FOXO3/HMOX1 axis promotes melanoma progression by regulating ferroptosis and immune escape

Melanoma represents a highly aggressive form of skin cancer characterized by significant invasiveness and immune evasion capabilities. Although heme oxygenase-1 (HMOX1) participates in cellular stress responses and ferroptosis, its precise functional roles in melanoma pathogenesis remain incompletely defined.

HMOX1 expression levels in melanoma tissues and cell lines were evaluated using immunohistochemistry (IHC), quantitative real-time PCR (qRT-PCR), and western blotting. HMOX1 function was investigated through short hairpin RNA (shRNA)-mediated knockdown, followed by assessment of cellular proliferation, migration, invasion, and ferroptosis sensitivity. Forkhead box O3 (FOXO3)-mediated transcriptional regulation of HMOX1 was experimentally validated using dual-luciferase reporter assays. The impact of HMOX1 expression in melanoma cells on CD8+ T cells was examined through co-culture experiments with peripheral blood mononuclear cells (PBMCs). The in vivo effect of HMOX1 knockdown was evaluated using a mouse subcutaneous xenograft model.

HMOX1 expression was significantly elevated in melanoma compared with normal controls and strongly correlated with poor prognosis. HMOX1 knockdown effectively suppressed melanoma cell proliferation, migration, and invasion, while simultaneously inducing ferroptosis, characterized by increased intracellular ferrous iron (Fe²⁺) and reactive oxygen species (ROS) levels, along with decreased glutathione peroxidase 4 (GPX4) expression. Additionally, HMOX1 depletion attenuated immune escape mechanisms, evidenced by reduced programmed death-ligand 1 (PD-L1) expression, promoted CD8⁺ T cell expansion in co-culture systems, and elevated tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ) secretion. Mechanistically, the transcription factor FOXO3 was identified as a transcriptional activator of HMOX1, thus establishing a FOXO3/HMOX1 regulatory axis that drives melanoma progression. In vivo xenograft experiments corroborated these findings, demonstrating significant tumor growth inhibition upon HMOX1 silencing.

FOXO3-mediated upregulation of HMOX1 promotes melanoma cell proliferation, invasion, immune escape, and ferroptosis resistance. The FOXO3/HMOX1 axis represents a potential therapeutic target for melanoma treatment.