Expression of cyclooxygenase-2 in human gastric adenomas and adenocarcinomas

BACKGROUND AND OBJECTIVES: The increased expression of cyclooxygenase (COX)-2 has been implicated in the development and progression of colorectal cancer. We sought to determine the involvement of COX-2 in human gastric cancer. MATERIALS AND METHODS: COX-2 mRNA was assayed in both gastric cancer cell lines and biopsy specimens from 37 gastric adenocarcinomas, five gastric adenomas, and five hyperplastic polyps by reverse transcription-polymerase chain reaction. RESULTS: COX-2 mRNA was found in four of five gastric cancer cell lines, two from intestinal type and two from diffuse type. COX-2 mRNA was expressed in 19 of 37 (51%) human gastric cancer specimens. The tumor diameter was greater in patients with COX-2 expression than in those without (6.5 +/- 4.6 vs. 3.8 +/- 2.7 cm, P < 0.05). The incidence of COX-2 mRNA expression was significantly higher in patients with pT2-pT4 tumors than in those with pT1 tumors (71 vs. 35%, P < 0.05). Significantly higher expression of COX-2 mRNA was also observed in patients with lymph node involvement than in those without (75 vs. 40%, P < 0.05). COX-2 mRNA was found in one of five adenomas, while it was absent in five hyperplastic polyps. The paired normal gastric musosa did not express COX-2 mRNA in any of the 47 patients. CONCLUSIONS: These results provide clinical evidence that COX-2 may contribute to tumor progression in human gastric adenocarcinoma.