Breast cancer has become the top killer of death worldwide among women with the number
about 519,000 deaths each year, and the deaths from cancer is projected to continue rising which was
reported by World Health Organization (WHO) recently. As breast cancer is a heterogenous disease
whose behavior is determined by the molecular characteristics, increased interests are to unravel the
molecular mechanisms of breast cancer development and progression. Bcl-2, as a protooncogene
identified in 1984, contributes to malignancy by protecting cells from apoptosis. Since the
identification of Bcl-2, a number of studies have been exploited to investigate their contribution to the
formation, progression, therapy resistance and prognostic potential in many cancers including breast
cancer. Preclinical studies have suggested that Bcl-2 overexpression enhances metastatic potential of
breast cancer cells. And in general, the expression of Bcl-2 has been associated with the presence of
good prognostic markers, such as hormonal receptor positivity, lower or absent p53 expression and a
favorable clinical outcome. The overexpression of Bcl-2 is also associated with drug resistance or
sensitivity to specific chemotherapy, radiotherapy and hormonal therapy. In recent years a number of
studies have shed light onto the role of Bcl-2 in mediating the effects of anticancer agents in order to
develop more efficient and more precisely targeted treatment strategy. The independent prognostic
value of Bcl-2 in breast cancer is demonstrated in many recent investigations as well. The aim of this
review is to give a summary of the role of Bcl-2 in breast cancer.
