In Vitro Evaluation of Combination Therapy with Doxorubicin and Quercetin for Uveal Melanoma

Background: Uveal melanoma is the most common intraocular malignancy in adults with a poor prognosis. Although local therapies are effective, treatment options for advanced disease remain limited. Combination strategies using chemotherapeutic agents and natural compounds, such as quercetin, are in focus for their potential to enhance antitumor efficiency and overcome resistance. Methods: The effects of doxorubicin, quercetin, and their combination were investigated in uveal melanoma cell lines. Cell viability was determined by an MTT assay, and apoptosis and cell cycle distribution by flow cytometry. Invasion assays were performed to evaluate metastatic potential, while modifications in signaling pathways were analyzed by Western blotting and qPCR. Results: Both doxorubicin and quercetin significantly reduced cell viability and induced apoptotic and necrotic cell death. The combination treatment demonstrated additional inhibitory effects in both cell lines, shown by increased SubG1 populations, reduced invasive capacity, and modulation of signaling pathways. Cell cycle analysis indicated treatment-induced growth inhibition. Notably, pathway modifications varied between cell lines, suggesting heterogeneous responses. Conclusions: Quercetin may potentiate certain antitumor effects of doxorubicin in uveal melanoma, particularly by reducing post-treatment invasiveness and modulating certain PI3K/AKT pathway-related proteins. These results support the possibility of quercetin-based combination therapies, although further molecular and in vivo studies are required.