A colchicine-sensitive uptake system in Morris hepatomas.

Abstract

The interference of microtubular disruptors with the uptake of amino acids and other low MW substrates was studied in rat Morris hepatomas, host liver and regenerating liver. Colchicine inhibits amino acid transport (.alpha.-aminoisobutyric acid, L-methionine and L-leucine) in hepatomas by 59-98%; transport in host and regenerating liver is not impeded but increased. In hepatomas, treatment with colchicine reduces the uptake of L-fucose, cytidine, urea and carbonate. Vinblastine, but not lumicolchicine or cytochalasin B, is an effective inhibitor. The inhibition of uptake is not linked to a decrease of cellular ATP and UTP. Apparently the transport of low MW substrates in hepatomas is related to microtubules or other colchicine-binding structures, e.g., of the plasma membrane. This colchicine-sensitive uptake system in hepatomas may be due to the malignant transformation of hepatocytes.