Autoradiographic Studies of Localization of Tritiated Methyl N-Carbamyl Maleamate in Ehrlich Ascites Tumor Cells.

SummaryThe intraperitoneal injection into mice with Ehrlich ascites tumor of trace amounts of H3-methyl N-carbamyl maleamate, a substance which in larger amounts produces destruction of spindle fibers, resulted in the appearance on autoradiography of grains chiefly in the cytoplasm and only rarely in the nucleus. In a number of instances the grains appeared to be distributed in a perinuclear fashion. Somewhat similar results were obtained when H3-methanol was administered. The administration of cold methyl N-carbamyl maleamate (1 mg) together with the labeled substance resulted in a marked enhancement of the uptake of the labeled material into the cells, while a similar experiment with non-radioactive methyl N-carbamyl maleamate and H3-methanol showed no increase in uptake of isotope by the tumor cells. It was concluded that H3-methyl carbamyl N-maleamate enters the tumor cells as an intact molecule and associates with cytoplasmic components. The relationship of some of these components to spindle fiber s...