Activity and expression of human telomerase in normal and malignant cells in gastric and colon cancer patients.

J Nowak, MD, D Januszkiewicz,MD, K Lewandowski, MD, K Nowicka-Kujawska, M Pernak, J Rembowska, W Cichy, MD

Institute of Human Genetics Polish Academy of Sciences,Institute of Pediatrics Academy of Medical Sciences, Department of Medical Diagnostics and Regional Hospital Poznan, Poland

Reactivation of telomerase is believed to play an important role in immortalization and carcinogenesis. Design: To investigate the expression of three components of telomerase complex (hTR, hTERT, TP1) along with telomerase activity in malignant and normal cells. Methods: Cells isolated from gastric and colon cancer, and normal mucosa from stomach and colon of corresponding patients. Expression of hTERT, hTR and TP1 has been studied by RT-PCR technique. Telomerase repeat amplification protocol-TRAP and PCR-ELISA was used for analysis telomerase activity. Results: The all telomerase components were consistently expressed in colon and gastric cancer cells, except those samples where RNA was most likely degraded. In contrast to hTR, the amplification signals for hTERT and TP1 from neoplastic RNA were heterogeneous (strong and week signals). In the majority of normal mucosa, expression of TP1 and hTERT has been found. The limiting dilution experiments indicated that the cancer cells have at least 100-fold higher telomerase activity in comparison to normal cells. Conclusions: It can be concluded that all cancer cells tested have higher telomerase expression and activity, as compared to normal cells. Therefore telomerase can be a good cancer marker provided quantitative analysis is carried out.

KEY WORDS: colon and gastric cancer, human telomerase reverse transcriptase, human telomerase RNA, reverse transcriptase polymerase chain reaction, telomerase associated protein.

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Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Diagnostic Markers.