Small‐Molecule Allosteric Inhibitors of Human Aspartate Transcarbamoylase Suppress Proliferation of Bone Osteosarcoma Epithelial Cells

• Published in: ChemMedChem 2024-07, Vol.19 (13), p.e202300688-n/a
• Main Authors: Wang, Chao, Zhang, Bidong, Cong, Yingying, Du, Xiaochen, Chen, Siyao, Visser, Lidia, Ruiz‐Moreno, Angel J., Zhang, Lili, Reggiori, Fulvio, Dömling, Alexander S. S., Groves, Matthew R.
• Format: Article
• Language: English
• Subjects: Allosteric properties; Allosteric Regulation - drug effects; Antineoplastic Agents - chemical synthesis; Antineoplastic Agents - chemistry; Antineoplastic Agents - pharmacology; Aspartate Carbamoyltransferase - antagonists & inhibitors; Aspartate Carbamoyltransferase - chemistry; Aspartate Carbamoyltransferase - metabolism; Aspartate Transcarbamoylase; Biosynthesis; Bone cancer; Bone Neoplasms - drug therapy; Bone Neoplasms - metabolism; Bone Neoplasms - pathology; Cancer; Cancer therapies; Cell cycle; Cell Line, Tumor; Cell proliferation; Cell Proliferation - drug effects; Clinical trials; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; E coli; Enzyme Inhibitors - chemical synthesis; Enzyme Inhibitors - chemistry; Enzyme Inhibitors - pharmacology; Enzyme kinetics; Epithelial cells; Epithelial Cells - drug effects; Epithelial Cells - metabolism; Epithelium; Eukaryotes; G1 phase; Homology; Humans; Inhibitors; Malaria; Molecular Docking; Molecular Docking Simulation; Molecular Structure; Non-competitive Inhibition; Osteoblastoma; Osteosarcoma; Osteosarcoma - drug therapy; Osteosarcoma - metabolism; Osteosarcoma - pathology; Parasites; Plant cells; Pyrimidine Biosynthesis; Sarcoma; Small Molecule Libraries - chemical synthesis; Small Molecule Libraries - chemistry; Small Molecule Libraries - pharmacology; Structure-Activity Relationship
• ISSN: 1860-7179; 1860-7187; 1860-7187
• DOI: 10.1002/cmdc.202300688

Aspartate transcarbamoylase (ATC) is the first committed step in de novo pyrimidine biosynthesis in eukaryotes and plants. A potent transition state analog of human ATCase (PALA) has previously been assessed in clinical trials for the treatment of cancer, but was ultimately unsuccessful. Additionally, inhibition of this pathway has been proposed to be a target to suppress cell proliferation in E. coli, the malarial parasite and tuberculosis. In this manuscript we screened a 70‐member library of ATC inhibitors developed against the malarial and tubercular ATCases for inhibitors of the human ATC. Four compounds showed low nanomolar inhibition (IC50 30–120 nM) in an in vitro activity assay. These compounds significantly outperform PALA, which has a triphasic inhibition response under identical conditions, in which significant activity remains at PALA concentrations above 10 μM. Evidence for a druggable allosteric pocket in human ATC is provided by both in vitro enzyme kinetic, homology modeling and in silico docking. These compounds also suppress the proliferation of U2OS osteoblastoma cells by promoting cell cycle arrest in G0/G1 phase. This report provides the first evidence for an allosteric pocket in human ATC, which greatly enhances its druggability and demonstrates the potential of this series in cancer therapy. A potent non‐competitive family of inhibitors of ATC, an enzyme responsible for the first committed step of de novo pyrimidine biosynthesis, are described. Kinetic assays demonstrate significantly improved efficacy against the current standard in ATC inhibition (PALA). Molecular modeling supports a substrate non‐competitive mode of action and cell‐based assays demonstrate their potential in an osteosarcoma epithelial model.