rho-Mediated protein tyrosine phosphorylation in lysophosphatidic-acid-induced tumor-cell invasion.
Rat ascites hepatoma cell (MM1) invade a mesothelial cell monolayer in vitro in assay medium containing serum, but not in serum-free medium. Serum could be completely replaced by 1-oleoyl lysophosphatidic acid (LPA) in inducing invasion. LPA-induced invasion was inhibited by genistein, a tyrosine-kinase inhibitor. Protein tyrosine phosphorylation in response to LPA was thus analyzed in order to determine the molecular mechanism of invasion. LPA of invasion-inducible concentrations evoked a transient increase in tyrosine phosphorylation, mainly of 110- to 130-kDa proteins in MM1 cells but not in mesothelial cells. These concentrations of LPA were over 10 times higher (10 to 25 micron) than those necessary to produce a variety of biological actions, such as tyrosine phosphorylation in fibroblasts, neurite retraction and platelet aggregation. Protein tyrosine phosphorylation and invasion by MM1 cells induced by LPA are largely regulated by rho p21, because both were inhibited by Clostridium botulinum C3 exo-enzyme, which is known to specifically inactivate rho p21. Invasion of MCL by MM1 cells induced by serum and that by B16FE7 cells induced by LPA were inhibited by genistein or C3 as well. By immunoprecipitation, we detected p 125 focal adhesion kinase (FAK) as a major protein of 110- to 130-kDa tyrosine phosphorylated in response to LPA. Tyrosine phosphorylation of paxillin by LPA was also detected.
Imamura
F
F
Department of Internal Medicine, Research Institute, Center for Adult Diseases, Osaka, Japan.
Shinkai
K
K
Mukai
M
M
Yoshioka
K
K
Komagome
R
R
Iwasaki
T
T
Akedo
H
H
D000818:Animals; D015815:Cell Adhesion Molecules / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D019204:GTP-Binding Proteins / Q000378:metabolism*; D019833:Genistein; D007529:Isoflavones / Q000494:pharmacology; D008114:Liver Neoplasms, Experimental / Q000378:metabolism*; D008246:Lysophospholipids / Q000494:pharmacology; D009361:Neoplasm Invasiveness; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D020741:rho GTP-Binding Proteins
D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D007529:Isoflavones; D008246:Lysophospholipids; D051419:Paxillin; D010750:Phosphoproteins; C496063:Pxn protein, rat; D019000:Phosphotyrosine; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496052:Ptk2 protein, rat; D019204:GTP-Binding Proteins; D020741:rho GTP-Binding Proteins