Immunohistochemistry with antibodies recognizing ER, PGR, Ki-67, and the p53, c-erbB2, and bcl-2 encoded proteins was performed on 291 primary breast carcinomas.
Its expression has been noted in lymphomas and colonic, lung, and breast carcinomas. bcl-2 protein is believed to play a role in the gastric carcinogenic sequence where it has been demonstrated in dysplastic epithelium.
We retrospectively studied Bcl-2 expression in 124 primary tumors from patients diagnosed with T1 (2 cm or less) breast carcinoma with (T1N1) or without (T1N0) lymph-node metastasis.
The observations from this study clearly indicate that Bcl-2 in human breast cancer is associated with ER status, and that expression is enhanced in ER+ve tumours following tamoxifen, in association with reduced cell proliferation.
We therefore propose that dysregulation of apoptosis contributes to the pathogenesis of breast cancer, at least in part, due to an imbalance between anti-apoptosis genes (such as bcl-2/bcl-x) and apoptosis-promoting genes (bax).
Thus, loss of bcl-2 expression in breast cancer is associated with a range of molecular markers of poor prognosis and may define part of an ER-negative, EGFR-positive phenotype.
Expression of Bcl-2 is associated with resistance to hormone therapy and recurrence in prostate carcinomas, whereas in lung and breast carcinomas it is associated with a better prognosis.
Bcl-2 has been shown to inhibit apoptosis triggered by wild-type p53 and an inverse correlation between Bcl-2 expression and p53 mutation has been observed in breast cancer and glioma.
Therefore, we propose that dysregulation of apoptosis might contribute to the pathogenesis of breast cancer at least in part due to an imbalance between members of the bcl-2 gene family.
Recently we have shown that the expression of bax-alpha, a death-promoting member of the bcl-2 family, is down-regulated in breast cancer and have provided evidence that low bax expression might contribute to the pathogenesis of breast cancer.
From these results, we infer the existence of hormonal regulation of Bcl-2 expression and evoke a novel role for estradiol and progestin in the genesis of breast cancer.
The purpose of this study was to investigate the relationship between bcl-2 and p53 expression and to clarify their roles in apoptosis in different histological graded breast carcinomas.
The utility of biomarkers involved in DNA damage repair (p53 protein), control of programmed cell death (p53 and Bcl-2 proteins), and cellular detoxification (glutathione S-transferase-pi [GST-pi] enzyme) in predicting local breast cancer recurrence was analyzed retrospectively in two cohorts of breast cancer patients.
Bax, one of the bcl-2 family genes, is expressed in a number of untransformed cell lines and various breast tissues, whereas only weak or no expression has been detected in breast cancer cell lines and malignant breast tissue.