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International Journal of Cell Biology
Volume 2011, Article ID 470597, 13 pages
http://dx.doi.org/10.1155/2011/470597
Review Article

When Cells Suffocate: Autophagy in Cancer and Immune Cells under Low Oxygen

1Deeley Research Centre, BC Cancer Agency, 2410 Lee Avenue, Victoria, BC, Canada V8R 6V5
2Department of Biochemistry and Microbiology, University of Victoria, Petch Bldg Ring Road, Victoria, BC, Canada V8P 5C2

Received 28 July 2011; Accepted 14 August 2011

Academic Editor: R. Seger

Copyright © 2011 Katrin Schlie et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Hypoxia is a signature feature of growing tumors. This cellular state creates an inhospitable condition that impedes the growth and function of all cells within the immediate and surrounding tumor microenvironment. To adapt to hypoxia, cells activate autophagy and undergo a metabolic shift increasing the cellular dependency on anaerobic metabolism. Autophagy upregulation in cancer cells liberates nutrients, decreases the buildup of reactive oxygen species, and aids in the clearance of misfolded proteins. Together, these features impart a survival advantage for cancer cells in the tumor microenvironment. This observation has led to intense research efforts focused on developing autophagy-modulating drugs for cancer patient treatment. However, other cells that infiltrate the tumor environment such as immune cells also encounter hypoxia likely resulting in hypoxia-induced autophagy. In light of the fact that autophagy is crucial for immune cell proliferation as well as their effector functions such as antigen presentation and T cell-mediated killing of tumor cells, anticancer treatment strategies based on autophagy modulation will need to consider the impact of autophagy on the immune system.