# Targeting S-Nitrosylation to Overcome Therapeutic Resistance in NRAS-Driven Melanoma

## TL;DR

This paper shows that blocking S-nitrosylation can help overcome treatment resistance in NRAS-mutant melanoma by improving the effectiveness of existing therapies and boosting immune responses.

## Contribution

The study introduces S-nitrosylation as a novel target to enhance MEK inhibitor efficacy and immune response in NRAS-driven melanoma.

## Key findings

- Blocking S-nitrosylation with NOS inhibitors restores sensitivity to MEK inhibitors in preclinical models.
- Inhibition of S-nitrosylation promotes dendritic cell activation and CD8+ T cell infiltration into tumors.
- S-nitrosylation plays a role in immune evasion and macrophage-mediated immune surveillance in NRAS-mutant melanoma.

## Abstract

NRAS-mutant melanoma is difficult to treat due to resistance to current therapies like MEK inhibitors. This study highlights how a chemical process called S-nitrosylation helps tumor cells keep growing and avoid the immune system by modifying the function of key proteins like MEK and ERK. Blocking this process increases the efficacy of MEK inhibitors, boosts immune response, and helps immune cells better attack the tumor cells. These findings suggest a promising new strategy to improve treatment by combining redox-targeting drugs with existing therapies in NRAS-driven melanoma.

NRAS-mutant melanoma represents a clinically challenging subset of melanoma with limited effective therapies and intrinsic resistance to targeted MEK inhibition. Recent findings highlight protein S-nitrosylation, a redox-dependent post-translational modification as a critical modulator of MEK-ERK signaling and immune evasion in this context. In this commentary, we discuss how S-nitrosylation of MAPK components, including MEK and ERK, sustains oncogenic signaling and attenuates immunogenic cell death. Targeting this modification with nitric oxide synthase (NOS) inhibitors such as L-NAME, L-NMMA and 1400w restore sensitivity of MEK inhibitor, promotes dendritic cell activation, and enhances CD8+ T cell infiltration in preclinical models such as immunogenic mouse models and individual patient derived, primary melanoma cells. We also explore the emerging role of S-nitrosylation in regulating macrophage-mediated immune surveillance and propose translational strategies for combining redox modulation with targeted and immune therapies. These insights offer a compelling framework for overcoming therapeutic resistance and reprogramming the tumor immune microenvironment to activate the cytotoxic T-cells and enhance the responses to immunotherapy in NRAS-driven cancers.