Regulation of epidermal growth factor receptor in human colon cancer cell lines by interferon alpha.

Abstract

The biology of growth factor receptor expression has implications for receptor specific cancer therapy. In this study, we examined: (a) regulation of epidermal growth factor receptor (EGFR) expression in a panel of 10 human colon cancer cell lines using interferon alpha (IFN-alpha); (b) ability of IFN-alpha to inhibit cell proliferation; and (c) sensitivity of IFN-alpha pretreated cells to EGF. Cell proliferation was measured both by crystal violet colorimetric and clonogenic assays. Cell surface, intracellular, and/or total cell protein expression of EGFR was assessed by indirect immunofluorescence flow cytometry and/or fluorescein isothiocyanate (FITC)-EGF binding and internalisation flow cytometric assay. IFN-alpha treatment upregulated expression of cell surface EGFR in seven of 10 colon cancer cell lines within 16 hours, reaching a peak within 48-96 hours; this was accompanied by transient elevation of intracellular EGFR and marked growth inhibition. IFN-alpha treated cancer cells were still sensitive to EGF proliferative stimulation. Our results indicate that cytostatic concentrations of IFN-alpha can enhance cell surface and intracellular EGFR expression in a proportion of human colon cancer cells. The antiproliferative action of IFN-alpha could not block the signal transduction of the EGF-EGFR pathway. This may have clinical implications for improving treatment based on targeting of EGFR.