Leukemic mitochondria. I. Acute myeloblastic leukemia.

Quantitative and qualitative electron microscopic studies were performed on the mitochondria of leukemic myeloblasts in 3 patients with myeloblastic leukemia and in 3 patients with myelomonoblastic leukemia. In addition, to confirm the presence of virus-like particles within mitochondria and better understand the interaction between the virus and mitochondrion, a rat embryo tissue culture infected with MSV-MLV (Moloney sarcoma virus-Moloney leukemia virus) was selected for detailed electron microscopic examination. Significant quantitative differences between normal and leukemic human mitochondria were not observed. However, qualitative abnormalities were found in the human leukemic mitochondria and in the tissue culture material. These abnormalities included variable forms of the leukemic mitochondria (twisted, tear-drop and irregular shapes), fewer cristae, disrupted mitochondria with virus-like particles, smaller granules in greater abundance, mitochondrial DNA, and contact between the mitochondrion and the nucleus. The tissue culture material revealed similar changes, but showed more virus particles which were located outside the cells, in intracytoplasmic sacs and within the mitochondria. In addition two striking features were observed in the tissue culture material not seen in the human material: a) Budding from the outer mitochondrial membrane into the mitochondrial matrix and b) virus particles attached to the cristae. Since mitochondria are important organelles in the glycolytic-oxidative phosphorylation pathways, perhaps all of us engaged in cancer research should take a closer look at the Warburg effect and carefully consider extranuclear factors operating in oncogenesis.