SPECIFIC ASSOCIATION OF HUMAN TELOMERASE ACTIVITY WITH IMMORTAL CELLSAND CANCER

Synthesis of DNA at chromosome ends by telomerase may be necessary for indefinite proliferation of human cells. A highly sensitive assay for measuring telomerase activity was developed. In cultured cells repres enting 18 different human tissues, 98 of 100 immortal and none of 22 m ortal populations were positive for telomerase. Similarly, 90 of 101 b iopsies representing 12 human tumor types and none of 50 normal somati c tissues were positive. Normal ovaries and testes were positive, but benign tumors such as fibroids were negative. Thus, telomerase appears to be stringently repressed in normal human somatic tissues but react ivated in cancer, where immortal cells are likely required to maintain tumor growth.