In vivo monitoring of therapy-induced apoptotic process in patients with chronic lymphocytic leukemia and acute non-lymphoblastic leukemia

Programmed cell death proteins and chronic leukemia

Apoptosis or programmed cell death is a genetically regulated process of cellular suicide. Apoptosis has been implicated in a wide range of pathological conditions, and mutations in apoptotic genes play important roles in the process of malignant transformation. Chronic leukemia represents a neoplastic disorder caused primarily by defective programmed cell death, as opposed to increased cell proliferation. This paper presents the main results of our ten-year research on the apoptosis of leukemia cells. The research included the morphological aspects of the process, the effect of antineoplastic agents on the induction of apoptosis in leukemia cells and expression analysis of the proteins involved in programmed cell death. Special attention was paid to the expression and interaction of the Bcl-2 family of proteins in leukemia cells. The ultimate aim of the study of apoptosis of leukemic cells is the discovery of new biological agents that might be used in the treatment of chronic leukemia.

The ultrastructural investigation of mitochondria in B-CLL cells during apoptosis

BACKGROUND: B-chronic lymphocytic leukemia (B-CLL) is an example of human malignancy caused by alternations in the pathways of apoptosis. Mitochondria play a critical role in the regulation of this process. The B-CLL cells dying in apoptosis showed typical morphological characteristics: the reduction of the nuclear volume is accompanied with the reduction of the cytoplasmatic volume, while many of organelles remain intact. The aim of our study was ultrastructural investigation of mitochondrial morphology in apoptotic B- CLL cells. METHODS: Our study included peripheral blood samples from 32 B-CLL patients. The samples were fixed in 4% glutar-aldehyde buffered in 0.1 cacodylate buffer and postfixed in 1% osmium tetroxide in the same buffer. The specimens were dehydrated in a graded series of alcohol and embedded in EPON 812. The ultra-thin sections were stained with uranyl acetate and lead citrate. Ultrastructural analysis of sections was performed on Philips electron microscope 208S at 80 kV. RESULTS: The most frequent mitochondrial abnormalities in apoptotic B-CLL cells were a reduction of size with a hyperdensity of their matrix (mitochondrial pyknosis), or markedly swollen mitochondria with peripherally placed, disorientated, and disintegrated cristae. In some apoptotic cells, we also detected close association of mitochondria with loops of rough endoplasmatic reticulum. CONCLUSION: The results of our study showed the numerous of mitochondria damages in B-CLL cells during apoptotic process. The correlation between ultrastructural damage and functional activity of mitochondria in apoptotic B-CLL cells is still not clear and requires further investigation.