Cell type- and estrogen receptor-subtype specific regulation of selective estrogen receptor modulator regulatory elements

Abstract

Selective estrogen receptor modulators (SERMs), such as tamoxifen and raloxifene can act as estrogen receptor (ER) antagonists or agonists depending on the cell type. The antagonistic action of tamoxifen has been invaluable for treating breast cancer, whereas the agonist activity of SERMs also has important clinical applications as demonstrated by the use of raloxifene for osteoporosis. Whereas the mechanism whereby SERMs function as antagonists has been studied extensively very little is known about how SERMs produce agonist effects in different tissues with the two ER types; ERα and ERβ. We examined the regulation of 32 SERM-responsive regions with ERα and ERβ in transiently transfected MC..