Glucose regulated protein 78 (GRP78) is overexpressed in colorectal carcinoma and regulates colorectal carcinoma cell growth and apoptosis

Glucose regulated protein 78 (GRP78) plays an important role in the development and progression of cancer. However, the role of GRP78 in colorectal carcinoma still remains unclear. In this study, using immunohistochemistry and RT-PCR, we explored the expression patterns of GRP78 in colorectal carcinoma. We knocked down GRP78 expression in RKO cells using shRNA-GRP78. Apoptosis and proliferation assay were performed. We found increased GRP78 expression with progression along the normal tissue–adenoma–carcinoma sequence, while there was no difference in the relative mRNA expression of GRP78 among normal, adenoma and colorectal carcinoma. The shRNA-GRP78 plasmid caused a significant reduction of GRP78 expression at both mRNA and protein levels. Furthermore, knockdown of GRP78 not only efficiently suppressed proliferation of RKO cells, but also induced early apoptosis of cells. In conclusion, our study demonstrated that GRP78 may play some important roles in the development and progression of colorectal carcinomas. The expression of GRP78 is associated with the enhanced proliferation of colorectal carcinoma cells and with their resistance to apoptosis.