Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
Department of Immunology, Norman Bethune College of Medicine, Jilin University, Changchun 130021, China.
Proc Natl Acad Sci U S A. 2017 Aug 8;114(32):E6623-E6631. doi: 10.1073/pnas.1706055114. Epub 2017 Jul 24.
Neuroblastoma is a childhood cancer that is fatal in almost half of patients despite intense multimodality treatment. This cancer is derived from neuroendocrine tissue located in the sympathetic nervous system. Glypican-2 (GPC2) is a cell surface heparan sulfate proteoglycan that is important for neuronal cell adhesion and neurite outgrowth. In this study, we find that GPC2 protein is highly expressed in about half of neuroblastoma cases and that high GPC2 expression correlates with poor overall survival compared with patients with low GPC2 expression. We demonstrate that silencing of GPC2 by CRISPR-Cas9 or siRNA results in the inhibition of neuroblastoma tumor cell growth. GPC2 silencing inactivates Wnt/β-catenin signaling and reduces the expression of the target gene N-Myc, an oncogenic driver of neuroblastoma tumorigenesis. We have isolated human single-domain antibodies specific for GPC2 by phage display technology and found that the single-domain antibodies can inhibit active β-catenin signaling by disrupting the interaction of GPC2 and Wnt3a. To explore GPC2 as a potential target in neuroblastoma, we have developed two forms of antibody therapeutics, immunotoxins and chimeric antigen receptor (CAR) T cells. Immunotoxin treatment was demonstrated to inhibit neuroblastoma growth in mice. CAR T cells targeting GPC2 eliminated tumors in a disseminated neuroblastoma mouse model where tumor metastasis had spread to multiple clinically relevant sites, including spine, skull, legs, and pelvis. This study suggests GPC2 as a promising therapeutic target in neuroblastoma.
神经母细胞瘤是一种儿童癌症，尽管采用了强化的多模式治疗，但仍有近一半的患者死亡。这种癌症来源于位于交感神经系统的神经内分泌组织。聚糖蛋白 2（GPC2）是一种细胞表面硫酸乙酰肝素蛋白聚糖，对于神经元细胞黏附和突起生长很重要。在这项研究中，我们发现 GPC2 蛋白在大约一半的神经母细胞瘤病例中高度表达，与 GPC2 低表达的患者相比，高 GPC2 表达与总生存率降低相关。我们证明，通过 CRISPR-Cas9 或 siRNA 沉默 GPC2 会导致神经母细胞瘤肿瘤细胞生长受到抑制。GPC2 沉默会使 Wnt/β-catenin 信号失活，并降低靶基因 N-Myc 的表达，N-Myc 是神经母细胞瘤肿瘤发生的致癌驱动基因。我们通过噬菌体展示技术分离出了针对 GPC2 的人源单域抗体，并发现这些单域抗体可以通过破坏 GPC2 和 Wnt3a 的相互作用来抑制活性 β-catenin 信号。为了探索 GPC2 作为神经母细胞瘤的潜在治疗靶点，我们开发了两种抗体治疗药物，免疫毒素和嵌合抗原受体（CAR）T 细胞。免疫毒素治疗被证明可以抑制小鼠的神经母细胞瘤生长。靶向 GPC2 的 CAR T 细胞消除了在弥散性神经母细胞瘤小鼠模型中的肿瘤，该模型中的肿瘤转移已扩散到多个临床相关部位，包括脊柱、颅骨、腿部和骨盆。这项研究表明 GPC2 是神经母细胞瘤有前途的治疗靶点。
