Transmembrane receptor CXCR7 increases the risk of extrahepatic metastasis of relatively well-differentiated hepatocellular carcinoma through upregulation of osteopontin

Abstract

Recurrence and metastasis are the main obstacles to improving the survival of patients with post-resective hepatocellular carcinoma (HCC). Our previous study suggests a critical role of CXCR7 in the metastasis of HCC. In the present study, the effect of CXCR7 as a risk factor for metastasis of HCC was evaluated. Immunohistochemical assay was performed on tissue microarrays based on HCC with extrahepatic metastases after hepatectomy. Two categories based on staining scores were used to evaluate the risk effect of CXCR7, respectively. The effect of CXCR7 on osteopontin (OPN) was explored by RNA interference. Based on the results, in both categories, highly expressed CXCR7 was a dependent risk factor for extrahepatic metastasis because of the potential association with relatively good cell differentiation. Stratification analyses indicated that CXCR7 was a strong independent risk factor (OR, 3.40; 95% CI, 1.07-18.84; P=0.038 in category 1 and OR, 6.40; 95% CI, 1.64-24.92; P=0.007 in category 2, respectively) in patients with Edmondson grade 1/2. Furthermore, CXCR7 correlated well and positively with expression of OPN (P=0.019 and P<0.001 in two categories, respectively) in HCC cases with Edmondson grade 1/2. Immunocytochemistry and RT-PCR demonstrated downregulation of OPN in a highly metastatic HCC cell line following knockdown of CXCR7. Taken together, these findings suggest that high expression of CXCR7 increases the risk of metastasis in post-resective HCC patients with relatively good differentiated tumors, potentially through upregulation of OPN. This group of patients may acquire a survival benefit from early detection and treatment of recurrence and metastasis.