Loss of CD155 expression predicts poor prognosis in hepatocellular carcinoma.

ABSTRACT

AIMS: CD155 is an important ligand in triggering tumour rejection by immune cells. However, the expression of CD155 and its clinical significance in hepatocellular carcinoma (HCC) remains unknown. METHODS AND RESULTS: We examined the expression level of CD155 in 174 HCC tissue samples by immunohistochemical staining and in HCC cell lines by flow cytometry; 63.8% (111 of 174) of HCC tissue samples showed negative CD155 expression. When compared with adjacent peritumour tissues, HCC tissues exhibited a significantly lower expression of CD155 (P < 0.001). Flow cytometry analysis indicated that HCC cell lines had low levels of CD155 expression. Moreover, negative CD155 expression was associated significantly with higher serum α-fetoprotein level (P = 0.016) and a higher incidence of portal vein tumour thrombus (P = 0.050). Importantly, patients with positive CD155 expression had better overall survival after surgery than those with negative CD155 expression (P = 0.005). Furthermore, Cox regression analyses showed that CD155 expression was an independent prognostic factor for HCC (P = 0.049). CONCLUSIONS: Our findings suggest that loss of CD155 expression may play an important role in the immune escape of HCC cells and thus CD155 may serve as a prognostic marker as well as a potential therapeutic target for HCC.