Mechanisms of TGFbeta-mediated fibroblastic transition

TGFβ介导的成纤维细胞转变机制

• 批准号: 6700228
• 负责人: Andrei V. Bakin
• 金额: $ 33.01万
• 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/6700228
• 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(TGFβ)家族的分泌因子在生物系统的发育、动态平衡和功能中起着重要作用(S)。许多人类疾病与转化生长因子β信号网络的异常运行有关。转化生长因子β具有肿瘤抑制活性，其信号通路的组成部分在癌症中经常发生突变或沉默。然而，TGFbeta通过刺激上皮向间充质转化(EMT)和细胞迁移而促进肿瘤的进展和侵袭性。EMT是一个复杂的过程，与上皮细胞接触的改变、细胞形态的改变、细胞骨架的重组、成纤维细胞标志物(纤维连接蛋白、波形蛋白)的表达和促进细胞迁移有关。TGFbeta的这些作用也参与了伤口修复和各种组织的纤维化。TGFβ诱导EMT和细胞迁移的机制(S)还不是很清楚。我们发现，p38丝裂原活化蛋白激酶(P38MAPK)的抑制剂可以抑制TGFβ介导的EMT和细胞迁移，而不抑制TGFbeta的抗增殖活性。因此，p38MAPK通路可能在TGFβ促肿瘤活性中起关键作用。我们还观察到p38MAPK的激活是由Rho家族GTP酶介导的。TGFbeta信号转导Rho样GTP酶和p38MAPK的机制尚未确定。我们假设，Rho家族GTP酶介导的激酶活性的TGFbeta受体激活p38MAPK通路是建立导致TGFbeta诱导的成纤维细胞转化和细胞迁移的细胞表型变化的程序所必需的。这一假设将通过以下具体目标进行检验。目的1：研究转化生长因子β受体的激酶功能在Rho样GTP酶激活和p38MAPK通路中的作用。目的：体外检测p38MAPK激活的MKK3和MKK6基因的显性负性突变和成分活性突变对转化生长因子β诱导的细胞内膜转化和细胞迁移的影响。目的：探讨p38MAPK通路在小鼠肿瘤细胞运动、侵袭和转移中的作用。这项研究将有助于确定TGFbeta的信号网络，并有助于设计新的选择性抑制TGFbeta的促肿瘤活性。