Differential expression of apoptosis related genes in the peripheral blood mononuclear cells of acute lymphoblastic/lymphocytic leukemia (ALL) patients

Apoptosis is the cell’s intrinsic death program which plays a crucial role in the regulation of many normal physiological processes in the body’s tissues. In leukemia patients, the extent of cancer cell susceptibility to apoptosis is correlated with clinical responses to chemotherapy and disease prognosis. The aim of this study was evaluation of the expression of apoptosis related genes in the peripheral blood mononuclear cells (PBMCs) of acute lymphoblastic/lymphocytic leukemia (ALL) patients. Peripheral blood samples were obtained from 20 patients with ALL and 20 healthy individuals. PBMCs were isolated using Ficoll-Paque density gradient centrifugation method. After RNA extraction and cDNA synthesis, gene expression levels of apoptosis related genes including caspase-3, 8, 9, BAX, and BAK genes were measured by real-time RT-PCR technique. Gene expression analysis showed that the expression levels of the initiator caspases-8 and -9 are increased in the PBMCs of adult ALL patients when compared with that in PBMCs of healthy individuals. Increased gene expression levels of the proapoptotic protein BAK was also detected in PBMCs of ALL patients. In contrast, decreased expression levels of the proapoptotic BAX and the executioner caspase-3 were observed in the PBMCs of ALL patients. These results suggest that the expression of genes involved in both extrinsic and intrinsic signaling pathways of apoptosis are induced in PBMCs of ALL patients while the gene expression of other proapoptotic molecule, BAK, and the executioner caspase-3 diminished in PBMCs cells of ALL patients. This findings indicate that resistance to apoptosis may be one of the hallmarks of ALL cells.