Increased expression of cyclooxygenase-2 to -1 in human colorectal cancers and adenomas, but not in hyperplastic polyps.
BACKGROUND
Non-steroidal anti-inflammatory drugs can reduce the risk of colorectal cancer. Reportedly, mRNA expression of cyclooxygenase-2 (COX-2) is elevated in human colorectal cancers compared with accompanying normal mucosa. The present study was undertaken to establish a simple analytical procedure to quantify COX-2 expression levels and to characterize COX-2 expression levels in human colorectal cancers, adenomas and hyperplastic polyps.


METHODS
The combination of PCR using common primers designed in the highly conserved regions and fluorescence-based single-strand conformation polymorphism (F-SSCP) analysis of the products is used for quantitative determination of the proportions of COX-2 mRNA in human colorectal cancers, adenomas, hyperplastic polyps and accompanying normal mucosa.


RESULTS
The present F-SSCP analysis was a simple and powerful method for quantitative determination of the proportions of COX-2 mRNA. The proportion of COX-2 mRNA was higher in cancer tissues than in accompanying normal mucosa in 46 of the 50 cancers. There was no significant correlation between the increase of the COX-2 proportion and tumor location or stages. The enhanced COX-2 expression was also observed in colorectal adenomas. On the other hand, the proportion of COX-2 mRNA in hyperplastic polyps was not significantly different from that in normal mucosa.


CONCLUSIONS
The proportion of COX-2 to COX-1 expression was elevated in most human colorectal cancers and adenomas, but not in hyperplastic polyps. Therefore, the increased proportion of COX-2 expression might be an early event in the carcinogenesis of colorectal cancer.
Maekawa
M
M
Division of Clinical Laboratory, National Cancer Center Research Institute, Tokyo, Japan. mmaekawa@gan2.ncc.go.jp
Sugano
K
K
Sano
H
H
Miyazaki
S
S
Ushiama
M
M
Fujita
S
S
Gotoda
T
T
Yokota
T
T
Ohkura
H
H
Kakizoe
T
T
Sekiya
T
T
D000236:Adenoma / Q000201:enzymology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000595:Amino Acid Sequence; D003110:Colonic Neoplasms / Q000201:enzymology*; D003111:Colonic Polyps; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000201:enzymology; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D011451:Prostaglandin-Endoperoxide Synthases / Q000737:chemistry / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012004:Rectal Neoplasms / Q000201:enzymology*
D012333:RNA, Messenger; D011451:Prostaglandin-Endoperoxide Synthases