TGFbeta IN THE BONE MICROENVIRONMENT: ROLE IN TUMOR METASTASIS

描述(申请人提供)：长期目标：这个长期项目的目标是开发针对转化生长因子-β(TGF())的治疗方法，以打破骨转移的恶性循环。骨骼微环境中的转化生长因子(TGF)显著改变转移瘤细胞的表型，使其产生刺激骨骼病变的因子。我们推测，肿瘤中的转化生长因子(TGF)信号是由骨微环境激活的，在肿瘤细胞中通过Smad途径发挥作用，并与缺氧协同作用，驱动恶性循环，促进溶骨性骨转移。同时抑制转化生长因子和缺氧将提供比单一药物更有效的骨转移治疗。第二个目标是研究不同肿瘤类型和不同骨转移表型(溶骨型和成骨型)对骨转移的抑制作用。具体目的：目的1比较在乳腺癌、前列腺癌和黑色素瘤的溶骨性骨转移模型以及乳腺癌和前列腺癌的成骨细胞模型中，完全阻断转化生长因子信号转导和选择性抑制Smad的作用。目的2将测试乳腺癌和前列腺癌的标准性类固醇消融治疗是否会增加骨转移，这种治疗会刺激骨吸收，并会增加骨微环境中的转化生长因子。目的研究缺氧诱导因子-1(HIF1)在体外和体内是否在分子水平上增加肿瘤细胞和骨转移瘤细胞中的转化生长因子(TGF)信号。AIM 4将使用新的成像程序来证明，当肿瘤在骨骼中生长时，通过Smad途径的信号被直接和特异性地激活。与健康相关：人类乳腺癌、前列腺癌和黑色素瘤骨转移的动物模型将被用于测试药物对骨转移的影响，并将迅速转化为临床。研究设计与方法：将在小鼠模型中研究三种同时引起溶骨性和成骨性骨转移的肿瘤类型。小鼠将接受具有良好特性的小分子转化生长因子(TGF)、Smads、低氧和骨吸收抑制剂的治疗。肿瘤和骨终点将通过X光照相、生物发光成像、组织学和定量骨组织形态计量学进行评估。基因报告活性的microPET成像将提供在骨骼微环境中生长的肿瘤中的转化生长因子(信号)激活的准确读数。在活体研究的基础上，还将对转化生长因子(和HIF)效应因子血管内皮生长因子和转化生长因子(抑制Smad7)和辅助抑制因子Ski和SnoN的作用以及对转化生长因子(-1)和Smad7启动子的影响进行详细的分子研究。原理与技术：动物模型允许对单一药物和联合疗法进行快速临床前测试，以治疗和预防骨转移，并提供肿瘤生长和骨反应的统计上有意义的终点。由于转化生长因子(抑制物)目前处于临床试验中，了解这种治疗对不同肿瘤类型以及溶骨性骨转移与成骨细胞性骨转移的影响是很重要的。骨肿瘤的成像可以在体内直接验证其他方法无法获得的机制。

DESCRIPTION (provided by applicant): Long-term Objectives: The goal of this long-term project is to develop therapy against transforming growth factor-beta (TGF() to break the vicious cycle of bone metastasis. TGF( in the bone microenvironment dramatically changes the phenotype of metastatic tumor cells, causing them to make factors that stimulate pathological changes in the skeleton. We hypothesize that TGF( signaling in tumors is activated by the bone microenvironment, acts through the Smad pathway in tumor cells and can synergize with hypoxia to drive the vicious cycle to promote osteolytic bone metastases. Inhibiting both TGF( and hypoxia will provide more effective treatment of bone metastases than single agents. A secondary goal is to characterize the effect of TGF( inhibition on bone metastases due to different tumor types as well as different bone metastases phenotypes (osteolytic vs. osteoblastic). Specific Aims: Aim 1 will compare the effects of total blockade of TGF( signaling versus selective inhibition of Smad in osteolytic bone metastasis models of breast cancer, prostate cancer and melanoma and osteoblastic models of breast and prostate cancer. Aim 2 will test if bone metastases are increased by standard sex-steroid ablation treatments for breast and prostate cancer, which stimulate bone resorption and can increase TGF( in the bone microenvironment. Aim 3 will test whether hypoxia via hypoxia-indicible factor-1( (Hif1() increases TGF( signaling in tumor cells both at the molecular level in vitro and in bone metastases in vivo. Aim 4 will use new imaging procedures to demonstrate that TGF( signaling via the Smad pathway is directly and specifically activated when tumors grow in bone. Health-relatedness: Animal models of human breast cancer, prostate cancer and melanoma metastases to bone will be utilized to test drugs for effects on bone metastases that will rapidly translate to the clinic. Research Design & Methods: Three tumor types that cause both osteolytic and osteoblastic bone metastases will be studied in a mouse model. Mice will be treated with well- characterized small-molecule inhibitors of TGF(, Smads, hypoxia, and bone resorption. Tumor and bone endpoints will be evaluated by X-radiography, bioluminescent imaging, histology, and quantitative bone histomorphometry. MicroPET imaging of gene-reporter activity will provide an accurate readout of activation of TGF( signaling in tumors growing in the bone microenvironment. In vivo studies will be complemented by detailed molecular studies on actions of the TGF( and Hif effector VEGF and the TGF( inhibitory Smad7 and the corepressors Ski & SnoN and effects on TGF( -1 and Smad7 promoters. Rationale & Techniques: Animal models permit rapid preclinical testing of single agent and combination therapies to treat and prevent bone metastases and provide statistically significant endpoints of tumor growth and bone responses. Since TGF( inhibitors are now in clinical trials, it is important to understand the effects of such treatment on different tumor types and osteolytic vs. osteoblastic bone metastases. Imaging of tumor in bone permits direct validation in vivo of mechanisms that are inaccessible by other means.