Role of Osteocytes in Myeloma Bone Disease

描述(由申请人提供)： 项目摘要多发性骨髓瘤(MM)生长在骨骼中并攻击骨骼，导致疼痛和与骨骼相关的病理，如骨折，以及导致死亡。肿瘤和骨微环境之间的许多相互作用已被了解，但没有一种涉及骨骼特有的途径，骨髓瘤骨病(MBD)在很大程度上仍然是无法治愈的。我们询问只由骨骼构成的因子是否对骨髓瘤细胞起特异性作用。无论是实验室细胞系还是患者的MM细胞，都表达激素成纤维细胞生长因子-23的受体，这种受体是由骨细胞产生的，骨中有丰富的细胞。在新诊断的患者中，MM患者完整的血清FGF23水平是对照组的3倍。重组FGF23使2株MM细胞24小时肝素酶基因表达增加5-18倍。乙酰肝素酶是一种分泌酶，能促进肿瘤在骨骼中的归巢和生长，是MM预后不良的标志。它通过因子RANK配体增加骨破坏，抑制骨形成，从骨基质中释放生长因子，并修饰MM蛋白syndecan-1。我们提出了骨髓瘤骨病的一个新的恶性循环：A)MM细胞刺激骨细胞分泌FGF23；B)FGF23增加MM细胞乙酰肝素酶的表达；C)乙酰肝素酶改变骨微环境，增加等级配体Dkk1、骨溶解和肿瘤生长；D)肝素酶增加骨中的肝细胞生长因子(HGF)，从而额外刺激MM细胞；E)FGF23可能增强MM与骨的黏附。这两位研究人员结合了对癌症的广泛个人兴趣：骨分子相互作用(JMC)和临床骨髓瘤(AS)的生物学，以及对骨髓瘤骨病的病因和改进治疗的共同兴趣。我们提出了四个特定的目标：1：确定MM增加FGF23的细胞途径，包括测试MM细胞产生的已知因素是否调节FGF23的产生，或者它是否受到肝素酶、HGF或批准的MM治疗Bortezomib的调节。2：确定循环FGF23在MM患者中的作用，询问MM患者FGF23和肝素酶浓度是否相关，并检测患者的MM细胞是否促进FGF23的骨释放。3：确定FGF23升高的肝素酶在MBD中的重要性。4.确定乙酰肝素酶在骨微环境中表达的分子机制。该项目使用了一种新的骨髓瘤实验模型：骨相互作用。在Evoca(体外器官培养试验)中，人MM细胞被培养在小鼠骨骼上，这支持了细胞系和患者样本的生长(这显著增加了骨骼中的FGF23)。我们将用启动子驱动分泌的荧光素酶建立MM细胞系，以分析肿瘤中基因活性随时间的变化：骨微环境。避免了用活体动物进行实验，降低了成本，提高了效率，同时消除了动物的痛苦和痛苦。Evoca使目标2中的新研究能够以原始样本测试FGF23：肝素酶恶性循环在个别患者中的重要性。FGF23和乙酰肝素酶的抑制剂正在进行临床试验。我们的研究将指导它们未来应用于骨髓瘤、骨疾病和其他癌症骨转移的治疗。

DESCRIPTION (provided by applicant): Project Summary Multiple myeloma (MM) grows in and attacks the skeleton, causing pain and bone-related pathologies, such as fracture, as well as contributing to death. Many interactions between the tumor and the bone microenvironment are understood, but none involves pathways unique to bone, and myeloma bone disease (MBD) remains largely incurable. We asked whether factors made only by bone acted specifically on myeloma cells. MM cells, both laboratory cell lines and from patients, expressed the receptor for the hormone fibroblast growth factor (FGF)-23, which is made by osteocytes, abundant cells in bone. In newly diagnosed patients, intact serum FGF23 was 3X higher in MM than in controls. Recombinant FGF23 increased heparanase mRNA 5-18x in 2 MM cell lines at 24hrs. Heparanase is a secreted enzyme that enhances tumor homing and growth in bone and is a marker of poor MM prognosis. It increases bone destruction via the factor RANK ligand and suppresses bone formation, releases growth factors from bone matrix and modifies the MM protein syndecan-1. We propose a new vicious cycle of myeloma bone disease: A) MM cells stimulate osteocytes to secrete FGF23; B) FGF23 increases heparanase expression by MM cells; C) Heparanase alters the bone microenvironment and increases RANK ligand, Dkk1, osteolysis & tumor growth; D) Heparanase increases hepatocyte growth factor (HGF) in bone, which additionally stimulates MM cells; E) FGF23 may enhance MM adhesion to bone. The two Investigators combine extensive individual interests in cancer:bone molecular interactions (JMC) and the biology of clinical myeloma (AS) with a shared interest in the etiology and improved treatment of myeloma bone disease. We propose Four Specific Aims: 1: Determine the cellular pathways by which MM increases FGF23, including testing if known factors made by MM cells regulate FGF23 production, or if it is regulated by heparanase, HGF or the approved MM treatment bortezomib. 2: Determine the role of circulating FGF23 in MM patients, asking if FGF23 & heparanase concentrations are correlated in MM patients and testing if MM cells from patients increase bone release of FGF23. 3: Determine the importance of FGF23-increased heparanase in MBD. 4. Determine molecular mechanisms that control heparanase expression in the bone microenvironment. The project uses a new experimental model of myeloma:bone interactions. In EVOCA (ex vivo organ culture assay), human MM cells are cultured on mouse bone, which supports growth of cell lines and patient samples (which dramatically increase FGF23 in bone). We will make MM cell lines with promoters driving secreted luciferases to analyze changes in gene activity over time in the tumor:bone microenvironment. Experiments with live animal are avoided, lowering costs & increasing efficiency, along with elimination of animal pain & suffering. EVOCA enables new studies in Aim 2 with primary samples to test the importance of the FGF23:heparanase vicious cycle in MBD in individual patients. Inhibitors of FGF23 & heparanase are in clinical trials. Our studies will guide their future application to the treatmentof myeloma bone disease and other cancer bone metastases.