Abstract 1334: Age related phenotypic changes in melanoma create a tumor vulnerability to ferroptosis.

Abstract Aging is an independent poor prognostic factor for melanoma, the most aggressive form of skin cancer. Among the characteristics of aging, the accumulation of iron, polyunsaturated fatty acids, and reactive oxygen species can reshape the skin microenvironment and lead to changes in how melanoma progresses in the aged skin. Here, we investigate the impact of these characteristics of the aged tumor microenvironment and how phenotypic changes in melanoma cells create a tumor vulnerability to ferroptosis, a caspase-independent lipid peroxidation-mediated type of cell death, a possible therapeutic opportunity for older patients. KEGG pathway enrichment analysis on the proteomic data from young and aged mice shows an enrichment in the ferroptosis pathway. Through immunohistochemistry, we confirmed this pro-ferroptosis signature in the skin and using human aged dermal fibroblasts in vitro, observed that their secretome enhanced the cytoxicity of ferroptosis inducers such as RSL-3 (a GPX4 inhibitor) on melanoma cells. To understand how ferroptosis impacts tumor growth in young and aged mice, we used a syngeneic tumor model with intra-dermal administration of Yumm1.7 cells and the treatment with a lipid peroxidation inducer (imidazole ketone erastin - IKE). Although showing a general effect, IKE treatment significantly reduced tumor growth in older mice. Tumors from aged mice showed stronger immunoreactivity to 4-HNE (lipid peroxidation byproduct) when compared to young. This occurred in parallel with increases in AXL and Wnt5a staining. To comprehend the mechanisms driving this age-specific effect, we investigated if the phenotype switch that occurs in melanoma cells present in the aged TME would favor ferroptosis. Correlation between transcriptomic (TCGA-SKCM) and sensitivity data (CTD^2) confirmed that phenotype-switching markers, such as Wnt5a, showed a strong correlation with ferroptosis-related transcripts and an inverse correlation with ferroptosis resistance. Using a panel of melanoma cell lines with distinct Wnt5a levels, we confirmed this association and observed that critical regulators of lipid peroxidation are downregulated with high Wnt5a high: GPX4, AIFM2, and GCH1. The association between Wnt5a levels and ferroptosis regulators were confirmed experiments with the knock down or overexpression of Wnt5a. In a 3D in vitro model, RSL-3 inhibited the invasion of melanoma cells. These results indicate that ferroptosis modulation could be used to prevent metastatic dissemination and is a promising avenue for combined treatment with existing clinical strategies. Citation Format: Murilo Ramos Rocha, Yash Chhabra, Alexis Erasta Carey, Cheyenne M. Palm, Kevin Y. Zhang, Joanne Kotelawala, Elizabeth Harper, Fan Huang, Ashani Weeraratna. Age related phenotypic changes in melanoma create a tumor vulnerability to ferroptosis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 1334.