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

描述（申请人提供）：转化生长因子-¿（TGF-¿）在癌症的发生和发展中起着至关重要的作用。癌细胞往往表现出TGF-¿的产生和激活增强，从而对细胞生理和行为产生自分泌作用。其中，TGF-¿诱导上皮细胞向间充质细胞转化（EMT）的能力引起了大量的关注，EMT导致细胞脱粘、运动性增加和侵袭。TGF-¿在癌细胞行为、肿瘤微环境和癌症进展中的作用已被广泛研究，但TGF-¿激活的潜在信号通路在癌细胞行为中的各自作用尚不清楚。在这方面的大多数研究都关注TGF-激活的Smads的作用，它们作为转录（co）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信号通路在响应TGF-¿时被直接激活。这些可以解释对TGF-¿的非转录反应，如迁移、细胞形状的变化和蛋白质翻译，但也可能影响smad的活性。非smad信号事件在TGF-介导的癌细胞行为和癌症进展中的作用基本上是未知的。我们最近报道，在TGF-¿诱导的上皮细胞EMT中，TGF-¿激活pi3激酶- akt - tor通路，导致蛋白质合成增加和细胞大小增加，该通路介导TGF-¿诱导的EMT细胞的运动和侵袭性增加。我们还报道，在对TGF-¿的反应中，ShcA被募集到I型TGF-¿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，T¿RI是一种双特异性激酶，解释了ShcA在Ser和Tyr上的磷酸化，而T¿RI响应于TGF-¿在Tyr上的磷酸化可能为TGF-¿激活PI3K-Akt-TOR和Shc-Erk MAPK通路提供了生化基础。最后，我们发现响应于TGF-¿的T¿RI磷酸化可诱导T¿RI sumoylation。T - RI summoylation反过来调节TGF-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。Aim 1将重点关注TGF-¿如何激活PI3K-Akt-TOR通路，以及TGF-¿信号中PI3K-Akt-TOR在细胞侵袭和癌症进展中的作用。Aim 2将研究TGF-¿-激活的ShcA-Erk MAP激酶信号在EMT、侵袭和癌症进展中的作用。目的3提出更好地表征T¿RI的summoylation，并了解其在TGF-反应和癌症进展中的作用。我们对这个项目的热情不仅是因为它内在的科学重要性，还因为它的转化潜力。公共卫生相关性：在大多数情况下，导致死亡的癌症进展不是第一个肿瘤生长的结果，而是因为肿瘤开始侵入其他组织并扩散到全身，从而产生更多的肿瘤，这一过程称为转移。癌症的侵袭和转移是由一种叫做TGF-¿的蛋白质驱动的，这种蛋白质是由肿瘤细胞自身产生的，并指导它们经历导致侵袭和转移的变化。近年来，TGF-¿激活的新信号通路被发现，并补充了之前研究的备受关注的信号通路。本研究旨在更好地了解这些额外通路的分子基础及其在癌细胞行为、癌症进展和转移中的作用。这一知识可能提供新的和更多的选择性途径，比迄今为止可能阻止癌症的侵袭和转移行为。

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. PUBLIC HEALTH RELEVANCE: The progression of cancer leading to death is in most cases not the result of the first tumor growing, but rather because that tumor starts invading other tissues and disseminating throughout the body to give rise to additional tumors, a process called metastasis. Cancer invasion and metastasis are driven by a protein called TGF-¿, which is made by the tumor cells themselves and instructs them to undergo the changes that lead to invasion and metastasis. Recently, novel signaling pathways were found that are activated by TGF-¿ and complement the previously studied one that received all attention. The proposed research aims at better understanding the molecular basis of these additional pathways and their roles in cancer cell behavior, cancer progression and metastasis. This knowledge is likely to provide new and more selective avenues than hitherto possible to block the invasive and metastatic behavior of cancers.