ABSTRACT
Mammalian pyruvate kinase catalyzes the final step of glycolysis, and its M2 isoform (PKM2) is widely expressed in proliferative tissues. Mutations in PKM2 are found in some human cancers; however, the effects of these mutations on enzyme activity and regulation are unknown. Here, we characterized five cancer-associated PKM2 mutations, occurring at various locations on the enzyme, with respect to substrate kinetics and activation by the allosteric activator fructose-1,6-bisphosphate (FBP). The mutants exhibit reduced maximal velocity, reduced substrate affinity, and/or altered activation by FBP. The kinetic parameters of five additional PKM2 mutants that have been used to study enzyme function or regulation also demonstrate the deleterious effects of mutations on PKM2 function. Our findings indicate that PKM2 is sensitive to many amino acid changes and support the hypothesis that decreased PKM2 activity is selected for in rapidly proliferating cells.
Subject(s)
Carrier Proteins/genetics , Membrane Proteins/genetics , Mutation , Neoplasms/genetics , Thyroid Hormones/genetics , Carrier Proteins/chemistry , Carrier Proteins/metabolism , Humans , Kinetics , Membrane Proteins/chemistry , Membrane Proteins/metabolism , Neoplasms/enzymology , Protein Multimerization/genetics , Protein Structure, Quaternary , Thyroid Hormones/chemistry , Thyroid Hormones/metabolism , Thyroid Hormone-Binding ProteinsABSTRACT
Mitochondrial apoptosis can be effectively targeted in lymphoid malignancies with the FDA-approved B cell lymphoma 2 (BCL-2) inhibitor venetoclax, but resistance to this agent is emerging. We show that venetoclax resistance in chronic lymphocytic leukemia is associated with complex clonal shifts. To identify determinants of resistance, we conducted parallel genome-scale screens of the BCL-2-driven OCI-Ly1 lymphoma cell line after venetoclax exposure along with integrated expression profiling and functional characterization of drug-resistant and engineered cell lines. We identified regulators of lymphoid transcription and cellular energy metabolism as drivers of venetoclax resistance in addition to the known involvement by BCL-2 family members, which were confirmed in patient samples. Our data support the implementation of combinatorial therapy with metabolic modulators to address venetoclax resistance.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/pharmacology , Bridged Bicyclo Compounds, Heterocyclic/pharmacology , Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy , Mitochondria/pathology , Proto-Oncogene Proteins c-bcl-2/antagonists & inhibitors , Sulfonamides/pharmacology , Adult , Aged , Aged, 80 and over , Animals , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Apoptosis/drug effects , Apoptosis/genetics , Bridged Bicyclo Compounds, Heterocyclic/therapeutic use , Cell Line, Tumor , Clonal Evolution/drug effects , Disease Progression , Drug Resistance, Neoplasm/drug effects , Drug Resistance, Neoplasm/genetics , Energy Metabolism/drug effects , Energy Metabolism/genetics , Female , Gene Expression Regulation, Neoplastic , Humans , Leukemia, Lymphocytic, Chronic, B-Cell/pathology , Male , Mice , Middle Aged , Mitochondria/drug effects , Myeloid Cell Leukemia Sequence 1 Protein/metabolism , Oxidative Phosphorylation/drug effects , Proto-Oncogene Proteins c-bcl-2/metabolism , Sulfonamides/therapeutic use , Treatment Outcome , Xenograft Model Antitumor AssaysABSTRACT
The M2 isoform of pyruvate kinase is expressed preferentially in cancer cells over other pyruvate kinase isoforms. PKM2 is unique in its ability to be regulated allosterically by nutrients and growth signaling pathways, allowing cells to adapt their metabolic program to match physiological needs in different environments. Here, we discuss the role of pyruvate kinase M2 in glioma and in cancer metabolism.
