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Potassium channels and adenosine signaling in T cells of head and neck cancer patients

Newton, Hannah S
http://orcid.org/0000-0002-6368-0803
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1603713656776019

Abstract Details

2020, PhD, University of Cincinnati, Medicine: Pathobiology and Molecular Medicine.
Background: Head and neck squamous cell carcinoma (HNSCC) is the seventh most common cancer worldwide. Patients with advanced HNSCC have a 50% five-year survival rate and often develop debilitating side effects to standard therapies. Thus, the use of more effective and less invasive treatments, such as immune checkpoint inhibitors, to treat cancers, including HNSCC, is imperative. However, while immune checkpoint inhibitors increase patient survival with limited side effects, the percentage of clinical response is low. Therefore, understanding the mechanisms of immunotherapy and immune system failure is important. The immune system fails, in part, due to the limited ability of CD8+ cytotoxic T cells to infiltrate the immunosuppressive tumor microenvironment (TME) and exert cytotoxic effects. T cell cytotoxicity and chemotaxis are mediated by K+ channels (KCa3.1 and Kv1.3); however, in cancer, K+ channel activity is deficient. In HNSCC circulating CD8+ T cells (PBTs), defective KCa3.1 leads to decreased T cell chemotaxis by the adenosine present in the TME. Moreover, in HNSCC CD8+ tumor infiltrating lymphocytes (TILs), dysfunctional Kv1.3 decreases TIL cytotoxicity. Aim: The aim of this research is to understand how immune checkpoint inhibitors, such as anti-programmed cell death 1 antibodies (a-PD1), impact K+ channels in HNSCC CD8+ PBTs/TILs and to develop a nanoparticle-based therapeutic approach to target inhibitory pathways upstream to K+ channels, such as adenosine signaling, in order to increase T cell infiltration and function in the tumor. Methods: Healthy donor blood samples and HNSCC blood/tumor samples were used to complete in vitro and ex vivo studies. T cell functionality was determined using electrophysiology, Ca2+ fluxing assays and chemotaxis assays. Flow cytometry and reverse transcription-qPCR were used to determine protein and mRNA levels. Immunofluorescence microscopy was used to visualize protein localization. Results and conclusions: We report that upfront a-PD1 treatment of HNSCC patients increases CD8+ PBT and TIL functionality through K+ channel-mediated mechanisms. Regardless of pathological response, TILs of HNSCC patients treated with a-PD1 had increased Kv1.3 activity and Ca2+ fluxes as compared to untreated HNSCC TILs. Furthermore, in activated PBTs, regardless of pathological response, a-PD1 increased KCa3.1 activity post-treatment. However, immediately post-treatment responder patients’ PBTs also had increased Kv1.3 activity and Ca2+ fluxing and their chemotaxis became insensitive to adenosine. The increase in Kv1.3 activity and Ca2+ fluxing in responders’ PBTs was long-lasting as they persisted after tumor resection; however, these PBTs regained adenosine sensitive chemotaxis. On the other hand, while the activated PBTs of non-responders maintained increased Kv1.3 activity, they lost the overall ability to chemotax. We then conducted further studies to determine whether a nanoparticle-based therapeutic delivery approach could be developed to increase CD8+ memory PBT chemotaxis in the presence of adenosine. Lipid nanoparticles targeting CD8+ memory PBTs and loaded with siRNAs to knock-down the adenosine A2A receptor (A2AR) were successful at decreasing A2AR mRNA expression and rescuing chemotactic ability. Overall this data shows that K+ channels are integral in patient response to a-PD1 and that targeting upstream inhibitory pathways of K+ channels are effective mechanisms to overcome the immunosuppressive TME.
Laura Conforti, Ph.D. (Committee Chair)
Edith Janssen, Ph.D. (Committee Member)
Scott Langevin, Ph.D. (Committee Member)
Peter Stambrook, Ph.D. (Committee Member)
Trisha Wise-Draper (Committee Member)
167 p.
Molecular Biology
head and neck cancer; immunotherapy; T cells; ion channels; lipid nanoparticles

Recommended Citations

Citations

  • Newton, H. S. (2020). Potassium channels and adenosine signaling in T cells of head and neck cancer patients [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1603713656776019

    APA Style (7th edition)

  • Newton, Hannah. Potassium channels and adenosine signaling in T cells of head and neck cancer patients. 2020. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1603713656776019.

    MLA Style (8th edition)

  • Newton, Hannah. "Potassium channels and adenosine signaling in T cells of head and neck cancer patients." Doctoral dissertation, University of Cincinnati, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1603713656776019

    Chicago Manual of Style (17th edition)

ucin1603713656776019
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This open access ETD is published by University of Cincinnati and OhioLINK.