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Modulation of epidermal growth factor receptors by gamma interferon in a breast cancer cell line
A Chakravarthy1, L C Chen, D Mehta
1University of Maryland Cancer Center, Division of Cell and Molecular Biology, Baltimore 21201.
Abstract:
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.
Insights
Interferons (IFNs) inhibit breast cancer cell growth by reducing Epidermal Growth Factor (EGF) receptors. Gamma interferon, but not alpha interferon, decreased EGF receptor numbers, correlating with reduced cell growth.
Area of Science:
- Oncology
- Cell Biology
- Immunology
Background:
- Interferons (IFNs) are known to inhibit cell growth.
- Interferons may interact with growth factors and their receptors to modulate cell proliferation.
- Epidermal Growth Factor (EGF) receptor (EGFR) signaling is implicated in the growth of various cancer types, including breast carcinoma.
Purpose of the Study:
- To investigate the effect of gamma interferon (IFN-γ) and alpha interferon (IFN-α) on Epidermal Growth Factor (EGF) receptor binding in the MDA 468 human breast carcinoma cell line.
- To determine if IFN-induced growth inhibition is associated with changes in EGFR expression or affinity.
Main Methods:
- MDA 468 human breast carcinoma cells were treated with varying doses and durations of IFN-γ and IFN-α.
- Cell growth inhibition was assessed.
- Epidermal Growth Factor (EGF) receptor binding was quantified using Scatchard analysis.
- Changes in the number and affinity of EGF receptors were evaluated.
Main Results:
- Both IFN-γ and IFN-α inhibited MDA 468 cell growth in a dose- and time-dependent manner.
- IFN-γ and EGF exhibited additive growth inhibition.
- IFN-γ treatment led to a significant decrease in the number of available EGF receptors after 5 days, without altering receptor affinity.
- IFN-α did not significantly affect EGF receptor number or affinity.
Conclusions:
- Gamma interferon significantly reduces EGF receptor expression in MDA 468 breast cancer cells.
- The decrease in EGF receptor number by IFN-γ is associated with growth inhibition.
- Interferons, particularly gamma interferon, represent a potential therapeutic strategy targeting EGFR signaling in breast cancer.