Nuclear expression of CXCR4 is associated with advanced colorectal cancer

CXCR4 and its ligand, SDF-1 alpha, play an important role in the targeted metastasis of colon cancer. In this study, we analyzed an expression of CXCR4 in clinical samples and showed that SDF-1 alpha affected the expression of CXCR4 in colon cancer cells. A total of 388 patients with colorectal cancer (CRC) who underwent surgery in Taipei Veterans General Hospital from 2000 to 2004 were included. The expression of CXCR4 in CRC was visualized by immunohistochemistry (anti-CXCR4 mAb, R&D 12G5). HCT116, SW480, and SW620 cells were treated with SDF-1 alpha in vitro and the CXCR4 proteins located in the cytoplasmic and nuclear compartments were separated and analyzed with western blotting. The frequency of cytoplasmic and nuclear expression of CXCR4 in colorectal cancers was 35.6% and 36.9%, respectively. Nuclear but not cytoplasmic expression of CXCR4 was associated with advanced CRC (p < 0.001) and lymphovascular invasion. However, in multivariate analysis, nuclear expression of CXCR4 did not correlate with patients' outcome. In the in vitro study, SDF-1 alpha, stimulation of three colorectal carcinoma lines enhanced the CXCR4 nuclear expression. Expression of the CXCR4 plays a role in CRC progression and may be associated with SDF-1 alpha stimulation.