Expression of growth factor receptors on human melanoma cells: Comparison of modulating effects of interferons and retinoids

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Abstract
Autocrine and paracrine growth factors are important mediators in malignant transformation. Interferons (IFN) and retinoids (RX) are well-known differentiative and immunomodulating agents with effects on subsets of different human tumors including malignant melanoma. In this study, we examined the modulating effects of three IFN and seven different RX on human melanoma cell lines regarding growth factor receptor expression. Growth factor receptor expression, including PDGF-R, NGF-R, EGF-R, IR, IGF-I-R, TFR and c-kit, was studied by immunohistochemistry and FACSscan analysis. Both groups of substances modulated the expression of some growth factor receptors. Upregulation of PDGF-R was seen after treatment with IFN as well as with RX. In contrast, EGF-R was found to be downregulated in two EGF-R-positive cell lines by IFN and, on the other hand, induced by RX in two EGF-R-negative cell lines. The expression of NGF-R was modulated ambiguously by these substances but demonstrated a cell line specificity in the different melanoma cell lines tested. Additionally, some of the tested growth factor receptors were not markedly changed regarding their expression by treatment with IFN and RX (IR, IGF-I-R, c-kit, TFR).