Bone Metastasis Factor-1 in Prostate Cancer/Bone Interaction

描述(申请人提供)：前列腺癌(PCa)一旦发生骨转移，总是致命的。前列腺癌骨转移的一个特征是明显的成骨细胞表型。了解导致骨内前列腺癌成骨细胞进展的机制将使我们能够预防、预测和治疗骨转移。为了实现这一目标，我们开发了一种策略，通过结合蛋白质纯化和蛋白质组学方法来识别前列腺癌“转移蛋白质组”，这是一种参与前列腺癌骨转移的蛋白质因素。为了确保这些发现具有临床相关性，我们在研究中使用了与疾病相关的样本，即前列腺癌患者的骨髓上清液，无论是否有骨转移。我们从前列腺癌骨转移患者的骨髓上清液中分离到一种新的骨转移因子--MDA-BF-1。多条证据表明，MDA-BF-1是一种旁分泌因子，由转移的前列腺癌细胞分泌，在前列腺癌骨转移中介导成骨细胞的增殖。首先，Western印迹显示，MDA-BF-1只存在于有骨转移的前列腺癌患者的骨髓上清液中，而不存在于无骨转移的患者的骨髓上清液中。其次，免疫组织化学分析表明，MDA-BF-1在正常前列腺上皮细胞中不表达，仅由转移性前列腺癌细胞产生。第三，具有成骨功能的骨源性细胞系(MDAPA2b)产生大量的MDA-BF-1，而具有溶骨功能的骨源性细胞系(PC-3)则不产生。第四，重组MDA-BF-1体外可诱导成骨细胞增殖，但不能诱导前列腺癌细胞增殖。第五，初步研究表明，MDA-BF-1在溶骨性PCa细胞系PC-3中的表达在体内产生了成骨反应，这些细胞被注射到骨中。相比之下，皮下注射细胞时，MDA-BF-1不影响PC-3细胞在体内的生长。这些观察结果提供了强有力的证据，表明MDA-BF-1具有成骨细胞刺激活性，可能是骨中前列腺癌成骨细胞进展的主要参与者。因此，我们假设MDA-BF-1是一种前列腺癌细胞-成骨细胞相互作用因子，介导前列腺癌的成骨细胞进展。为了验证这一假说，我们提出：目的1.阐明MDA-BF-1对成骨细胞/PCa细胞相互作用的影响；目的2.探讨MDA-BF-1介导成骨细胞增殖和分化的机制；目的3.纯化、鉴定和克隆MDA-BF-1受体(BF1受体)。

DESCRIPTION (provided by applicant): Prostate cancer (PCa) is invariably fatal once bone metastasis occurs. A characteristic of prostate cancer bone metastasis is the striking osteoblastic phenotype. Understanding the mechanisms that lead to the osteoblastic progression of prostate cancer in bone will enable us to prevent, predict, and treat bone metastasis. Towards this goal, we have developed a strategy to identify the prostate cancer "Metastasis Proteome," protein factors that are involved in prostate cancer bone metastasis, by a combination of protein purification and Proteomics approaches. To ensure that the findings are clinically relevant, we have used disease-relevant samples, i.e., bone marrow supernatant from prostate cancer patients with or without bone metastasis, in our study. We have isolated a novel bone metastasis factor, MDA-BF-1, from the bone marrow supernatants of prostate cancer patients with bone metastasis. Several lines of evidence suggest that MDA-BF-1 is a paracrine factor that is secreted by the metastatic prostate cancer cells and mediates osteoblast proliferation in prostate cancer bone metastasis. First, Western blot showed that MDA-BF-1 is only present in the bone marrow supernatant of prostate cancer patients with bone metastasis but not in those without bone metastasis. Second, immunohistochemical analysis showed that MDA-BF-1 is not expressed in normal prostate epithelial cells and is only produced by the metastatic prostate cancer cells. Third, a bone-derived cell line with osteoblastic features (MDA PCa 2b) produces a high amount of MDA-BF-1, while a bone-derived cell line with osteolytic features (PC-3) does not. Fourth, recombinant MDA-BF-1 induced osteoblast but not prostate cancer cell proliferation in vitro. Fifth, preliminary studies showed that expression of MDA-BF-1 in the osteolytic PCa cell line PC-3 generated an osteoblastic response in vivo when these cells were injected into bone. In contrast, MDA-BF-1 does not affect PC-3 cell growth in vivo when the cells were injected subcutaneously. These observations provide strong evidence that MDA-BF-1 has osteoblast stimulating activity and may be a major player in the osteoblastic progression of prostate cancer in bone. We thus hypothesize that MDA-BF-1 is a prostate cancer cell-osteoblast interacting factor that mediates osteoblastic progression of prostate cancer in bone. To test this hypothesis, we propose to: Aim 1. Elucidate the effects of MDA-BF-1 on osteoblast/PCa cell interactions in vivo in an osseous PCa animal model; Aim 2. Investigate the mechanism of MDA-BF-1-mediated osteoblast proliferation and differentiation; and Aim 3. Purify, identify, and clone the receptor for MDA-BF-1 (BF1-receptor).