TGF-beta-induced non-Smad signaling events and cancer cell behavior

描述（由申请人提供）：转化生长因子-<$（TGF-<$）在癌症发生和进展中起关键作用。 癌细胞通常表现出增强的TGF-β产生和活化，导致对细胞生理和行为的自分泌效应。 其中，大量的注意力集中在TGF-β诱导上皮细胞向间质细胞转化（EMT）的能力，导致去粘附，增加运动性和侵袭性。 TGF-β的作用在癌细胞行为中，肿瘤微环境和癌症进展是广泛研究的主题，但对潜在的TGF-β激活的信号通路在癌细胞行为中的各自作用了解较少。 这方面的大多数研究都涉及TGF-β激活的Smads的作用，Smads作为转录（辅助）因子调节基因表达。 最近的研究，包括本实验室的一些研究，已经表征了非Smad信号通路，这些信号通路直接响应TGF-β而被激活。 这些可以解释对TGF-β的非转录反应，如迁移，细胞形状和蛋白质翻译的变化，但也可能影响Smads的活性。 非Smad信号传导事件在TGF-β对癌细胞行为和癌症进展的作用中的功能基本上是未知的。 我们最近报道，在TGF-β诱导的上皮细胞EMT中，TGF-β激活PI 3-激酶-Akt-TOR通路，导致蛋白质合成增加和细胞大小增加，并且该通路介导经历TGF-β诱导的EMT的细胞的运动性和侵袭性增加。 我们还报道，在对TGF-β的反应中，ShcA被募集到I型TGF-β受体T-RI上，并在Ser和Tyr上磷酸化，进而导致Erk MAP激酶的激活。 我们观察到，RI是一种双特异性激酶，可解释ShcA在Ser和Tyr上的磷酸化，而T <$RI在Tyr上的磷酸化可为TGF-<$激活PI 3 K-Akt-TOR和Shc-Erk MAPK通路提供生化基础。 最后，我们发现T_R1的磷酸化对TGF-β的反应诱导T_R1类小泛素化。 T-RI类小泛素化反过来调节TGF-β信号依赖的癌细胞侵袭。 我们建议在分子水平上进一步表征这些信号事件的机制，并利用这些知识来解决它们在癌细胞行为和癌症进展中的作用。 目标1将重点关注TGF-β如何激活PI 3 K-Akt-TOR通路，以及TGF-β信号传导的这一组成部分在细胞侵袭和癌症进展中的作用。 目的2研究TGF-β激活的ShcA-Erk MAP激酶信号通路在EMT、侵袭和肿瘤进展中的作用。 目的3提出更好地表征T <$RI的sumoylation，并了解其在TGF-β反应和癌症进展中的作用。 我们对该计划的热情不仅是由其固有的科学重要性驱动的，而且也是由其转化潜力驱动的。

DESCRIPTION (provided by applicant): Transforming growth factor-¿ (TGF-¿) plays a critical role in cancer initiation and progression. Carcinoma cells often have shown enhanced TGF-¿ production and activation, resulting in autocrine effects on cell physiology and behavior. Among these, a lot of attention has focused on TGF-¿'s ability to induce an epithelial to mesenchymal transition (EMT) that results in de-adhesion, increased motility and invasion. The roles of TGF-¿ in cancer cell behavior, tumor microenvironment and cancer progression are subject of extensive investigation, but the respective roles of the underlying TGF-¿-activated signaling pathways in cancer cell behavior are less understood. Most studies in this context address the roles of TGF-¿-activated Smads, which serve as transcription (co)factors to regulate gene expression. Recent studies, including some from this lab, have characterized non-Smad signaling pathways that are directly activated in response to TGF-¿. These may explain non-transcription responses to TGF-¿ such as migration, changes in cell shape and protein translation, yet may also affect the activities of the Smads. The functions of the non-Smad signaling events in the TGF-¿-directed effects on cancer cell behavior and cancer progression are essentially unknown. We recently reported that, in TGF-¿-induced epithelia EMT, TGF-¿ activates the PI3-kinase-Akt-TOR pathway, resulting in increased protein synthesis and cell size, and that this pathway mediates the increased motility and invasion of cells that undergo TGF-¿-induced EMT. We also reported that, in response to TGF-¿, ShcA is recruited to the type I TGF-¿ receptor T¿RI and phosphorylated on Ser and Tyr, in turn resulting in activation of Erk MAP kinase. Our observation that T¿RI is a dual specificity kinase explains ShcA phosphorylation on Ser and Tyr, whereas T¿RI phosphorylation on Tyr in response to TGF-¿ may provide the biochemical basis for activation of both the PI3K-Akt-TOR and the Shc-Erk MAPK pathways by TGF-¿. Finally, we discovered that phosphorylation of T¿RI in response to TGF-¿ induces T¿RI sumoylation. T¿RI sumoylation in turn regulates TGF-¿-signaling dependent invasion of cancer cells. We propose to further characterize the mechanisms of these signaling events at the molecular level and to use this knowledge to address their roles in cancer cell behavior and cancer progression. Aim 1 will focus on how TGF-¿ activates the PI3K-Akt-TOR pathway and on the role of this component of TGF-¿ signaling in cell invasion and cancer progression. Aim 2 will study the role of TGF-¿-activated ShcA-Erk MAP kinase signaling in EMT, invasion and cancer progression. Aim 3 proposes to better characterize the sumoylation of T¿RI and to understand its role in the TGF-¿ response and cancer progression. Our enthusiasm for this program is driven not only by its inherent scientific importance, but also by its translational potential.