Combined action of acivicin and d-galactosamine on pyrimidine nucleotide metabolism in hepatoma cells

Abstract

The glutamine antagonist acivicin, l-(αS,5S)-α- amino-3- chloro-4,5- dihydro-5- isoxazoleacetic acid, strongly reduced CTP and GTP contents in AS-30D rat hepatoma cells in suspension. UTP only dropped to 63% of the respective control after 4hr; however, by combining acivicin with the uridylate-trapping sugar analogue d-galactosamine, a synergistic decrease in UTP contents to 7% of control was induced. Incorporation of 14CO 2 into purine and pyrimidine nucleotides followed by radio-high performance liquid chromatography showed marked inhibition of purine and pyrimidine biosynthesis de novo; the latter was reduced to 35% of control. The inhibitory potency of acivicin on glutamine-dependent carbamoyl-phosphate synthetase and consequently on de novo uracil nucleotide formation was also reflected by the complete suppression of the d-galactosamine-induced rise in total uridylate. Induction of UTP deficiency by interference with the first and rate-limiting step in pyrimidine biosynthesis de novo together with a trapping of uridylate by d-galactosamine may provide a promising approach to the chemotherapy of hepatocellular carcinoma.