Cited by 149Metabolism, Diabetes, and CancerCancer, Hypoxia, and MetabolismPI3K/AKT/mTOR signaling in cancer

Mechanisms by which low glucose enhances the cytotoxicity of metformin to cancer cells both in vitro and in vivo

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Zhuang, Yongxian, Chan, Daniel K., Haugrud, Allison B., Miskimins, W. Keith·2014·PLoS ONE

Abstract

Different cancer cells exhibit altered sensitivity to metformin treatment. Recent studies suggest these findings may be due in part to the common cell culture practice of utilizing high glucose, and when glucose is lowered, metformin becomes increasingly cytotoxic to cancer cells. In low glucose conditions ranging from 0 to 5 mM, metformin was cytotoxic to breast cancer cell lines MCF7, MDAMB231 and SKBR3, and ovarian cancer cell lines OVCAR3, and PA-1. MDAMB231 and SKBR3 were previously shown to be resistant to metformin in normal high glucose medium. When glucose was increased to 10 mM or above, all of these cell lines become less responsive to metformin treatment. Metformin treatment significantly reduced ATP levels in cells incubated in media with low glucose (2.5 mM), high fructose (25 mM) or galactose (25 mM). Reductions in ATP levels were not observed with high glucose (25 mM). This was compensated by enhanced glycolysis through activation of AMPK when oxidative phosphorylation was inhibited by metformin. However, enhanced glycolysis was either diminished or abolished by replacing 25 mM glucose with 2.5 mM glucose, 25 mM fructose or 25 mM galactose. These findings suggest that lowering glucose potentiates metformin induced cell death by reducing metformin stimulated glycolysis. Additionally, under low glucose conditions metformin significantly decreased phosphorylation of AKT and various targets of mTOR, while phospho-AMPK was not significantly altered. Thus inhibition of mTOR signaling appears to be independent of AMPK activation. Further in vivo studies using the 4T1 breast cancer mouse model confirmed that metformin inhibition of tumor growth was enhanced when serum glucose levels were reduced via low carbohydrate ketogenic diets. The data support a model in which metformin treatment of cancer cells in low glucose medium leads to cell death by decreasing ATP production and inhibition of survival signaling pathways. The enhanced cytotoxicity of metformin against cancer cells was observed both in vitro and in vivo.

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  1. [31]Sandulache VC, Ow TJ, Pickering CR, Frederick MJ, Zhou G, et al (2011) Glucose, not glutamine, is the dominant energy source required for proliferation and survival of head and neck squamous carcinoma cells. Cancer 117: 2926– 2938. 21692052 PMC3135768

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Authors
Zhuang, Y., Chan, D. K., Haugrud, A. B., & Miskimins, W. K.
Affiliations
  • Sanford Research (US)
  • University of South Dakota (US)
Corresponding author
Zhuang, Yongxian
Venue
PLoS ONE
Published
2014-09-25
Volume
9
Issue
9
Pages
e108444
ISSN
1932-6203 (ISSN-L)
OpenAlex
W2011662441
Cited by
149
References
42
Citations by year
2026: 7 · 2025: 8 · 2024: 17 · 2023: 14 · 2022: 8 · 2021: 15 · 2020: 16 · 2019: 17 · 2018: 13 · 2017: 13 · 2016: 14 · 2015: 7
FWCI
4.64
Type
journal article
Language
en
Open access
Locations
  • PLoS ONE (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
  • National Institutes of Health
  • National Cancer Institute (R01CA180033)
  • National Institute of General Medical Sciences (5P20GM10358, P20GM103548)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Metabolism, Diabetes, and Cancer
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cancer Research › Cancer, Hypoxia, and Metabolism
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › PI3K/AKT/mTOR signaling in cancer
Keywords
metformin, low glucose, tumor cell killing, breast cancer, ovarian cancer, glycolysis, AMPK, mTOR signaling, Akt phosphorylation, ATP depletion, fructose, galactose, ketogenic diet, tumor growth inhibition, metformin resistance
MeSH terms
Adenosine Triphosphate, Animals, Antineoplastic Agents, Blood Glucose, Cell Survival, Glucose, Glycolysis, Hypoglycemic Agents, Metformin, Neoplasms, Oxidative Phosphorylation, Phosphorylation, Drug Resistance, Neoplasm, Cell Line, Tumor, Proto-Oncogene Proteins c-akt, Mice, AMP-Activated Protein Kinases, Diet, Ketogenic, TOR Serine-Threonine Kinases

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