Ngan Elly S W, Sit Francesco Y L, Lee KingLiu, Miao Xiaoping, Yuan Zhengwei, Wang Weilin, Nicholls John M, Wong Kenneth K Y, Garcia-Barcelo Mercè, Lui Vincent C H, Tam Paul K H
Department of Surgery, University of Hong Kong, Pokfulam, Hong Kong, SAR, China, and Department of Pediatric Surgery, The Second Affiliated Hospital of China Medical University, Shenyang, China.
Clin Cancer Res. 2007 Feb 1;13(3):868-75. doi: 10.1158/1078-0432.CCR-06-2176.
Neuroblastoma is a common pediatric tumor that is derived from improperly differentiated neural crest cells (NCC). We recently revealed that endocrine gland-derived vascular endothelial growth factor/prokineticin-1 (EG-VEGF/Prok-1) is a key factor mediating the growth and differentiation of enteric NCCs during development. In this report, we further elucidate its role in neuroblastoma progression.
We studied the expression and copy number of EG-VEGF/Prok-1 receptors (PK-R1 and PK-R2) in 26 neuroblastoma tumors by real-time reverse transcription-PCR and immunohistochemical analysis. Implication of EG-VEGF/Prok-1 signaling in neuroblastoma progression was further shown in a neuroblastoma cell line (SK-N-SH).
We found that all neuroblastoma samples from stages II to IV expressed both PK-R1 and PK-R2. Kruskall-Wallis signed rank tests revealed that the expression level of PK-R1 transcript is associated with the stages and metastasis of the neuroblastoma (P<0.05), and PK-R2 is persistently higher in advanced-stage neuroblastoma samples. About 38% of the neuroblastoma tumors (10:26) possessed MYCN amplification, whereas no PK-R1 and PK-R2 amplifications were detected, suggesting that the overexpression of the receptors was not due to gene amplification. Subsequent functional studies showed that EG-VEGF/Prok-1 activates the Akt pathway to induce the proliferation of neuroblastoma cells. Targeted down-regulation studies revealed that EG-VEGF/Prok-1-mediated proliferation requires the presence of these two receptors, and that PK-R2 is essential for inhibiting apoptosis. In vitro migration and invasion assays also indicated that EG-VEGF/Prok-1 significantly enhances the cell migration/invasion of SK-N-SH.
Our study has shown for the first time that aberrant EG-VEGF/Prok-1 signaling favors neuroblastoma progression and could be a potential target for future neuroblastoma treatment.
神经母细胞瘤是一种常见的儿科肿瘤，起源于分化异常的神经嵴细胞（NCC）。我们最近发现，内分泌腺衍生的血管内皮生长因子/促动力蛋白-1（EG-VEGF/Prok-1）是发育过程中调节肠道神经嵴细胞生长和分化的关键因子。在本报告中，我们进一步阐明其在神经母细胞瘤进展中的作用。
我们通过实时逆转录-PCR和免疫组织化学分析，研究了26例神经母细胞瘤肿瘤中EG-VEGF/Prok-1受体（PK-R1和PK-R2）的表达和拷贝数。在神经母细胞瘤细胞系（SK-N-SH）中进一步显示了EG-VEGF/Prok-1信号传导在神经母细胞瘤进展中的作用。
我们发现，所有II至IV期神经母细胞瘤样本均表达PK-R1和PK-R2。Kruskall-Wallis符号秩检验显示，PK-R1转录本的表达水平与神经母细胞瘤的分期和转移相关（P<0.05），且PK-R2在晚期神经母细胞瘤样本中持续较高。约38%的神经母细胞瘤肿瘤（10/26）存在MYCN扩增，而未检测到PK-R1和PK-R2扩增，这表明受体的过表达并非由于基因扩增。随后的功能研究表明，EG-VEGF/Prok-1激活Akt通路以诱导神经母细胞瘤细胞增殖。靶向下调研究表明，EG-VEGF/Prok-1介导的增殖需要这两种受体的存在，且PK-R2对抑制细胞凋亡至关重要。体外迁移和侵袭试验还表明，EG-VEGF/Prok-1显著增强了SK-N-SH细胞的迁移/侵袭能力。
我们的研究首次表明，异常的EG-VEGF/Prok-1信号传导促进神经母细胞瘤进展，可能成为未来神经母细胞瘤治疗的潜在靶点。
