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

描述(申请人提供)：转化生长因子-β(转化生长因子-β)在癌症的发生和发展中起关键作用。癌细胞经常表现出增强的转化生长因子-β的产生和激活，从而对细胞的生理和行为产生自分泌效应。其中，大量的注意力集中在转化生长因子-S诱导上皮细胞向间充质细胞转化的能力，从而导致黏附解除、运动能力增加和侵袭。关于转化生长因子β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，但转化生长因子激活的信号通路在癌细胞行为中的各自作用尚不清楚。在这一背景下，大多数研究都涉及到转化生长因子激活的Smads的作用，它作为转录(Co)因子来调节基因表达。最近的研究，包括本实验室的一些研究，已经确定了非Smad信号通路的特征，这些信号通路直接被转化生长因子-β激活。这些可能解释了对转化生长因子β的非转录反应，如迁移、细胞形状变化和蛋白质翻译，但也可能影响Smads的活性。非Smad信号事件在转化生长因子对癌细胞行为和癌症进展的影响中的作用基本上是未知的。我们最近报道，在转化生长因子-β诱导的上皮细胞内皮细胞转化中，转化生长因子-β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，并且该途径介导了经历转化生长因子-β诱导的内皮细胞转化过程中细胞的运动性和侵袭性增加。我们还报道，作为对转化生长因子-β的反应，SHCA被募集到I型转化生长因子-β受体T？RI上，并在丝氨酸和酪氨酸上被磷酸化，进而导致Erk MAP激酶的激活。我们观察到T？RI是SHCA在丝氨酸和酪氨酸上的双特异性磷酸化，而T？RI在TYR上的磷酸化可能为转化生长因子-β激活PI3K-Akt-TOR和Shc-Erk MAPK通路提供生化基础。最后，我们发现在转化生长因子-β的作用下，T？RI的磷酸化导致T？RI的苏莫化。T？RI苏莫化反过来调节依赖于转化生长因子信号的癌细胞的侵袭。我们建议在分子水平上进一步表征这些信号事件的机制，并利用这一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将集中在转化生长因子β如何激活PI3K-Akt-TOR通路，以及转化生长因子β信号在细胞侵袭和癌症进展中的作用。目的2研究转化生长因子激活的SHCA-Erk MAP激酶信号在子宫内膜癌发生、侵袭和肿瘤进展中的作用。目的3建议更好地表征T？RI的总和甲基化，并了解其在转化生长因子-β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固有的科学重要性，也是因为它的翻译潜力。与公共卫生相关：在大多数情况下，癌症的发展导致死亡并不是第一个肿瘤生长的结果，而是因为该肿瘤开始侵袭其他组织，并在全身扩散，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名为转化生长因子-β的蛋白质驱动的，这种蛋白质是由肿瘤细胞自己制造的，指示它们经历导致侵袭和转移的变化。最近，新的信号通路被发现，它被转化生长因子-β激活，并补充了先前研究的受到所有关注的信号通路。这项拟议的研究旨在更好地了解这些额外途径的分子基础及其在癌细胞行为、癌症进展和转移中的作用。这一知识可能会提供比迄今更具选择性的新途径来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.