Differential requirements of the MAP kinase and PI3 kinase signaling pathways in Src- versus insulin and IGF-1 receptors-induced growth and transformation of rat intestinal epithelial cells

Nguyen, Kevin Tri; Wang, Wang-June; Chan, Joseph L.-K.; Wang, Lu‐Hai

doi:10.1038/sj.onc.1203911

Cited by 40 publications

(27 citation statements)

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“…Cell culture and maintenance Rat intestine epithelial cells were maintained in Dulbecco's modified Eagle's medium (DMEM)-containing 10% fetal calf serum (FCS) (Nguyen et al, 2000).…”

Section: Methodsmentioning

confidence: 99%

Synergistic effect between EGF and TGF-β1 in inducing oncogenic properties of intestinal epithelial cells

et al. 2007

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Transforming growth factor (TGF)-b1 has a biphasic effect on rat intestinal epithelial (RIE) cells. By itself, TGF-b1 functions as a tumor suppressor by inhibiting the growth, migration and invasion of RIE cells. We show in this study that in conjunction with epidermal growth factor (EGF), TGF-b1 helped to augment migration, invasion and anchorage-independent growth (AIG) compared to that by EGF alone. EGF plus TGF-b1 induced a dramatic morphological change characteristic of epithelial-mesenchymal transition (EMT). The mechanism for this enhanced effect of TGF-b1 and EGF on oncogenic properties was explored by analysis of EGF-and TGF-b1-mediated signaling pathways and complementary DNA arrays. TGF-b1 augmented EGF-mediated signaling of mitogen-activated protein kinase (MAPK) and AKT by enhancing and prolonging the activation of the former and prolonging the activation of the latter. Inhibition of MAPK, but not phosphoinositide-3 kinase (PI3K), abolished TGF-b1 plus EGF-induced EMT and downregulation of E-cadherin at mRNA and protein levels. By contrast, cell migration and invasion were sensitive to inhibition of either MAPK or PI3 kinase. TGF-b1 plus EGF-induced AIG was significantly more resistant to inhibition of PI3K and MAPK compared to that induced by EGF alone. EGF and TGF-b1 synergistically induced the expression of a series of proteases including matrix metalloproteinase (MMP) 1 (collagenase), MMP3, MMP9, MMP10, MMP14 and cathepsin. Among them, the expression of MMP1, MMP3, MMP9 and MMP10 was MAPK dependent. Inhibition of the MMPs or cathepsin significantly blocked EGF plus TGF-b1-induced invasion, but had no effect on colony formation.Phospholipase C (PLC) and Cox2 induced by EGF plus TGF-b1 also played a significant role in invasion, whereas PLC was also important for colony formation. Our study reveals specific signaling functions and induction of genes differentially required for enhanced effect of EGF-and TGF-b1-induced oncogenic properties, and helps to explain the tumor-promoting effect of TGF-b1 in human cancer with elevated expression or activation of TGF-b1 and receptor protein tyrosine kinases.

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“…Cell culture and maintenance Rat intestine epithelial cells were maintained in Dulbecco's modified Eagle's medium (DMEM)-containing 10% fetal calf serum (FCS) (Nguyen et al, 2000).…”

Section: Methodsmentioning

confidence: 99%

Synergistic effect between EGF and TGF-β1 in inducing oncogenic properties of intestinal epithelial cells

et al. 2007

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“…Akt activity is reduced in osteoclasts isolated from c-Src-deficient mice (9,10). Akt activity is up-regulated in Src-transformed cells and is activated by v-Src in a coexpression system in both insect Sf9 cells and mammalian cells (11,12). However, the mechanisms by which these tyrosine kinases regulate Akt activity is not understood yet.…”

mentioning

confidence: 98%

“…Recent studies (7)(8)(9)(10)(11)(12) suggest that tyrosine kinases may also play an important role in activation of Akt. Several groups reported that Syk and Btk are required for B cell antigen receptormediated activation of Akt in B lymphocytes (7,8).…”

mentioning

confidence: 99%

Regulation of Akt/PKB Activation by Tyrosine Phosphorylation

Chen¹,

Kim²,

Yang³

et al. 2001

Journal of Biological Chemistry

224

190

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Activation of Akt/PKB by growth factors requires multiple phosphorylation events. Phosphorylation of Thr 308 and Ser 473 of Akt by its upstream kinase(s) or autophosphorylation is critical for optimal activation of its kinase activity. Here, we present evidence that tyrosine phosphorylation is required for Akt activation. Epidermal growth factor treatment induces tyrosine phosphorylation of Akt in COS1 and PC3M cells, which is abrogated by PP2, a selective inhibitor for Src family tyrosine kinases. Elevated Akt activity is observed in v-Src transformed NIH3T3 cells, which is accompanied with increased tyrosine phosphorylation of Akt. Akt activity induced by growth factors is significantly reduced in SYF cells lacking Src, Yes, and Fyn, which can be restored by introducing c-Src, but not the kinaseinactive Src, back to these cells. Furthermore, we have identified two tyrosine residues near the activation loop of Akt that are important for its activation. Substitution of these residues with phenylalanine abolishes Akt kinase activity stimulated by growth factors. These two YF mutants fail to block Forkhead transcription factor activity in 293 cells and are unable to prevent apoptosis induced by matrix detachment. Our data suggest that, in addition to phosphorylation of Thr 308 and Ser 473 , tyrosine phosphorylation of Akt may be essential for its biological function.

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“…These transformation traits result from v-Src activating numerous signalling molecules involved in regulation of actin cytoskeleton, cell adhesion and migration and in control of cell proliferation and survival (Martin, 2001;Parsons and Parsons, 2004). Among these molecules, the Ras GTPase, the phosphatidylinositol 3-kinase (PI3K), the STAT family of transcription factors and their downstream effectors are found activated in different cell settings transformed by v-Src, although their relative contribution to transformation may vary depending on the cell type (Penuel and Martin, 1999;Nguyen et al, 2000;Odajima et al, 2000).…”

Section: Introductionmentioning

confidence: 99%