Desensitization of T lymphocyte function by CXCR3 ligands in human hepatocellular carcinoma

AIM: Despite the presence of lymphocyte infiltration, human hepatocellular carcinoma (HCC) is typically a rapidly progressive disease. The mechanism of regulation of lymphocyte migration is poorly understood. In this study,we investigated various factors regulating T cell migration in HCC patients. We examined serum CXC chemokine levels in HCC patients and demonstrated the production of CXC chemokines by HCC cell lines. We determined the effect of both HCC patient serum and tumor cell conditioned supernatant upon lymphocyte expression of chemokine receptor CXCR3 as well as lymphocyte migration. Lastly,we examined the chemotactic responses of lymphocytes derived from HCC patients.METHODS: The serum chemokines IP-10 (CXCL10) and Mig (CXCL9) levels were measured by cytometric bead array (CBA) and the tumor tissue IP-10 concentration was measured by ELISA. The surface expression of CXCR3 on lymphocytes was determined by flow cytometry. The migratory function of lymphocytes to the corresponding chemokines was assessed using an in vitro chemotactic assay. Phosphorylation of extracellular signal-regulated kinase (ERK) was determined by Western blot analysis.RESULTS: Increased levels of IP-10 and Mig were detected in HCC patient serum and culture supernatants of HCC cell lines. The IP-10 concentration in the tumor was significantly higher than that in the non-involved adjacent liver tissues.HCC cell lines secreted functional chemokines that induced a CXCR3-specific chemotactic response of lymphocytes.Furthermore, tumor-cell-derived chemokines induced initial rapid phosphorylation of lymphocyte ERK followed by later inhibition of ERK phosphorylation. The culture of normal lymphocytes with HCC cell line supernatants or medium containing serum from HCC patients resulted in a significant reduction in the proportion of lymphocytes exhibiting surface expression of CXCR3. The reduction in T cell expression of CXCR3 resulted in reduced migration toward the ligand IP-10, and both CD4+ and CD8+ T cells from HCC patients exhibited diminished chemotactic responses to IP-10 in vitro compared to T cells from healthy control subjects.CONCLUSION: This study demonstrates functional desensitization of the chemokine receptor CXCR3 in lymphocytes from HCC patients by CXCR3 ligands secreted by tumor cells. This may cause lymphocyte dysfunction and subsequently impaired immune defense against the tumor.

Tumor cyclooxygenase-2 levels correlate with tumor invasiveness in human hepatocellular carcinoma

AIM: Recent studies suggested that cyclooxygenase-2(COX-2) enhances tumor angiogenesis via upregulationof vascular endothelial growth factor (VEGF). AlthoughCOX-2 expression has been demonstrated in hepatocellularcarcinoma (HCC), the significance of COX-2 in progressionof HCC remains unclear. This study evaluated the clinico-pathological correlation of COX-2 level and its relationshipwith VEGF level in HCC.METHODS: Fresh tumor tissues were obtained from 100patients who underwent resection of HCC. COX-2 proteinexpression was examined by immunohistochemistry, andquantitatively by an enzyme immunometric assay (EIA)of tumor cytosolic COX-2 levels. Tumor cytosolic VEGFlevels were measured by an ELISA.RESULTS: Immunostaining showed expression of COX-2in tumor cells. Tumor cytosolic COX-2 levels correlatedwith VEGF levels (r = 0.469, P＜0.001). Correlation withclinicopathological features showed significantly highertumor cytosolic COX-2 levels in the presence of multipletumors (P = 0.027), venous invasion (P = 0.030),microsatellite lesions (P = 0.037) and advanced tumorstage (P = 0.008). Higher tumor cytosolic COX-2 levelswere associated with worse patient survival.CONCLUSION: This study shows that elevated tumorCOX-2 levels correlate with elevated VEGF levels andinvasiveness in HCC, suggesting that COX-2 plays a significantrole in the progression of HCC.

Clinical significance of serum vascular cell adhesion molecule-1 levels in patients with hepatocellular carcinoma

AIM: To evaluate the correlation between serum vascular cellular adhesion molecule-1 (VCAM-1) levels and clinicopathological features in patients with hepatocellular carcinoma (HCC).METHODS: Ninety-six patients who underwent HCC resection were recruited in the study. Preoperative serum levels of soluble VCAM-1 were measured by enzyme-linked immunosorbent assay.RESULTS: Serum VCAM-1 level in HCC patients was inversely correlated with platelet count (r=-0.431,P＜0.001)and serum albumin level (r=-0.279, P＜0.001), and positively correlated with serum bilirubin level (r=-0.379, P＜0.001).Serum VCAM-1 level was not associated with tumor characteristics such as tumor size, venous invasion,presence of microsatellite nodules, tumor grade and tumor stage. Serum VCAM-1 level was significantly higher in HCC patients with cirrhosis compared with those without cirrhosis (median 704 vs 546 ng/mL, P＜0.001). Furthermore, a significantly better disease-free survival was observed in HCC patients with low VCAM-1 level (P=0.019).CONCLUSION: Serum VCAM-1 level appears to reflect the severity of underlying chronic liver disease rather than the tumor status in HCC patients, and low preoperative serum VCAM-1 level is predictive of better disease-free survival after surgery.