title: Comprehensive analysis of receptor tyrosine kinase activation in human melanomas reveals autocrine signaling through IGF-1R.
abstract: Melanomas depend on autocrine signals for proliferation and survival; however, no systematic screen of known receptor tyrosine kinases (RTKs) has been performed to identify which autocrine signaling pathways are activated in melanoma. Here, we performed a comprehensive analysis of 42 RTKs in six individual human melanoma tumor specimens as well as 17 melanoma cell lines, some of which were derived from the tumor specimens. We identified five RTKs that were active in almost every one of the melanoma tissue specimens and cell lines, including two previously unreported receptors, insulin-like growth factor receptor 1 (IGF-1R) and macrophage-stimulating protein receptor (MSPR), in addition to three receptors (vascular endothelial growth factor receptor, fibroblast growth factor receptor, and hepatocyte growth factor receptor) known to be autocrine activated in melanoma. We show, by quantitative real time PCR, that all melanoma cell lines expressed genes for the RTK ligands such as HGF, IGF-1, and MSP. Addition of antibodies to either IGF-1 or HGF, but not to MSP, to the culture medium blocked melanoma cell proliferation, and even caused net loss of melanoma cells. Antibody addition deactivated IGF-1R and hepatocyte growth factor receptors, as well as mitogen-activated protein kinase signaling. Thus, IGF-1 is a new growth factor for autocrine driven proliferation of human melanoma in vitro. Our results suggest that IGF-1-IGF-1R autocrine pathway in melanoma is a possible target for therapy in human melanomas.
authors.affiliation: Department of Surgery, Division of Surgical Oncology, School of Medicine, University of Virginia Health System, Charlottesville, Virginia 22908, USA.
authors.forename: Kerrington R
authors.initials: KR
authors.lastname: Molhoek
authors.forename: Amber L
authors.initials: AL
authors.lastname: Shada
authors.forename: Mark
authors.initials: M
authors.lastname: Smolkin
authors.forename: Sudhir
authors.initials: S
authors.lastname: Chowbina
authors.forename: Jason
authors.initials: J
authors.lastname: Papin
authors.forename: David L
authors.initials: DL
authors.lastname: Brautigan
authors.forename: Craig L
authors.initials: CL
authors.lastname: Slingluff
mesh_terms: D019898:Autocrine Communication; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D008024:Ligands; D008545:Melanoma / Q000201:enzymology* / Q000235:genetics / Q000556:secondary; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D017526:Receptor, IGF Type 1 / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors
chemical_list: D008024:Ligands; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1; D020928:Mitogen-Activated Protein Kinases