Activity and expression of human telomerase in normal and malignant cells in gastric and colon cancer patients.
BACKGROUND
The reactivation of telomerase is believed to play an important role in immortalization and carcinogenesis.


OBJECTIVE
To investigate the expression of three components of the telomerase complex (hTR, hTERT and TP1), along with telomerase activity in malignant and normal cells.


METHODS
Cells were isolated from gastric and colon cancer, and from normal mucosa from the stomach and colon of participating patients. Expression of hTERT, hTR and TP1 has been studied by the reverse transcriptase polymerase chain reaction (PCR) technique. The telomerase repeat amplification protocol and PCR enzyme-linked immunosorbent assay were used for analysis of telomerase activity.


RESULTS
All telomerase components were consistently expressed in colon and gastric cancer cells. Neoplastic RNA produced consistently very strong amplification signals either for hTR, hTERT or TP1. The expression of hTR was observed in RNA isolated from all normal mucosa samples and from peripheral blood lymphocytes. The expression of TP1 and hTERT has been found in the majority of normal cells; however, the amplification signals produced were usually much weaker than in malignant cells. The limiting dilution experiments indicated that the cancer cells have at least 100-fold higher telomerase activity and at least 25-fold higher TP1 and hTERT expression in comparison to normal cells.


CONCLUSIONS
It can be concluded that all the cancer cells tested have higher telomerase expression and activity than normal cells. Therefore, telomerase can be a good cancer marker, provided that quantitative analysis is carried out.
Nowak
Jerzy
J
Institute of Human Genetics, Polish Academy of Sciences, Poznanuú, Poland. nowakjs@man.poznan.pl
Januszkiewicz
Danuta
D
Lewandowski
Krzysztof
K
Nowicka-Kujawska
Karina
K
Pernak
Monika
M
Rembowska
Jolanta
J
Nowak
Tomasz
T
Wysocki
Jacek
J
D002352:Carrier Proteins / Q000378:metabolism; D003110:Colonic Neoplasms / Q000201:enzymology*; D004268:DNA-Binding Proteins; D005753:Gastric Mucosa / Q000201:enzymology; D015870:Gene Expression; D006801:Humans; D007413:Intestinal Mucosa / Q000201:enzymology; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction / Q000379:methods; D012313:RNA; D062085:RNA, Long Noncoding; D012334:RNA, Neoplasm / Q000235:genetics; D022661:RNA, Untranslated / Q000378:metabolism; D016601:RNA-Binding Proteins; D013274:Stomach Neoplasms / Q000201:enzymology*; D019098:Telomerase / Q000235:genetics / Q000378:metabolism*
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D009363:Neoplasm Proteins; D062085:RNA, Long Noncoding; D012334:RNA, Neoplasm; D022661:RNA, Untranslated; D016601:RNA-Binding Proteins; C104342:TEP1 protein, human; C422952:telomerase RNA; D012313:RNA; D019098:Telomerase