CXCR4 and VEGF expression in the primary site and the metastatic site of human osteosarcoma: analysis within a group of patients, all of whom developed lung metastasis. The chemokine, CXCL12, and its receptor, CXCR4, have recently been shown to play an important role in metastasis of several kinds of carcinoma. It has also been demonstrated that VEGF regulates both the expression of CXCR4 and invasiveness in breast cancer cell lines. We compared the immunohistochemical expression of CXCR4 and VEGF between the primary site and a concordant pulmonary metastatic site in 30 osteosarcoma patients, all of which had undergone thoracotomy. Microvessel density (MVD) as shown by immunostaining of CD34 and proliferative activity with MIB-1 monoclonal antibody was also evaluated. CXCR4 expression (primary, 33.3% positive vs metastatic, 66.6% positive; P = 0.0097) and MVD (primary, 29.86 +/- 6.87/0.26 mm2 vs metastatic, 43.32 +/- 8.65/0.26 mm2; P = 0.0015) in the metastatic site were both significantly increased compared with those in the primary site, whereas no difference between primary and metastatic sites was observed with regard to VEGF expression. There was a significant positive correlation between immunohistochemical CXCR4 and VEGF expression (P = 0.0269). In total population, the MIB-1-labeling index (LI) was significantly higher in tumors, which showed immunoreactivity for VEGF (MIB-1-LI in VEGF-positive tumors, 24.29 +/- 5.4 vs VEGF-negative tumors, 18.33 +/- 4.16; P = 0.034). Furthermore, those patients with VEGF-positive primary tumors had a significantly worse prognosis compared with the patients with VEGF-negative primary tumors (P = 0.0053). Our results suggested that CXCR4 expression was associated with metastatic progression, and immunohistochemical VEGF expression in the primary site had predictive value for the osteosarcoma patients, who developed lung metastasis.