15-Hydroxyprostaglandin dehydrogenase as a marker in colon carcinogenesis: analysis of the prostaglandin pathway in human colonic tissue

BACKGROUND/AIMS Cyclooxygenase-2 (COX-2), 15-hydroxyprostaglandin dehydrogenase (15-PGDH), and microsomal prostaglandin E synthase-1 (mPGEs-1) regulate prostaglandin E2 (PGE2) expression and are involved in colon carcinogenesis. We investigated the expression of PGE2 and its regulating genes in sporadic human colon tumors and matched normal tissues. METHODS Twenty colonic adenomas and 27 colonic adenocarcinomas were evaluated. COX-2 and 15-PGDH expression was quantified by real-time polymerase chain reaction. The expression of PGE2 and mPGEs-1 was measured using enzyme-linked immunosorbent assay and Western blotting, respectively. RESULTS The expression of COX-2, mPGEs-1, and PGE2 did not differ between the adenomas and matched distant normal tissues. 15-PGDH expression was lower in adenomas than in the matched normal colonic tissues (P<0.001). In adenocarcinomas, mPGEs-1 and PGE2 expression was significantly higher (P<0.001 and P=0.020, respectively), and COX-2 expression did not differ from that in normal tissues (P=0.207). 15-PGDH expression was significantly lower in the normal colonic mucosa from adenocarcinoma patients than in the normal mucosa from adenoma patients (P=0.018). CONCLUSIONS Early inactivation of 15-PGDH, followed by activation of COX-2 and mPGEs-1, contributes to PGE2 production, leading to colon carcinogenesis. 15-PGDH might be a novel candidate marker for early detection of field defects in colon carcinogenesis.