Mechanisms of TGFbeta-mediated fibroblastic transition

TGFβ介导的成纤维细胞转变机制

• 批准号: 6720812
• 负责人: Andrei V. Bakin
• 金额: $ 32.64万
• 依托单位: ROSWELL PARK CANCER INSTITUTE CORP
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-02-03 至 2007-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6720812
• 关键词: breast neoplasms; cell migration; cell motility; cell transformation; fibroblasts; fibronectins; green fluorescent proteins; growth factor receptors; guanosinetriphosphatase activating protein; laboratory mouse; metastasis; mitogen activated protein kinase; neoplasm /cancer invasiveness; neoplasm /cancer therapy; neoplastic process; neoplastic transformation; protein kinase; transcription factor; transforming growth factors; tumor promoters; vimentin; western blottings

The transforming growth factor beta (TGFbeta) family of secreted factors play important role(s) in development, homeostasis and functioning of biological systems. A number of human diseases are associated with abnormal operation of the TGFbeta signaling network. TGFbeta exhibits a tumor suppressor activity and components of its signaling pathway are frequently mutated or silenced in cancers. However, TGFbeta contributes to the progression and invasiveness of tumors by stimulating an epithelial to mesenchymal transition (EMT) and cell migration. EMT is a complex process associated with alterations in epithelial cell contacts, changes in cell morphology, reorganization of the cell cytoskeleton, expression of fibroblastic markers (fibronectin, vimentin) and enhancement of cell migration. These effects of TGFbeta are also involved in wound repair and fibrosis of various tissues. The mechanism(s) of TGFbeta-induced EMT and cell migration are not well understood. We made the important observation that TGFbeta- mediated EMT and cell migration are impaired by inhibitors of p38 mitogen activated protein kinase (p38Mapk), without inhibition of the antiproliferative activity of TGFbeta. Thus, the p38Mapk pathway may play a critical role in TGFbeta's tumor promoting activity. We also observed that p38Mapk activation is mediated by Rho-family GTPases. The mechanism by which TGFbeta signals to Rho-like GTPases and p38Mapk has not yet been defined. We hypothesize that activation of the p38Mapk pathway by kinase- active TGFbeta receptors mediated by Rho-family GTPases is required for setting up a program of changes in the cell phenotype leading to TGFbeta-induced fibroblastic transition and cell migration. This hypothesis will be tested by the following specific aims. Aim 1: To examine the role of kinase function of TGFbeta receptors in activation of Rho-like GTPases and the p38Mapk pathway. Aim 2: To examine in vitro the effect of dominant negative and constitutively active mutants of MKK3 and MKK6, p38Mapk activating kinases, on the TGFbeta-induced EMT and cell migration. Aim 3: To evaluate the role of the p38Mapk pathway in tumor cell motility, invasiveness and metastasis in mouse models. The proposed research will help to define the TGFbeta signaling network and will facilitate the design of novel selective inhibition of TGFbeta's tumor promoting activity.

转化生长因子β (TGFbeta) 分泌因子家族在生物系统的发育、体内平衡和功能中发挥着重要作用。 许多人类疾病与 TGFbeta 信号网络的异常运行有关。 TGFbeta 表现出肿瘤抑制活性，其信号通路成分在癌症中经常发生突变或沉默。 然而，TGFbeta 通过刺激上皮间质转化 (EMT) 和细胞迁移，促进肿瘤的进展和侵袭。 EMT 是一个复杂的过程，与上皮细胞接触的改变、细胞形态的变化、细胞骨架的重组、成纤维细胞标记物（纤连蛋白、波形蛋白）的表达和细胞迁移的增强有关。 TGFbeta 的这些作用还涉及各种组织的伤口修复和纤维化。 TGFbeta 诱导 EMT 和细胞迁移的机制尚不清楚。 我们发现，p38 丝裂原激活蛋白激酶 (p38Mapk) 抑制剂会损害 TGFbeta 介导的 EMT 和细胞迁移，但不会抑制 TGFbeta 的抗增殖活性。 因此，p38Mapk 通路可能在 TGFbeta 的肿瘤促进活性中发挥关键作用。 我们还观察到 p38Mapk 激活是由 Rho 家族 GTPases 介导的。 TGFbeta 向 Rho 样 GTPases 和 p38Mapk 发出信号的机制尚未确定。 我们假设，Rho 家族 GTPases 介导的激酶活性 TGFbeta 受体激活 p38Mapk 途径是建立细胞表型变化程序，导致 TGFbeta 诱导的成纤维细胞转变和细胞迁移所必需的。 这一假设将通过以下具体目标进行检验。 目标 1：检查 TGFbeta 受体激酶功能在 Rho 样 GTP 酶和 p38Mapk 通路激活中的作用。 目标 2：体外检查 MKK3 和 MKK6（p38Mapk 激活激酶）的显性失活和组成型活性突变体对 TGFbeta 诱导的 EMT 和细胞迁移的影响。 目标 3：评估 p38Mapk 通路在小鼠模型中肿瘤细胞运动、侵袭和转移中的作用。 拟议的研究将有助于定义 TGFbeta 信号网络，并将有助于设计新型选择性抑制 TGFbeta 肿瘤促进活性的药物。