Pyrazofurin, a pyrimidine nucleoside analogue with antineoplastic activity, inhibits cell proliferation and DNA synthesis in cells by inhibiting uridine 5'-phosphate (UMP) synthase[1]. Pyrazofurin is an active, sensitive orotate-phosphoribosyltransferase inhibitor with IC50s between 0.06-0.37 µM in the three squamous cell carcinoma (SCC) cell lines Hep-2, HNSCC-14B and HNSCC-14C[2].
[1]. Ringer DP, et al. Alteration in de novo pyrimidine biosynthesis during uridine reversal of pyrazofurin-inhibited DNA synthesis. Neuropsychopharmacology. J Biochem Toxicol. 1991 Spring;6(1):19-27. [2]. Peters GJ, et al. Antipyrimidine effects of five different pyrimidine de novo synthesis inhibitors in three head and neck cancer cell lines. Nucleosides Nucleotides Nucleic Acids. 2018;37(6):329-339.