Cyclooxygenase-2 expression is related to prostaglandin biosynthesis and angiogenesis in human gastric cancer

Although recent studies have demonstrated that cyclooxygenase (COX)-2 is ov erexpressed in various cancers including gastric cancer, the mechanisms und erlying the contribution of COX-2 to tumorigenesis and tumor promotion stil l remain unclear. To determine the role of COX-2, we investigated the COX-2 expression, the prostaglandin (PG) levels, and the microvessel density in 42 patients with primary gastric adenocarcinoma, COX-2 protein was overexpr essed in 31 (74%) of 42 gastric cancers based on an immunoblot analysis. Th e intensity of COX-2 expression was found to significantly correlate with l ymph node involvement. The COX-2 overexpressed cases showed significantly e levated levels of prostaglandin E-2 (PGE(2)) in cancer tissues in compariso n with the normal gastric mucosa by an immunoassay (201 +/- 90 versus 161 /- 57 ng/mg protein; P < 0.05), However, the COX-2 overexpression was not r elated to the levels of thromboxane B-2 and 6-keto-prostaglandin F-1 alpha. The density of microvessel immunostained with CD34 was significantly highe r in patients demonstrating COX-2 overexpression than in those without such expression (63 +/- 21 versus 45 +/- 17/200 x; P < 0.01), Our data thus sug gested COX-2 overexpression to be associated with increased PGE, biosynthes is and angiogenesis in gastric cancer, which indicates that COX-2 may play a role in the development of gastric cancer.