Intestinal transformation results in transforming growth factor-beta-dependent alteration in tumor cell-cell matrix interactions.
BACKGROUND
An alteration in the expression of and response to transforming growth factor-beta 1 (TGF-beta 1) appears to be an important event during colorectal carcinogenesis. However, the precise role of TGF-beta 1 in colorectal carcinogenesis is not clear. We have previously described in detail the changes in cell proliferation and differentiation caused by chronic exposure to TGF-beta 1. In this study we sought to better characterize the changes in tumor cell-cell matrix interactions seen during TGF-beta 1-mediated intestinal transformation.


METHODS
Rat intestinal epithelial cells (RIE) and RIE cells transformed by chronic exposure to TGF-beta 1 (RIE-Tr) were treated with TGF-beta 1 and production of components of the plasmin/plasminogen system measured by ELISA and Western blotting. TGF-beta 1 effects on invasion and adhesion were determined in vitro. The role of urokinase on TGF-beta 1-mediated invasion and adhesion were determined using immunoneutralization. The role of COX-2 was determined using a specific COS-2 inhibitor.


RESULTS
TGF-beta 1 had no effect on RIE-1 adhesion to collagen types I and IV, fibronectin, and laminin, or invasion through collagen types I and IV. However, 5 ng/mL TGF-beta 1 significantly increased the invasiveness and decreased the adhesiveness of RIE-Tr. This effect of TGF-beta 1 on RIE-Tr was associated with a significant increase in plasmin activity secondary to increased expression of uPA. TGF-beta 1 had no effect on either uPA receptor or PAI-1 in this system. Antibodies to uPA completely blocked the TGF-beta 1-mediated invasiveness of the RIE-Tr cells and returned their adhesiveness to basement membrane proteins to baseline. Addition of the selective Cox-2 inhibitor SC-58125 resulted in a dose-dependent decrease in TGF-beta 1-mediated invasion and uPA expression.


CONCLUSIONS
This study provides additional evidence for TGF-beta 1 as a tumor promoter during intestinal carcinogenesis and a possible new mechanism for Cox-2-related colon carcinogenesis.
Berger
David H
DH
Department of Surgery, Baylor College of Medicine, and the Veterans Affairs Medical Center, Houston, TX 77030, USA.
O'Mahony
Christine A
CA
Sheng
Hongmiao
H
Shao
Jinyi
J
Albo
Daniel
D
DuBois
Raymond N
RN
Beauchamp
R Daniel
RD
D000818:Animals; D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced*; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D005109:Extracellular Matrix / Q000502:physiology*; D005341:Fibrinolysin / Q000378:metabolism; D007413:Intestinal Mucosa / Q000503:physiopathology*; D007527:Isoenzymes / Q000037:antagonists & inhibitors; D009361:Neoplasm Invasiveness; D011451:Prostaglandin-Endoperoxide Synthases; D011720:Pyrazoles / Q000008:administration & dosage; D051381:Rats; D016212:Transforming Growth Factor beta / Q000378:metabolism / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism
D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D011720:Pyrazoles; C508962:Tgfb1 protein, rat; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; C090859:1-((4-methylsulfonyl)phenyl)-3-trifluoromethyl-5-(4-fluorophenyl)pyrazole; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator