TY - JOUR
T1 - Glutamine synthetase is necessary for sarcoma adaptation to glutamine deprivation and tumor growth
AU - Issaq, Sameer H.
AU - Mendoza, Arnulfo
AU - Fox, Stephen D.
AU - Helman, Lee J.
N1 - Funding Information:
This work was supported by grants from the Intramural Research Program of the National Institutes of Health, the National Cancer Institute, and the Center for Cancer Research. The authors thank members of the Helman lab for support and thoughtful discussions, Quynh Le and Ria Kidner for assistance with immunoblotting, Thorkell Andresson for assistance with amino acid analysis, and Maria Figueroa and Elena Kuznetsova for assistance with in vivo studies.
Funding Information:
1Pediatric Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA. 2Protein Characterization Laboratory, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD, USA. 3Present address: Departments of Pediatrics and Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA. 4Present address: Children’s Center for Cancer and Blood Diseases, Children’s Hospital Los Angeles, Los Angeles, CA, USA
Publisher Copyright:
© 2019, The Author(s).
PY - 2019/3/1
Y1 - 2019/3/1
N2 - Despite a growing body of knowledge about the genomic landscape and molecular pathogenesis of sarcomas, translation of basic discoveries into targeted therapies and significant clinical gains has remained elusive. Renewed interest in altered metabolic properties of cancer cells has led to an exploration of targeting metabolic dependencies as a novel therapeutic strategy. In this study, we have characterized the dependency of human pediatric sarcoma cells on key metabolic substrates and identified a mechanism of adaptation to metabolic stress by examining proliferation and bioenergetic properties of rhabdomyosarcoma and Ewing sarcoma cells under varying concentrations of glucose and glutamine. While all cell lines tested were completely growth-inhibited by lack of glucose, cells adapted to glutamine deprivation, and restored proliferation following an initial period of reduced growth. We show that expression of glutamine synthetase (GS), the enzyme responsible for de novo glutamine synthesis, increased during glutamine deprivation, and that pharmacological or shRNA-mediated GS inhibition abolished proliferation of glutamine-deprived cells, while having no effect on cells grown under normal culture conditions. Moreover, the GS substrates and glutamine precursors glutamate and ammonia restored proliferation of glutamine-deprived cells in a GS-dependent manner, further emphasizing the necessity of GS for adaptation to glutamine stress. Furthermore, pharmacological and shRNA-mediated GS inhibition significantly reduced orthotopic xenograft tumor growth. We also show that glutamine supports sarcoma nucleotide biosynthesis and optimal mitochondrial bioenergetics. Our findings demonstrate that GS mediates proliferation of glutamine-deprived pediatric sarcomas, and suggest that targeting metabolic dependencies of sarcomas should be further investigated as a potential therapeutic strategy.
AB - Despite a growing body of knowledge about the genomic landscape and molecular pathogenesis of sarcomas, translation of basic discoveries into targeted therapies and significant clinical gains has remained elusive. Renewed interest in altered metabolic properties of cancer cells has led to an exploration of targeting metabolic dependencies as a novel therapeutic strategy. In this study, we have characterized the dependency of human pediatric sarcoma cells on key metabolic substrates and identified a mechanism of adaptation to metabolic stress by examining proliferation and bioenergetic properties of rhabdomyosarcoma and Ewing sarcoma cells under varying concentrations of glucose and glutamine. While all cell lines tested were completely growth-inhibited by lack of glucose, cells adapted to glutamine deprivation, and restored proliferation following an initial period of reduced growth. We show that expression of glutamine synthetase (GS), the enzyme responsible for de novo glutamine synthesis, increased during glutamine deprivation, and that pharmacological or shRNA-mediated GS inhibition abolished proliferation of glutamine-deprived cells, while having no effect on cells grown under normal culture conditions. Moreover, the GS substrates and glutamine precursors glutamate and ammonia restored proliferation of glutamine-deprived cells in a GS-dependent manner, further emphasizing the necessity of GS for adaptation to glutamine stress. Furthermore, pharmacological and shRNA-mediated GS inhibition significantly reduced orthotopic xenograft tumor growth. We also show that glutamine supports sarcoma nucleotide biosynthesis and optimal mitochondrial bioenergetics. Our findings demonstrate that GS mediates proliferation of glutamine-deprived pediatric sarcomas, and suggest that targeting metabolic dependencies of sarcomas should be further investigated as a potential therapeutic strategy.
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U2 - 10.1038/s41389-019-0129-z
DO - 10.1038/s41389-019-0129-z
M3 - Article
C2 - 30808861
AN - SCOPUS:85062068597
SN - 2157-9024
VL - 8
JO - Oncogenesis
JF - Oncogenesis
IS - 3
M1 - 20
ER -