Interferon-gamma downregulates epidermal growth factor receptors on human melanoma cells.

Unregulated expression of epidermal growth factor receptor (EGF-R) is a common event in neoplastic transformation and has been shown to be associated with melanocytic tumor progression. Modulation of such a receptor by pharmacological agents could therefore be of clinical interest. We have studied EGF-R expression, its response to epidermal growth factor (EGF) and modulation effects by interferon gamma (IFN gamma) on human melanoma cells. Addition of EGF, anti-EGF and anti-EGF-R antibodies had no effect on proliferation of six melanoma cell lines tested. We report in this communication that EGF-R expression on human melanoma cells can be modulated by IFN-gamma. In the melanoma cell lines treated with IFN gamma, proliferative behavior was not affected; however, we demonstrate a downregulation of EGF-R expression on the protein level, by immunohistochemistry and flow cytometric analysis, and an accumulation of EGF-R mRNA by Northern blot analysis. The results suggest that IFN gamma downregulates EGF-R expression at a posttranscriptional level on human melanoma cells. This EGF/EGF-R interaction and its modulation by IFN gamma on human melanoma cells needs to be further clarified regarding its in vivo significance for the treatment and prognosis of malignant melanoma.