Inhibition by platelet-activating factor of Src- and hepatocyte growth factor-dependent invasiveness of intestinal and kidney epithelial cells. Phosphatidylinositol 3'-kinase is a critical mediator of tumor invasion.
This study was designed to characterize platelet-activating factor receptor (PAF-R) expression and function in normal and cancerous human colonic epithelial cells. PAF-R gene transcripts were analyzed by reverse transcription-polymerase chain reaction and Southern blot, using three sets of primers corresponding either to the coding region of the human PAF-R sequence (polymerase chain reaction product: 682 base pairs (bp)) or to the leukocyte- and tissue-type transcripts of 166 and 252 bp, respectively. An elongated splice variant was identified in the 5'-untranslated region of the tissue-type PAF-R transcript (334 bp) in colonic epithelial crypts and tumors. In human colonic PCmsrc cells transformed by c-src oncogene, the hepatocyte growth factor (HGF)-dependent invasiveness of collagen gels was abolished by 0.1 microM PAF and restored by the PAF-R antagonists WEB2086 and SR27417. PAF blocked HGF-induced tyrosine phosphorylation of p125 focal adhesion kinase. The phosphatidylinositol 3'-kinase (PI3'-K) inhibitors wortmannin and LY294002 totally blocked the HGF-induced invasion. Similar effects were observed in ts-srcMDCK kidney epithelial cells transformed by a v-Src temperature-sensitive mutant: (i) PAF and wortmannin exerted additive inhibitory effects on Src-induced invasion and (ii) activated and dominant negative forms of p110alpha PI3'-K, respectively, amplified and abrogated the Src- and HGF-dependent invasiveness of parental and ts-srcMDCK cells. We also provided the first evidence for the contribution of rapamycin-insensitive, pertussis toxin-dependent G-protein pathways to the integration of the signals emerging from activated Met and PAF receptors. These results indicate that PI3'-K is a critical transducer of invasiveness and strongly suggest that PAF exerts a negative control on invasion by inhibiting this signaling pathway. A possible beneficial role of PAF analogs on tumor invasion is therefore proposed.
Kotelevets
L
L
INSERM U482 and IFR 65, Hôpital Saint-Antoine, 75571 Paris Cedex 12, France.
Noë
V
V
Bruyneel
E
E
Myssiakine
E
E
Chastre
E
E
Mareel
M
M
Gespach
C
C
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001381:Azepines / Q000494:pharmacology; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects*; D002867:Chromones / Q000494:pharmacology; D003110:Colonic Neoplasms / Q000378:metabolism; D004285:Dogs; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D019204:GTP-Binding Proteins / Q000502:physiology; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D016391:Genes, src / Q000235:genetics*; D017228:Hepatocyte Growth Factor / Q000494:pharmacology*; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D037342:Pertussis Toxin; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D010972:Platelet Activating Factor / Q000494:pharmacology*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D010980:Platelet Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000235:genetics*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D015398:Signal Transduction / Q000502:physiology; D013844:Thiazoles / Q000494:pharmacology; D014170:Transformation, Genetic / Q000235:genetics; D014230:Triazoles / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D000077191:Wortmannin
D000730:Androstadienes; D001381:Azepines; D015815:Cell Adhesion Molecules; D002867:Chromones; D009025:Morpholines; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010972:Platelet Activating Factor; D010975:Platelet Aggregation Inhibitors; D010980:Platelet Membrane Glycoproteins; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D013844:Thiazoles; D014230:Triazoles; D010566:Virulence Factors, Bordetella; C039351:platelet activating factor receptor; C052518:WEB 2086; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D017228:Hepatocyte Growth Factor; D037342:Pertussis Toxin; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D019204:GTP-Binding Proteins; C071317:Foropafant; D000077191:Wortmannin