Telomerase Activity in Acute and Chronic Leukemia Patients Undergoing Chemotherapy

Introduction: Leukemia is a malignant disorder resulting from clonal proliferation of lymphoid or myeloid precursors with arrested maturation. It has been shown recently that telomers and telomerase activity are involved in the control of cell proliferation, regulation of cell senescence in the most somatic cells, and unlimited proliferation capacity of the malignant cells including leukemic cells. Previous studies determined the frequent expression of telomerase activity in most human solid tumors and hematological malignancies, however so far few studies have addressed telomerase activity in both Bone marrow (BM) and peripheral blood (PB) in adult acute and chronic leukemia patients at diagnosis and after chemotherapy.

Materials & Methods: Telomerase activity in adult chronic leukemia patients at diagnosis and after chemotherapy was determined using telomerase PCR-ELISA techniques.. BM and PB samples were obtained from 25 patients without any previous therapy, including 17 patients with acute and 8 patients with chronic leukemia. BM control samples obtained from the ribs of patients with heart diseases during operation. After separation of MNCs from PB and BM, cell extraction was prepared. TRAP-PCR was carried out on all prepared cell lysates and the PCR products were subjected to native PAGE and visualized by silver nitrate staining.

Results: High telomerase activity was detected in MNC¢S from all leukemia patients at diagnosis. This activity in PB and BM of patients was respectively 11.4 and 7 fold higher than those of control group (p=0.001). Telomerase activity in BM MNC’S from leukemic patients was 3 to 4 fold higher than PB MNC’S and 35-fold higher than PB MIN¢S activity in control donors. After chemotherapy and response to treatment, telomerase activity decreased 5 to 10 fold in most patients (p=0.001)

Conclusion: Considering the convenience of PB sampling and several fold increase in telomerase activity of PB samples from leukemia patients compared to control donors, telomerase activity measurement can be suggested as a primitive diagnostic tumor biomarker