Expression of CXCR-4 and IDO in human colorectal cancer: An immunohistochemical approach.

C-X-C chemokine receptor type 4 (CXCR4), the receptor for the chemokine stromal cell-derived factor (SDF)-1 [also known as C-X-C motif chemokine 12 (CXCL12)], is involved in lymphocyte trafficking. Recent studies have demonstrated that, during pregnancy, a placental enzyme called indoleamine 2, 3-dioxygenase (IDO) exerts a key role in suppressing the maternal T-cell response against the fetus. In the present study, the significance of CXCR4 and IDO expression in human colorectal cancer (CRC) has been investigated by immunohistochemical assay, and their association with survival was analyzed. Tumor specimens (n=60) from patients with different American Joint Committee on Cancer (AJCC) stages of CRC (I or IV) were assessed. In the stage IV group, 23 of 30 cases (77%) stained positive for CXCR4, and 9 of 30 (30%) were positive for IDO. By contrast, in the stage I group, 7 of 30 cases (23%) stained positive for CXCR4, and 15 of 30 cases (50%) were positive for IDO. The 5-year survival rate of those with high CXCR4 expression in tumor specimens (n=30) was significantly worse compared with those with negative CXCR4 expression (16.3 vs. 60.7%, P=0.02). By contrast, the 5-year survival rate of those with high IDO expression in tumor specimens (n=24) was not significantly different compared with those with negative IDO expression (36.4 vs. 56.8%). In the stage I group, 4 patients in the high IDO expression group (n=15) had distant metastases (2 in the liver 1 in the brain, and 1 in the lung). Taken together, CXCR4 appears to be a novel predictive indicator of survival, and IDO expression in the early stage may be a predictor of distant metastasis.