Cyclooxygenase-2 in sporadic colorectal polyps: immunohistochemical study and its importance in the early stages of colorectal tumorigenesis.
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.
Tatsu
Kazuhito
K
Department of Legal Medicine, Faculty of Medicine, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama, Japan 930-0194.
Hayashi
Shinichi
S
Shimada
Ichiroh
I
Matsui
Kazuhiro
K
D000230:Adenocarcinoma / Q000201:enzymology* / Q000473:pathology; D000236:Adenoma / Q000201:enzymology* / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism; D002452:Cell Count; D003111:Colonic Polyps / Q000201:enzymology* / Q000473:pathology; D015179:Colorectal Neoplasms / Q000201:enzymology* / Q000473:pathology; D051546:Cyclooxygenase 2; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D009378:Neoplasms, Multiple Primary / Q000201:enzymology* / Q000473:pathology; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*
D014408:Biomarkers, Tumor; D008565:Membrane Proteins; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases