The proteasome inhibitor Bortezomib (Velcade) as potential inhibitor of estrogen receptor-positive breast cancer

Around 70% of breast cancers express the estrogen receptor α (ERα) and depend on estrogen for growth, survival and disease progression. The presence of hormone sensitivity is usually associated with a favorable prognosis. Use of adjuvant anti-endocrine therapy has significantly decreased breast cancer mortality in patients with early-stage disease, and anti-endocrine therapy also plays a central role in the treatment of advanced stages. However a subset of hormone receptor-positive breast cancers do not benefit from anti-endocrine therapy, and nearly all hormone receptor-positive metastatic breast cancers ultimately develop resistance to anti-hormonal therapies. Despite new insights into me…