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

简介(申请人提供)：转化生长因子是正常、良性和恶性前列腺生长的负性调节因子。在正常前列腺中发挥生长抑制/凋亡作用的同时，在老化的前列腺中过度产生转化生长因子-β1，从而导致良性前列腺增生症(BPH)和前列腺癌的发生。我们先前证实，转化生长因子-S信号的激活导致细胞凋亡，转化生长因子受体(T2RII)的缺失与前列腺癌的发生发展密切相关。在体外和体内，T2RII在人前列腺癌细胞中的过表达使得对转化生长因子-β的反应能够通过凋亡介导的生长抑制。以雄激素敏感型和转化生长因子反应型前列腺癌LNCaP T2RII细胞为模型，发现转化生长因子β1可诱导细胞凋亡，雄激素可增强其诱导细胞凋亡的作用。最近基于蛋白质组学的方法发现了两个新的细胞内转化生长因子途径效应物，它们独立于Smads发挥作用，调节前列腺癌细胞的凋亡结果。在这一建议中，我们假设转化生长因子-1信号通过Smad4非依赖的细胞内效应因子的变化和与雄激素受体(AR)的串扰来调节前列腺生长，并且该网络的功能失活加速了恶性表型和肿瘤进展的表现。以下四个特定目标将验证这一假说：特定目标1将表征Smad非依赖性信号效应分子--禁止素和粘连蛋白--作为前列腺良恶性上皮细胞中转化生长因子-β作用的新介质的功能参与。目的2明确雄激素受体(AR)在转化生长因子β1与雄激素诱导前列腺肿瘤上皮细胞凋亡和上皮间质转化(EMT)信号相互作用中的意义。具体目标3将在肿瘤微环境的背景下，确定cofilin作为前列腺(间质)成纤维细胞引导转化生长因子-β信号传导能力的一种新的调节因子的作用。特定目的4将利用条件基因敲除小鼠DNT2RII，在体内表征功能受损的转化生长因子-β信号对前列腺生长、肿瘤启动和进展的生理后果，以在与TraMP转基因小鼠模型杂交时产生双转基因。这些研究将为促进前列腺生长和肿瘤进展的转化生长因子信号网络的机械性放松提供新的见解。了解细胞如何读取转化生长因子β，将有助于描绘介导特定转化生长因子β效应的转录程序，并提供一个框架，以确定正常、良性和癌前前列腺癌细胞中的转化生长因子β1生长抑制/凋亡反应可能选择性地被癌细胞中的侵袭和转移反应所取代的机制。 公共卫生相关性：该应用的长期目标是描述转化生长因子-1和雄激素信号通路之间的功能相互作用，这些信号通路独立于Smad效应器并且在组织微环境的背景下有助于解除对转化生长因子-1介导的在肿瘤发生和发展过程中对前列腺生长的影响的调节。该应用还将探索将转化生长因子β从正常和良性前列腺生长中的肿瘤抑制因子转化为晚期转移癌中的肿瘤促进剂的机制。

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.