Analysis of telomerase activity and expression and telomere length in leukemic cells

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

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

Telomerase is thought to play important role in cell immortalization and carcinogenesis. Telomerase is a ribonucleoprotein complex which catalyses the extension of telomeric DNA. The aim of the work was to investigate the expression of three components of telomerase complex (hTR, hTERT, TP1) along with telomerase activity and telomere length in leukemic cells. Cells have been isolated from peripheral blood and bone marrow of children with acute lymphoblastic (ALL) and nonlymphoblastic (ANLL) leukemia. Controls included normal peripheral blood lymphocytes and K562 cells. Expression of hTERT, hTR and TP1 has been studied by RT-PCR technique. Telomerase repeat amplification protocol-TRAP and PCR-ELISA (Roche) was used for analysis of telomerase activity. For studying telomere length Telo TAGGGTelomere length assay (Roche) has been used. Expression of three components of telomerase as well as telomerase activity has been found in all leukemic cells. Chemiluminescent detection of terminal restriction fragments (TRF) from DNA isolated from ALL cells showed variable patterns expressing considerable heterogeneity of telomere length. The ALL cells appeared to have both long and short telomere lengths, in contrast to normal lymphocytes, which produced limited pattern of TRF (meaning short telomeres). The ANLL cells produced predominantly short telomere' pattern despite high telomerase activity and expression. It can be concluded that high telomerase activity and expression in leukemic cells is not always correlated with long telomeres (TRF pattern).

KEY WORDS: acute lymphoblastic leukemia, acute non-lymphoblastic leukemia, human telomerase reverse transcriptase, human telomerase RNA, reverse transcriptase polymerase chain reaction, telomerase associated protein, telomere length.

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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 Molecular Pathology.