Src induces urokinase receptor gene expression and invasion/intravasation via activator protein-1/p-c-Jun in colorectal cancer.
The urokinase receptor [urokinase plasminogen activator receptor (u-PAR)] promotes invasion and metastasis and is associated with poor patient survival. Recently, it was shown that Src induces u-PAR gene expression via Sp1 bound to the u-PAR promoter region -152/-135. However, u-PAR is regulated by diverse promoter motifs, among them being an essential activator protein-1 (AP-1) motif at -190/-171. Moreover, an in vivo relevance of Src-induced transcriptional regulators of u-PAR-mediated invasion, in particular intravasation, and a relevance in resected patient tumors have not sufficiently been shown. The present study was conducted (a) to investigate if, in particular, AP-1-related transcriptional mediators are required for Src-induced u-PAR-gene expression, (b) to show in vivo relevance of AP-1-mediated Src-induced u-PAR gene expression for invasion/intravasation and for resected tissues from colorectal cancer patients. Src stimulation of the u-PAR promoter deleted for AP-1 region -190/-171 was reduced as compared with the wild-type promoter in cultured colon cancer cells. In gelshifts/chromatin immunoprecipitation, Src-transfected SW480 cells showed an increase of phospho-c-Jun, in addition to JunD and Fra-1, bound to region -190/-171. Src-transfected cells showed a significant increase in c-Jun phosphorylated at Ser(73) and also Ser(63), which was paralleled by increased phospho-c-jun-NH(2)-kinase. Significant decreases of invasion/in vivo intravasation (chorionallantoic membrane model) were observed in Src-overexpressing cells treated with Src inhibitors, u-PAR-small interfering RNA, and dominant negative c-Jun (TAM67). In resected tissues of 20 colorectal cancer patients, a significant correlation between Src activity, AP-1 complexes bound to u-PAR region -190/-171, and advanced pN stage were observed. These data suggest that Src-induced u-PAR gene expression and invasion/intravasation in vivo is also mediated via AP-1 region -190/-171, especially bound with c-Jun phosphorylated at Ser(73/63), and that this pathway is biologically relevant for colorectal cancer patients, suggesting therapeutic potential.
Leupold
Jörg H
JH
Department of Experimental Surgery Mannheim Faculty, University of Heidelberg, Heidelberg, Germany.
Asangani
Irfan
I
Maurer
Gabriele D
GD
Lengyel
Ernst
E
Post
Stefan
S
Allgayer
Heike
H
D000818:Animals; D002642:Chick Embryo; D015179:Colorectal Neoplasms / Q000201:enzymology* / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D005799:Genes, Dominant; D006801:Humans; D009361:Neoplasm Invasiveness; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000037:antagonists & inhibitors / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics*; D055293:Receptors, Urokinase Plasminogen Activator; D015398:Signal Transduction / Q000187:drug effects; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D050656:Transcription Factor AP-2 / Q000378:metabolism; D000099169:Fos-Related Antigen 1
D010750:Phosphoproteins; D047428:Protein Kinase Inhibitors; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D016392:Proto-Oncogene Proteins pp60(c-src); D034741:RNA, Small Interfering; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D018808:Transcription Factor AP-1; D050656:Transcription Factor AP-2; D000099169:Fos-Related Antigen 1; C524898:PLAUR protein, human