Rearrangements of minisatellites in the human telomerase reverse transcriptase gene are not correlated with its expression in colon carcinomas

Telomerase activation is crucial in human carcinogenesis. The limiting comp onent of telomerase, the catalytic subunit (hTERT), is undetectable in norm al somatic cells but present in most tumor cells, including the earliest st ages of colon carcinoma, The mechanisms involved in the differential expres sion in normal and tumor cells are not understood. In normal cells hTERT ex pression is shut down by a repressor, and upregulation could be a consequen ce of cis-acting changes in the hTERT gene, making it resistant to repressi on, We have identified a polymorphic and a monomorphic minisatellite in the second intron of the hTERT gene, and polymorphic one in intron 6, The poly morphic minisatellite in intron 2 contains binding sites for c-Myc, which h as been shown to upregulate hTERT transcription, Screening colon carcinoma DNAs for rearrangements of hTERT minisatellites we detected no changes in 3 3 samples from tumors, most of which express hTERT, This indicates that siz e rearrangements of the hTERT minisatellites are not required for telomeras e expression in colon carcinomas, Minor changes and one LOH were seen in fi ve tumors.