These results indicate that Bmi-1 may play an important role in radiosensitivity, and the suppression of its expression might be a potential therapeutic target for breast cancer.
Bmi-1 mRNA is significantly up-regulated in adjacent normal breast tissue in breast cancer patients compared to normal breast tissue from noncancerous patients.
Bmi-1 was expressed in 53.2% of breast cancer patients by immunohistochemistry, and the expression of Bmi-1 was significantly correlated with favorable prognostic indices at diagnosis.
Here, we report that the expression of Bmi-1 and Mel-18 inversely correlates in a number of breast cancer cell lines and in a significant number of breast tumor samples.
The higher expression levels of Bmi-1 correlated with well-established markers of poor clinical outcome in breast cancer such as positive p53 immunostaining and negative progesterone receptors.
Our data suggest that the oncogenic role of Bmi-1 in human primary breast carcinomas is not determined by its capacity to inhibit INK4a/ARF proteins or to induce telomerase activity.