Site of action of two novel pyrimidine biosynthesis inhibitors accurately predicted by the COMPARE program

• Published in: Biochemical pharmacology 1995-03, Vol.49 (7), p.947-954
• Main Authors: Cleaveland, Emily S., Monks, Anne, Vaigro-Wolff, Anne, Zaharevitz, Daniel W., Paull, Kenneth, Ardalan, Katherine, Cooney, David A., Ford, Harry
• Format: Article
• Language: English
• Subjects: Aminobiphenyl Compounds - pharmacology; antimetabolites; Antineoplastic agents; Antineoplastic Agents - pharmacology; Binding Sites; Biological and medical sciences; Biphenyl Compounds - pharmacology; BNID; brequinar; Cell Division - drug effects; Chemotherapy; cytidine; DCL; Humans; Imidazoles - pharmacology; Medical sciences; MOLT-4 lymphoblasts; Naphthoquinones - pharmacology; Oxidoreductases - antagonists & inhibitors; Oxidoreductases Acting on CH-CH Group Donors; Pharmacology. Drug treatments; Pyrimidines - biosynthesis; Software; Structure-Activity Relationship; Tumor Cells, Cultured; uridine
• ISSN: 0006-2952; 1873-2968
• DOI: 10.1016/0006-2952(95)00009-O

The computer algorithm COMPARE provides information regarding the biological mechanism of action of a compound. In this study, excellent correlations were obtained for 2,2′-[3,3′-dimethoxy[1,1′-biphenyl]-4,4′-diyl)diimino]bis-benzoic acid (redoxal) and 1-( p-bromophenyl)-2-methyl-1 H-naphth[2,3- d]imidazole-4,9-dione (BNID) and two well-studied dihydroorotate dehydrogenase (DHOD) inhibitors, dichloroallyl lawsone and brequinar, in terms of antiproliferative activity against tumor cell lines in vitro. When redoxal and BNID were incubated with MOLT-4 cells for 72 hr, 50% growth inhibition was achieved at 0.7 and 3.5 μM, respectively. After 24 hr of incubation, pyrimidine triphosphate pools were shown to be decreased by 50% by redoxal (1 μM) and BNID (0.25 μM). Addition of either uridine (50 μM) or cytidine (100 μM) antagonized the cellular cytotoxicity caused by either drug; uridine corrected the UTP and CTP deficit, whereas cytidine corrected only the CTP deficit. Exposure of MOLT-4 cells to a 1 μM concentration of either drug for 18 hr followed by a 1-hr exposure to [ 14C]bicarbonate showed a 97% decrease of incorporation of [ 14C] into pyrimidine triphosphates accompanied by a 91- and 82-fold increase in radioactive incorporation into l-dihydroorotate and N-carbamyl-L-aspartate, respectively. By direct exposure of DHOD prepared from MOLT-4 cell mitochondria to a range of concentrations of the two drugs, apparent K i values of 0.33 μM (redoxal) and 0.53 μM (BNID) were determined. These data provide direct evidence for inhibition of DHOD by redoxal and BNID in MOLT-4 lymphoblasts.