Modulation of epidermal growth factor receptors by gamma interferon in a breast cancer cell line.

Interferons (IFNs) may inhibit cell growth via their interaction with growth factors and their receptors. We examined the ability of IFN to modulate Epidermal Growth Factor (EGF) receptor binding in a human breast carcinoma cell line, MDA 468. Gamma interferon and alpha interferon inhibited growth of MDA 468 cells in a dose and time-dependent manner. IFN-gamma and Epidermal Growth Factor (EGF), a known inhibitor of MDA 468 growth, inhibited growth in an additive fashion. Growth inhibition by gamma but not alpha interferon was associated with a decrease in the number of EGF receptors (EGFRs) after 5 days. Scatchard analysis of receptor binding data revealed that gamma but not alpha interferon reduced the number of available EGF receptor binding sites without any change in the affinity of the receptor. IFN significantly affected EGF receptor expression, and the decrease in receptor expression was associated with growth inhibition.