Expression profile of the putative catalytic subunit of the telomerase gene.
Telomerase, a ribonucleoprotein complex, adds hexameric repeats called telomeres to the growing ends of chromosomal DNA. The enzyme telomerase activity is present in a vast majority of tumors but is repressed in most normal tissues. Recently, two groups have reported the molecular cloning of the putative catalytic subunit (hEST2/hTRT) of the telomerase gene. We investigated the expression of this gene in diverse tumor-derived cell lines and tumors as well as in various normal tissues. The expression of hEST2/hTRT was detectable in tumor-derived cell lines, primary breast tumors, pancreatic tumors, and kidney tumors. Furthermore, the expression of hEST2/hTRT was down-regulated in response to a differentiation inducer. However, several normal tissues also expressed varying levels of hEST2/hTRT. Early passage cultures of endothelial fibroblasts and some epithelial cells also expressed the telomerase gene, albeit at low levels. In contrast, the expression of TLP1/TP1, the human homologue of Tetrahymena p80 telomerase subunit, was similar in all of these samples. Our results indicate that the differences in expression of hEST2/hTRT in tumor versus normal cells are relative and are not absolute.
Ramakrishnan
S
S
Roche Research Center, Hoffmann-La Roche, Inc., Nutley, New Jersey 07110, USA.
Eppenberger
U
U
Mueller
H
H
Shinkai
Y
Y
Narayanan
R
R
D001943:Breast Neoplasms / Q000201:enzymology; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D015536:Down-Regulation; D015870:Gene Expression; D018922:HL-60 Cells; D006801:Humans; D009369:Neoplasms / Q000201:enzymology*; D016133:Polymerase Chain Reaction; D019098:Telomerase / Q000235:genetics*; D014018:Tissue Distribution; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D014212:Tretinoin; D019098:Telomerase