ASS1 (D4O4B) XP^® Rabbit mAb #70720

Argininosuccinate synthetase (ASS1) catalyzes the formation of argininosuccinate from citrulline and aspartate, the rate-limiting step in the urea cycle that is responsible for the synthesis of arginine and the clearance of nitrogenous waste (1). ASS1 is ubiquitously and differentially expressed in different cell types and tissues. Mutations in ASS1 are associated with citrullinemia type I, an autosomal recessive disease characterized primarily by elevated serum and urine citrulline levels in human patients (2, 3).

Loss of ASS1 expression is one of the common metabolic alterations observed in many cancers, and it is a prognostic biomarker of reduced metastasis-free survival. ASS1 deficiency leads to the dependence of extracellular arginine for survival, proliferation, and cell growth. Ariginine starvation induces autophagy and apoptosis in ASS1 deficient cells and this has been exploited as a therapeutic intervention for the tumors with loss of ASS1 expression (4, 5). Pegylated arginine deiminase (ADI-PEG20), an enzyme that degrades arginine into citrulline, causes significant growth inhibition in tumors that have lost ASS1 expression, such as hepatocellular carcinoma, breast cancer, and sarcoma (6-8).