereas 0 of 17 normal tissues or 2 hyperkeratotic lesions had detectable telomerase activity. Our data indicate that activation of telomerase activity is fre quent in HNSCC and may occur early in the tumorigenesis process. The reactivation of telomerase may be a useful marker for cancer risk assess ment in the oral cavity.