Roles of Chemokine Receptor 4 (CXCR4) and Chemokine Ligand 12 (CXCL12) in Metastasis of Hepatocellular Carcinoma Cells

Chemokines are involved in human hepatocellular carcinoma (HCC) carcinogenesis. However, the exact mechanism of chemokines in HCC carcinogenesis remains unknown. Here we investigated the roles of chemokine receptor 4 (CXCR4) and chemokine ligand 12 (CXCL12) in the metastasis of HCC. We found that the expression levels of CXCR4 mRNA in HCC tissues, MHCC97 cells, and HUVEC cells were 2.52 ± 1.13, 2.34 ± 1.16 and 1.63 ± 1.26, respectively and that the CXCR4 protein levels were 1.38 ± 0.13, 1.96 ± 0.32 and 1.86 ± 0.21, respectively. In contrast, CXCR4 was not detected in normal hepatic tissues. In 78 HCC patients, we also found that the concentration of CXCL12 in cancerous ascitic fluid was 783-8,364 pg/ml and that CXCL12 mRNA level in HCC metastasis portal lymph nodes was 1.21 ± 0.87 but undetectable in normal hepatic tissues. Finally we discovered that recombinant human CXCL12 could induce MHCC97 cells and HUVEC cells to migrate with chemotactic indexes (CI) of 3.9 ± 1.1 and 4.1 ± 1.6, respectively. Cancerous ascetic fluid could also induce the migration of MHCC97 cells with a CI of 1.9 ± 0.8. Thus, our data suggest that CXCR4 and CXCL12 may play an important role in the metastasis of HCC by promoting the migration of tumor cells.