Pigment epithelium-derived factor prevents melanoma growth via angiogenesis inhibition

Pigment epithelium-derived factor (PEDF) has recently been shown to be the most potent inhibitor of angiogenesis in the mammalian eye, and is involved in the pathogenesis of angiogenic eye disease such as proliferative diabetic retinopathy. However, a functional role for PEDF in tumor growth and angiogenesis remains to be determined. Melanoma is one of the most highly invasive and metastatic tumors. Malignant Melanoma is an increasingly common malignancy and also one the most invasive and metastatic tumors, and its mortality rates have been rapidly increasing above those of any other cancer in recent years. Surgical resection and systemic chemotherapy are the main therapeutic strategies for the treatment of malignant melanoma. However, these approaches are insufficiently effective and may be associated with significant adverse effects. Angiogenesis, a process by which new vascular networks are formed from pre-existing capillaries, is required for tumors to grow, invade and metastasize. Tumor vessels are genetically stable, and less likely to accumulate mutations that allow them to develop drug resistance in a rapid manner. Therefore, targeting vasculatures that support tumor growth, rather than cancer cells, is currently considered the most promising approach to malignant melanoma therapy. Now, novel anti-angiogenic agents with tolerable side effects are actually desired for the treatment of patients with malignant melanoma. In this paper, we review the current understanding of anti-angiogenic therapy for malignant melanoma, especially focusing on PEDF, which was recently identified as the most potent endogenous inhibitor of angiogenesis in the mammalian eye.