Expression of Cyclooxygenase-2 and Bcl-2 in human gastric adenomas

Cyclooxygenase (COX)-2 is the rate-limiting enzyme in prostaglandin synthesis. An increased expression has been implicated in the development and progression of human gastric cancers and colorectal adenomas and cancers. This study aimed to determine the involvement and association of COX-2 and Bcl-2 in precancerous gastric adenomas.

Seventy-nine gastric polyps were obtained by endoscopic mucosal resection or polypectomy from January, 2000 to July, 2003. Immunohistochemical expression of COX-2 and Bcl-2 was observed, and their relationships with various clinicopathological factors were analyzed.

Histologically, 13 hyperplastic polyps and 66 tubular adenomas, of which 17 showed high-grade dysplasia, were observed. Increased COX-2 expression was observed in low-grade and high-grade tubular adenomas compared to hyperplastic polyps (p=0.004 and p=0.001, respectively). COX-2 expression was significantly higher in larger (>1 cm) compared with smaller (<1 cm) tubular adenomas (o=0.034), but no relation was observed in hyperplastic polyps. While Bcl-2 expression differed significantly according to histology, increased Bcl-2 expression was observed especially in COX-2 positive low-grade tubular adenomas.

COX-2 expression increased in a size-dependent manner in tubular adenomas, suggesting a role in polyp growth. The increased expression of Bcl-2 in tubular adenomas, especially in COX-2 positive tubular adenomas, suggests that COX-2 action may be related to Bcl-2 expression.