ABSTRACT
TASIN (Truncated APC-Selective Inhibitors) compounds are selectively toxic to colorectal cancer cells with APC mutations, although their mechanism of action remains unknown. Here, we found that TASINs inhibit three enzymes in the postsqualene cholesterol biosynthetic pathway including EBP, DHCR7, and DHCR24. Even though all three of these enzymes are required for cholesterol biosynthesis, only inhibition of the most upstream enzyme, EBP, led to cancer cell death via depletion of downstream sterols, an observation that was confirmed by genetic silencing of EBP. Pharmacologic inhibition or genetic silencing of either DHCR7 or DHCR24 had no impact on cell viability. By using photoaffinity probes to generate a relationship between chemical structure and probe competition, we identified compounds that selectively inhibit either EBP or DHCR7. These studies identify EBP, but not downstream enzymes in the cholesterol biosynthetic pathway, as a target in APC mutant colorectal cancer and also have implications for the clinical development of highly selective EBP inhibitors.
Subject(s)
Antineoplastic Agents/pharmacology , Colorectal Neoplasms/drug therapy , Enzyme Inhibitors/pharmacology , Steroid Isomerases/antagonists & inhibitors , Adenomatous Polyposis Coli Protein/genetics , Antineoplastic Agents/chemistry , Biosynthetic Pathways/drug effects , Cholesterol/metabolism , Colorectal Neoplasms/genetics , Colorectal Neoplasms/metabolism , Drug Discovery , Enzyme Inhibitors/chemistry , HCT116 Cells , Humans , Mutation , Nerve Tissue Proteins/antagonists & inhibitors , Nerve Tissue Proteins/metabolism , Oxidoreductases Acting on CH-CH Group Donors/antagonists & inhibitors , Oxidoreductases Acting on CH-CH Group Donors/metabolism , Steroid Isomerases/metabolismABSTRACT
Selective toxicity among cancer cells of the same lineage is a hallmark of targeted therapies. As such, identifying compounds that impair proliferation of a subset of non-small-cell lung cancer (NSCLC) cell lines represents one strategy to discover new drugs for lung cancer. Previously, phenotypic screens of 202â¯103 compounds led to the identification of 208 selective NSCLC toxins ( McMillan , E. A. , Cell , 2018 , 173 , 864 ). The mechanism of action for the majority of these compounds remains unknown. Here, we discovered the target for a series of quinazoline diones (QDC) that demonstrate selective toxicity among 96 NSCLC lines. Using photoreactive probes, we found that the QDC binds to both mitochondrial complex I of the electron transport chain and hydroxyacyl CoA dehydrogenase subunit alpha (HADHA), which catalyzes long-chain fatty acid oxidation. Inhibition of complex I is the on-target activity for QDC, while binding to HADHA is off-target. The sensitivity profile of the QDC across NSCLC lines correlated with the sensitivity profiles of six additional structurally distinct compounds. The antiproliferative activity of these compounds is also the consequence of binding to mitochondrial complex I, reflecting significant structural diversity among complex I inhibitors. Small molecules targeting complex I are currently in clinical development for the treatment of cancer. Our results highlight complex I as a target in NSCLC and report structurally diverse scaffolds that inhibit complex I.
Subject(s)
Antineoplastic Agents/chemistry , Carcinoma, Non-Small-Cell Lung/diet therapy , Electron Transport Complex I/antagonists & inhibitors , Enzyme Inhibitors/chemistry , Lung Neoplasms/diet therapy , Quinazolinones/chemistry , 3-Hydroxyacyl CoA Dehydrogenases/metabolism , Antineoplastic Agents/pharmacology , Cell Line, Tumor , Cell Proliferation/drug effects , Drug Screening Assays, Antitumor , Enzyme Inhibitors/pharmacology , Fatty Acids/metabolism , Gene Knockout Techniques , Humans , Mitochondrial Trifunctional Protein, alpha Subunit/genetics , Mitochondrial Trifunctional Protein, alpha Subunit/metabolism , Molecular Structure , Molecular Targeted Therapy , Oxidation-Reduction , Oxygen Consumption , Protein Binding , Protein Conformation , Proteomics , Quinazolinones/pharmacology , Structure-Activity Relationship , Substrate SpecificityABSTRACT
Metabolic remodeling is now widely regarded as a hallmark of cancer, but it is not clear whether individual metabolic strategies are frequently exploited by many tumours. Here we compare messenger RNA profiles of 1,454 metabolic enzymes across 1,981 tumours spanning 19 cancer types to identify enzymes that are consistently differentially expressed. Our meta-analysis recovers established targets of some of the most widely used chemotherapeutics, including dihydrofolate reductase, thymidylate synthase and ribonucleotide reductase, while also spotlighting new enzymes, such as the mitochondrial proline biosynthetic enzyme PYCR1. The highest scoring pathway is mitochondrial one-carbon metabolism and is centred on MTHFD2. MTHFD2 RNA and protein are markedly elevated in many cancers and correlated with poor survival in breast cancer. MTHFD2 is expressed in the developing embryo, but is absent in most healthy adult tissues, even those that are proliferating. Our study highlights the importance of mitochondrial compartmentalization of one-carbon metabolism in cancer and raises important therapeutic hypotheses.
Subject(s)
Aminohydrolases/genetics , Folic Acid/metabolism , Metabolic Networks and Pathways/genetics , Methylenetetrahydrofolate Dehydrogenase (NADP)/genetics , Mitochondria/metabolism , Multienzyme Complexes/genetics , Neoplasms/enzymology , Neoplasms/genetics , Aminohydrolases/metabolism , Cell Death , Cell Line, Transformed , Cell Proliferation , Gene Expression Regulation, Neoplastic , Humans , Methylenetetrahydrofolate Dehydrogenase (NADP)/metabolism , Multienzyme Complexes/metabolism , RNA Interference , RNA, Messenger/genetics , RNA, Messenger/metabolismABSTRACT
Metabolic reprogramming has been proposed to be a hallmark of cancer, yet a systematic characterization of the metabolic pathways active in transformed cells is currently lacking. Using mass spectrometry, we measured the consumption and release (CORE) profiles of 219 metabolites from media across the NCI-60 cancer cell lines, and integrated these data with a preexisting atlas of gene expression. This analysis identified glycine consumption and expression of the mitochondrial glycine biosynthetic pathway as strongly correlated with rates of proliferation across cancer cells. Antagonizing glycine uptake and its mitochondrial biosynthesis preferentially impaired rapidly proliferating cells. Moreover, higher expression of this pathway was associated with greater mortality in breast cancer patients. Increased reliance on glycine may represent a metabolic vulnerability for selectively targeting rapid cancer cell proliferation.
