Immunohistochemical expression of Bcl-2 protein in breast lesions: Correlation with Bax, p53, Rb, C-erbB-2, EGFR and proliferation indices

Expression of bcl-2 protein was investigated and correlated with Bax, p53 a nd Rb proteins c-erbB-2 EGFR and the proliferation indices PCNA, Ki-67 and MIBI as well as with the conventional clinicopathological parameters in 95 cases for breast cancer tissue and 20 cases of benign hyperplastic lesions. Bcl-2 and Bax: proteins immunoreactivity was detected in normal hyperplast ic and neoplastic breast epithelium. Expression of the bcl-2 protein was de tected in 40% of carcinomas (>10% positive neoplastic cells) and 85.2% of t he benign hyperplastic lesions. Bax protein expression was detected in 8.1% of the carcinomas and 5.3% in the hyperplastic group. Rb and p53 proteins were defected in 75.5% and 45.5% of carcinomas. No relationship was observe d between bcl-2 expression and patient's age, tumour size, tumour type and grade, lymphnode status, Rb protein expression and proliferation indices. H owever; a strong positive relationship was detected between bcl-2 and Bax ( p=0.008), estrogen (ER) (p=0.007 and progesterone receptors' (PgR) status ( p=0.0003). An inverse correlation with p53 protein (p=0.004) was detected. Furthermore, a strong correlation was also observed between pRb and p53 (p= 0.001). The results indicate that in breast cancer bcl-2 protein expression may be under hormonal control. Since the expression is bcl-2 protein was i nversely correlated with p53 protein expression, we suggest that bcl-2 may be related with favourable outcome in breast cancer.