CC chemokine ligand 7 expression in liver metastasis of colorectal cancer

The main cause of death for colorectal cancer (CRC) patients is the development of metastatic lesions at sites distant from the primary tumor. Therefore, it is important to find biomarkers that are related to the metastasis and to study the possible mechanisms. Recent data have shown that soluble attractant molecules called chemokines support the metastasis of certain cancers to certain organs. To identify molecular regulators that are differentially expressed in liver metastasis of CRC, PCR array analysis was performed and CC chemokine ligand 7 (CCL7) showed remarkable overexpression in liver metastatic tumor tissues. To validate the results of the PCR array, 30 patients with primary CRC and liver metastases were selected. Immunohistochemistry and real-time PCR analysis showed that CCL7 was expressed in normal colonic epithelium and the expression was higher in liver metastases compared to primary CRC (P<0.001). Real-time PCR showed that the expression of CCR1, CCR2 and CCR3 was also higher in liver metastases compared to primary CRC (P=0.001, P=0.033 and P<0.001, respectively). In conclusion, correlation of CCL7 overexpression and its receptor expression with colon cancer liver metastasis suggests that CCL7 as a novel target in liver metastasis of CRC may be of potential clinical value for the prevention of hepatic recurrences.