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.
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.
复制标题
Src- 与胰岛素和 IGF-1 受体诱导的大鼠肠上皮细胞生长和转化中 MAP 激酶和 PI3 激酶信号通路的不同需求。
作者：
Nguyen,KT;Wang,WJ;Chan,JL;Wang,LH
关于致癌蛋白酪氨酸激酶转化上皮细胞的具体信号转导途径的研究很少。在此，我们研究了MAP(MAPK)和磷脂酰肌醇3-(PI3K)激酶在胰岛素受体(GAG-IR)、胰岛素样生长因子-1受体(GAG-IGFR)和v-Src致癌形式转化大鼠肠上皮(RIE)细胞过程中的需求。在GAG-IR和GAG-IGFR转化的细胞中，MAPK没有明显的激活，而在v-Src转化的细胞中却被激活。用MEK抑制剂PD98059处理MAPK活性低于基础水平的浓度时，表明MAPK是亲代和转化的RIE细胞单层生长所必需的部分。然而，MAPK对三种癌基因转化细胞的病灶形成能力并不是必需的。GAG-IR-和GAG-IGFR-的克隆形成能力也不是必需的，但对v-Src转化的细胞是部分必需的。PI3K在三种癌基因转化的RIE细胞中均显著激活。PI3K抑制剂LY294002有效地抑制了三种癌基因转化细胞的单层生长。然而，在LY294002浓度下，PI3K途径下游成分Akt的激活形式不可检测到，v-Src-RIE细胞的集落形成和病灶形成能力仅受到轻微影响，而Gag-IR/IGFR-RIE细胞的集落和病灶形成能力受到极大抑制。使用不同的药物抑制剂Wortmannin和PI3K的显性阴性形式ΔP85证实了这些结果。类似地，雷帕霉素可以抑制PI3K-Akt通路下游的p70S6激酶，也可以抑制Gag-IR/IGFR诱导的聚集和克隆形成，但不能抑制v-Src诱导的聚集和克隆形成。我们得出结论：MAPK和PI3K信号通路对于RIE细胞的转化具有不同的需求，IGFR和Src的需求模式不同于成纤维细胞的转化。
There have been few studies on the specific signaling pathways involved in the transformation of epithelial cells by oncogenic protein tyrosine kinases. Here we investigate the requirement of MAP (MAPK) and phosphatidylinositol 3-(PI3K) kinases in the transformation of rat intestinal epithelial (RIE) cells by oncogenic forms of insulin receptor (gag-IR), insulin-like growth factor-1 receptor (gag-IGFR), and v-Src. MAPK is not significantly activated in cells transformed by gag-IR and gag-IGFR but is activated in v-Src transformed cells. Treatment with PD98059, a MEK inhibitor, at concentrations where MAPK activity was reduced below the basal level showed that MAPK is partially required for the monolayer growth of parental and transformed RIE cells. However, MAPK is not essential for the focus forming ability of the three oncogene-transformed cells. It is also not necessary for the colony forming ability of gag-IR-and gag-IGFR-, but is partially required for v-Src-transformed cells. PI3K is significantly activated in all three oncogene transformed RIE cells. LY294002, a PI3K inhibitor, potently inhibited monolayer growth of all three oncogene-transformed cells. However, at concentrations of LY294002 where activated forms of Akt, a downstream component of the PI3K pathway, were undetectable, colony and focus forming abilities of the v-Src-RIE cells were only slightly affected whereas those of gag-IR/IGFR-RIE cells were greatly inhibited. These results were confirmed using a different pharmacological inhibitor, wortmannin, and a dominant negative form of PI3K, Δp85. Similarly, rapamycin, known to inhibit p70S6 kinase, a downstream component of the PI3K-Akt pathway, also inhibited gag-IR/IGFR-induced, but not v-Src-induced, focus and colony formation. We conclude that the MAPK and PI3K signaling pathways are differentially required for transformation of RIE cells by oncogenic IR and IGFR versus Src and the pattern of requirements is different from that of fibroblast transformation.