Systemic Pro-opiomelanocortin Expression Induces Melanogenic Differentiation and Inhibits Tumor Angiogenesis in Established Mouse Melanoma

Abstract

Malignant melanoma is one of the leading causes of cancer mortality worldwide, underlining the need for effective novel therapies. In this study, the therapeutic efficacy and mechanism of systemic pro-opiomelanocortin (POMC) therapy were evaluated in mice bearing established melanoma. Injection of adenovirus encoding POMC (Ad-POMC) led to hepatic POMC overexpression and elevated adrenocorticotropin (ACTH) levels in the circulation. Systemic POMC therapy significantly attenuated the growth of established melanoma and prolonged the survival of tumor-bearing mice. Histological analysis revealed that systemic POMC therapy induced melanogenic differentiation while reducing melanoma growth. In addition, POMC therapy also elicited a significant reduction in the neovascular network of melanoma. Last, we demonstrated that POMC-derived peptides, including ACTH, α-melanocyte-stimulating hormone (α-MSH), and β-MSH, are involved in POMC-mediated melanogenic differentiation and angiogenesis inhibition. In summary, systemic POMC therapy suppresses melanoma growth via induction of melanogenic differentiation and angiogenesis blockade, thereby demonstrating its potential as a novel treatment modality for melanoma. Pro-opiomelanocortin (POMC) encodes a prohormone that is processed into various anti-inflammatory neuropeptides. Here, Liu and colleagues demonstrate that adenoviral vector-mediated gene transfer of POMC has antiangiogenic effects on melanoma and endothelial cells in vitro. The authors also evaluated the therapeutic potential of POMC gene transfer on tumor differentiation induction and tumor angiogenesis in established mouse melanoma models.