Akt/PKB activity is required for Ha-Ras-mediated transformation of intestinal epithelial cells
Akt/PKB activity is required for Ha-Ras-mediated transformation of intestinal epithelial cells
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DOI：
10.1074/jbc.m010093200
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发表时间：
2001-04-27
影响因子：
4.8
通讯作者：
DuBois, RN
中科院分区：
文献类型：
--
作者：
Sheng, HM;Shao, JY;DuBois, RN
磷脂酰肌醇3-激酶(PI3K)/蛋白激酶B(PKB/Akt)被认为是RAS激活的致癌信号通路，但PI3K/Akt在PAS介导的肠上皮细胞转化中的作用目前尚不清楚。在这里，我们证明了致癌基因Ha-RAS的诱导表达导致了大鼠肠上皮细胞(RIE-IHA-RAS)中PKB/Akt的激活，这一激活可被PI3K活性抑制剂阻断。PI3K抑制剂LY-294002部分逆转了Ha-PAS诱导的细胞形态改变，并对细胞凋亡有一定的刺激作用。抑制PI3K后最明显的表型改变是诱导G(1)期细胞周期停滞。LY-294002可阻断Ha-PAS诱导的细胞周期蛋白D1和细胞周期蛋白依赖性激酶2的表达，并上调p27(Kip2)的表达。LY-294002和Wortmannin均显著抑制RIE-IHA-RAS细胞的贴壁非依赖性生长。Raf(Delta Raf-22W或Raf BXB)和Akt(Akt-MYR)的强制表达导致了RIE细胞的转化，这是单独使用Raf突变构建体或Akt-MYR无法实现的。这些发现揭示了PI3K/Akt在PAS介导的肠上皮细胞转化中的重要作用。
PhosphatidyIinositol 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 Pas-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-Pas and resulted in a modest stimulation of apoptosis. The most pronounced phenotypic alteration following inhibition of PI3K was induction of G(1) phase cell cycle arrest. LY-294002 blocked the Ha-Pas-induced expression of cyclin D1, cyclin-dependent kinase (CDK) 2, and increased the levels of p27(kip2). 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 (Delta Raf-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 Pas-mediated transformation of intestinal epithelial cells.