Cyclooxygenase-2 inhibition as a strategy for treating gastric adenocarcinoma.

Cyclooxygenase-2 (COX-2) has been proven to play critical roles in inflammation as well as in cancer. Some studies have shown that the anti-inflammatory, immunosuppressive and anti-arthritic effects of celecoxib are mainly attributed to the inhibition of COX-2 expression. The present study aimed to investigate the function of COX-2 in human gastric adenocarcinoma (GAC). Forty-five cases of human GAC tissues and corresponding adjacent non-cancerous tissues (ANCTs) were collected. The expression of COX-2 and proliferating cell nuclear antigen (PCNA) was assessed using immunohistochemical assay through a tissue microarray procedure. GAC cells (SGC-7901 and MKN-45) in vitro were treated with COX-2 siRNA or different concentrations of celecoxib to observe their effects on cell proliferation, invasion and the underlying molecular mechanisms. As a consequence, the expression of COX-2 and PCNA was found in cancer tissues with a higher strong reactivity rate, compared with the ANCTs (80.0 vs. 53.3%, P=0.011; 68.9 vs. 48.9%, P=0.047), and COX-2 was positively associated with lymph node metastasis of GAC patients (P=0.011). Targeted knockdown of COX-2 inhibited the proliferation, migration and invasion of GAC cells with decreased expression of PCNA. COX-2 inhibitor celecoxib also suppressed the proliferative activities of GAC cells with decreased expression of COX-2 and PCNA. In addition, the tumor volume in the MKN-45 subcutaneous tumor model treated with siCOX-2 was significantly smaller than that of the negative control (NC) group (P<0.01). Taken together, our findings offer a strong preclinical rationale to target COX-2 signaling as a therapeutic strategy to improve the treatment of gastric adenocarcinoma.