title: Targeting RAS/RAF/MEK/ERK signaling in metastatic melanoma.
abstract: The RAS/RAF/MEK/ERK pathway has been reported to be activated in over 80% of all cutaneous melanomas, making it the focus of many scientific studies in the melanoma field. Discoveries of mutations and aberrant expression of components in this cascade, in particular, BRAF and NRAS render a deeper understanding of the mechanisms responsible for oncogenesis and provide new therapeutic strategies for this deadly disease. This review starts with a comprehensive discussion on the role of this pathway in initiation and progress of melanoma. Mechanistically, mutated BRAF and NRAS exert most of the oncogenic effects through the activation of the MAPK pathway, which both drive the uncontrolled growth of melanoma cells and regulate the cell survival. In a subsequent section, clinical efficacy of targeted small-molecule inhibitors is highlighted. BRAF-targeted therapies (e.g., vemurafenib, dabrafenib) have showed impressive results in systemic therapy for melanoma harboring activating BRAF V600E mutations. MEK inhibitors show limited activity in phase I trials, and inhibitors directly targeting mutated NRAS, to date, have not been realized. Furthermore, the emerging mechanisms underlying both intrinsic and acquired drug resistance as well as approaches to prevent or abrogate the onset of therapeutic escape are addressed. Finally, the promising vistas and major challenges involving small-molecule inhibitors targeting this MAPK pathway in melanoma therapy are briefly discussed. It can be envisaged that disseminated melanoma is no longer such a bleak prognosis in future given the research and development of new signal transduction inhibitors based on our evolving understanding of melanoma genetics and intracellular signaling.
authors.affiliation: Department of Dermatology, The Second Affiliated Hospital of Dalian Medical University, Dalian, Liaoning Province, People's Republic of China. wangaxdl@hotmail.com
authors.forename: Ao-Xue
authors.initials: AX
authors.lastname: Wang
authors.forename: Xiao-Yi
authors.initials: XY
authors.lastname: Qi
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D008545:Melanoma / Q000188:drug therapy* / Q000378:metabolism / Q000556:secondary; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D058990:Molecular Targeted Therapy; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D012878:Skin Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D048490:raf Kinases / Q000378:metabolism; D018631:ras Proteins / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D047428:Protein Kinase Inhibitors; D048490:raf Kinases; D020928:Mitogen-Activated Protein Kinases; D018631:ras Proteins
keywords: BRAF inhibitor; MEK; melanoma; resistance; signaling