MCF-7/TAMR-1 Human Breast Cancer Cell Line MCF-7/TAMR-1 is a tamoxifen-resistant cell line derived from the MCF-7/S0.5 human breast cancer cell line by long term treatment with the drug tamoxifen.

Estrogen receptor-positive breast cancer is the most common type of breast cancer. About 80% of all breast cancers express the estrogen receptor (ER+) and depend on estrogen to support the growth and spread of the cancer cells. Hormonal therapy, such as tamoxifen, may help slow or stop the growth of ER+ breast cancers by blocking the actions of estrogen. Primary or acquired tamoxifen resistance poses a major clinical challenge in the treatment of ER+ breast cancer. The MCF-7/TAMR-1 cell line provides a model cell system for studying tamoxifen resistance, elucidating signaling pathways involved in tamoxifen-resistant growth, and identifying new predictive markers for response to hormonal therapy.MCF-7/TAMR-1 is a tamoxifen-resistant cell line derived from the MCF-7/SO.5 cell line that has been adapted to grow at low serum concentration under the long-term treatment with 1 M with tamoxifen. MCF-7/TAMR-1 cells should be maintained in 1 M tamoxifen and may be compared with the parental MCF-7/S0.5 cells, which are sensitive to tamoxifen.