Cyclooxygenase-2 expression is associated with initiation of hepatocellular carcinoma, while prostaglandin receptor-1 expression predicts survival

AIM To determine whether cyclooxygenase-2 (COX-2) and prostaglandin E1 receptor (EP1) contribute to disease and whether they help predict prognosis. METHODS We retrospectively reviewed the records of 116 patients with hepatocellular carcinoma (HCC) who underwent surgery between 2008 and 2011 at our hospital. Expression of COX-2 and EP1 receptor was examined by immunohistochemistry of formalin-fixed, paraffin-embedded tissues using polyclonal antibodies. Possible associations between immunohistochemical scores and survival were determined. RESULTS Factors associated with poor overall survival (OS) were alpha-fetoprotein > 400 ng/mL, tumor size ≥ 5 cm, and high EP1 receptor expression, but not high COX-2 expression. Disease-free survival was not significantly different between patients with low or high levels of COX-2 or EP1. COX-2 immunoreactivity was significantly higher in well-differentiated HCC tissues (Edmondson grade I-II) than in poorly differentiated tissues (Edmondson grade III-IV) (P = 0.003). EP1 receptor immunoreactivity was significantly higher in poorly differentiated tissue than in well-differentiated tissue (P = 0.001). CONCLUSION COX-2 expression appears to be linked to early HCC events (initiation), while EP1 receptor expression may participate in tumor progression and predict survival.