Effects of nNOS Inhibitors on Melanoma-Induced Immunosuppression

Author

Kate Alison Lozada, Chapman UniversityFollow

Date of Award

Summer 8-2022

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Pharmaceutical Sciences

First Advisor

Sun Yang

Second Advisor

Rennolds Ostrom

Third Advisor

Jennifer Totonchy

Fourth Advisor

Miao Zhang

Abstract

The incidence of cutaneous melanoma (CM) rises despite advances in immunotherapy and targeted therapy. Studies have shown that interferon-gamma (IFN-γ), a pro-tumorigenic cytokine in CM, induces the expression of programmed death-ligand 1 (PD-L1), leading to the escape of melanoma cells from immunosurveillance. Our previous study suggests that neuronal nitric oxide synthase (nNOS)-mediated nitric oxide (NO) signaling is crucial for melanoma progression and forms a mechanistic rationale behind nNOS inhibition as a novel treatment strategy for CM. An additional study demonstrated that IFN-γ interacts with nNOS signaling in melanoma and novel nNOS inhibitors (nNOSi) effectively diminished the induction of PD-L1 post IFN-γ exposure. In this study, we determined the effects of nNOSi on melanoma-induced immunosuppression of T cells. Fresh whole blood samples were collected from 11 disease-free human donors (7 male, 10 Caucasian) between the ages of 20 – 40 years old. CD3⁺ T cells derived from peripheral blood mononuclear cells (PBMCs) were co-incubated with human metastatic melanoma cells in the presence or absence of IFN-γ (250 U/ml). A selective nNOSi MAC-3-190 was added to suppress nNOS-NO signaling in melanoma cells. IL-2⁺ T cells detected by flow cytometry represent the activation of CD4⁺ T cells and CD8⁺ T cells. Our ex vivo study demonstrated that co-incubation with melanoma significantly reduced the average relative percent of IL-2⁺ in CD4⁺ and CD8⁺ T cell populations to below 0.5-fold compared to T cell alone (p+ and CD8⁺ T cell populations remained inactivated when co-incubated with IFN-γ-treated melanoma cells as indicated by the decrease in IL-2⁺ T cells to 0.5-fold of control (p+ T cells as shown by the increase in IL-2⁺ T cells to 0.8-fold of control compared to IFN-γ-treated melanoma (p

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Recommended Citation

Lozada, KAJ. Effects of nNOS Inhibitors on Melanoma-Induced Immunosuppression. [master’s thesis]. Irvine, CA: Chapman University; 2022. https://doi.org/10.36837/chapman.000401