ABSTRACT
Inhibition of murine double minute 2 (MDM2)-p53 protein-protein interaction with small molecules has been shown to reactivate p53 and inhibit tumor growth. Here, we describe rational, structure-guided, design of novel isoindolinone-based MDM2 inhibitors. MDM2 X-ray crystallography, quantum mechanics ligand-based design, and metabolite identification all contributed toward the discovery of potent in vitro and in vivo inhibitors of the MDM2-p53 interaction with representative compounds inducing cytostasis in an SJSA-1 osteosarcoma xenograft model following once-daily oral administration.
Subject(s)
Antineoplastic Agents/pharmacology , Isoindoles/pharmacology , Osteosarcoma/drug therapy , Protein Multimerization/drug effects , Proto-Oncogene Proteins c-mdm2/metabolism , Tumor Suppressor Protein p53/metabolism , Animals , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/metabolism , Bone Neoplasms/drug therapy , Cell Line, Tumor , Cell Proliferation/drug effects , Crystallography, X-Ray , Drug Stability , Female , Humans , Isoindoles/chemical synthesis , Isoindoles/metabolism , Macaca fascicularis , Male , Mice, Inbred BALB C , Mice, Nude , Microsomes, Liver/metabolism , Molecular Structure , Protein Binding , Structure-Activity Relationship , Xenograft Model Antitumor AssaysABSTRACT
Extracellular regulated kinase 5 (ERK5) signalling has been implicated in driving a number of cellular phenotypes including endothelial cell angiogenesis and tumour cell motility. Novel ERK5 inhibitors were identified using high throughput screening, with a series of pyrrole-2-carboxamides substituted at the 4-position with an aroyl group being found to exhibit IC50 values in the micromolar range, but having no selectivity against p38α MAP kinase. Truncation of the N-substituent marginally enhanced potency (â¼3-fold) against ERK5, but importantly attenuated inhibition of p38α. Systematic variation of the substituents on the aroyl group led to the selective inhibitor 4-(2-bromo-6-fluorobenzoyl)-N-(pyridin-3-yl)-1H-pyrrole-2-carboxamide (IC50 0.82⯵M for ERK5; IC50â¯>â¯120⯵M for p38α). The crystal structure (PDB 5O7I) of this compound in complex with ERK5 has been solved. This compound was orally bioavailable and inhibited bFGF-driven Matrigel plug angiogenesis and tumour xenograft growth. The selective ERK5 inhibitor described herein provides a lead for further development into a tool compound for more extensive studies seeking to examine the role of ERK5 signalling in cancer and other diseases.
Subject(s)
Antineoplastic Agents/pharmacology , Mitogen-Activated Protein Kinase 14/antagonists & inhibitors , Mitogen-Activated Protein Kinase 7/antagonists & inhibitors , Nuclear Proteins/antagonists & inhibitors , Protein Kinase Inhibitors/pharmacology , Transcription Factors/antagonists & inhibitors , Administration, Oral , Animals , Antineoplastic Agents/administration & dosage , Antineoplastic Agents/chemistry , Biological Availability , Cell Cycle Proteins , Cell Line, Tumor , Cell Proliferation/drug effects , Dose-Response Relationship, Drug , Drug Screening Assays, Antitumor , Female , Humans , Mice , Mice, Nude , Mitogen-Activated Protein Kinase 14/metabolism , Mitogen-Activated Protein Kinase 7/metabolism , Molecular Structure , Neoplasms, Experimental/drug therapy , Neoplasms, Experimental/metabolism , Neoplasms, Experimental/pathology , Nuclear Proteins/metabolism , Protein Kinase Inhibitors/administration & dosage , Protein Kinase Inhibitors/chemistry , Structure-Activity Relationship , Transcription Factors/metabolismABSTRACT
The extracellular-related kinase 5 (ERK5) is a promising target for cancer therapy. A high-throughput screen was developed for ERK5, based on the IMAP FP progressive binding system, and used to identify hits from a library of 57â¯617 compounds. Four distinct chemical series were evident within the screening hits. Resynthesis and reassay of the hits demonstrated that one series did not return active compounds, whereas three series returned active hits. Structure-activity studies demonstrated that the 4-benzoylpyrrole-2-carboxamide pharmacophore had excellent potential for further development. The minimum kinase binding pharmacophore was identified, and key examples demonstrated good selectivity for ERK5 over p38α kinase.
