Differential expression of COX-2: A potential marker for clinical phenotypes of Gastric Cancer

COX-2 is a key enzyme in prostaglandin synthesis which can be induced by many growth factors and pro-inflammatory cytokines. COX-2 is related to inflammation and carcinogenesis. It’s over expression leads to the accumulation of prostaglandins and thereby promoting carcinogenesis. By using the semi-quantitative reverse transcription PCR and immunohistochemistry, we show that COX-2 was frequently over expressed in gastric carcinoma. COX-2 was significantly differentially expressed within different clinical parameters such as tumor stages (I+II and III+IV), metastasis (lymph node and liver), tumor invasion types (serosal, and lymphatic), histological types (intestinal and diffuse), gender and age groups. We also demonstrate that H. pylori infected samples show significantly higher expression of COX-2 than non infected samples. We also demonstrate that H. pylori negative samples do not show differential expression of COX-2 in histology type, but H. pylori infected sample show significant differentially higher expression of COX-2 in intestinal histology type. Interestingly, we have also found that the level of COX-2 immunoreactivity gradually increases with tumor stages; I+II and III+IV similar to RT-PCR data. Thus, our data suggest that the COX-2 expression and its cross talk with H. pylori infection may be critical in the progression of gastric cancer.