Expression And Significance Of BAG-1 In Breast Cancer

Objective To explore the expression of BAG-1, an anti-apopotic protein in breast cancer and its relationship with the expressions of HSP70 and Bcl-2 and their possible roles in the development and progression of breast cancer. Methods Streptavidin-biotin peroxidase (S-P) method of immunohistochemical staining was used to detect the expressions of BAG-1, HSP70 and Bcl-2 in 10 cases of lobular hyperplasia, 10 cases of simplex hyperplasia of duct, 10 cases of atypical hyperplasia adjacent normal breast tissues and 56 cases of breast cancer. Result 1. BAG-1 was undetectable in hyperplasia tissues of breast lobule and simplex hyperplasia tissues of breast duct or weakly expressed (1/10) in atypical hyperplasia tissues. In contrast, BAG-1 was expressed in 69.6%(39/56) of 56 cases of breast cancer. There was a statistical significance between the expression of BAG-1 in breast cancer and that in these tissues(P<0.05). BAG-1 positive cells showed a cytoplasmic(24/39), nuclear (11/39) or cytoplasmic plus nuclear(4/39) staining. 2. HSP70 was also detected in all cases (100%) of hyperplasia tissues of breast lobule, simplex hyperplasia tissues of breast duct and atypical hyperplasia tissues. But the positive rates of the high level expressions of HSP70 in these tissues were 0%. HSP70 was also detected in the majority (96.4%) of 56 cases of breast cancer, and the high level expression of HSP70 in 56 cases of breast cancer was 82.1 %. There was no statistical significance between the expression of HSP70 in breast cancer and that in these tissues(P>0.05). But there was a statisticalsignificance between the high level expression of HSP70 in breast cancer and that in these tissues(P<0.05). HSP70 positive cells showed a cytoplasmic (38/54), nuclear (4/54) or cytoplasmic plus nuclear (12/54) staining. 3. Bcl-2 positive cells (100%) demonstrated cytoplasmic staining, the positive rates of Bcl-2 in 10 cases of lobular hyperplasia, 10 cases of simplex hyperplasia of duct, 10 cases of atypical hyperplasia and 56 cases of breast cancer were 10%(1/10), 10%(1/10), 20%(2/10) and 73.2%(41/56) respectively. There was a statistical significance between the expression of Bcl-2 in breast cancer and that in these tissues(P<0.05). 4.There was no significant correlation between expression of BAG-1, HSP70 and Bcl-2 and patient's age, tumour size, lymph node metastasea or differentiation(PX).05). 5.HSP70 expression correlated positively with BAG-1(P<0.05). 6. Bcl-2 expression correlated positively with BAG-1(P<0.05). Conclusion The adnormal expression of BAG-1 may contribute to the development and progression of breast cancer and the effect of BAG-Ion breast cancer might relate to the activities of HSP70 and Bcl-2.