ABSTRACT
Cancer cells preferentially use glycolysis rather than oxidative phosphorylation for their rapid growth. They consume large amount of glucose to produce lactate even when oxygen is abundant, a phenomenon known as the Warburg effect. This metabolic change originates from a shift in the expression of alternative spliced isoforms of the glycolytic enzyme pyruvate kinase (PK), from PKM1 to PKM2. While PKM1 is constitutively active, PKM2 is switched from an inactive dimer form to an active tetramer form by small molecule activators. The prevalence of PKM2 in cancer cells relative to the prevalence of PKM1 in many normal cells, suggests a therapeutic strategy whereby activation of PKM2 may counter the abnormal cellular metabolism in cancer cells, and consequently decreased cellular proliferation. Herein we describe the discovery and optimization of a series of PKM2 activators derived from the 2-((2,3-dihydrobenzo[b][1,4] dioxin-6-yl)thio)-1-(2-methyl-1-(methylsulfonyl)indolin-5-yl) ethanone scaffold. The synthesis, SAR analysis, enzyme active site docking, enzymatic reaction kinetics, selectivity and pharmaceutical properties are discussed.
Subject(s)
Carrier Proteins/agonists , Enzyme Activation/drug effects , Indoles/chemistry , Indoles/pharmacology , Membrane Proteins/agonists , Neoplasm Proteins/agonists , Neoplasms/enzymology , Thyroid Hormones/agonists , Caco-2 Cells , Carrier Proteins/metabolism , Humans , Membrane Proteins/metabolism , Molecular Docking Simulation , Neoplasm Proteins/metabolism , Neoplasms/drug therapy , Protein Isoforms/antagonists & inhibitors , Protein Isoforms/metabolism , Protein Multimerization/drug effects , Pyruvate Kinase/metabolism , Sulfinic Acids/chemistry , Sulfinic Acids/pharmacology , Thyroid Hormones/metabolism , Thyroid Hormone-Binding ProteinsABSTRACT
A transition-state analogue inhibitor that covalently reversibly binds to an enzyme formally consists of two parts: the chemical site, CS and the recognition site, RS. We have experimentally and theoretically demonstrated that the trend of binding affinity in a series of isoselective inhibitors (with identical RS and different CS fragments) depends mainly on their CS fragments. Isoselective inhibitors have the same affinity trend toward different enzymes of the same family with a common catalytic mechanism. Thus, very good correlation between experimentally determined and theoretically calculated Ki values was demonstrated. A practical outcome is the application of the described method as a tool for an expert analysis in virtual screening of inhibitor libraries and in the design of new enzyme inhibitors.
