Nicotinic acetylcholine receptors and neuroblastoma

描述(申请人提供)：神经母细胞瘤是一种起源于自主神经前体细胞的癌症，发生在肾上腺髓质或婴儿和幼儿的腹部或胸部的脊柱旁肿瘤。如果在1岁以上的儿童中发现这种癌症，几乎总是一种高度恶性的侵袭性癌症，会在4-5年内导致儿童死亡，即使是在剧烈的化疗方案结合放射治疗和骨髓移植之后也是如此。该项目将确定一种不寻常的烟碱型乙酰胆碱受体是否为治疗神经母细胞瘤的新靶点。我们已经从4期神经母细胞瘤患者的骨髓抽吸物中分离出细胞。在免疫缺陷小鼠的异种移植试验中，这些细胞可分为肿瘤启动细胞(TICS)和非肿瘤启动细胞(Non-TICS)。我们发现，编码烟碱型乙酰胆碱受体(NAChR)亚单位的基因CHRNA5在抽动症中的表达水平是非抽动症的7-19倍。此外，CHRNA5在抽动症中比正常神经源性神经脊干细胞高2-10倍，在原发神经母细胞瘤和肿瘤来源的细胞系(SH-SY5Y、SKN-KCN、SKN-KCNR)中，CHRNA5水平高于正常交感神经节。在高通量药物筛选中，发现了一种nAChR拮抗剂MG 624，它可以抑制痉挛的增殖。根据我们的表达数据，我们假设含有a5的尼古丁受体与神经母细胞瘤的恶性表型有关，因此可能成为药物的新靶点，因为这些受体在正常的自主神经系统中并不常见。拟议的目标将通过以下方式验证这一假设：1)使用RNAi来确定神经母细胞瘤细胞(抽搐和原发肿瘤细胞系)的恶性表型是否需要一个或多个nAChR亚基，以及它们对MG 624的敏感性；2)确定CHRNA5和/或其他亚基在正常皮肤来源的前体细胞中的过度表达是否足以产生转化的表型。

DESCRIPTION (provided by applicant): Neuroblastoma is a cancer arising from autonomic neuron progenitor cells that occurs in the adrenal medulla or as paraspinal tumors in the abdomen or thorax of infants and young children. If it is identified in children over the age of 1, it is nearly always a highly malignant, aggressive cancer that kills the child within 4-5 years, even after a strenuous chemotherapeutic regimen combined with radiation and a bone marrow transplant. This project will determine whether an unusual nicotinic acetylcholine receptor is a novel target for therapeutics in treating neuroblastoma. We have isolated cells from bone marrow aspirates obtained from patients with stage 4 neuroblastoma. When tested in xenograft assays in immunodeficient mice, the cells can be categorized into tumor-initiating cells (TICs) and non-tumor initiating cells (non-TICs). We have discovered that the gene encoding the a5 nicotinic acetylcholine receptor (nAChR) subunit, CHRNA5, is expressed at 7- 19-fold higher levels in TICs than in non-TICs. Furthermore, CHRNA5 is 2-10-fold higher in TICs than in normal neurogenic neural crest stem cells, and CHRNA5 is elevated in primary neuroblastoma tumors and cell lines derived from tumors (SH-SY5Y, SKN-KCN, SKN-KCNR) above levels found in normal sympathetic ganglia. In a high throughput drug screen for compounds that would reduce proliferation of TICs, MG 624, a nAChR antagonist, was identified. Based upon our expression data, we hypothesize that nicotinic receptors containing a5 contribute to the malignant phenotype of neuroblastoma and therefore may be a new target for drugs because these receptors are uncommon in the normal autonomic nervous system. The proposed aims will test this hypothesis by: 1) using RNAi to determine whether one or more nAChR subunits is necessary for the malignant phenotype of neuroblastoma cells (TICs and cell lines from primary tumors) and their sensitivity to MG 624; 2) determining whether overexpression of CHRNA5 and/or other subunits in normal skin-derived precursors is sufficient to produce a transformed phenotype.