Suppression of breast cancer: modulation of estrogen receptor and downregulation of gene expression using natural products.

The main cause of cancer death among women is breast cancer. The most common type of breast cancer is the estrogen receptor positive breast cancer. Discovery of estrogen receptor provided a highly effective target for treatment of hormone-dependent breast cancer. Selective estrogen receptor inhibitors are useful for halting the growth of breast cancer cells and inducing apoptosis. Tamoxifen, a popular selective estrogen receptor modulator, can treat breast cancer but also has unfavourable side effects due to its estrogenic activity in other tissues. Many herbal remedies and bioactive natural compounds, such as genistein, resveratrol, ursolic acid, betulinic acid, epigallocatechin-3-gallate, prenylated isoflavonoids, zearalenol, coumestrol, pelargonidin, delphinidin, and biochanin A, have the ability to specifically modulate the estrogen receptor alpha. Moreover, several of these compounds speed up cell death by supressing estrogen receptor gene expression. This opens wide avenue to introduce number of natural medicines with a revolutionary therapeutic impact and few side effects.