ErbB receptors mediate both migratory and proliferative activities in human melanocytes and melanoma cells

Abstract

Epidermal growth factor receptor (EGFR) activation by transforming growth factor alpha (TGFalpha) has been implicated in autocrine growth in melanoma, but does not alter melanocyte proliferation. This raises the possibility that different signalling pathways are activated via EGFR or ErbB receptors. Here, we demonstrate that ErbB2, ErbB3 and ErbB4 are expressed in cultured human melanocytes. Western analyses with receptor-specific antisera revealed protein bands with Mr values of 185 and 160 kDa, corresponding to ErbB2 and ErbB3, respectively. Blots probed with ErbB4 antibodies showed bands with Mr values of 180, 120 and 80 kDa, corresponding to the receptor and its reported variants. Two malignant melanoma cell lines expressed ErbB2 and ErbB3, but not the full-length ErbB4 receptor. As TGFalpha binds to EGFR and the heregulins (HRG) bind to ErbB3 and ErbB4, these growth factors were examined for effects on receptor activation and on cell growth and motility in a scratch wound closure assay. In normal melanocytes, HRGbeta1 activated the phosphorylation of tyrosine residues of proteins that immunoprecipitated with EGFR and ErbB4 antisera, and significantly enhanced cell migration but not proliferation. Neither TGFalpha nor HRGalpha1 promoted migration or growth in normal melanocytes. By contrast, TGFalpha stimulated migratory activity in the MM96L cell line, but not in the MELJG line, whereas HRGbeta1 significantly enhanced cell growth, but not migration, in both malignant cell lines. The apparent transition of HRGbeta1 from a migratory to a proliferative function after malignant transformation, and the change in TGFalpha from a non-migratory to a migratory activity in one melanoma line, suggests multiple switches in ErbB signalling pathways via EGFR/ErbB heterodimer formation.

Embryonic requirements for ErbB signaling in neural crest development and adult pigment pattern formation

“…Normal human melanocytes express EGFR, ERBB2, ERBB3 and ERBB4, and stimulation with ligand promotes migration in vitro (Gordon-Thomson et al, 2001;Stove et al, 2003;Gordon-Thomson et al, 2005;Mirmohammadsadegh et al, 2005). ErbB receptors also are expressed in melanoma cells, and are associated with melanoma progression in a teleost model (Wellbrock et al, 2002;Gomez et al, 2004) and with human melanoma proliferation in vitro (Stove et al, 2003;Gordon-Thomson et al, 2005;Funes et al, 2006). Our finding that the picasso mutant phenotype results from lesions in erbb3b provides the first evidence that ErbB signals are required to promote normal pigment cell and pigment pattern development in vivo [although Fitch et al (Fitch et al, 2003) describe melanocytosis resulting from EGFR overexpression in skin].…”

The ERBB3 receptor in cancer and cancer gene therapy

“…312,313 Although another investigation reported that ERBB3 was found in only a minority of melanomas, and only in those that were not metastatic, 314 and several melanoma cell lines did not express ERBB3, 315 ERBB3 showed a fourfold increase in expression in melanoma micrometastases and 14-fold increase in macrometastases, compared with normal lymph nodes. 316 NRG-stimulated migration but not proliferation of melanocytes, and had the opposite effect in two melanoma cell lines, 317 suggesting qualitative changes in ERBB pathway signaling during melanoma development. Muc4, a transmembrane mucin that promotes growth and metastasis of melanoma cells, caused increased membrane localization and stability of ERBB2 and ERBB3.…”

The fibroblast-derived paracrine factor neuregulin-1 has a novel role in regulating the constitutive color and melanocyte function in human skin

“…Because NRG-1-ErbB signaling has been recently reported to affect melanocyte development and melanoma migration (Gordon-Thomson et al, 2005;Buac et al, 2009), the result was of immediate interest. To validate the expression of NRG-1 by fibroblasts at the protein level, we used immunohistochemistry to examine the expression of NRG-1 in normal human skin samples from types I and VI skin ( Fig.…”