Effects of nNOS Inhibitors on Melanoma-Induced Immunosuppression

<p>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 <em>ex vivo</em> 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 (<em>p</em>+ 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 (<em>p</em>+ T cells as shown by the increase in IL-2⁺ T cells to 0.8-fold of control compared to IFN-γ-treated melanoma (<em>p</em></p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Pharmaceutical Sciences

Year dc:date.available

2022

Author dc:creator

• Lozada, Kate Alison

Contributors dc:contributor

• Sun Yang
• Rennolds Ostrom
• Jennifer Totonchy
• Miao Zhang

• melanoma
• immunotherapy
• nNOS inhibitors
• IL-2
• T cell
• PD-L1
• Other Pharmacy and Pharmaceutical Sciences
• Pharmaceutics and Drug Design

Repository record dc:identifier

https://digitalcommons.chapman.edu/pharmaceutical_sciences_theses/25

OAI identifier oai:identifier

oai:digitalcommons.chapman.edu:pharmaceutical_sciences_theses-1025