Parkinson's Disease-Related Protein, α-Synuclein, in Malignant Melanoma

Background: Melanoma is the major cause of skin cancer death worldwide. Parkinson's disease is a neurodegenerative disorder that is caused by mutation of alpha-synuclein or other genes. Importantly, epidemiological studies have reported co-occurrence of melanoma and Parkinson's disease, suggesting that these two diseases could share common genetic components. Methodology/Principal Findings: Recently, we found that human melanoma cell lines highly express alpha-synuclein, whereas the protein is undetectable in the non-melanoma cancer cell lines tested. To investigate the expression of alpha-synuclein in human melanoma tissues, we immunostained sections of melanoma, nevus, non-melanocytic cutaneous carcinoma, and normal skin. alpha-Synuclein was positively detected in 86% of the primary and 85% of the metastatic melanoma sections, as well as in 89% of nevus sections. However, alpha-synuclein was undetectable in non-melanocytic cutaneous carcinoma and normal skin. Conclusions/Significance: The Parkinson's disease-related protein, alpha-synuclein, is expressed in both malignant and benign melanocytic lesions, such as melanomas and nevi. Although alpha-synuclein cannot be used to distinguish between malignant and benign melanocytic skin lesions, it might be a useful biomarker for the diagnosis of metastatic melanoma.