Biomarkers for Melanoma Diagnosis and the Technologies Used to Identify Them

Melanoma is a malignant tumor originating from melanocytes (pigment-producing cells). Although the tumor is mainly detected in skin (cutaneous melanoma), it can also be detected in the eye (uveal melanoma), gastrointestinal (GI) tract and oral mucosa and genital tract (mucosal melanoma) (Landreville et al., 2008; Akaraviputh et al., 2010; Bakalian et al., 2008; Rigel et al., 2010; Seetharamu et al., 2010). Melanoma can be classified as belonging to one of four subtypes: superficial spreading, nodular, lentigo maligna, and acral lentiginous melanoma. These subtypes are characterized based on prognosis, incidence of metastasis and the frequency of gene mutations (e.g., BRAF and NRAS) (Saldanha et al., 2006; Jaeger et al., 2007; Markovic et al., 2007; Jonsson et al., 2010). Superficial spreading melanoma is the most common form of melanoma found in Caucasian populations, while the acral lentiginous melanoma is frequently detected in Asian and African populations (Cress and Holly, 1997; Weyers et al., 1999). Several important risk factors that have been linked to the development of melanoma have been identified. Of these risk factors, most can be considered to be either environmental factors, such as exposure to ultraviolet (UV) radiation, especially in childhood, or other host factors such as family history and melanocytic nevi (Markovic et al., 2007; Schulman and Fisher, 2009), but other cancer risk factors such as smoking (Osterlind et al., 1988), diet (Osterlind et al., 1988; Veierod et al., 1997) or hormone therapy (Naldi et al., 2005) have not been found to be associated with an increased risk of melanoma. The risk of developing melanoma is higher in Caucasian than in Asian or African populations. This is closely related to skin pigmentation as melanin has been shown to have a protective function for UV-induced melanoma and Caucasian populations show low levels of melanogenesis (Lens and Dawes, 2004; Hu et al., 2008; Jemal et al., 2010). In general, the melanocortin-1 receptor (MC1R), which is a G-protein-coupled receptor (GPCR), stimulates melanogenesis through the activation of adenylate cyclase and protein kinase A (PKA) (Jordan and Jackson, 1998; Rouzaud et al., 2003). Its genetic variants are associated with melanoma