Nicotinic acetylcholine receptors and neuroblastoma

描述（由申请人提供）：神经母细胞瘤是一种由自主神经元祖细胞引起的癌症，发生在肾上腺髓质或婴儿和幼儿腹部或胸部的脊柱旁肿瘤。如果在1岁以上的儿童中发现，它几乎总是一种高度恶性的侵袭性癌症，即使在剧烈的化疗方案结合放射和骨髓移植后，也会在4-5年内杀死儿童。该项目将确定一种不寻常的烟碱乙酰胆碱受体是否是治疗神经母细胞瘤的新靶点。我们从4期神经母细胞瘤患者的骨髓穿刺液中分离出细胞。当在免疫缺陷小鼠中的异种移植物测定中测试时，细胞可被分类为肿瘤起始细胞（TIC）和非肿瘤起始细胞（非TIC）。我们已经发现编码α 5烟碱乙酰胆碱受体（nAChR）亚基的基因CHRNA 5在TIC中的表达水平比在非TIC中高7- 19倍。此外，TIC中的CHRNA 5比正常神经源性神经嵴干细胞高2-10倍，并且CHRNA 5在原发性神经母细胞瘤肿瘤和源自肿瘤的细胞系（SH-SY 5 Y、SKN-KCN、SKN-KCNR）中升高至高于正常交感神经节中发现的水平。在一个高通量药物筛选的化合物，将减少TIC的增殖，MG 624，nAChR拮抗剂，被确定。基于我们的表达数据，我们假设含有α 5的烟碱受体有助于神经母细胞瘤的恶性表型，因此可能是药物的新靶点，因为这些受体在正常自主神经系统中不常见。提出的目标将通过以下方式来测试这一假设：1）使用RNAi来确定一个或多个nAChR亚基是否是神经母细胞瘤细胞（来自原发性肿瘤的TIC和细胞系）的恶性表型及其对MG 624的敏感性所必需的; 2）确定CHRNA 5和/或正常皮肤来源的前体中的其他亚基的过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.