[Effects of cyclooxygenase-2 and proliferating cell nuclear antigen on the onset and development of familial adenomatous polyposis].

Background and objective: Long-term use of cyclooxygenase-2 (COX-2) inhibitors can reduce the incidence of digestive cancers, such as colorectal cancers. Proliferating cell nuclear antigen (PCNA) is an important marker of cellular abnormal proliferation. This study was to evaluate the roles and correlation of COX-2 and PCNA in the onset and development of familial adenomatous polyposis (FAP) diseases.

Methods: Thirty-six specimens of FAP adenomas tissues and 32 specimens of FAP carcinoma tissues from 11 FAP families, and 34 specimens of normal colonic mucosa were collected under colonoscopy from November 2004 to July 2007 in the General Hospital of Beijing Military Command. Immunohistochemistry was used to detect the expressions of COX-2 and PCNA.

Results: The positive expression rates of COX-2 in normal colonic mucosa, FAP adenoma, and carcinoma tissues were 0 (0/34), 80.6% (29/36), and 93.8% (30/32), respectively. Proliferation index (PI) in normal mucosa, FAP adenoma, and carcinoma tissues were 17.79+/-7.49, 34.47+/-10.57, and 71.75+/-9.22, respectively. Expressions of COX-2 and PCNA were significantly higher in the FAP adenoma and the carcinoma tissues than in the normal colonic mucosa(P<0.01). The expression of PCNA was significantly higher in the FAP carcinoma tissues than in the FAP adenoma (P<0.01). The expression of PCNA was higher in the FAP adenoma tissues with positive COX-2 than in the FAP adenomas tissues with negative COX-2 (P<0.01).

Conclusions: COX-2 may play an important role in the development of FAP adenomas and colorectal carcinogenesis. COX-2 and PCNA may be important factors in the research on colorectal precancerous lesions and interventional therapy for colorectal neoplasm.