AMPK-deficiency forces metformin-challenged cancer cells to switch from carbohydrate metabolism to ketogenesis to support energy metabolism

• Type of Material: Article
• Authors: Flavio R Palma, Northwestern University; Bianca A Ratti, Univ Estadual Maringa; Veronica Paviani, Northwestern University; Diego R Coelho, Northwestern University; Rodrigo Miguel, Northwestern University; Jeanne M Danes, Northwestern University; Sofia Zaichik, University of Illinois at Chicago; Andre L de Abreu, Universidade Estadual de Maringa; Sueli O Silva, Universidade Estadual de Maringa; Yiliang Chen, Medical College of Wisconsin; Roy L Silverstein, Medical College of Wisconsin; Uppal Karan, Emory University; Dean Jones, Emory University; Marcelo G Bonini, Northwestern University
• Language: English
• Date: 2021-07-21
• Publisher: SPRINGERNATURE
• Publication Version: Final Published Version
• Copyright Statement: © 2021, The Author(s), under exclusive licence to Springer Nature Limited
• Final Published Version (URL): http://dx.doi.org/10.1038/s41388-021-01943-x
• Title of Journal or Parent Work: ONCOGENE
• Volume: 40
• Issue: 36
• Start Page: 5455
• End Page: 5467
• Grant/Funding Information: The authors are grateful for funding from the U.S. National Institutes of Health, NIAID R01AI131267 (to M.G.B.); NIEHS R01028149 (to M.G.B.); NCI R01CA216882 (to M.G.B.) and DOD/ARO grant number 72983 (to M.G.B.); and American Heart Association Scientist Development Grant #17SDG33661117 (to Y.C.).
• Keywords: Science & Technology; PATHWAY; Cell Biology; ACTIVATED PROTEIN-KINASE; Biochemistry & Molecular Biology; Oncology; Life Sciences & Biomedicine; Genetics & Heredity

Abstract

Epidemiologic studies in diabetic patients as well as research in model organisms have indicated the potential of metformin as a drug candidate for the treatment of various types of cancer, including breast cancer. To date most of the anti-cancer properties of metformin have, in large part, been attributed either to the inhibition of mitochondrial NADH oxidase complex (Complex I in the electron transport chain) or the activation of AMP-activated kinase (AMPK). However, it is becoming increasingly clear that AMPK activation may be critical to alleviate metabolic and energetic stresses associated with tumor progression suggesting that it may, in fact, attenuate the toxicity of metformin instead of promoting it. Here, we demonstrate that AMPK opposes the detrimental effects of mitochondrial complex I inhibition by enhancing glycolysis at the expense of, and in a manner dependent on, pyruvate availability. We also found that metformin forces cells to rewire their metabolic grid in a manner that depends on AMPK, with AMPK-competent cells upregulating glycolysis and AMPK-deficient cell resorting to ketogenesis. In fact, while the killing effects of metformin were largely rescued by pyruvate in AMPKcompetent cells, AMPK-deficient cells required instead acetoacetate, a product of fatty acid catabolism indicating a switch from sugar to fatty acid metabolism as a central resource for ATP production in these cells. In summary, our results indicate that AMPK activation is not responsible for metformin anticancer activity and may instead alleviate energetic stress by activating glycolysis.