Cbl Proteins as Regulators of Tyrosine Kinase Signaling

rtk，如EGFR、HER2、MET和RET，在广泛的上皮恶性肿瘤中经常不适当地活跃（由于突变或过表达）。我的实验室克隆了哺乳动物Cbl蛋白家族的三个成员中的两个，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 finger E3s，并且所有哺乳动物的Cbl蛋白都介导活化的EGFR的泛素化，导致活化的EGFR信号复合物的降解。在我的实验室，与其他实验室合作，以及其他研究人员的工作表明，Cbl蛋白调节许多rtk和信号通路。此外，我的实验室还对Cbl蛋白的结构功能分析做出了贡献。最近，我的实验室已经鉴定并表征了与Cblc相互作用并修改其功能的蛋白质，这是表征最不完善的Cbl蛋白质，鉴定并表征了与Cbl蛋白质相互作用的E2蛋白质，并鉴定了人类和小鼠上皮肿瘤中Cbl蛋白质的突变形式。正在进行的工作：1)研究泛素偶联酶（E2s）与Cbl蛋白的作用谱。2)通过质谱分析鉴定活性复合物中的蛋白，研究与Cbl蛋白协同介导RTK下调的蛋白。3)研究小鼠和人实体肿瘤中发现的Cbl蛋白突变。在一个转化项目中，我们发现EGFR在2%的乳腺癌肿瘤中被放大，这证明了一个不好的结果。此外，我们发现EGFR扩增的肿瘤经常在PI3K通路中具有激活突变（40-70%）。正在进行的工作是1)表征EGFR抑制剂+/- PIK3CA抑制剂在体外和体内杀死这些途径中发生突变的细胞的能力；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.