Contact Inhibition of Hepatocyte Growth Regulated by Functional Association of the c-Met/Hepatocyte Growth Factor Receptor and LAR Protein-tyrosine Phosphatase

Abstract

Contact inhibition, the inhibition of cell proliferation by tight cell-cell contact is a fundamental characteristic of normal cells. Using primary cultured hepatocytes, we investigated the mechanisms of contact inhibition that decrease the mitogenic activity of hepatocyte growth factor (HGF), focusing on the regulation of c-Met/HGF-receptor activation. In hepatocytes cultured at a sparse cell density, HGF stimulation induced prolonged c-Met tyrosine phosphorylation for over 5 h and a marked mitogenic response. In contrast, HGF stimulation induced transient c-Met tyrosine phosphorylation in <3 h and failed to induce mitogenic response in hepatocytes cultured at a confluent cell density. Treatment of the confluent cells with HGF plus orthovanadate, a broad spectrum protein-tyrosine phosphatase inhibitor, however, prolonged c-Met tyrosine phosphorylation for over 5 h and permitted the subsequent mitogenic response. The mitogenic response to HGF was associated with the duration of c-Met tyrosine phosphorylation even in the sparse cells. We found that the activity and expression of the protein-tyrosine phosphatase LAR increased following HGF stimulation specifically in confluent hepatocytes and not in sparse hepatocytes. LAR and c-Met were associated, and purified LAR dephosphorylated tyrosine-phosphorylated c-Met in in vitro phosphatase reactions. Furthermore, antisense oligonucleotides specific for LAR mRNA suppressed the expression of LAR, allowed prolonged c-Met tyrosine phosphorylation, and led to acquisition of a mitogenic response in hepatocytes even under the confluent condition. Thus functional association of LAR and c-Met underlies the inhibition of c-Met-mediated mitogenic signaling through the dephosphorylation of c-Met, which specifically occurs under the confluent condition. Contact inhibition, the inhibition of cell proliferation by tight cell-cell contact is a fundamental characteristic of normal cells. Using primary cultured hepatocytes, we investigated the mechanisms of contact inhibition that decrease the mitogenic activity of hepatocyte growth factor (HGF), focusing on the regulation of c-Met/HGF-receptor activation. In hepatocytes cultured at a sparse cell density, HGF stimulation induced prolonged c-Met tyrosine phosphorylation for over 5 h and a marked mitogenic response. In contrast, HGF stimulation induced transient c-Met tyrosine phosphorylation in <3 h and failed to induce mitogenic response in hepatocytes cultured at a confluent cell density. Treatment of the confluent cells with HGF plus orthovanadate, a broad spectrum protein-tyrosine phosphatase inhibitor, however, prolonged c-Met tyrosine phosphorylation for over 5 h and permitted the subsequent mitogenic response. The mitogenic response to HGF was associated with the duration of c-Met tyrosine phosphorylation even in the sparse cells. We found that the activity and expression of the protein-tyrosine phosphatase LAR increased following HGF stimulation specifically in confluent hepatocytes and not in sparse hepatocytes. LAR and c-Met were associated, and purified LAR dephosphorylated tyrosine-phosphorylated c-Met in in vitro phosphatase reactions. Furthermore, antisense oligonucleotides specific for LAR mRNA suppressed the expression of LAR, allowed prolonged c-Met tyrosine phosphorylation, and led to acquisition of a mitogenic response in hepatocytes even under the confluent condition. Thus functional association of LAR and c-Met underlies the inhibition of c-Met-mediated mitogenic signaling through the dephosphorylation of c-Met, which specifically occurs under the confluent condition. Inhibition of cell proliferation regulated by cell-cell contact is a fundamental characteristic of normal cells by which cellular adhesion successfully maintains formation and highly organized tissue architecture. On the other hand, the loss of contact inhibition is associated with cellular transformation, which is a precursor to malignant disorder (1Stoker M. Curr. Top. Dev. Biol. 1967; 2: 107-128Crossref PubMed Scopus (58) Google Scholar, 2Fisher H.W. Yeh J. Science. 1967; 155: 581-582Crossref PubMed Scopus (69) Google Scholar, 3Aaronson S.A. Todaro G.J. Science. 1968; 162: 1024-1026Crossref PubMed Scopus (312) Google Scholar, 4Abercrombie M. Nature. 1979; 281: 259-262Crossref PubMed Scopus (290) Google Scholar, 5D'Souza-Schorey C. Trends Cell Biol. 2005; 15: 19-26Abstract Full Text Full Text PDF PubMed Scopus (181) Google Scholar). However, the molecular machineries involved in contact regulation are not fully understood. Although contact inhibition is a general characteristic of normal cells, the extent to which cells are inhibited by cell-cell contact differs significantly depending on cell types. Hepatocytes in primary culture provide a most appropriate experimental model in investigating contact inhibition (6Nakamura T. Tomita Y. Ichihara A. J. Biochem. (Tokyo). 1983; 94: 1029-1035Crossref PubMed Scopus (195) Google Scholar, 7Nakamura T. Yoshimoto K. Nakayama Y. Tomita Y. Ichihara A. Proc. Natl. Acad. Sci. U. S. A. 1983; 80: 7229-7233Crossref PubMed Scopus (276) Google Scholar, 8Nakamura T. Nakayama Y. Ichihara A. J. Biol. Chem. 1984; 259: 8056-8058Abstract Full Text PDF PubMed Google Scholar, 9Mizuno K. Higuchi O. Tajima H. Yonemasu T. Nakamura T. J. Biochem. (Tokyo). 1993; 114: 96-102Crossref PubMed Scopus (32) Google Scholar). Mature hepatocytes, which are terminally differentiated cells, undergo proliferation depending on exogenous growth factors. Proliferation of primary cultured hepatocytes is strictly regulated by cell-cell contact. When hepatocytes are cultured at sparse cell density, the cells undergo DNA synthesis in response to growth factors. However, when the cells are in a confluent density, DNA synthesis is mostly inhibited even in the presence of growth factors. Hepatocyte growth factor (HGF) 2The abbreviations used are: HGF, hepatocyte growth factor; LAR, leukocyte common antigen-related protein-tyrosine phosphatase; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; PTP, protein-tyrosine phosphatase; DEP-1, high cell density-enriched PTP-1; RT, reverse transcription; ERK1/2, extracellular signal-regulated kinases 1 and 2. plays pivotal roles in hepatocyte proliferation through the specific receptor c-Met tyrosine kinase (10Nakamura T. Nawa K. Ichihara A. Biochem. Biophys. Res. Commun. 1984; 122: 1450-1459Crossref PubMed Scopus (1095) Google Scholar, 11Nakamura T. Nishizawa T. Hagiya M. Seki T. Shimonishi M. Sugimura A. Tashiro K. Shimizu S. Nature. 1989; 342: 440-443Crossref PubMed Scopus (1982) Google Scholar, 12Miyazawa K. Tsubouchi H. Naka D. Takahashi K. Okigaki M. Arakaki N. Nakayama H. Hirono S. Sakiyama O. Takahashi K. Gohda E. Daikuhara Y. Kitamura N. Biochem. Biophys. Res. Commun. 1989; 163: 967-973Crossref PubMed Scopus (599) Google Scholar, 13Bottaro D.P. Rubin J.S. Faletto D.L. Chan A.M. Kmiecik T.E. Vande Woude G.F. Aaronson S.A. Science. 1991; 251: 802-804Crossref PubMed Scopus (2090) Google Scholar, 14Naldini L. Vigna E. Narsimhan R.P. Gaudino G. Zarnegar R. Michalopoulos G.K. Comoglio P.M. Oncogene. 1991; 6: 501-504PubMed Google Scholar). Disruption of the HGF-c-Met pathway in hepatocytes results in impaired liver regeneration (15Borowiak M. Garratt A.N. Wustefeld T. Strehle M. Trautwein C. Birchmeier C. Proc. Natl. Acad. Sci. U. S. A. 2004; 101: 10608-10613Crossref PubMed Scopus (407) Google Scholar, 16Huh C.G. Factor V.M. Sanchez A. Uchida K. Conner E.A. Thorgeirsson S.S. Proc. Natl. Acad. Sci. U. S. A. 2004; 101: 4477-4482Crossref PubMed Scopus (629) Google Scholar). c-Met tyrosine phosphorylation is a triggering event that forms phosphotyrosine-mediated activation cascades of the downstream signaling molecules of c-Met to elicit hepatocyte proliferation in response to HGF stimulation (14Naldini L. Vigna E. Narsimhan R.P. Gaudino G. Zarnegar R. Michalopoulos G.K. Comoglio P.M. Oncogene. 1991; 6: 501-504PubMed Google Scholar, 17Ponzetto C. Bardelli A. Zhen Z. Maina F. dalla Zonca P. Giordano S. Graziani A. Panayotou G. Comoglio P.M. Cell. 1994; 77: 261-271Abstract Full Text PDF PubMed Scopus (896) Google Scholar). Conversely, it has been proposed that protein-tyrosine phosphatase (PTP) activities are involved in regulating the balance of tyrosine phosphorylation states of receptor tyrosine kinases, including c-Met and the possible downstream signal mediators, such as Shc, the Stat families, phospholipase Cγ1, β-catenin, γ-catenin, and p120CAS in the normal liver (18Ruff S.J. Chen K. Cohen S. J. Biol. Chem. 1997; 272: 1263-1267Abstract Full Text Full Text PDF PubMed Scopus (95) Google Scholar). However, the precise role of PTPs in hepatocyte proliferation is not well clarified. In the present study, focusing on the activation states of c-Met, we investigated the mechanisms by which tight cell-cell contact in primary hepatocytes prevents mitogenic response to HGF. We found that LAR, a transmembrane protein-tyrosine phosphatase, plays a definitive role in inactivation, i.e. tyrosine dephosphorylation of c-Met through their physical interaction, which specifically occurs in hepatocytes under the confluent condition. Additionally, specific suppression of LAR expression prolonged tyrosine phosphorylation of c-Met and released contact inhibition. Our results indicate that regulation of the activation states of c-Met by LAR underlies contact inhibition of the mitogenic response to HGF in hepatocytes. Cell Culture—Hepatocytes were prepared from 7-week-old male Sprague-Dawley rats by in situ perfusion of the liver with collagenase, as described elsewhere (6Nakamura T. Tomita Y. Ichihara A. J. Biochem. (Tokyo). 1983; 94: 1029-1035Crossref PubMed Scopus (195) Google Scholar, 19Seglen P.O. Methods Cell Biol. 1976; 13: 29-83Crossref PubMed Scopus (5225) Google Scholar). The cells were cultured on plastic dishes coated with type I collagen at a cell density of 1.2 × 105/cm2 for the confluent culture and 0.3 × 105/cm2 for the sparse culture. The cells were cultured in Williams' E medium supplemented with 5% (v/v) fetal bovine serum, 5 nm insulin, and 10 nm dexamethasone under normal atmosphere conditioned by 5% CO2. Analysis of Mitogenic Response—DNA synthesis of hepatocytes was measured by the incorporation of 5′-bromo-2′-deoxyuridine (BrdUrd) into nuclei, as described elsewhere (20Gratzner H.G. Science. 1982; 218: 474-475Crossref PubMed Scopus (2365) Google Scholar, 21Dolbeare F. Gratzner H. Pallavicini M.G. Gray J.W. Proc. Natl. Acad. Sci. U. S. A. 1983; 80: 5573-5577Crossref PubMed Scopus (907) Google Scholar). Briefly, following preculture for 20 h, the hepatocytes were stimulated with 10 ng/ml HGF and labeled with 10 μm BrdUrd for 30 h. The cells were fixed and permeabilized with methanol. The samples were further treated with 2 m HCl for 15 min and neutralized with 0.1 m sodium tetraborate for 10 min. The samples were incubated with anti-BrdUrd mouse monoclonal antibody (BD Biosciences) and probed by Alexa-549-labeled anti-mouse IgG (Invitrogen). The nuclei were stained by Hoechst 33342. The number of the nuclei stained for BrdUrd and Hoechst were counted using laser microscopy. Immunoprecipitation and cells were in a of 10 1 1 and and the cell were by at × for 10 min. The cell were incubated with mouse monoclonal antibody antibody for 2 h. The were with for antibody for The cell were to and subsequent to were incubated with mouse monoclonal antibody antibody signal-regulated kinases mouse monoclonal antibody antibody antibody antibody for 2 h. The were further incubated with anti-mouse IgG IgG antibody The were with were by to the by and K. A. Biochem. PubMed Scopus Google with Briefly, tyrosine on were by purified tyrosine kinase and and used for a of The cell prepared as described were incubated in at for 5 min and to using which the tyrosine-phosphorylated The was by a of and to by a m and 1 and in a and 1 The was further incubated in supplemented with for 10 h at 30 to tyrosine phosphatase in the the from the was in 1 m for 30 min at and neutralized by The was with and tyrosine-phosphorylated were stained by The was using a laser PTPs were as for LAR in were fixed by in permeabilized by in and incubated with antibody for 2 h. by cells were incubated with were stained with Hoechst 33342. for LAR and the nuclei were by laser microscopy. In cultured under the sparse were stimulated by 10 ng/ml HGF for 20 and in a with of 10 10 1 1 and The nuclei were by at × for 5 and the were at × for 10 min. The were in of a of 5 10 and and used for the in in vitro reactions. the of LAR, hepatocytes cultured under confluent were stimulated with 10 ng/ml HGF for 5 h. The cells were in a as described and LAR was from the cell using antibody with The were with m and LAR was by the was by the using a were by cell and purified LAR, for 30 min at 30 and by the of 1 c-Met was from the and to to the tyrosine phosphorylation and of c-Met using and was prepared from hepatocytes using a and incubated with to was by reverse using The LAR mRNA was by using and to and from the of the of LAR for were from The of LAR mRNA in hepatocytes were by for of LAR, as in was prepared and as described was using of reverse reverse reverse reverse reverse The were on and by DNA to LAR antisense DNA for LAR mRNA was as to the from the of LAR mRNA number and the was as and oligonucleotides were to the of confluent hepatocytes using (Invitrogen). the medium was for the and the cells were further cultured in the presence of 10 ng/ml HGF for 5 h. of LAR and c-Met and the tyrosine phosphorylation of c-Met were by as described the of the suppression of LAR expression on mitogenic response to HGF, confluent hepatocytes were with 10 antisense for 20 h and cultured in the presence of 10 ng/ml HGF for 30 h. The mitogenic response in hepatocytes was by BrdUrd as described Mitogenic by cell regulation of mitogenic primary hepatocytes were cultured at sparse × at confluent × at cell density. preculture for 20 h, the cells were cultured in the presence of HGF for 30 h, and DNA synthesis was measured using BrdUrd the sparse a cells BrdUrd incorporation in the of HGF, and the BrdUrd increased following stimulation with HGF The of cells BrdUrd incorporation that cells in the of HGF, it over in the presence of HGF. the confluent cells were 5% in the of HGF. However, in to the sparse HGF failed to DNA The results that mitogenic of hepatocytes are strictly regulated sparse and confluent When hepatocytes were cultured at cell the cells were in the HGF stimulated DNA synthesis in the sparse not in the confluent which the that the contact inhibition regulated by factors. to the mitogenic response of hepatocytes is associated with cell in the expression of a were using In the sparse hepatocytes, in expression was h HGF and it a h following the In contrast, the expression not even in the presence of HGF when cells were cultured under the confluent condition. results indicate that hepatocytes under the confluent at a even HGF of and c-Met under the of cells, into following extracellular is regulated by the extracellular signal-regulated kinases Cell 1994; 6: PubMed Scopus Google Scholar). for the possible of in the mitogenic response to HGF in hepatocytes, we the activation of The sparse hepatocytes were stimulated with HGF, and the phosphorylation of tyrosine and on were by The phosphorylation of was not in the of HGF, it was at 5 min the HGF which were signal of HGF the with for the signal-regulated kinase kinase of ERK1/2, phosphorylation of ERK1/2, and in expression following HGF stimulation were When was by BrdUrd with the BrdUrd even HGF stimulation that activation was for the c-Met-mediated of hepatocytes. We activation is by cell In the sparse cells, were highly at 5 min and were for to h HGF stimulation In confluent hepatocytes, phosphorylation of was induced for to 5 min and was highly 20 min HGF However, the phosphorylation and to the h The results that activation by HGF stimulation was in the sparse cells and transient in confluent cells, that signal to activation was regulated by cell The in the duration of activation was of the that activation of the receptor regulated by cell we the tyrosine phosphorylation states of c-Met HGF Hepatocytes cultured under sparse confluent were stimulated with HGF, and tyrosine phosphorylation of c-Met was by and subsequent with antibody and In sparse cells, tyrosine phosphorylation of c-Met was in the of HGF. On the stimulation with HGF, the tyrosine phosphorylation was induced 5 min and a at min the stimulation the phosphorylation was for at 5 h following HGF stimulation In confluent cells, tyrosine phosphorylation of c-Met was induced 5 min and a at 20 min following HGF stimulation was that the tyrosine phosphorylation of c-Met under the confluent and h HGF it to the c-Met tyrosine phosphorylation h following HGF stimulation in the confluent hepatocytes, we the of tyrosine phosphatase activity in of c-Met the of for protein-tyrosine with broad on c-Met tyrosine phosphorylation were in confluent hepatocytes In the presence of c-Met tyrosine phosphorylation increased even HGF and the phosphorylation following HGF even under the confluent the of c-Met tyrosine phosphorylation was for at 5 h by that protein-tyrosine in the loss of tyrosine phosphorylation of c-Met under the confluent condition. c-Met for c-Met tyrosine phosphorylation in the presence of cell into the we the expression of and BrdUrd incorporation in confluent hepatocytes and with the results in HGF failed to expression when cells were cultured at confluent density. However, in the presence of expression increased even following HGF stimulation in the presence of of hepatocytes DNA synthesis HGF stimulation under the confluent HGF on the states of the cells c-Met tyrosine phosphorylation for <3 h was not associated with mitogenic a c-Met tyrosine phosphorylation for at 5 h led to the of mitogenic tyrosine phosphorylation of c-Met h to induce the mitogenic response to HGF. sparse hepatocytes were stimulated with HGF for and 5 and the medium was for of HGF, and c-Met tyrosine phosphorylation was of sparse hepatocytes with HGF highly induced tyrosine phosphorylation of c-Met 1 h, the tyrosine phosphorylation to the 2 h the of In the of HGF stimulation for h, c-Met tyrosine phosphorylation was highly at 1 and h, it to the 2 h the of the of hepatocytes with HGF for 5 h c-Met tyrosine phosphorylation the The DNA synthesis for 30 h following the of HGF stimulation that the stimulation with HGF for 1 h failed to induce DNA HGF stimulation for and 5 h increased the to and results indicate that c-Met tyrosine phosphorylation for over h is for into the of LAR in of on c-Met tyrosine phosphorylation, in that protein-tyrosine is involved in the dephosphorylation of c-Met h following HGF stimulation in confluent hepatocytes. protein-tyrosine for dephosphorylation of c-Met, we the expression of tyrosine in hepatocytes, using tyrosine phosphatase Hepatocytes were cultured under the sparse confluent and the prepared from cells following HGF stimulation were to using a the of tyrosine The dephosphorylated were as at molecular of in and were in and the a The was not in sparse hepatocytes even HGF However, in confluent hepatocytes, the was at 1 h, and it increased h following HGF The that the tyrosine phosphatase is a for the protein-tyrosine phosphatase for the dephosphorylation of c-Met under the confluent condition. on the molecular we that the protein-tyrosine phosphatase is a of the protein-tyrosine phosphatase expression of LAR in hepatocytes was by using antibody In the sparse cells, expression of LAR was of HGF On the other hand, expression of LAR was in the confluent cells, and the expression was stimulated h HGF for LAR in hepatocytes that LAR was in the of HGF, and expression was and specifically in the hepatocytes following 5 h of HGF stimulation the in LAR expression in confluent hepatocytes regulated we measured the expression of LAR mRNA by Although the of of the LAR mRNA were to the in the a in not sparse and confluent cells, and the not even HGF The results that the in LAR following HGF stimulation in confluent hepatocytes is regulated forms of LAR in extracellular and are in a of cells and P. M. H. J. Biol. Chem. 1994; Full Text PDF PubMed Google Scholar, N. F. Biochem. J. 1994; PubMed Scopus Google Scholar, J.S. J. Cell Biol. PubMed Scopus Google Scholar, J. J.S. T. Z. Res. PubMed Scopus Google Scholar, P. H. J. Cell Biol. PubMed Scopus Google we of LAR mRNA using focusing on extracellular and was prepared from sparse and confluent hepatocytes, was using of and DNA of were The from confluent hepatocytes are in and the was in the of sparse cells with DNA of we found that the of LAR mRNA in the primary hepatocytes was with the of LAR in the liver N. F. Biochem. J. 1994; PubMed Scopus Google Scholar). LAR in hepatocytes type and is by of in the type and in the of LAR and c-Met in Hepatocytes and in of LAR to expression of LAR are of the possible of LAR in the of c-Met tyrosine phosphorylation in confluent hepatocytes. we the association of LAR and Hepatocytes were cultured in sparse confluent and the cell were to and subsequent When c-Met was from the sparse cells, LAR was not in the with c-Met In the for confluent cells, a association of LAR and c-Met was at and 5 h stimulation with HGF In the reverse c-Met was by to the with antibody association LAR and c-Met was in confluent hepatocytes that were stimulated by HGF over 1 h, LAR was not from sparse cells. LAR is to c-Met, possible activity of LAR to c-Met was by in vitro tyrosine phosphatase The cell tyrosine-phosphorylated c-Met were prepared from sparse hepatocytes and were incubated as the with purified the c-Met was from the and the of c-Met and tyrosine phosphorylation states were by using antibody and antibody When LAR was not to the c-Met was as a tyrosine-phosphorylated However, the c-Met was significantly dephosphorylated when LAR was present in the results indicate that association LAR and c-Met dephosphorylation of the tyrosine of c-Met in confluent hepatocytes. of Contact Inhibition by of LAR further for the functional association LAR and c-Met, we the specific of LAR results in in contact i.e. acquisition of prolonged tyrosine phosphorylation of c-Met and mitogenic response following HGF Hepatocytes under the confluent were treated with antisense oligonucleotides for LAR mRNA of antisense oligonucleotides suppressed oligonucleotides on expression of LAR in In hepatocytes treated with was induced and c-Met tyrosine phosphorylation was suppressed at 5 h with HGF In contrast, in hepatocytes treated with antisense expression of LAR was and tyrosine phosphorylation of c-Met was following HGF stimulation c-Met tyrosine phosphorylation by of LAR is associated with cell confluent hepatocytes were to of DNA synthesis by BrdUrd following antisense In hepatocytes treated with the the not even stimulation with HGF. However, in the cells treated with antisense oligonucleotides for LAR, HGF stimulation the to a that HGF. results indicate that specific suppression of LAR expression mitogenic response in hepatocytes even when the cells were at confluent density. LAR is a transmembrane protein-tyrosine phosphatase M. H. J. PubMed Scopus Google Scholar). of extracellular with and type and a tyrosine phosphatase M. H. J. PubMed Scopus Google Scholar, M. M. H. J. PubMed Scopus Google Scholar). The of the extracellular of LAR are characteristic of cell adhesion that LAR in the suppression of protein-tyrosine phosphorylation in response to in cell-cell adhesion Curr. Cell Biol. PubMed Scopus Google Scholar). In using primary hepatocytes, we found that association of LAR with c-Met is regulated by cell-cell contact and that LAR plays a role in contact inhibition of c-Met-mediated mitogenic response through the dephosphorylation of c-Met, which specifically occurs in the confluent hepatocytes. We that c-Met tyrosine phosphorylation and phosphorylation HGF stimulation under the sparse were stimulated under the confluent it is that of c-Met and in the confluent hepatocytes was associated with the loss of mitogenic response to HGF. that activation of is for the of expression in the in of cells Biochem. J. 1997; PubMed Scopus Google Scholar, S. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, K. S.J. Oncogene. PubMed Scopus Google Scholar, H. C. S. D. G. M. P. C. G. Cell Biol. PubMed Scopus Google Scholar). In the primary hepatocytes, were dephosphorylated c-Met in confluent cells and a possible of in the loss of c-Met activation is to a primary event to the contact inhibition, DNA synthesis was not even in sparse hepatocytes, when c-Met activation was for <3 h by stimulation of HGF and In the present study, we found that expression of LAR was regulated by The contact is of the expression of LAR was mostly in sparse hepatocytes. has in cell LAR is with cell density Biochem. J. PubMed Scopus Google Scholar). The cell expression of LAR was by association with that cell-cell adhesion involved in the in LAR expression in hepatocytes. The other is the stimulation with HGF. The LAR expression was in confluent cells HGF The in LAR expression following HGF stimulation that c-Met-mediated are involved in the for the expression of has been that LAR to the molecules to such as and Biochem. J. PubMed Scopus Google Scholar, H. J. Cell Biol. PubMed Scopus Google Scholar, T. J. A. J. Cell Biol. 1997; PubMed Scopus Google Scholar, T. A. E. A. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google and LAR T. A. E. A. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). that LAR plays a role in cell signal by regulating the tyrosine phosphorylation states of the that c-Met is associated with T. M. A. K. Comoglio P.M. J. Cell Biol. 1994; PubMed Scopus Google Scholar, S. Biochem. Biophys. Res. Commun. PubMed Scopus Google Scholar). present that LAR was associated with c-Met in confluent not sparse hepatocytes involved in a by which tyrosine in c-Met are dephosphorylated by LAR at confluent cell density. of the extracellular was to a for LAR P. H. J. Cell Biol. PubMed Scopus Google Scholar). However, the is to involved in contact inhibition in hepatocytes, LAR in hepatocytes in the type which is for to for c-Met inactivation, M. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google that the protein-tyrosine phosphatase forms a with c-Met and tyrosine of However, we not expression of association and c-Met not that is not involved in the contact at in hepatocytes. In we for the that activation of c-Met receptor in hepatocytes is regulated by cell-cell contact and that functional LAR and c-Met is a for the contact regulation of the mitogenic response in hepatocytes. Our results the of of the LAR and c-Met in the regulation of tissue regeneration and malignant of cells. on the for cell regulation of c-Met on the of the of tissue with