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Slide 15

Tamoxifen and Cancer

The first SERM to be investigated extensively for its anticancer properties is a drug called tamoxifen (Nolvadex®).
Tamoxifen blocks the action of estrogen in breast tissue by binding to the estrogen receptors of breast cells, thereby preventing estrogen molecules from binding to these receptors. But unlike what occurs when estrogen binds to its receptor, tamoxifen binds but does not change the receptor’s shape, so coactivators are unable to bind. As a result, the genes that stimulate cell proliferation cannot be activated.
By interfering with estrogen receptors in this way, tamoxifen blocks the ability of estrogen to stimulate the proliferation of breast cells.