Interaction of signaling pathways with lipid metabolites

该项目的重点是研究前列腺素和亚油酸代谢物调节生长因子信号通路特别是EGFR通路的机制。以叙利亚仓鼠胚胎（SHE）细胞和人类结肠直肠细胞为模型，研究脂质与信号通路的相互作用。在SHE细胞中，亚油酸代谢物13(S)-HODE刺激egf依赖性DNA合成，而前列腺素抑制生长。13(S)-HODE的加入上调了EGFR磷酸化事件，包括刺激MAP激酶活性。亚油酸代谢物减弱了supB+细胞中EGFR的去磷酸化，从而上调了整个EGFR通路。目前，我们正在研究EGFR与连接受体到MAP激酶途径的适配器蛋白的相互作用。我们有证据表明，一种新发现的蛋白gab1将EGFR与SHP-2联系起来，SHP-2是一种与肿瘤进展相关的酪氨酸磷酸酶。EGFR、gab1和SHP-2之间形成三元络合物。我们克隆了仓鼠Gab1 cDNA，并在10W+8（非致瘤性）和10W2T（致瘤性）细胞中表达。10W2T细胞中外源性Gab1的表达恢复了egf依赖性的SHP-2与EGFR的关联，这表明Gab1在EGFR和SHP-2之间起连接作用。此外，外源Gab1表达显著增强了10W+8细胞中egf依赖性有丝分裂活性，而在10W2T细胞中仅表现出边际效应。这些结果表明，Gab1在EGFR信号通路中通过EGFR - Gab1的形成与SHP-2共同作用。SHP-2复杂。Gab1表达的改变可能与对EGF的反应性改变有关，因此，Gab1表达的改变可能是SHE细胞肿瘤进展的关键事件。此外，我们正在探索Cox/Lox与ppar之间的关系。我们的假设是，在肿瘤中观察到的高Cox/Lox表达减弱了PPARg的抗肿瘤活性，这是通过MAP激酶信号通路介导的作用

The focus of this project is to examine the mechanism(s) by which prostaglandins and linoleic acid metabolites modulate growth factor signaling pathways particularly the EGFR pathway. Syrian hamster embryo (SHE) cells and human colorectal cells are used as models to study the interaction of lipids with signaling pathways. In SHE cells, the linoleate metabolite, 13(S)-HODE stimulates EGF-dependent DNA synthesis while prostaglandins inhibited growth. The addition of 13(S)-HODE up-regulated the EGFR phosphorylation events including a stimulation of MAP kinase activity. The linoleic acid metabolite attenuated the de-phosphorylation of the EGFR in the supB+ cells thereby up-regulating the entire EGFR pathway. Currently, we are studying the interaction of the EGFR with the adapter proteins that connect the receptor to the MAP kinase pathway. We have evidence that a newly described protein Gab-1, links EGFR to SHP-2 a tyrosine phosphatase associated with neoplastic progression. A ternary complex forms between the EGFR, Gab-1 and SHP-2. We cloned the hamster Gab1 cDNA and expressed it in both 10W+8 (non-tumorigenic) and 10W2T (tumorigenic) cells. Exogenous Gab1 expression in 10W2T cells restored the EGF-dependent association of SHP-2 with EGFR, which indicates that Gab1 functions as a linker between EGFR and SHP-2. Furthermore, exogenous Gab1 expression significantly enhanced EGF-dependent mitogenic activity in 10W+8 cells, while it only showed a marginal effect in 10W2T cells. These results identify Gab1 as an important co-player with SHP-2 in the EGFR signaling pathway via the formation of the EGFR?Gab1?SHP-2 complex. Altered expression of Gab1 is likely to be involved in the altered responsiveness to EGF, therefore, may be a key event in neoplastic progression of SHE cells. In addition, we are exploring the relationship between Cox/Lox and PPARg. Our hypothesis is that high Cox/Lox expression observed in tumors attenuates the anti-tumorigenic activity of PPARg and this is mediated effect through the MAP kinase signaling pathway