Cbl Proteins as Regulators of Tyrosine Kinase Signaling

RTK，如EGFR、HER 2、MET和RET，通常具有不适当的活性（由于 突变或过表达）在广泛的上皮恶性肿瘤中。我的实验室克隆了 哺乳动物Cbl蛋白家族三个成员中的两个，并证明它们是 哺乳动物细胞中EGFR的负调节因子。我们已经证明Cbl蛋白是RING蛋白， 指E3和所有哺乳动物Cbl蛋白介导活化EGFR的泛素化， 导致活化的EGFR信号传导复合物的降解。在我的实验室工作， 与其他实验室的合作，以及其他研究人员已经显示了Cbl蛋白质 调节许多RTK和信号通路。此外，我的实验室还为 Cbl蛋白的结构功能分析。最近我的实验室发现 与Cblc相互作用并改变其功能的特征蛋白质， 特征化的Cbl蛋白，鉴定并表征了E2蛋白，其与 Cbl蛋白，并鉴定了人和小鼠上皮细胞中Cbl蛋白的突变形式， 肿瘤的正在进行的工作：1）研究泛素结合酶（E2）的谱， Cbl蛋白的功能。2)研究与Cbl蛋白协作的蛋白质， 通过质谱鉴定活性复合物中的蛋白质介导RTK下调 分析. 3)研究在鼠和人实体瘤中发现的Cbl蛋白的突变。4)一 筛选以鉴定Cblb E3抑制剂在一个翻译项目中，我们发现EGFR是 在2%的乳腺癌肿瘤中扩增，这预示着一个糟糕的结果。我们还 已经发现EGFR扩增的肿瘤经常在PI 3 K中具有激活突变， 途径（40-70%）。正在进行的工作是1）表征EGFR抑制剂+/-PIK 3CA的能力 在体外和体内杀死在这些途径中具有突变的细胞的抑制剂;和2） 评价这些抑制剂对肿瘤起始细胞的作用。

RTKs, such as EGFR, HER2, MET and RET, are often inappropriately active (due to mutation or overexpression) in a wide array of epithelial malignancies. My laboratory cloned two of the three members of the mammalian Cbl protein family and demonstrated that they are negative regulators of the EGFR in mammalian cells. We have shown that Cbl proteins are RING finger E3s and that all mammalian Cbl proteins mediate ubiquitination of the activated EGFR, resulting in the degradation of the activated EGFR signaling complex. Work in my lab, in collaborations with other laboratories, and by other investigators has shown the Cbl proteins regulate many RTKs and signaling pathways. In addition, my lab has contributed to the structure function analysis of the Cbl proteins. More recently my laboratory has identified and characterized proteins which interact with and modify the function of Cblc, the least well characterized Cbl protein, identified and are characterizing E2 proteins that interact with the Cbl proteins, and identified mutant forms of Cbl proteins in human and mouse epithelial tumors. Ongoing work: 1) investigates the spectrum of ubiquitin conjugating enzymes (E2s) that function with Cbl proteins. 2) investigates the proteins that collaborate with Cbl proteins to mediate RTK downregulation by identifying proteins in the active complex by mass spec analysis. 3) studies mutations of Cbl proteins found in murine and human solid tumors. 4) a screen to identify Cblb E3 inhibitors In a translational project we have found that EGFR is amplified in 2% of breast cancer tumors and that this protends a poor outcome. Further, we have found that the EGFR amplified tumors frequently have activating mutations in the PI3K pathway (40-70%). Ongoing work is 1) characterizing the ability of EGFR inhibitors +/- PIK3CA inhibitors to kill cells with mutations in these pathways in vitro and in vivo; and 2) evaluating the effects of these inhibitors on tumor initiating cells.