Expression and functions of the repressor element 1 (RE-1)-silencing transcription factor (REST) in breast cancer

The repressor element 1 (RE-1)-silencing transcription factor (REST), also known as the neuron-restrictive silencer factor (NRSF) or repressor binding to the X2 box (XBR), REST/NRSF/XBR, is originally discovered as a transcriptional repressor of a large number of primarily terminal neuronal differentiation genes in non-neuronal cells and neural stem cells (NSCs). Recently, the tumor-suppressor function of REST is finally proved. However, the expression profile and function of REST in breast cancer are not very clear. In this study, the expression of REST was detected in breast cancer tissue by immunohistochemistry. The results showed that REST expression was significantly lower in breast cancer samples compared to normal and benign breast samples (P < 0.05). Furthermore, the shRNA approach was used to investigate the function of REST in human breast cancer cells. Knocking down REST expression by shRNA in the human breast cancer MCF-7 cells resulted in an increase in cell proliferation, suppression in apoptosis, and reduced sensitivity to anticancer drug with a concurrent significantly up-regulated expression of Bcl-2. These data implied a significant role of REST in breast cancer. The reduced expression of REST might contribute to the breast cancer pathogenesis.