Bcl-2 Protein Level and Telomerase Enzyme Activity In Patients With Acute Leukemias

¹Amina El–Sayed Hussein, ²Nadia A. Sadek, ¹Ghoneim HM, ³Nadia El-Sayed Zaki and ⁴Dekra El-Aghbary

Departments of ¹Immunology and ²Hematology, Medical Research Institute and ³Hematology Unit, ⁴Internal Medicine Department, Faculty of Medicine, Alexandria University, Egypt and ⁴Hematology Department, Sana’a University, Yemen.

The aim of this work was to investigate the linkage between the deregulation of apoptosis and telomerase activity in patients with acute leukemias and evaluate the level of Bcl-2 protein and teleomerase activity as parameters for monitoring the disease state before and after chemotherapy. The study was carried out on 10 patients with acute lymphoplastic leukemia (ALL), 17 patients with acute myeloid leukemia (AML) and 10 healthy age and sex-matched controls. They were subjected to history taking, clinical examination, complete blood picture and bone marrow aspiration with cytochemistry and/or immunophenotyping to confirm diagnosis. Estimation of serum Bcl-2 protein was done by ELISA, while determination of telomerase activity in mononuclear cell extracts was performed by PCR-ELISA. At initial presentation, the Bcl-2 levels were significantly higher in both ALL (P<0.001) and AML (P<0.001) patients compared to the controls. After chemotherapy, the levels were still significantly higher than the prechemotherapy in both groups of patients. Similarly, the telomerase activity, was significantly higher in patients with ALL (P<0.05) and AML (P<0.05) at presentation when compared to the controls. After chemotherapy, statistically significant decrease in the mean telomerase activity was observed in comparison to the pre-therapy mean values in both ALL (P<0.01) and AML (P<0.001) patients. A statistically significant positive correlation (r=0.568, P<0.001) was found between Bcl-2 protein level and telomerase activity before chemotherapy but there was no correlation (r=0.013, P>0.05) between the two parameters post-chemotherapy. It is concluded that telomerase activity and Bcl-2 level are closely linked. It is possible that Bcl-2 modulates telomerase activity in highly replicating cells. Telomerase is a good tumour marker in acute leukemias and is of value in monitoring treatment outcome and disease activity.