Study On The Relationships Of Expression Of Cdx2 And Cyclooxygenase-2 To Colonic Adenomatous Polyp And Colon Cancer

Background & Aims : Caudal-related homeodomain transcription 2 - Cdx2, an intestinal specific transcription factor in intestinal mucosa villi and crypts, plays a key role in the development and maintenance of the intestinal epithelial phenotype. Cyclooxygenase (COX) is a key enzyme in the synthesis of prostaglandins (PGs) and thromboxanes (TXs). There are three COX isoforms: COX-1, COX-2 and COX-3. COX-2 expression has been found poorly in normal tissue, but it can be induced by many proinflammatory cytokines. To explore the relationship with Cdx2, COX-2, colonic adenomatous polyp and colon cancer, Cdx2 and COX-2 gene products were detected.Methods: Immunohistochemical staining was used to detected Cdx2 and COX-2 expression in the tissues of 30 colonic adenomatous polyps,30 colon cancer and 30 normal colonic mucosa specimens.Results: 1. The positive rates of Cdx2 are 100.00% in normal mucosa, 86.67% in colon adenomatous polyps and 63.33% in colon cancer. It was shown that the positive rate of Cdx2 expression in colon cancer tissues was significantly lower than that in normal colonic mucosa (p<0.005) and in colonic adenomatous polyp (p<0.05). 2. It was shown that the intensity of Cdx2 expression in colon cancer tissues was significantly lower than that in normal colonic mucosa (p<0.01) and in colonic adenomatous polyp (p<0.05). The intensity of Cdx2 expression in colonic adenomatous polyp was lowerthan that in normal colonic mucosa (pO.Ol), The intensity of Cdx2 expression in villous adenoma was lower than that in tubular adenoma (p<0.05). The intensity of Cdx2 expression in low differentiation colon cancer tissues was significantly lower than that in high differentiation, and that in tubular adenocarcinoma was lower than that in papillary adenocarcinoma (p<0.05). 3. The positive rates of COX-2 are 26.67% in normal mucosa, 53.33% in colon polyps and 80.00% in colon cancer. It was shown that the positive rate of COX-2 expression in colon cancer tissues was significantly higher than that in normal colonic mucosa (p<0.005) and in colonic polyps (p<0.05). 4. It was shown that the intensity of COX-2 expression in colon cancer tissues was significantly higher than that in normal colonic mucosa (p<0.01) and in colonic adenomatous polyp (p<0.05). The intensity of COX-2 expression in colonic adenomatous polyp was higher than that in normal colonic mucosa (p<0.05). The intensity of COX-2 expression in tubular adenoma was lower than that in villous adenoma (p<0.01) and in tubulovillous adenoma (p<0.05). The intensity of COX-2 expression in low differentiation colon cancer tissues was significantly higher than that in high differentiation (p<0.01) and in moderate differentiation (p<0.05). In tubular adenocarcinoma the intensity of COX-2 expression was higher than that in papillary adenocarcinoma (p<0.05). Conclusions: Cdx2 is an intestine-specific tumor suppressor gene encoding homeodomain-containing transcription factor. Cyclooxygenases-2(COX-2) are rate-limiting enzymes in the synthesis of prostaglandins(PGs). Cdx2 down-regulation and COX-2 up-regulation may play an important role in the development of in the tissues of colon cancer and colonic adenomatous polyp. In addition, reduced Cdx2 expression and COX-2 up-regulation may have associated with cell differentiation and pathologic grade of colonicadenomatous polyp and colon cancer.