Estrogen-dependent regulation of osteoprotegerin production by breast cancer cells

Osteoprotegerin (OPG) is a secreted glycoprotein that acts as decoy receptor for receptor activator of NF-κB ligand (RANKL), an essential stimulator of osteoclasts and promoter of cancer migration and for TNF-α-related apoptosis inducing ligand (TRAIL), an inducer of apoptosis. While alterations of RANKL and OPG have been linked to skeletal disorders, the role of OPG in breast cancer remains largely unclear. We evaluated the regulation of OPG by sex hormones in two breast cancer cell lines, MCF–7 (estrogen receptor-α-positive) and MDA-MB–231 (estrogen receptor-α-negative) and the regulation of apoptosis and viab…