Expression of Cyclooxygenase-2 and its Relationship to p53 Accumulation in Colorectal Cancers

PURPOSE: Cyclooxygenase (COX)-2 is an inducible isoform responsive to cytokines, mitogens, and growth factors, and is believed to be an important enzyme related to colorectal cancer (CRC). Existing evidence suggests that COX-2 expression is normally suppressed by wild-type p53 but not mutant p53, suggesting that loss of p53 function may result in the induction of COX-2 expression. The aim of this study was to determine the relationship between COX-2 expression and p53 levels in CRC. MATERIALS AND METHODS: Patients with sporadic colorectal adenocarcinoma (n = 161) who underwent curative surgery in Chosun University Hospital were enrolled in this study. Expression of COX-2 and p53 proteins was examined by immunohistochemistry in paraffin-embedded cancer tissue blocks, and the relationship between COX-2 and/or p53 expression with clinicopathologic parameters was analyzed. RESULTS: Expression of COX-2 was positive in 47.8% of colorectal cancers, and significantly associated with the depth of tumor invasion (p = 0.042). In contrast, p53 was positive in 50.3% of the cases, and was associated with both age (p = 0.025) and the depth of tumor invasion (p = 0.014). There was no correlation between COX-2 expression and p53 expression (p = 0.118). CONCLUSION: These results suggest that COX-2 expression might play an important role in the progression of colorectal cancer. However, COX-2 expression was not associated with mutational p53. Further studies are needed to clarify the regulatory mechanisms governing COX-2 overexpression in colorectal cancers.