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The effects of hypoxia on Natural Killer cells: linking hypoxia inducible factor-1 alpha and metabolism to the anti-tumor response

Cluff, Emily Rose (2021) The effects of hypoxia on Natural Killer cells: linking hypoxia inducible factor-1 alpha and metabolism to the anti-tumor response. Masters thesis, Northern Arizona University.

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Abstract

Natural Killer (NK) Cells play an integral role in the anti-tumor immune response by recognizing and inducing apoptosis of tumor cells and producing cytokines. The tumor microenvironment (TME) surrounding solid tumors has been characterized as a hypoxic (<1% O2) area. Cellular adaptive responses to hypoxia are mediated by, the master regulator of hypoxia, hypoxia-inducible factor-1a (HIF-1a). However, the effects of hypoxia on NK cell function have been inconclusive. Further, the mechanisms involved in the upregulation of HIF-1a in NK cells has not been described. The studies detailed in this thesis investigate the mechanisms involved in the upregulation of HIF-1a. We demonstrate IL-2 mediated signaling through the PI3K/mTOR pathway is critical for upregulation HIF-1a protein. The proteasomal degradation inhibitor, MG132, revealed that HIF-1a protein is made under normoxia (21% O2) in IL-2 stimulated NK cells but is readily degraded. Other proinflammatory molecules such as IL-12 and IL-18 were able to upregulate HIF-1a protein as well. Freshly isolated human NK cells isolated from the peripheral blood were unable to upregulate HIF-1a in hypoxia, however, once expanded NK cells were able to stabilize HIF-1a. Interestingly, we observed hypoxia enhanced cell killing against the colorectal adenocarcinoma cell line DLD-1 and production of IFN-γ in the NKL cell line. However, freshly isolated PBMC NK cells showed impaired killing after hypoxic exposure. Expansion of PBMC NK cells not only increased cytotoxicity, but restored NK cell killing in hypoxia. Both glucose availability and glycolysis were shown to play a role in regulating HIF-1α protein expression in IL-2 stimulated NKL cells under hypoxia. Further, NKL cells upregulated HIF-1α target genes involved in skewing the metabolic needs of NKL cells away from oxidative phosphorylation and to glycolysis under hypoxia.

Item Type: Thesis (Masters)
Publisher’s Statement: © Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author.
Keywords: Cancer ; HIF-1α; Hypoxia; Natural Killer Cells; NKL cells; Xcelligence
Subjects: R Medicine > RC Internal medicine > RC0254 Neoplasms. Tumors. Oncology (including Cancer)
MeSH Subjects: C Diseases > C04 Neoplasms
NAU Depositing Author Academic Status: Student
Department/Unit: Graduate College > Theses and Dissertations
College of the Environment, Forestry, and Natural Sciences > Biological Sciences
Date Deposited: 23 Feb 2022 18:18
Last Modified: 23 Feb 2022 18:18
URI: https://openknowledge.nau.edu/id/eprint/5743

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