Telomerase activation and cell proliferation during 7,12-dimethylbenz[a]anthracene-induced hamster cheek pouch carcinogenesis

Telomerase is a ribonucleoprotein complex intimately involved in cell immor talization and carcinogenesis. This enzyme is activated and stabilizes telo mere length in almost all types of cancer. Telomerase may be necessary for continuous cell proliferation. In this study, we analyzed telomerase activi ty in hamster experimental oral lesions (starting from epithelial hyperplas ia through dysplasia, carcinoma in situ, and invasive carcinoma) evoked by 7,12-dimethylbenz[a]anthracene, and in normal mucosa. We also analyzed prol iferative activity in these lesions by using immunohistochemical analysis a nd flow cytometry. Histologically normal epithelium expressed weak telomera se activity. The telomerase activity count increased rapidly in the early s tage of carcinogenesis and gradually in the late stage. Cell-proliferative activity closely correlated with progression of disease. These findings ind icate that telomerase activation is an early event and that increases in te lomerase activity upregulate cell proliferation in chemically induced hamst er oral carcinogenesis. (C) 1999 Wiley-Liss, Inc.