Background and aim: Hepatocellular carcinoma (HCC) is unique in that its carcinogenesis is related to inflammatory changes and regenerative activities in the background liver. Although there are some data on cyclooxygenase (COX)-2 expression in HCC by immunohistochemical studies, little is known about the possible role of COX-2 in inducing hepatitis and/or carcinoma. To elucidate whether COX-2 is involved in a part of these processes, we attempted to examine COX-2 mRNA both in the adjacent non-tumoral liver and in HCC.
Methods: Twenty-two matched sets of adjacent liver and HCC specimens were analyzed for COX-2 mRNA expression using a real-time quantitative reverse transcription polymerase chain reaction. Cyclooxygenase-2 protein expression was also determined by immunohistochemistry.
Results: Cyclooxygenase-2 mRNA expression was significantly higher in the adjacent liver than in HCC (P = 0.016). Cyclooxygenase-2 mRNA expression in adjacent liver tissues was positively correlated with the modified histological activity index scores (r = 0.575, P = 0.006), the serum alanine aminotransferase levels (r = 0.536, P = 0.010), and the Ki-67 labeling indices (r = 0.698, P = 0.001). In contrast, COX-2 mRNA expression in HCC was not correlated with any of the clinicopathological features.
Conclusions: Cyclooxygenase-2 is expressed at higher levels in the adjacent liver than in HCC, and it may be associated with high levels of necroinflammation and regeneration in the background liver. Conversely, COX-2 may have a lesser role in the progression of HCC.