Telomeres and Telomerase in Pediatric Patients with T-Cell Acute Lymphoblastic Leukemia (T-ALL).

Shortened telomeres and elevated levels of telomerase activity are apparently characteristic features of hematologic neoplasias such as high-grade lymphomas and relapsing leukemia. Thus, their measurement might be useful for monitoring disease conditions or predicting clinical outcome. In order to investigate the potential of telomere length (TRF) and telomerase activity (TA) as prognostic indicator in pediatric patients with T-cell acute lymphoblastic leukemia (T-ALL) we analyzed TRF and TA in samples from 20 patients (age range 2–17.5 years). In addition, as TA is limited by the expression of the telomerase catalytic subunit (hTERT) we analyzed hTERT expression. We found that TRF varied widely (3.5 – 8.1 kb; mean ± SD: 6.4 +/− 1.3 kb) in leukemic cells and was significantly shorter (p<0.0001) than that of age-matched controls (8.3 ± 0.4 kb; n=19). Elevated levels of TA were present in 95% of the leukemic samples. Furthermore, expression of hTERT demonstrated a wide interindividual variability (range 141–424,000 normalized units). A statistically significant association between TA and hTERT expression was not found and TRF, TA and hTERT expression was not associated with the clinical outcome in pediatric T-ALL, thereby limiting their prognostic significance.