Background/aims: Cyclooxygenase-2 (Cox-2) is an isoform of cyclooxygenase, which is the key enzyme converting arachidonic acids to prostaglandins. It has been reported that Cox-2 is overexpressed in colon cancer, and that inhibition of this enzyme activity reduces colon cancer development in humans and animals. However, the significance of Cox-2 in human liver cancer is still unclear. To clarify significance of Cox-2 in liver cancer, we immunohistochemically examined expression of this enzyme in cancerous and non-cancerous tissues of hepatocellular carcinoma (HCC).
Methodology: Twenty-nine patients with HCC were examined; 10 patients had well differentiated HCC, 10 had moderately differentiated HCC, and 9 had poorly differentiated HCC.
Results: Twenty-eight of 29 (97%) patients with HCC exhibited a positive staining. More intense staining of Cox-2 in cancer tissue rather than non-cancerous tissue was observed in 7 of 10 (70%) patients with well differentiated HCC, in 3 of 10 (30%) with moderately differentiated HCC, and in 3 of 9 (33%) with poorly differentiated HCC, respectively. Rate of higher expression of Cox-2 in cancer tissue rather than in non-cancerous tissue of well differentiated HCC was increased, compared to that of moderately and poorly differentiated HCC (7/10 vs. 6/19, p < 0.05).
Conclusions: The results of the present study showed that Cox-2 is related to HCC whose histology is well differentiated.