Tumor-specific transcription factor binding to an activator protein-2/Sp1 element of the urokinase-type plasminogen activator receptor promoter in a first large series of resected gastrointestinal cancers.
OBJECTIVE
Evidence for transactivation of genes via specific promoter elements has been derived from studies on tumor cell lines but rarely on resected tumors. However, the proof of an in vivo relevance and the identification of patients with a potential tumor-specific gene expression is essential to transfer molecular-targeting strategies into clinical applications. This study gives the first clinical evidence that urokinase-type plasminogen activator receptor (u-PAR) gene expression is tumor-specifically regulated via an activator protein (AP)-2/Sp1 promoter element in a large patient subpopulation.


METHODS
In 145 gastrointestinal cancer patients, electrophoretic mobility shift analysis and supershift assays for u-PAR-promoter region -152/-135 were performed in tumors and corresponding normal tissues. u-PAR protein levels were measured by ELISA.


RESULTS
Binding of Sp1 to region -152/-135 in tumors in contrast to corresponding normal mucosae was observed in 55% of colorectal and in 52% of gastric cancer patients. Tumor-specific binding of an AP-2-related factor was seen in 59% of colorectal and in 63% of gastric cancer patients. A significant correlation between AP-2 (P < 0.0001) and Sp1 (P = 0.0003) binding with a high u-PAR expression was observed in tumors but not in normal mucosae. Tissues of five nontumor patients did not show transcription factor binding to this region.


CONCLUSIONS
This is the first study to show the tumor-specific binding of trans-activators to the u-PAR promoter region (-152/-135) biochemically in a large series of resected tumors. For the subpopulation of approximately 60% of patients with tumor-restricted u-PAR-transactivation, a molecular targeting of this region or its activating pathways should be pursued as a new antimetastasis therapy approach.
Schewe
Denis Martin
DM
Department of Surgery, Klinikum Grosshadern, Ludwig Maximilians University of Munich, 81377 Munich, Germany.
Leupold
Joerg H
JH
Boyd
Douglas D
DD
Lengyel
Ernst R
ER
Wang
Heng
H
Gruetzner
Klaus Uwe
KU
Schildberg
Friedrich W
FW
Jauch
Karl W
KW
Allgayer
Heike
H
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004268:DNA-Binding Proteins / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011401:Promoter Regions, Genetic; D011956:Receptors, Cell Surface / Q000235:genetics*; D055293:Receptors, Urokinase Plasminogen Activator; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000378:metabolism*
D004268:DNA-Binding Proteins; C524898:PLAUR protein, human; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D016329:Sp1 Transcription Factor; D050656:Transcription Factor AP-2; D014157:Transcription Factors