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 RTKs has been performed to identify which autocrine signaling pathways are activated in melanoma. Here we performed a comprehensive analysis of 42 receptor tyrosine kinases (RTKs) in 6 individual human melanoma tumor specimens as well as 17 melanoma cell lines, some of which were derived from the tumor specimens. We identified 5 RTKs that were active in almost every one of the melanoma tissue specimens and cell lines, including two previously unreported receptors, IGF1R and MSPR, in addition to three receptors (VEGFR, FGFR and HGFR) known to be autocrine activated in melanoma. We show by real time quantitative PCR that all melanoma cell lines expressed genes for the RTK ligands HGF, IGF1 and MSP. Addition of antibodies to either IGF1 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 IGF1R and HGFR receptors, as well as MAPK signaling. Thus, IGF1 is a new growth factor for autocrine driven proliferation of human melanoma in vitro. Our results suggest that IGF1-IGF1R autocrine pathway in melanoma is a possible target for therapy in human melanomas.

Amuvatinib has cytotoxic effects against NRAS-mutant melanoma but not BRAF-mutant melanoma

“…Melanoma cell lines with BRAF V600E mutations showed relatively little basal RTK signaling, with the exceptions of ephrin A4 and one cell line (WM9) with EGFR/ERBB2/ERBB3 activity (Figure 1A). The analysis detailed here differs significantly from previous studies of RTK activity in melanoma cell lines in utilizing mass spectrometry to give precise, quantitative readouts on specific phosphorylation sites (Figure 1A) (7, 8). In agreement with previously published studies, we noted basal tyrosine phosphorylation of Axl at Y702 in all of the NRAS -mutant melanoma cell lines that was lacking in those that were BRAF -mutant (12).…”

“…Melanoma cell lines and tumor specimens express a large number of cell surface receptor tyrosine kinases (RTKs), all with the potential to drive cell growth and survival (7, 8). There is some preclinical evidence that multi-targeted kinase inhibitors, such as RAF-265, may have in vivo activity against patient-derived BRAF wild-type melanoma xenografts, including those with NRAS Q61R mutations (9).…”

Ron receptor tyrosine kinase signaling as a therapeutic target

“…The majority of cancer models indicate that Ron is highly expressed in the epithelial cells of the tumor [16]. In addition to the numerous cancers in which Ron overexpression has been identified, recent reports indicate that Ron is also upregulated in human gliomas [17], melanoma [18] and Merkel cell carcinoma [19]. Merkel cell carcinoma is a neuroendocrine tumor of the skin; the addition of these 3 cancer subtypes suggest Ron is also playing a role in both neurological and skin cancers, expanding its role to most known cancer subtypes.…”

Inhibition of human breast cancer Matrigel invasion by Streptolysin O activation of the EGF receptor ErbB1

“…Furthermore, the results revealed that in MDA-MB-231 cells only a few RTKs are active. In other human cell lines that we have examined, such as melanomas, we found a different subset of activated RTKs [6], demonstrating the responsiveness and validity of the assay. Combination treatment of peroxyvanadate plus SLO did not reveal differences in RTK activation relative to control cells treated with peroxyvanadate alone (Figure 2B).…”