Role of Wnt5a in the interactions of prostate cancer cells and the bone microenvironment.

前列腺癌有很高的向骨内转移的倾向，通常会形成骨硬化性病变。在第一个资助期，我们鉴定了Wnt5a在亲骨性前列腺癌原代细胞中特异性表达，并发现Wnt5a过表达在体外诱导细胞凋亡和抑制增殖，相应地抑制皮下和骨内肿瘤的生长和随后的骨破坏。一致的是，在397名前列腺癌患者的队列中，Wnt5a的高肿瘤表达与较长的生存期相关。基于这些结果及其对骨重建和免疫反应的已知调节，我们推测WNT5a影响骨转移的关键步骤，并代表了前列腺癌和相关骨转移治疗的一个治疗靶点。为了验证我们的假设，我们将解决以下具体目标：(I)确定骨髓细胞来源的Wnt5a对前列腺癌细胞生物学的旁分泌作用。潜在的机制将使用RNAi和特定的抑制剂来确定。缺乏Wnt5a的条件性基因敲除小鼠将被用于确定小鼠前列腺癌细胞的迁移和骨转移。(Ii)采用颅骨培养法检测肿瘤来源的Wnt5a对体外培养骨细胞的旁分泌作用。肿瘤来源的Wnt5a形成转移前的生态位并促进骨转移的潜力将在小鼠模型中使用多模式骨成像进行研究。此外，Wnt5a与骨转移的存在和类型的相关性将使用我们建立的组织微阵列(TMA)来验证。(Iii)评价肿瘤来源的WNT5a在体内外对免疫细胞迁移和功能的调节作用。这些研究将有助于阐明Wnt5a在前列腺癌和骨转移中的作用，并确定其是否适合作为新的生物标志物和潜在的药物靶点。

Prostate cancer has a high propensity to home to bone and commonly forms osteosclerotic lesions. In the first funding period, we identified Wnt5a to be specifically expressed in primary samples of osteotropic prostate cancer cells and found that overexpression of Wnt5a induced apoptosis and inhibited proliferation in vitro and correspondingly inhibited subcutaneous and intratibial tumor growth and subsequent bone destruction. Congruently, a high tumor expression of Wnt5a was associated with a longer survival in a cohort of 397 prostate cancer patients. Based on these results and its known regulation of bone remodeling and immune reactions, we hypothesize that Wnt5a affects key steps of skeletal metastases and represents a therapeutic target in the treatment of prostate cancer and related bone metastases. To test our hypotheses we will address the following specific aims: (I) To determine the paracrine effects of bone marrow cell-derived Wnt5a on prostate cancer cell biology. Underlying mechanisms will be determined using RNAi and specific inhibitors. Conditional knock-out mice that lack Wnt5a will be used to determine migration and skeletal metastasis of murine prostate cancer cells. (II) To examine the paracrine effects of tumor-derived Wnt5a on bone cells in vitro and ex vivo using calvaria cultures. The potential of tumor-derived Wnt5a to form a pre-metastatic niche and to promote bone metastases will be investigated in mouse models using multimodal bone imaging. Further, correlations of Wnt5a with the presence and type of bone metastases will be validated using our established tissue microarray (TMA). (III) To assess the modulation of immune cell migration and function by tumor-derived Wnt5a in vitro and in vivo. These studies will help to clarify the contribution of Wnt5a in prostate cancer and bone metastasis and to define its suitability as a novel biomarker and potential drug target.