Association of cyclooxygenase-2 expression with Hp-cagA infection in gastric cancer

AIM: To observe the expression of cyclooxygenase-2 (COX-2) and to investigate the association between COX-2 expression and infection with cytotoxic-associated gene A (cagA) positive strain Helicobacter pylori(Hp) in human gastric cancer, and subsequently to provide fresh ideas for the early prevention of gastric cancer. METHODS: 32 Specimens of gastric cancer and corresponding adjacent normal gastric mucosa were obtained from patients who had undergone surgical operations of gastric cancer. All the samples including 1 case of stomach malignant lymphoma and 31 cases of gastric adenocarcinoma were confirmed by pathology diagnosis. The expression of COX-2 in 32 specimens of gastric cancer and corresponding adjacent normal gastric mucosa was quantitatively determined and analyzed with Flow Cytometry, and the levels of COX-2 protein were compared between specimens with cagA(+) Hp infection and those without cagA(+) Hp infection. The cagA gene in 32 specimens of gastric cancer was detected by polymerase chain reaction (PCR) method. RESULTS: Twenty-seven of 32 (84 %) specimens of gastric cancer showed over-expression of COX-2, compared with the adjacent normal gastric mucosa. cagA(+) gene were detected from 19 specimens of gastric cancer, but not from the other 13 specimens. The levels of COX-2 protein in 19 specimens of gastric cancer with cagA(+) Hp infection (the number of positive cells was 73.82 +/- 18.2) were significantly higher than those in the 13 specimens without cagA(+) Hp infection (the number of positive cells was 35.92 +/- 22.1). CONCLUSION: COX-2 is overexpressed in gastric cancer and cagA(+) Hp infection could up-regulate the expression of COX-2 in gastric cancer in human. There may also exist another way or channel to regulate the expression of COX-2 in gastric cancer in addition to cagA(+) Hp infection. Therefore, applying COX-2 selective inhibitors could be an effective and promising way to prevent gastric cancer.