A selective cyclooxygenase 2 inhibitor suppresses the growth of H-ras-transformed rat intestinal epithelial cells.
OBJECTIVE
Constitutive expression of cyclooxygenase 2 (COX-2) has been found in 85% of colorectal cancers. Ras mutations are found in 50% of colorectal adenocarcinomas. The aim of this study was to determine the role of COX-2 in ras-induced transformation in rat intestinal epithelial (RIE) cells.


METHODS
Cell growth was determined by cell counts. The expression of COX-2 was examined by Northern and Western analyses. For tumorigenicity assays, cells were inoculated into dorsal subcutaneous tissue of athymic nude mice. DNA-fragmentation assays were performed to detect apoptosis.


RESULTS
The expression of COX-2 was increased in RIE-Ras cells at both messenger RNA (9-fold) and protein (12-fold) levels. Prostaglandin I2 levels were elevated 2.15-fold in RIE-Ras cells. Serum deprivation further increased COX-2 expression 3.8-fold in RIE-Ras cells. Treatment with a selective COX-2 antagonist (SC58125) inhibited the growth of RIE-Ras cells through inhibition of cell proliferation and by induction of apoptosis. SC-58125 treatment reduced the colony formation in Matrigel by 83.0%. Intraperitoneal administration of SC-58125 suppressed RIE-Ras tumor growth in nude mice by 60.3% in 4 weeks. SC-58125 treatment also induced apoptosis in RIE-Ras cells as indicated by increased DNA fragmentation.


CONCLUSIONS
Overexpression of COX-2 may contribute to tumorigenicity of ras-transformed intestinal epithelial cells. Selective inhibition of COX-2 activity inhibits growth of ras-transformed intestinal epithelial cells and induces apoptosis.
Sheng
G G
GG
Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
Shao
J
J
Sheng
H
H
Hooton
E B
EB
Isakson
P C
PC
Morrow
J D
JD
Coffey
R J
RJ
DuBois
R N
RN
Beauchamp
R D
RD
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015197:Carcinogenicity Tests; D002455:Cell Division / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D003094:Collagen / Q000494:pharmacology; D051546:Cyclooxygenase 2; D004247:DNA / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D004338:Drug Combinations; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D011905:Genes, ras / Q000502:physiology*; D007413:Intestinal Mucosa / Q000201:enzymology* / Q000473:pathology*; D007414:Intestinal Neoplasms / Q000473:pathology; D007527:Isoenzymes / Q000378:metabolism*; D007797:Laminin / Q000494:pharmacology; D051379:Mice; D008819:Mice, Nude; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D011509:Proteoglycans / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D051381:Rats
D004338:Drug Combinations; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D007797:Laminin; D011509:Proteoglycans; D011720:Pyrazoles; C059485:matrigel; C090859:1-((4-methylsulfonyl)phenyl)-3-trifluoromethyl-5-(4-fluorophenyl)pyrazole; D003094:Collagen; D004247:DNA; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases