Frequent amplification of the Telomerase Reverse Transcriptase gene in human tumors

Activation of telomerase is a crucial step during cellular immortalization and malignant transformation of human cells and requires the induction of t he catalytic component, human telomerase reverse transcriptase (hTERT), enc oded by the hTERT gene. It is poorly understood how the hTERT gene is activ ated in human cancer cells. In the present study, we examined the hTERT gen e copy number in human ranter cell lints and in primary tumor tissues. Ampl ification of the hTERT gene was observed in 8 of 26 (31%) tumor cell lines and 17 of 58 (30%) primary tumors examined (8 of 21 lung tumors, 3 of 10 ce rvical tumors, 5 of 19 breast carcinomas, and 1 of 8 neuroblastomas), In ad dition, 13 of 26 (50%) cell lines and 13 of 58 (22%) primary tumors display ed gain of hTERT gene copies with 3-4 copies/cell. The present findings imp ly that the hTERT Locus may be a frequent target for amplification during t umorigenesis and that this genetic event probably contributes to the dysreg ulation of telomerase activity occurring in human tumors.