TY - JOUR
T1 - Akt/PKR Activity Is Required for Ha-Ras-mediated Transformation of Intestinal Epithelial Cells
AU - Sheng, Hongmiao
AU - Shao, Jinyi
AU - DuBois, Raymond N.
PY - 2001/4/27
Y1 - 2001/4/27
N2 - Phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PKB/Akt) is thought to serve as an oncogenic signaling pathway which can be activated by Ras. The role of PI3K/Akt in Ras-mediated transformation of intestinal epithelial cells is currently not clear. Here we demonstrate that inducible expression of oncogenic Ha-Ras results in activation of PKB/Akt in rat intestinal epithelial cells (RIE-iHa-Ras), which was blocked by treatment with inhibitors of PI3K activity. The PI3K inhibitor, LY-294002, partially reversed the morphological transformation induced by Ha-Ras and resulted in a modest stimulation of apoptosis. The most pronounced phenotypic alteration following inhibition of PI3K was induction of G1 phase cell cycle arrest. LY-294002 blocked the Ha-Ras-induced expression of cyclin D1, cyclin-dependent kinase (CDK) 2, and increased the levels of p27kip. Both LY-294002 and wortmannin significantly reduced anchorage-independent growth of RIE-iHa-Ras cells. Forced expression of both the constitutively active forms of Raf (ΔRaf-22W or Raf BXB) and Akt (Akt-myr) resulted in transformation of RIE cells that was not achieved by transfection with either the Raf mutant construct or Akt-myr alone. These findings delineate an important role for PI3K/Akt in Ras-mediated transformation of intestinal epithelial cells.
AB - Phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PKB/Akt) is thought to serve as an oncogenic signaling pathway which can be activated by Ras. The role of PI3K/Akt in Ras-mediated transformation of intestinal epithelial cells is currently not clear. Here we demonstrate that inducible expression of oncogenic Ha-Ras results in activation of PKB/Akt in rat intestinal epithelial cells (RIE-iHa-Ras), which was blocked by treatment with inhibitors of PI3K activity. The PI3K inhibitor, LY-294002, partially reversed the morphological transformation induced by Ha-Ras and resulted in a modest stimulation of apoptosis. The most pronounced phenotypic alteration following inhibition of PI3K was induction of G1 phase cell cycle arrest. LY-294002 blocked the Ha-Ras-induced expression of cyclin D1, cyclin-dependent kinase (CDK) 2, and increased the levels of p27kip. Both LY-294002 and wortmannin significantly reduced anchorage-independent growth of RIE-iHa-Ras cells. Forced expression of both the constitutively active forms of Raf (ΔRaf-22W or Raf BXB) and Akt (Akt-myr) resulted in transformation of RIE cells that was not achieved by transfection with either the Raf mutant construct or Akt-myr alone. These findings delineate an important role for PI3K/Akt in Ras-mediated transformation of intestinal epithelial cells.
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U2 - 10.1074/jbc.M010093200
DO - 10.1074/jbc.M010093200
M3 - Article
C2 - 11278613
AN - SCOPUS:0035958062
SN - 0021-9258
VL - 276
SP - 14498
EP - 14504
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 17
ER -