Analysis of cyclooxygenase expression in human colorectal adenomas.
BACKGROUND
Evidence from rodent intestinal tumorigenesis models suggests that both cyclooxygenase-1 and cyclooxygenase-2 may play important roles in the development and progression of human sporadic colorectal adenomas. However, previous studies of cyclooxygenase isoform expression in human colorectal adenomas have produced conflicting data. Cyclooxygenase-1 expression has been poorly studied, and cyclooxygenase-2 positivity of adenomas has been variable depending on the detection technique used. It also remains unclear whether villous adenomas express cyclooxygenase-2.


METHODS
Cyclooxygenase isoform expression in human sporadic colorectal adenomas was analyzed by reverse transcription-polymerase chain reaction, Western blot analysis, and immunohistochemistry.


RESULTS
Variable cyclooxygenase-1 expression was detected in all adenomas (n = 9) by both reverse transcription-polymerase chain reaction and Western blot analysis. Cyclooxygenase-2 expression was detected in eight (89 percent) of nine adenomas by reverse transcription-polymerase chain reaction and immunohistochemistry. Cyclooxygenase-2 protein was not detected by Western blot analysis in any adenoma. Cyclooxygenase-2 was expressed by all histopathologic types of adenoma and localized predominantly to superficial interstitial cells, in which it was associated with increased adenoma size.


CONCLUSIONS
Cyclooxygenase-1 is expressed at variable levels by all adenomas. Cyclooxygenase-2 is expressed by the majority of adenomas, including those of the villous type, at levels below the sensitivity of Western blot analysis.
Chapple
Keith S
KS
Academic Unit of Surgery, Department of Histopathology, University of Leeds, St. James's University Hospital, Leeds, United Kingdom.
Scott
Nigel
N
Guillou
Pierre J
PJ
Coletta
P Louise
PL
Hull
Mark A
MA
D000236:Adenoma / Q000201:enzymology*; D018253:Adenoma, Villous / Q000201:enzymology; D000328:Adult; D000368:Aged; D015153:Blotting, Western; D015179:Colorectal Neoplasms / Q000201:enzymology*; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D007527:Isoenzymes; D008565:Membrane Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496511:PTGS1 protein, human; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases