Melanoma Development: Current Knowledge on Melanoma Pathogenesis.

The pathogenic features of melanomas include growth and amplification of atypical melanocytes associated with several features (self-sufficiency of growth factors, insensitivity to growth inhibitors, evasion of cellular apoptosis, limitless replicative potential, sustained angiogenesis, tissue invasion, and metastasis). These melanoma pathogenic events can be triggered by activating oncogenes or inactivating tumor-suppressor genes by means of molecular mechanisms such as dotted mutations, deletions, and translocations or epigenetic mechanisms such as microRNA expression and promoter methylation. In melanomas, an analysis of the gene aberrations in the genome has led to the discovery of the complex interaction of signaling pathways. Progression of melanomas also involves genetic instability and selective growth of cells with favorable mutations. Additional factors include genetic predisposition, mutagenesis, and suppressed host immune response. Some of the most important signaling pathways involved in the pathogenesis of melanoma are the MAPK, PI3K/PTEN/AKT, and MITF signaling pathways. Obtaining insight into the biology of melanocytes and pathogenesis of melanomas is important for the development of a targeted therapy (such as vemurafenib, dabrafenib, trametinib) as well as the immunotherapy (e.g. pembrolizumab, nivolumab, ipilimumab), which has enabled a substantial breakthrough in the treatment of patients with melanoma.