Cyclooxygenase-2 alters transforming growth factor-beta 1 response during intestinal tumorigenesis.
BACKGROUND
Recent investigation suggests that cyclooxygenase-2 plays an important role in colorectal carcinogenesis. Transforming growth factor-beta1 (TGF-beta 1) is one of the most potent stimulators of cyclooxygenase-2 expression. A key step in intestinal tumorigenesis involves alteration of the normal cellular response to TGF-beta 1. We have hypothesized that overexpression of cyclooxygenase-2 alters intestinal epithelial response to TGF-beta 1.


METHODS
RIE-1 cells were stably transfected with rat cyclooxygenase-2 complementary DNA in either the sense (RIE-S) or antisense (RIE-AS) orientation. Tumor cell invasion was assessed with a modified Boyden collagen type I invasion assay in the presence of TGF-beta 1, antibody to urokinase plasminogen activator (uPA), or the selective cyclooxygenase-2 inhibitor SC-58125. Expression of uPA, uPA receptor, and plasminogen activator inhibitor-1 were determined by Western blot and enzyme-linked immunosorbent assay.


RESULTS
RIE-1 and RIE-AS did not invade although RIE-S cells were minimally invasive at baseline. TGF-beta 1 had no effect on RIE-1 or RIE-AS invasion; however, TGF-beta 1 significantly upregulated RIE-S cell invasion. All 3 RIE cell lines produce minimal uPA under basal conditions. TGF-beta 1 upregulated uPA production only in the RIE-S cells. Both antibody to uPA and SC-58125 reversed TGF-beta-mediated RIE-S cell invasion. SC-58125 inhibited TGF-beta-mediated RIE-S uPA production.


CONCLUSIONS
These results demonstrate that overexpression of cyclooxygenase-2 alters intestinal epithelial response to TGF-beta 1, which may be a mechanism by which cyclooxygenase-2 promotes colon carcinogenesis.
O'Mahony
C A
CA
Department of Surgery Medical College of Pennsylvania/Hahnemann University, Philadelphia 19129, USA.
Beauchamp
R D
RD
Albo
D
D
Tsujii
M
M
Sheng
H M
HM
Shao
J
J
Dubois
R N
RN
Berger
D H
DH
D000818:Animals; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D007414:Intestinal Neoplasms / Q000201:enzymology / Q000209:etiology / Q000473:pathology*; D007527:Isoenzymes / Q000502:physiology*; D009361:Neoplasm Invasiveness; D011451:Prostaglandin-Endoperoxide Synthases / Q000502:physiology*; D051381:Rats; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D014568:Urokinase-Type Plasminogen Activator / Q000096:biosynthesis
D007527:Isoenzymes; D016212:Transforming Growth Factor beta; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D014568:Urokinase-Type Plasminogen Activator