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Restoration of estrogen responsiveness by blocking the HER-2/neu pathway
Lois Witters1, Linda Engle, Allan Lipton
1Department of Medicine, Penn State College of Medicine, Hershey, PA 17033, USA.
Abstract:
HER-2/neu gene amplification or protein overexpression is evident in 20-30% of primary breast cancers. Its amplification correlates with poor prognosis. There appears to be an association between HER-2/neu overexpression and estrogen independence. The MCF-7 human breast carcinoma cell line is estrogen-dependent and sensitive to the anti-estrogen, tamoxifen (TAM). This line, when transfected with the HER-2/neu gene, becomes estrogen-independent and resistant to TAM. Blockade of the HER-2/neu receptor with 1-5 nM of the humanized HER-2/neu antibody, Herceptin, restored estrogen, as well as TAM, sensitivity. These results suggest that Herceptin or similar drugs may restore estrogen sensitivity and the administration of a HER-2/neu inhibitor with an anti-estrogen to premenopausal patients should be considered.
Insights
HER-2/neu gene amplification in breast cancer leads to poor prognosis and estrogen independence. Blocking HER-2/neu with Herceptin restored estrogen and tamoxifen sensitivity in cell lines.
Area of Science:
- Oncology
- Molecular Biology
- Pharmacology
Background:
- HER-2/neu gene amplification/overexpression occurs in 20-30% of breast cancers, correlating with poor prognosis.
- HER-2/neu overexpression is associated with estrogen independence and resistance to tamoxifen (TAM).
Purpose of the Study:
- To investigate the effect of HER-2/neu blockade on estrogen and tamoxifen sensitivity in breast cancer cells.
- To explore potential therapeutic strategies involving HER-2/neu inhibitors and anti-estrogens.
Main Methods:
- Utilized the estrogen-dependent MCF-7 human breast carcinoma cell line.
- Transfected MCF-7 cells with the HER-2/neu gene to induce estrogen independence and TAM resistance.
- Treated transfected cells with varying concentrations (1-5 nM) of the humanized HER-2/neu antibody, Herceptin.
Main Results:
- HER-2/neu transfection rendered MCF-7 cells estrogen-independent and tamoxifen-resistant.
- Herceptin treatment effectively blocked HER-2/neu receptor activity.
- Blockade of HER-2/neu with Herceptin restored both estrogen and tamoxifen sensitivity to the transfected cells.
Conclusions:
- HER-2/neu receptor signaling plays a critical role in mediating estrogen independence and tamoxifen resistance in breast cancer.
- Herceptin and similar HER-2/neu inhibitors show potential in restoring sensitivity to endocrine therapies.
- Combination therapy with HER-2/neu inhibitors and anti-estrogens may be a viable strategy for premenopausal breast cancer patients.