TGF-Beta Signaling Effectors in Prostate Growth Regulation/Tumor Progression

描述（申请人提供）：转化生长因子-¿（TGF-¿）是正常、良性和恶性前列腺生长的负调节因子。TGF- 1在正常前列腺中具有抑制生长/细胞凋亡的作用，但在衰老的前列腺中过量产生TGF- 1有助于良性前列腺增生（BPH）和前列腺癌的发展。我们之前已经证实TGF- 5信号的激活导致细胞凋亡的诱导，TGF- 2受体（T2RII）的缺失有助于前列腺肿瘤的生长。T2RII在人前列腺癌细胞中过表达，使TGF-¿在体外和体内响应于凋亡介导的生长抑制。以LNCaP T2RII前列腺癌细胞（雄激素敏感和TGF-¿响应）为模型，发现TGF-¿1诱导细胞凋亡，雄激素可增强这一作用。最近基于蛋白质组学的方法发现了两种新的TGF-通路的细胞内效应物，它们独立于Smads调节前列腺癌细胞的凋亡结果。在本研究中，我们假设TGF-¿1信号通过smad4非依赖性细胞内效应物的改变和与雄激素受体（AR）的串扰调节前列腺生长，而该网络的功能失活加速了恶性表型的表现和肿瘤的进展。以下四个特异性目的将验证这一假设：特异性目的1将表征Smad独立的信号效应物，禁止素和cofilin，作为TGF-在前列腺良性和恶性上皮细胞中的作用的新介质的功能参与。特异性目的2将确定雄激素受体（AR）在TGF-¿1与雄激素信号相互作用中对前列腺肿瘤上皮细胞凋亡和上皮向间质转化（EMT）的意义。特异性Aim 3将在肿瘤微环境中确定cofilin作为前列腺（基质）成纤维细胞指导TGF-¿信号传导能力的新调节剂的作用。Specific Aim 4将利用条件敲除小鼠DNT2RII来表征功能受损的TGF-¿信号对前列腺生长、肿瘤发生和进展的体内生理影响，并与TRAMP转基因小鼠模型杂交产生双转基因。这些研究将为TGF -信号网络调控前列腺生长和肿瘤进展的机制提供新的见解。了解细胞如何读取TGF-¿将有助于描述介导特定TGF-¿效应的转录程序，并为定义TGF-¿1生长抑制/凋亡反应在正常、良性和癌前前列腺细胞中的机制提供框架，通过该机制，TGF-¿1生长抑制/凋亡反应可能被癌细胞的侵袭性和转移性反应选择性地取代。

DESCRIPTION (provided by applicant): Transforming growth factor-¿ (TGF-¿) is a negative regulator of normal, benign and malignant prostate growth. While serving a growth-inhibitory/apoptotic role in the normal prostate, overproduction of TGF- ¿ 1 in the aging prostate contributes to the development of benign prostate hyperplasia (BPH) and prostate cancer. We previously established that activation of TGF-s ¿ signaling leads to apoptosis induction and loss of TGF ¿ RII receptor (T2RII) contributes to prostate tumorigenic growth. Overexpression of T2RII in human prostate cancer cells enables apoptosis-mediated-growth suppression in response to TGF- ¿ in vitro and in vivo. Using the LNCaP T2RII prostate cancer cells (androgen-sensitive and TGF- ¿ responsive) as a model, it was shown that TGF- ¿1 induces apoptosis and this effect was enhanced by androgens. Recent proteomic-based approaches identified two new intracellular effectors of TGF-¿ pathway that act independent of Smads to regulate apoptotic outcomes in prostate cancer cells. In this proposal we hypothesize that TGF- ¿ 1 signaling via changes in Smad4-independent intracellular effectors and cross-talk with the androgen receptor (AR) regulates prostate growth, and functional inactivation of this network accelerates the manifestation of the malignant phenotype and tumor progression. The following four Specific Aims will test this hypothesis: Specific Aim 1 will characterize the functional involvement of Smad- independent signaling effectors, prohibitin and cofilin, as novel mediators of TGF-¿ action in prostate benign and malignant epithelial cells. Specific Aim 2 will identify the significance of the androgen receptor (AR) in the signaling interaction between TGF-¿1 and androgens towards apoptosis and epithelial to mesenchymal transition (EMT) of prostate tumor epithelial cells. Specific Aim 3 will establish the role of cofilin as a novel regulator of the ability of prostate (stroma) fibroblasts to direct TGF- ¿ signaling, in the context of the tumor microenvironment. Specific Aim 4 will characterize the in vivo physiological consequences of a functionally impaired TGF-¿ signaling on prostate growth, tumor initiation and progression using a conditional knockout mouse DNT2RII, to generate double transgenics upon crossing with the TRAMP transgenic mouse model. These studies will provide new insights into the mechanistic deregulation of TGF¿ signaling network that contributes to prostate growth and tumor progression. Understanding how cells read TGF- ¿ will enable both the delineation of the transcriptional programs that mediate specific TGF- ¿ effects and provide a framework for defining the mechanism via which TGF- ¿ 1 growth inhibitory/apoptotic responses in normal, benign and pre-malignant prostate cells, might be selectively replaced by invasive and metastatic responses in cancer cells. PUBLIC HEALTH RELEVANCE: The long term objective of the application is to characterize the functional interplay between the TGF- ¿ 1 and androgen signaling pathways that independently of Smad effectors and in the context of tissue microenvironment contribute to deregulation of TGF ¿ 1 mediated effects on prostate growth during tumor initiation and progression. The application will also pursue the mechanism converting TGF- ¿ from a tumor suppressor in normal and benign prostate growth, to a tumor promoter in advanced metastatic cancer.