TGF-beta1 (transforming growth factor-beta1)-mediated adhesion of gastric carcinoma cells involves a decrease in Ras/ERKs (extracellular-signal-regulated kinases) cascade activity dependent on c-Src activity.
Signalling by integrin-mediated cell anchorage to extracellular matrix proteins is co-operative with other receptor-mediated signalling pathways to regulate cell adhesion, spreading, proliferation, survival, migration, differentiation and gene expression. It was observed that an anchorage-independent gastric carcinoma cell line (SNU16) became adherent on TGF-beta1 (transforming growth factor beta1) treatment. To understand how a signal cross-talk between integrin and TGF-beta1 pathways forms the basis for TGF-beta1 effects, cell adhesion and signalling activities were studied using an adherent subline (SNU16Ad, an adherent variant cell line derived from SNU16) derived from the SNU16 cells. SNU16 and SNU16Ad cells, but not integrin alpha5-expressing SNU16 cells, showed an increase in adhesion on extracellular matrix proteins after TGF-beta1 treatment. This increase was shown to be mediated by an integrin alpha3 subunit, which was up-regulated in adherent SNU16Ad cells and in TGF-beta1-treated SNU16 cells, compared with the parental SNU16 cells. After TGF-beta1 treatment of SNU16Ad cells on fibronectin, Tyr-416 phosphorylation of c-Src was increased, but Ras-GTP loading and ERK1/ERK2 (extracellular-signal-regulated kinases 1 and 2) activity were decreased, which showed a dependence on c-Src family kinase activity. Studies on adhesion and signalling activities using pharmacological inhibitors or by transient-transfection approaches showed that inhibition of ERK1/ERK2 activity increased TGF-beta1-mediated cell adhesion slightly, but not the basal cell adhesion significantly, and that c-Src family kinase activity and decrease in Ras/ERKs cascade activity were required for the TGF-beta1 effects. Altogether, the present study indicates that TGF-beta1 treatment causes anchorage-independent gastric carcinoma cells to adhere by an increase in integrin alpha3 level and a c-Src family kinase activity-dependent decrease in Ras/ERKs cascade activity.
Kim
Hwang-Phill
HP
Cancer Research Institute, Department of Tumor Biology, College of Medicine, Seoul National University, 28, Yongon-Dong, Chongno-Gu, Seoul 110-799, South Korea.
Lee
Mi-Sook
MS
Yu
Jiyon
J
Park
Jin-Ah
JA
Jong
Hyun-Soon
HS
Kim
Tae-You
TY
Lee
Jung Weon
JW
Bang
Yung-Jue
YJ
D000818:Animals; D002277:Carcinoma / Q000378:metabolism / Q000473:pathology*; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology*; D016895:Culture Media, Serum-Free; D019175:DNA Methylation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005109:Extracellular Matrix; D005353:Fibronectins; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006160:Guanosine Triphosphate / Q000502:physiology; D006801:Humans; D039422:Integrin alpha3 / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D016023:Integrins / Q000032:analysis; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D021122:Protein Subunits; D051381:Rats; D013274:Stomach Neoplasms / Q000378:metabolism / Q000473:pathology*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1; D020703:ras GTPase-Activating Proteins / Q000502:physiology; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*
D016895:Culture Media, Serum-Free; D004791:Enzyme Inhibitors; D005353:Fibronectins; D039422:Integrin alpha3; D016023:Integrins; D009363:Neoplasm Proteins; D021122:Protein Subunits; C508960:TGFB1 protein, human; C508962:Tgfb1 protein, rat; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D020703:ras GTPase-Activating Proteins; D006160:Guanosine Triphosphate; D019869:Phosphatidylinositol 3-Kinases; D019061:src-Family Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases