Molecular and Cellular Mechanisms of Resistance to mTORC1 Inhibition in the Skin

 描述（由申请人提供）：精准医学时代迎来了大量靶向治疗，许多靶向治疗旨在抑制PI 3 K/AKT/mTOR信号传导，这是人类肿瘤中最常见的上调致癌信号传导途径之一。然而，这些抑制剂在早期临床试验中的结果很大程度上令人失望。这些药物表现不佳的最令人信服的解释之一是缓解了许多调节致癌信号通路的负反馈途径。过去十年的研究表明，PI 3 K/AKT/mTOR信号转导的下调经常导致上游受体酪氨酸激酶（RTK）信号转导（包括ErbB受体信号转导）的反馈抑制丧失。现在，关键的挑战是阐明这种作用的基本分子和细胞机制，以便设计合理的策略来规避肿瘤对这些抑制剂的耐药性。使用新的小鼠模型，允许特定的扰动mTORC 1信号，我们证明，mTORC 1在调节生理EGFR水平和细胞间粘附在体内小鼠皮肤中起着关键作用。在这里，我们建议使用这些强大的遗传系统来梳理出mTORC 1抑制导致EGFR信号传导的矛盾上调和粘附连接成熟的抑制的相互关联的机制，这可能是介导肿瘤对PI 3 K/AKT/mTOR抑制剂耐药性的关键事件。目的1将通过评估mTORC 1扰动对角质形成细胞中EGFR运输和降解的影响来确定mTORC 1反馈如何抑制上游EGFR水平和信号传导。目的2将通过检测EGFR/PI 3 K/AKT和Rho家族GT3信号转导在粘附连接成熟过程中的作用，并鉴定mTORC 1调节的连接形成下游磷酸化蛋白质组，来确定mTORC 1信号转导如何调节粘附连接成熟。最后，目的3将探讨mTORC 1干扰EGFR和细胞-细胞粘附的影响如何影响两阶段癌变模型中已建立的皮肤乳头状瘤的癌进展。使用同基因和体内系统，这项工作澄清了几个基本的分子和细胞机制，上皮肿瘤可能会产生耐药性mTORC 1抑制。

 DESCRIPTION (provided by applicant): The era of precision medicine has ushered in a large number of targeted therapeutics, many aimed at inhibiting PI3K/AKT/mTOR signaling, one of the most commonly up-regulated oncogenic signaling pathways in human tumors. However, these inhibitors have had largely disappointing results in early clinical trials. One of the most compelling explanations for the poor performance of these drugs has been the relief of numerous negative feedback pathways that regulate oncogenic signaling circuits. The last decade of work has revealed that down-regulation of PI3K/AKT/mTOR signaling frequently results in loss of feedback inhibition of upstream receptor tyrosine kinase (RTK) signaling, including ErbB receptor signaling. Now, the key challenge is to elucidate the basic molecular and cellular mechanisms by which this works so that rational strategies can be devised to circumvent tumor resistance to these inhibitors. Using novel mouse models that allow specific perturbation of mTORC1 signaling, we demonstrate that mTORC1 plays a critical role in regulating physiologic EGFR levels and cell-cell adhesion in vivo in the murine skin. Here, we propose to use these powerful genetic systems to tease out the interconnected mechanisms by which mTORC1 inhibition leads to paradoxical up- regulation of EGFR signaling and suppression of adherens junction maturation, potentially key events mediating tumor resistance to PI3K/AKT/mTOR inhibitors. Aim 1 will determine how mTORC1 feedback inhibits upstream EGFR levels and signaling by assessing the effects of mTORC1 perturbation on EGFR trafficking and degradation in keratinocytes. Aim 2 will establish how mTORC1 signaling modulates adherens junction maturation by examining the role of EGFR/PI3K/AKT and Rho family GTPase signaling in this process, and identifying the mTORC1-regulated phospho-proteome downstream of junction formation. Finally, Aim 3 will explore how effects of mTORC1 perturbation on EGFR and cell-cell adhesion affect carcinoma progression of established skin papillomas in two-stage carcinogenesis models. Using isogenic and in vivo systems, this work clarify several basic molecular and cellular mechanisms by which epithelial tumors may develop resistance to mTORC1 inhibition.