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Science (New York, N.Y.) Jan 2011Adenosine monophosphate-activated protein kinase (AMPK) is a conserved sensor of intracellular energy activated in response to low nutrient availability and...
Adenosine monophosphate-activated protein kinase (AMPK) is a conserved sensor of intracellular energy activated in response to low nutrient availability and environmental stress. In a screen for conserved substrates of AMPK, we identified ULK1 and ULK2, mammalian orthologs of the yeast protein kinase Atg1, which is required for autophagy. Genetic analysis of AMPK or ULK1 in mammalian liver and Caenorhabditis elegans revealed a requirement for these kinases in autophagy. In mammals, loss of AMPK or ULK1 resulted in aberrant accumulation of the autophagy adaptor p62 and defective mitophagy. Reconstitution of ULK1-deficient cells with a mutant ULK1 that cannot be phosphorylated by AMPK revealed that such phosphorylation is required for mitochondrial homeostasis and cell survival during starvation. These findings uncover a conserved biochemical mechanism coupling nutrient status with autophagy and cell survival.
Topics: AMP-Activated Protein Kinases; Adaptor Proteins, Signal Transducing; Animals; Autophagy; Autophagy-Related Protein-1 Homolog; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Cell Line; Cell Line, Tumor; Cell Survival; Energy Metabolism; Hepatocytes; Humans; Insulin; Intracellular Signaling Peptides and Proteins; Liver; Metformin; Mice; Mitochondria, Liver; Phenformin; Phosphorylation; Protein Serine-Threonine Kinases; Sequestosome-1 Protein; Signal Transduction; Transcription Factor TFIIH; Transcription Factors
PubMed: 21205641
DOI: 10.1126/science.1196371 -
Trends in Cancer Aug 2021Biguanides are a class of antidiabetic drugs that includes phenformin and metformin; however, the former was withdrawn from approval in many countries due to its... (Review)
Review
Biguanides are a class of antidiabetic drugs that includes phenformin and metformin; however, the former was withdrawn from approval in many countries due to its toxicity. Findings from retrospective epidemiological studies in diabetic populations and preclinical laboratory models have demonstrated that biguanides possess antitumor activities that suggest their repurposing for cancer prevention and treatment. However, a better understanding of how these biguanides behave as antitumor agents is needed to guide their improved applications in cancer therapy, spurring increased interest in their pharmacology. Here, we present evidence for proposed mechanisms of action related to their antitumor activity, including their effects on central carbon metabolism in cancer cells and immune-modulating activity, and then review progress on biguanide repurposing in cancer therapeutics and the possible re-evaluation of phenformin as a cancer therapeutic agent.
Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Biguanides; Cell Line, Tumor; Clinical Trials as Topic; Disease Models, Animal; Drug Repositioning; Drug Synergism; Humans; Immune Checkpoint Inhibitors; Neoplasms; Oxidative Phosphorylation; Protein Kinase Inhibitors; Tumor Microenvironment; Xenograft Model Antitumor Assays
PubMed: 33865798
DOI: 10.1016/j.trecan.2021.03.001 -
Nature Cancer Nov 2022The pancreatic tumor microenvironment drives deregulated nutrient availability. Accordingly, pancreatic cancer cells require metabolic adaptations to survive and...
The pancreatic tumor microenvironment drives deregulated nutrient availability. Accordingly, pancreatic cancer cells require metabolic adaptations to survive and proliferate. Pancreatic cancer subtypes have been characterized by transcriptional and functional differences, with subtypes reported to exist within the same tumor. However, it remains unclear if this diversity extends to metabolic programming. Here, using metabolomic profiling and functional interrogation of metabolic dependencies, we identify two distinct metabolic subclasses among neoplastic populations within individual human and mouse tumors. Furthermore, these populations are poised for metabolic cross-talk, and in examining this, we find an unexpected role for asparagine supporting proliferation during limited respiration. Constitutive GCN2 activation permits ATF4 signaling in one subtype, driving excess asparagine production. Asparagine release provides resistance during impaired respiration, enabling symbiosis. Functionally, availability of exogenous asparagine during limited respiration indirectly supports maintenance of aspartate pools, a rate-limiting biosynthetic precursor. Conversely, depletion of extracellular asparagine with PEG-asparaginase sensitizes tumors to mitochondrial targeting with phenformin.
Topics: Animals; Mice; Humans; Pancreatic Neoplasms; Asparagine; Adenocarcinoma; Symbiosis; Tumor Microenvironment
PubMed: 36411320
DOI: 10.1038/s43018-022-00463-1 -
Cell Jul 2015The mitochondrial electron transport chain (ETC) enables many metabolic processes, but why its inhibition suppresses cell proliferation is unclear. It is also not well...
The mitochondrial electron transport chain (ETC) enables many metabolic processes, but why its inhibition suppresses cell proliferation is unclear. It is also not well understood why pyruvate supplementation allows cells lacking ETC function to proliferate. We used a CRISPR-based genetic screen to identify genes whose loss sensitizes human cells to phenformin, a complex I inhibitor. The screen yielded GOT1, the cytosolic aspartate aminotransferase, loss of which kills cells upon ETC inhibition. GOT1 normally consumes aspartate to transfer electrons into mitochondria, but, upon ETC inhibition, it reverses to generate aspartate in the cytosol, which partially compensates for the loss of mitochondrial aspartate synthesis. Pyruvate stimulates aspartate synthesis in a GOT1-dependent fashion, which is required for pyruvate to rescue proliferation of cells with ETC dysfunction. Aspartate supplementation or overexpression of an aspartate transporter allows cells without ETC activity to proliferate. Thus, enabling aspartate synthesis is an essential role of the ETC in cell proliferation.
Topics: Aspartate Aminotransferase, Cytoplasmic; Aspartic Acid; Cell Proliferation; DNA, Mitochondrial; Electron Transport; Humans; Jurkat Cells; Mitochondria; Mutation; Phenformin; Pyruvic Acid
PubMed: 26232224
DOI: 10.1016/j.cell.2015.07.016 -
Proceedings of the National Academy of... Mar 2021-amplified neuroblastoma is a lethal subset of pediatric cancer. MYCN drives numerous effects in the cell, including metabolic changes that are critical for oncogenesis....
-amplified neuroblastoma is a lethal subset of pediatric cancer. MYCN drives numerous effects in the cell, including metabolic changes that are critical for oncogenesis. The understanding that both compensatory pathways and intrinsic redundancy in cell systems exists implies that the use of combination therapies for effective and durable responses is necessary. Additionally, the most effective targeted therapies exploit an "Achilles' heel" and are tailored to the genetics of the cancer under study. We performed an unbiased screen on select metabolic targeted therapy combinations and correlated sensitivity with over 20 subsets of cancer. We found that -amplified neuroblastoma is hypersensitive to the combination of an inhibitor of the lactate transporter MCT1, AZD3965, and complex I of the mitochondrion, phenformin. Our data demonstrate that MCT4 is highly correlated with resistance to the combination in the screen and lowly expressed in -amplified neuroblastoma. Low MCT4 combines with high expression of the MCT2 and MCT1 chaperone CD147 in -amplified neuroblastoma, altogether conferring sensitivity to the AZD3965 and phenformin combination. The result is simultaneous disruption of glycolysis and oxidative phosphorylation, resulting in dramatic disruption of adenosine triphosphate (ATP) production, endoplasmic reticulum stress, and cell death. In mouse models of -amplified neuroblastoma, the combination was tolerable at concentrations where it shrank tumors and did not increase white-blood-cell toxicity compared to single drugs. Therefore, we demonstrate that a metabolic combination screen can identify vulnerabilities in subsets of cancer and put forth a metabolic combination therapy tailored for -amplified neuroblastoma that demonstrates efficacy and tolerability in vivo.
Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Basigin; Cell Line, Tumor; Cell Proliferation; Electron Transport Complex I; Gene Amplification; Humans; Mice; Mitochondria; Monocarboxylic Acid Transporters; N-Myc Proto-Oncogene Protein; Neuroblastoma; Phenformin; Pyrimidinones; Symporters; Thiophenes; Xenograft Model Antitumor Assays
PubMed: 33762304
DOI: 10.1073/pnas.2009620118 -
Oncotarget Jul 2017Phenformin's recently demonstrated efficacy in melanoma and Gleevec's demonstrated anti-proliferative action in chronic myeloid leukemia may lie within these drugs'... (Review)
Review
Phenformin's recently demonstrated efficacy in melanoma and Gleevec's demonstrated anti-proliferative action in chronic myeloid leukemia may lie within these drugs' significant pharmacokinetics, pharmacodynamics and structural homologies, which are reviewed herein. Gleevec's success in turning a fatal leukemia into a manageable chronic disease has been trumpeted in medical, economic, political and social circles because it is considered the first successful targeted therapy. Investments have been immense in omics analyses and while in some cases they greatly helped the management of patients, in others targeted therapies failed to achieve clinically stable recurrence-free disease course or to substantially extend survival. Nevertheless protein kinase controlling approaches have persisted despite early warnings that the targeted genomics narrative is overblown. Experimental and clinical observations with Phenformin suggest an alternative explanation for Gleevec's mode of action. Using 13C-guided precise flux measurements, a comparative multiple cell line study demonstrated the drug's downstream impact on submolecular fatty acid processing metabolic events that occurred independent of Gleevec's molecular target. Clinical observations that hyperlipidemia and diabetes are both reversed in mice and in patients taking Gleevec support the drugs' primary metabolic targets by biguanides and statins. This is evident by structural data demonstrating that Gleevec shows pyridine- and phenyl-guanidine homology with Phenformin and identical phenylcarbamoyl structural and ligand binding homology with Lipitor. The misunderstood mechanism of action of Gleevec is emblematic of the pervasive flawed reasoning that genomic analysis will lead to targeted, personalized diagnosis and therapy. The alternative perspective for Gleevec's mode of action may turn oncotargets towards metabolic channel reaction architectures in leukemia and melanoma, as well as in other cancers.
Topics: Atorvastatin; Humans; Imatinib Mesylate; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Melanoma; Metformin; Phenformin
PubMed: 28418852
DOI: 10.18632/oncotarget.16238 -
British Medical Journal Feb 1972
Review
Topics: Adolescent; Adult; Appetite Depressants; Child; Diagnosis; Diet, Reducing; Fasting; Female; Humans; Male; Metformin; Methylcellulose; Middle Aged; Obesity; Phenformin
PubMed: 4552434
DOI: 10.1136/bmj.1.5799.560 -
Biomedicine & Pharmacotherapy =... Mar 2022Cancer is one of the main causes of human mortality and brain tumors, including invasive pituitary adenomas, medulloblastomas and glioblastomas are common brain... (Review)
Review
Cancer is one of the main causes of human mortality and brain tumors, including invasive pituitary adenomas, medulloblastomas and glioblastomas are common brain malignancies with poor prognosis. Therefore, the development of innovative management strategies for refractory cancers and brain tumors is important. In states of mitochondrial dysfunction - commonly encountered in malignant cells - cells mostly shift to anaerobic glycolysis by increasing the expression of LDHA (Lactate Dehydrogenase-A) gene. Oxamate, an isosteric form of pyruvate, blocks LDHA activity by competing with pyruvate. By blocking LDHA, it inhibits protumorigenic cascades and also induces ROS (reactive oxygen species)-induced mitochondrial apoptosis of cancer cells. In preclinical studies, oxamate blocked the growth of invasive pituitary adenomas, medulloblastomas and glioblastomas. Oxamate also increases temozolomide and radiotherapy sensitivity of glioblastomas. Oxamate is highly polar, which may preclude its clinical utilization due to low penetrance through cell membranes. However, this obstacle could be overcome with nanoliposomes. Moreover, different oxamate analogs were developed which inhibit LDHC4, an enzyme also involved in cancer progression and germ cell physiology. Lastly, phenformin, an antidiabetic agent, exerts anticancer effects via complex I inhibition in the mitochondria and leading the overproduction of ROS. Oxamate combination with phenformin reduces the lactic acidosis-causing side effect of phenformin while inducing synergistic anticancer efficacy. In sum, oxamate as a single agent and more efficiently with phenformin has high potential to slow the progression of aggressive cancers with special emphasis to brain tumors.
Topics: Animals; Brain Neoplasms; Cell Line, Tumor; Glycolysis; Humans; L-Lactate Dehydrogenase; Mitochondria; Neoplasms; Oxamic Acid; Phenformin; Radiation Tolerance; Reactive Oxygen Species; Temozolomide
PubMed: 35124385
DOI: 10.1016/j.biopha.2022.112686 -
Proceedings of the National Academy of... Mar 2022SignificanceMetformin is the most commonly prescribed drug for the treatment of type 2 diabetes mellitus, yet the mechanism by which it lowers plasma glucose...
SignificanceMetformin is the most commonly prescribed drug for the treatment of type 2 diabetes mellitus, yet the mechanism by which it lowers plasma glucose concentrations has remained elusive. Most studies to date have attributed metformin's glucose-lowering effects to inhibition of complex I activity. Contrary to this hypothesis, we show that inhibition of complex I activity in vitro and in vivo does not reduce plasma glucose concentrations or inhibit hepatic gluconeogenesis. We go on to show that metformin, and the related guanides/biguanides, phenformin and galegine, inhibit complex IV activity at clinically relevant concentrations, which, in turn, results in inhibition of glycerol-3-phosphate dehydrogenase activity, increased cytosolic redox, and selective inhibition of glycerol-derived hepatic gluconeogenesis both in vitro and in vivo.
Topics: Animals; Electron Transport Complex IV; Gluconeogenesis; Glucose; Glycerol; Glycerolphosphate Dehydrogenase; Guanidines; Hypoglycemic Agents; Liver; Metformin; Oxidation-Reduction; Phenformin; Pyridines
PubMed: 35238637
DOI: 10.1073/pnas.2122287119 -
FEBS Open Bio May 2021Inhibitors of ataxia-telangiectasia mutated (ATM), such as KU-55933 (Ku), represent a promising class of novel anticancer drugs. In addition, the biguanide derivative...
Inhibitors of ataxia-telangiectasia mutated (ATM), such as KU-55933 (Ku), represent a promising class of novel anticancer drugs. In addition, the biguanide derivative phenformin exhibits antitumor activity superior to that of the AMPK activator metformin. Herein, we assessed the potential combinatorial therapeutic efficacy of phenformin and Ku when used to inhibit the growth of liver cancer cells, and we assessed the mechanisms underlying such efficacy. The Hep-G2 and SMMC-7721 liver cancer cell lines were treated with phenformin and Ku either alone or in combination, after which the impact of these drugs on cellular proliferation was assessed via 3-(4,5-dimethylthiazol) 2, 5-diphenyltetrazolium and colony formation assays, whereas Transwell assays were used to gauge cell migratory activity. The potential synergy between these two drugs was assessed using the CompuSyn software, while flow cytometry was employed to evaluate cellular apoptosis. In addition, western blotting was utilized to measure p-ATM, p-AMPK, p-mTOR, and p-p70s6k expression, while mitochondrial functionality was monitored via morphological analyses, JC-1 staining, and measurements of ATP levels. Phenformin and Ku synergistically impacted the proliferation, migration, and apoptotic death of liver cancer cells. Together, these compounds were able to enhance AMPK phosphorylation while inhibiting the phosphorylation of mTOR and p70s6k. These data also revealed that phenformin and Ku induced mitochondrial dysfunction as evidenced by impaired ATP synthesis, mitochondrial membrane potential, and abnormal mitochondrial morphology. These findings suggest that combination treatment with phenformin and Ku may be an effective approach to treating liver cancer via damaging mitochondria within these tumor cells.
Topics: AMP-Activated Protein Kinases; Apoptosis; Ataxia Telangiectasia; Ataxia Telangiectasia Mutated Proteins; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Movement; Cell Proliferation; China; Drug Synergism; Drug Therapy, Combination; Humans; Liver Neoplasms; Mitochondria; Morpholines; Phenformin; Phosphorylation; Pyrones; Ribosomal Protein S6 Kinases, 70-kDa; TOR Serine-Threonine Kinases
PubMed: 33742560
DOI: 10.1002/2211-5463.13152