The miR-214-MFN2 axis drives mitochondrial dysfunction, metabolic reprogramming and metastatic progression in melanoma

Malignant melanoma (MM) is the most aggressive form of skin cancer. MicroRNAs (miRNAs) regulate cellular programmes involved in tumour progression, including metabolic adaptation and mitochondrial homeostasis. Among them, miR-214 is frequently upregulated in MM, promoting tumour progression and metastatic dissemination, although its role in metabolic reprogramming remains poorly understood. Here, we investigated the effects of miR-214 on melanoma metabolism and mitochondrial function using in vitro and in vivo models. miR-214 overexpression enhanced glucose uptake, lactate production, glycolytic flux, and glycolytic enzyme activities, while reducing tricarboxylic acid cycle activity, electron transport chain function, oxidative phosphorylation, and mitochondrial ATP production. These alterations were accompanied by changes in mitochondrial morphology, membrane potential, permeability transition pore opening, reactive oxygen species production, and Ca²⁺ homeostasis. Mechanistically, miR-214 modulated the expression of key regulators of mitochondrial dynamics including OPA1, MFN1, MFN2 and DRP1, and identified MFN2 as a direct miR-214 target. MFN2 silencing reproduced several features of the miR-214-induced phenotype, including mitochondrial dysfunction, elongated mitochondrial networks, and increased migratory and metastatic properties. Conversely, MFN2 restoration in miR-214-overexpressing cells rescued mitochondrial morphology and function and reduced migration, transendothelial migration, extravasation, and tumour dissemination in mouse models. Restoration of mitochondrial integrity was also confirmed in MFN2-rescued miR-214-overexpressing melanoma murine xenografts, supporting the relevance of this pathway in vivo. However, glycolytic activation persisted despite MFN2 re-expression, indicating that MFN2 specifically mediates mitochondrial alterations, whereas additional targets likely sustain glycolytic reprogramming. Pharmacological inhibition of glycolysis or mitochondrial oxidative stress also attenuated mitochondrial dysfunction and melanoma cell migration. Collectively, our findings identify a previously unrecognized miR-214–MFN2 axis linking mitochondrial dysfunction to MM dissemination and reveal distinct MFN2-dependent and MFN2-independent mechanisms underlying miR-214-driven metabolic reprogramming, providing a mechanistic framework and potential therapeutic opportunities to limit melanoma progression