Antagonistic effects of 6-mercaptopurine and coenzyme A on mitochondria and mitosis in tissue culture.

The partial mitotic inhibition caused by 6-mercaptopurine in tissue cultures of Crocker mouse sarcoma 180 and embryonic mouse skin is blocked by co-enzyme A. 6-Mercaptopurine and coenzyme A also have opposite effects on mitochondrial morphology. Mitochondria in cells treated with 6-mercaptopurine become thin and fragmented. Coenzyme A blocks this effect, and alone coenzyme A makes for longer and thicker mitochondria. 6-Mercaptopurine inhibits lipogenesis in embryo skin fibroblasts, and this inhibition is partly counteracted by coenzyme A, which by itself makes for a greater accumulation of lipid droplets in the cytoplasm. It is suggested that at least one part of the action by which 6-mercaptopurine decreases mitotic incidence in tissue cultures may be an interference on the part of 6-mercaptopurine, acting as an antimetabolite of coenzyme A, in mitochondrial function related to cell division.