Volume 2 Supplement 1

Metabolism, Diet and Disease 2014: Cancer and metabolism

Open Access

Inhibition of glutamine uptake regulates mTORC1, glutamine metabolism and cell growth in prostate cancer

  • Qian Wang1, 2,
  • Rae-Anne Hardie1, 2,
  • Seher Balaban3,
  • Mark Schreuder3,
  • Andrew Hoy3, 4,
  • Michelle van Geldermalsen1, 2,
  • Ladan Fazli5,
  • Rajini Nagarajah1,
  • Charles Bailey2, 6,
  • John Rasko6, 7 and
  • Jeff Holst1, 2
Cancer & Metabolism20142(Suppl 1):P27

https://doi.org/10.1186/2049-3002-2-S1-P27

Published: 28 May 2014

Background

Amino acids such as glutamine are important for tumor cell growth, survival and metabolism. There is renewed interest in glutamine metabolism due to the importance of reductive carboxylation in cancer. The amino acid transporter ASCT2 (SLC1A5) mediates uptake of glutamine in cancer cells. We have recently reported that ASCT2 expression is significantly upregulated in melanoma, and ASCT2 inhibition significantly decreases glutamine uptake, cell growth, cell cycle and mTORC1 pathway activation [1]. We have previously shown that ASCT2 expression is regulated by the androgen receptor in prostate cancer [2], and in this current study we further examine ASCT2 expression levels in prostate cancer. Our specific aim was to determine the impact of inhibiting ASCT2-mediated glutamine uptake and metabolism on cell growth.

Materials and methods

We have assessed the role of ASCT2 in prostate cancer using: (1) tissue microarray analysis of ASCT2 protein expression in patients before and after neoadjuvant hormone therapy, (2) cell lines (LNCaP and PC-3) and (3) xenograft (PC-3) models in vivo. Glutamine uptake, cell growth, cell cycle, mTORC1 pathway and glutamine metabolism pathways were assessed using a variety of ASCT2 inhibitors and shRNA mediated ASCT2 knockdown.

Results

ASCT2 is highly expressed in primary prostate cancer, but levels decrease after neoadjuvant hormone therapy, before increasing again in recurrent disease. Inhibition of ASCT2 function by benzylserine led to decreases in glutamine uptake, glutamine metabolism (oxygen consumption rate, glutamine oxidation and lipogenesis), cell cycle progression, mTORC1 pathway activation and cell growth. These data were confirmed after shRNA-mediated ASCT2 knockdown in vitro. Furthermore, shRNA knockdown in PC-3 cell xenografts led to a significant reduction in tumor growth in vivo.

Conclusions

ASCT2-mediated glutamine uptake is essential for multiple pathways including glutamine metabolism and mTORC1 signaling, thereby regulating cellular energy, protein synthesis and cell growth. As such, ASCT2 is a putative therapeutic target in prostate cancer.

Authors’ Affiliations

(1)
Origins of Cancer Laboratory, Centenary Institute
(2)
Sydney Medical School, University of Sydney
(3)
Discipline of Physiology, Bosch Institute, University of Sydney
(4)
Boden Institute of Obesity, Nutrition, Exercise & Eating Disorders, University of Sydney
(5)
Department of Urologic Sciences, University of British Columbia
(6)
Gene and Stem Cell Therapy Program, Centenary Institute
(7)
Cell and Molecular Therapies, Royal Prince Alfred Hospital

References

  1. Wang Q, Beaumont KA, Otte NJ, Font J, Bailey CG, van Geldermalsen M, Sharp DM, Tiffen JC, Ryan RM, Jormakka M, Haass NK, Rasko JEJ, Holst J: Targeting glutamine transport to suppress melanoma cell growth. Int J Cancer. 2014, Epub 17 FebGoogle Scholar
  2. Wang Q, Tiffen J, Bailey CG, Lehman ML, Ritchie W, Fazli L, Metierre C, Feng Y, Li E, Gleave M, Buchanan G, Nelson CC, Rasko JEJ, Holst J: Targeting amino acid transport in metastatic castration-resistant prostate cancer: Effects on cell cycle, cell growth and tumor development. J Natl Cancer Inst. 2013, 105: 1463-1473. 10.1093/jnci/djt241.View ArticlePubMedGoogle Scholar

Copyright

© Wang et al; licensee BioMed Central Ltd. 2014

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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