Increased Ammonium Toxicity in Response to Exogenous Glutamine in Metastatic Breast Cancer Cells

Violet A Kiesel; Madeline P Sheeley; Shawn S Donkin; Michael K Wendt; Stephen D Hursting; Dorothy Teegarden

doi:10.3390/metabo12050469

Increased Ammonium Toxicity in Response to Exogenous Glutamine in Metastatic Breast Cancer Cells

Metabolites. 2022 May 23;12(5):469. doi: 10.3390/metabo12050469.

Authors

Violet A Kiesel¹, Madeline P Sheeley¹, Shawn S Donkin², Michael K Wendt^{3

4}, Stephen D Hursting^{5

6

7}, Dorothy Teegarden^{1

4}

Affiliations

¹ Department of Nutrition Science, Purdue University, West Lafayette, IN 47907, USA.
² Department of Animal Science, Purdue University, West Lafayette, IN 47907, USA.
³ Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA.
⁴ The Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.
⁵ Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
⁶ Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
⁷ Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, NC 28081, USA.

Abstract

Several cancers, including breast cancers, show dependence on glutamine metabolism. The purpose of the present study was to determine the mechanistic basis and impact of differential glutamine metabolism in nonmetastatic and metastatic murine mammary cancer cells. Universally labeled ¹³C₅-glutamine metabolic tracing, qRT-PCR, measures of reductive-oxidative balance, and exogenous ammonium chloride treatment were used to assess glutamine reprogramming. Results show that 4 mM media concentration of glutamine, compared with 2 mM, reduced viability only in metastatic cells, and that this decrease in viability was accompanied by increased incorporation of glutamine-derived carbon into the tricarboxylic acid (TCA) cycle. While increased glutamine metabolism in metastatic cells occurred in tandem with a decrease in the reduced/oxidized glutathione ratio, treatment with the antioxidant molecule N-acetylcysteine did not rescue cell viability. However, the viability of metastatic cells was more sensitive to ammonium chloride treatment compared with nonmetastatic cells, suggesting a role of metabolic reprogramming in averting nitrogen cytotoxicity in nonmetastatic cells. Overall, these results demonstrate the ability of nonmetastatic cancer cells to reprogram glutamine metabolism and that this ability may be lost in metastatic cells.

Keywords: ammonium toxicity; breast cancer; glutamine metabolism; metabolic reprogramming; metastasis.

Abstract

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