Overexpression of Thy1/CD90 in human hepatocellular carcinoma is associated with HBV infection and poor prognosis

Thy1/CD90 is an important marker of many types of stem cells. It functions as a tumor suppressor in ovarian cancer and in nasopharyngeal carcinoma. In this study, the expression status of Thy1 in clinical hepatocellular carcinoma (HCC) tissue samples was investigated. Relationships of Thy1 expression with clinical parameters and patient survival rate were analyzed. The quantities of Thy1 mRNA were statistically higher in tumor tissues than those in the adjacent non-tumor tissues (p < 0.001). Immunohistochemical data confirmed that Thy1 protein was increased in 73% of HCC samples. Thy1 expression was not influenced by chronic alcohol exposure or cirrhosis. Overexpression in Thy1 was correlated with age (p = 0.006), hepatitis B virus (HBV) infection (p = 0.044), and histological grade (p = 0.014). Patients with the highest level of Thy1 expression showed the poorest prognosis (p = 0.040). In conclusion, overexpression of Thy1 may not suppress the development of HCC. Thy1 could provide a clinical prognostic marker for HCC.