Mitochondria-mediated apoptosis in patients with adenocarcinoma of the breast: Correlation with histological grade and menopausal status

The present study was designed to investigate the abnormalities in the expression of apoptosis-associated proteins that lead to the progression of breast cancer. Sixty breast cancer patients histologically categorized as grade I, II and III, and as pre- and post-menopausal were chosen for the study. We analyzed the expression of the anti-apoptotic and pro-apoptotic Bcl-2 family proteins as well as cytochrome C, Apaf-1 and caspases in tumour and adjacent tissues by immunohistochemical and Western blot analyses. The breast tumours analyzed in the present study were characterized by increased expression of Bcl-2, Bcl-xL and Mcl-1, associated with downregulation in the expression of Bax, cytosolic cytochrome C, Apaf-1 and caspases. The magnitude of the changes was however more pronounced in premenopausal patients and in grade III tumours. The results of the present study confirm that differential expression patterns of Bcl-2 family proteins and caspases are involved in evasion of apoptosis and in the progression of breast cancer.