Loss of CD155 expression predicts poor prognosis in hepatocellular carcinoma

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.