Targeting DKK-1 To Prevent Osteosarcoma Metastasis

摘要 骨肉瘤是青少年和青壮年最常见的原发骨肿瘤。 积极的手术和强化化疗提供了高达75%的长期存活 被诊断为局部疾病的患者，但这种方法只治愈了20%的 出现转移。许多强化治疗的尝试都没有得到改善 这种令人沮丧的预后，因此迫切需要新的治疗方法 对骨肉瘤生物学有更深入的了解。Wnt信号通路一直是人们关注的焦点 骨肉瘤在正常骨生物学中的作用研究。典型的，β-连环蛋白- 依赖的Wnt信号驱动正常的成骨细胞分化。据报， 经典Wnt信号的分泌型抑制因子Dickkopf-1(DKK-1)在 新诊断的骨肉瘤患者的血液，并优先表达 生长中肿瘤侵袭边缘的骨肉瘤细胞。DKK-1的抑制作用增强 小鼠骨肉瘤细胞中的非规范Wnt(NcWnt)信号转导。我们的实验室证明了 在免疫缺陷骨肉瘤小鼠的血液中可以检测到人DKK-1 患者来源的异种移植物和抗DKK-1的中和抗体增加cWnt 在原发肿瘤中的信号转导，诱导分化和消除转移的标志。 综上所述，这些发现表明，DKK-1调节 CWnt和ncWnt在OS中的信号转导，影响肿瘤重要基因的表达 分化和转移。我们将检验这一假说，并生成临床前数据来指导 以DKK-1为靶点的三种靶向治疗骨肉瘤的研究 目标。SA1：确定DKK-1调节cWnt和cWnt之间平衡的机制 骨肉瘤中的ncWnt信号转导。SA2：优化DKK-1的时机和实施 骨肉瘤临床前模型中的抑制作用。SA3：验证血清DKK-1水平作为一种 骨肉瘤患者疾病负担和治疗反应的生物标志物。成功 这项研究的完成将更好地确定Wnt信号在OS生物学中的作用，提供可靠的 临床前数据为DKK-1靶向治疗预防OS转移的临床试验提供信息，以及 开发一种新的、非侵入性的复发风险和治疗反应的生物标志物。

Abstract Osteosarcoma is the most common primary bone tumor of adolescents and young adults. Aggressive surgery and intensive chemotherapy provide long term survival to up to 75% of patients diagnosed with localized disease, but this approach only cures 20% of patients who present with metastasis. Numerous attempts at treatment intensification have failed to improve this dismal prognosis, so there is an urgent need for new treatment approaches based on a deeper understanding of osteosarcoma biology. The Wnt signaling pathway has been a focus of investigation in osteosarcoma because of its role in normal bone biology. Canonical, β-catenin- dependent Wnt signaling drives normal osteoblast differentiation. It has been reported that the secreted inhibitor of canonical Wnt (cWnt) signaling, Dickkopf-1 (DKK-1) is found at high levels in the blood of newly diagnosed osteosarcoma patients and is preferentially expressed by osteosarcoma cells at the invasive edge of growing tumors. Inhibition of DKK-1 increases noncanonical Wnt (ncWnt) signaling in murine osteosarcoma cells. Our laboratory demonstrated that human DKK-1 can be detected in the blood of immune deficient mice bearing osteosarcoma patient-derived xenografts and that a neutralizing antibody against DKK-1 increased cWnt signaling in the primary tumor, inducing markers of differentiation and abolishing metastasis. Taken together, these findings suggest the hypothesis that DKK-1 regulates the balance between cWnt and ncWnt signaling in OS, affecting expression of genes important for tumor cell differentiation and metastasis. We will test this hypothesis and generate preclinical data to guide the implementation of treatments targeting DKK-1 in osteosarcoma patients through three specific aims. SA1: To define the mechanism by which DKK-1 regulates the balance between cWnt and ncWnt signaling in osteosarcoma. SA2: To optimize the timing and implementation of DKK-1 inhibition in preclinical models of osteosarcoma. SA3: To validate serum DKK-1 level as a biomarker of disease burden and response to therapy in osteosarcoma patients. Successful completion of this study will better define the role of Wnt signaling in OS biology, provide robust preclinical data to inform a clinical trial of DKK-1 targeted therapy to prevent OS metastasis, and develop a novel, noninvasive biomarker of relapse risk and response to treatment.