ABSTRACT
Chemistry has been developed to specifically functionalize two structurally similar classes of indole-based MK2 inhibitors at positions prompted by a combination of X-ray crystallographic and computer assisted drug design. A gain in molecular potency was obtained by introducing aminomethyl groups to the lactam rings of 6-arylcarbamoyl-tetrahydro-beta-carbolinone and 6-arylcarbamoyl-dihydropyrazino[1,2-a]indolone MK2 inhibitors. In addition, improvements in molecular potency were achieved by expansion of the lactam from a 6- to 7-membered ring leading to 7-arylcarbamoyl-tetrahydro-[1,4]diazepino[1,2-a]indolones.
Subject(s)
Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Indoles/chemical synthesis , Indoles/pharmacology , Intracellular Signaling Peptides and Proteins/antagonists & inhibitors , Protein Serine-Threonine Kinases/antagonists & inhibitors , Animals , Crystallography, X-Ray , Drug Design , Indoles/chemistry , Intracellular Signaling Peptides and Proteins/metabolism , Mice , Models, Molecular , Molecular Structure , Protein Serine-Threonine Kinases/metabolism , Structure-Activity RelationshipABSTRACT
We have previously shown that heat shock protein (Hsp) 27 or its upstream activator p38 mitogen-activated protein kinase (MAPK) confers resistance to bortezomib and dexamethasone (Dex) in multiple myeloma (MM) cells. This study examined anti-MM activity of a novel p38 MAPK inhibitor, BIRB 796, alone and in combination with conventional and novel therapeutic agents. BIRB 796 blocked baseline and bortezomib-triggered upregulation of p38 MAPK and Hsp27 phosphorylation, thereby enhancing cytotoxicity and caspase activation. The Hsp90 inhibitor 17-allylamino-17-demethoxy-geldanamycin (17-AAG) upregulated protein expression and phosphorylation of Hsp27; conversely, BIRB 796 inhibited this phosphorylation and enhanced 17-AAG-induced cytotoxicity. Importantly, BIRB 796 inhibited Hsp27 phosphorylation induced by 17-AAG plus bortezomib, thereby enhancing cytotoxicity. In bone marrow stromal cells (BMSC), BIRB 796 inhibited phosphorylation of p38 MAPK and secretion of interleukin-6 (IL-6) and vascular endothelial growth factor triggered by either tumour necrosis factor-alpha or tumour growth factor-beta1. BIRB 796 also inhibited IL-6 secretion induced in BMSCs by adherence to MM cells, thereby inhibiting tumour cell proliferation. These studies therefore suggest that BIRB 796 overcomes drug-resistance in the BM microenvironment, providing the framework for clinical trials of a p38 MAPK inhibitor, alone and in combination with bortezomib, Hsp90 inhibitor, or Dex, to improve patient outcome in MM.
Subject(s)
Drug Resistance, Neoplasm/drug effects , Multiple Myeloma/drug therapy , Naphthalenes/therapeutic use , Protein Kinase Inhibitors/therapeutic use , Protein Serine-Threonine Kinases/antagonists & inhibitors , Pyrazoles/therapeutic use , Signal Transduction/drug effects , Antineoplastic Agents, Hormonal/therapeutic use , Apoptosis/drug effects , Benzoquinones/therapeutic use , Boronic Acids/therapeutic use , Bortezomib , Cell Adhesion/drug effects , Cell Line, Tumor , Cell Proliferation/drug effects , Coculture Techniques , Cytotoxicity Tests, Immunologic , Dexamethasone/therapeutic use , HSP90 Heat-Shock Proteins/antagonists & inhibitors , HSP90 Heat-Shock Proteins/metabolism , Humans , Immunoblotting/methods , Interleukin-6/metabolism , Intracellular Signaling Peptides and Proteins , Lactams, Macrocyclic/therapeutic use , Multiple Myeloma/metabolism , Multiple Myeloma/pathology , Naphthalenes/pharmacology , Phosphorylation , Protein Kinase Inhibitors/pharmacology , Protein Serine-Threonine Kinases/metabolism , Pyrazines/therapeutic use , Pyrazoles/pharmacology , Stem Cells , Transforming Growth Factor beta/pharmacology , Tumor Necrosis Factor-alpha/pharmacology , Vascular Endothelial Growth Factor A/metabolism , p38 Mitogen-Activated Protein Kinases/antagonists & inhibitors , p38 Mitogen-Activated Protein Kinases/metabolismABSTRACT
We report on a series of N-pyrazole, N'-aryl ureas and their mode of binding to p38 mitogen activated protein kinase. Importantly, a key binding domain that is distinct from the adenosine 5'-triphoshate (ATP) binding site is exposed when the conserved activation loop, consisting in part of Asp168-Phe169-Gly170, adopts a conformation permitting lipophilic and hydrogen bonding interactions between this class of inhibitors and the protein. We describe the correlation of the structure-activity relationships and crystallographic structures of these inhibitors with p38. In addition, we incorporated another binding pharmacophore that forms a hydrogen bond at the ATP binding site. This modification affords significant improvements in binding, cellular, and in vivo potencies resulting in the selection of 45 (BIRB 796) as a clinical candidate for the treatment of inflammatory diseases.
