Cyclooxygenase-2 in sporadic colorectal polyps: Immunohistochemical study and its importance in the early stages of colorectal tumorigenesis

• Published in: Pathology, research and practice Vol. 201; no. 6; pp. 427 - 433
• Main Authors: Tatsu, Kazuhito, Hayashi, Shinichi, Shimada, Ichiroh, Matsui, Kazuhiro
• Format: Journal Article
• Language: English
• Published: Germany Elsevier GmbH 01.01.2005
• Subjects: Adenocarcinoma - enzymology; Adenocarcinoma - pathology; Adenoma - enzymology; Adenoma - pathology; Adult; Aged; Aged, 80 and over; Biomarkers, Tumor - metabolism; Carcinoma in adenoma; Cell Count; Colonic Polyps - enzymology; Colonic Polyps - pathology; Colorectal adenoma; Colorectal Neoplasms - enzymology; Colorectal Neoplasms - pathology; Cyclooxygenase 2; Early Diagnosis; Female; Humans; Immunohistochemistry; Male; Membrane Proteins; Middle Aged; Neoplasms, Multiple Primary - enzymology; Neoplasms, Multiple Primary - pathology; Prostaglandin-Endoperoxide Synthases - metabolism; Immunohistochemistry; Colorectal adenoma; Cyclooxygenase-2; Carcinoma in adenoma
• ISSN: 0344-0338; 1618-0631
• DOI: 10.1016/j.prp.2005.03.009

Cyclooxygenase-2 (COX-2) is one of the important targets for the chemoprevention of colorectal cancer by non-steroidal anti-inflammatory drugs (NSAIDs). To evaluate the role of COX-2 in early stages of colorectal tumorigenesis, we immunohistochemically investigated the frequency and localization of COX-2 in sporadic colorectal polyps that showed various histology using a commercially available monoclonal antibody. A total of 105 colorectal polyps were examined. These included 33 low-grade adenomas (LGAs), 28 high-grade adenomas (HGAs), 32 HGAs with p53 overexpression (HGAs-p53), and 12 cases of carcinoma in adenoma (CIA). Regarding the immunohistochemical expression of p53, MIB-1, and CD63, histological classification was made for each case. COX-2 was expressed in neoplastic epithelial cells and interstitial macrophages that were distributed mainly in the superficial areas of polyps. COX-2 labeling indices (LIs) were 8.2% in LGAs, 6.3% in HGAs, 0.9% in HGAs-p53, and 0.6% in the carcinomatous components of CIAs. COX-2 LIs were significantly higher in adenomas, including LGAs and HGAs, than in HGAs-p53 and CIAs ( p < 0.001 ). Within CIAs, significantly higher COX-2 LIs were obtained in the adenomatous components than in the carcinomatous components ( p < 0.05 ). The size of polyps was not correlated with COX-2 expression irrespective of their histology. The results show that COX-2 might be involved in early stages of colorectal tumorigenesis. Colorectal adenomas could be a target for the chemopreventive strategy irrespective of their sizes.