DETECTION OF TELOMERASE ACTIVITY IN MALIGNANT AND NONMALIGNANT SKIN CONDITIONS

Telomeres are the end regions of linear chromosomes, and in normal som atic cells the lengths of telomeres shorten with successive cell divis ions, Telomerase, a ribonucleoprotein enzyme, maintains the length of telomeres in immortal and germline cells. Although present in human fe tal tissues, shortly after birth telomerase activity is not detectable except in germline cells, hematopoietic cells, and most human primary tumors. In the present study we show telomerase activity to be presen t in 73 of 77 basal cell carcinomas, 15 of 18 nonmetastatic cutaneous squamous cell carcinomas, and 6 of 7 cutaneous melanomas, contrasting with extremely low levels detected in sun-protected skin, Sun-damaged skin, psoriatic lesional skin, and skin from lesions of poison ivy der matitis, however, have increased levels of telomerase activity compare d to sun-protected skin, although less than that detected in tumor tis sue, Because telomerase activity can be found in inflammatory lesions of the skin, this indicates that telomerase activity does not always c orrelate with the malignant phenotype, In addition, we show that telom erase activity is localized to the epidermis of newborn foreskin, whic h suggests that telomerase is expressed constitutively by cells in the epidermis. Finding higher levels of telomerase activity in sun-expose d skin compared to nonexposed skin suggests that environmental factors may modulate telomerase activity.