多体素1H-MRS参数Cho/Cr差异与胶质瘤干细胞分布相关性及其胆碱代谢的机制研究

Residual cancer stem cells (CSCs) after surgical resection are the major cause of poor prognosis in glioma patients. To prevent post-operative recurrence, it is important to eliminate completely the glioma CSCs. However there is currently no valid modality to locate in vivo CSC-enriched foci in the tumor. Our preliminary results showed an association between high choline metabolism and enrichment of glioma CSCs. This study tries to further establish and validate the causal relationship by expanding the number of sample. The mechanisms underlying altered choline metabolism and how disrupted choline metabolism promotes progression of glioma CSCs will be also investigated. We will employ 1H-MRS imaging and neuro-navigational system to obtain tumor tissues from multiple areas with distinct choline/creatine ratios. To ascertain CSC enrichment in the area with high choline metabolism, we will determine the identity of CSCs in the specimens by the expression of stem cell markers, neurosphere culture and xenograft transplantation. Meanwhile, we will assay the expression of genes involved in choline metabolism. The change of glioma cell proliferation, apoptosis and tumorigenicity will be examined after the inhibition of a rate-limiting choline metabolic enzyme, to understand the roles of elevated choline metabolism played in glioma growth and progression. This study will facilitate to pinpoint the area enriched with glioma CSCs, providing the theoretical basis for the targeted treatment of glioma.

手术残留的肿瘤干细胞是胶质瘤预后不良的重要原因；只有彻底清除胶质瘤干细胞，才有望减少复发。但目前尚无法识别胶质瘤干细胞富集区域。课题前期工作初步证明胆碱高代谢与胶质瘤干细胞富集具有相关性；本研究拟通过扩大样本量进一步确定两者的联系，并阐述胶质瘤干细胞富集区胆碱代谢活跃的机制以及胆碱代谢异常对其生长的促进作用。本课题运用多体素1H-MRS获取代谢差异的影像数据，术中导航辅助下准确获取Cho/Cr代谢差异区域组织。检测不同代谢区样本胶质瘤干细胞标志物的表达差异，观察原代培养细胞自我复制及致瘤性的差异，确定Cho/Cr高代谢区为胶质瘤干细胞富集区；同时测定不同代谢区组织胆碱代谢酶蛋白和相关调控蛋白，阐明胶质瘤干细胞胆碱代谢活跃的机制。进而观察胆碱激酶被抑制后胶质瘤细胞增殖、凋亡和致瘤性的变化，研究胆碱高代谢对胶质瘤生长的促进作用。此研究有助于识别胶质瘤干细胞富集区，为胶质瘤的针对性治疗提供依据。

胶质瘤是最常见的原发性脑肿瘤，占神经上皮组织肿瘤的60-70%。胶质瘤在生长过程中广泛浸润周围脑组织，导致手术无法彻底切除，术后复发率高，预后差。目前针对胶质瘤的治疗方案主要是手术切除联合术后放化疗的综合治疗，尤其对于功能区或某些特殊位置的胶质瘤，其手术治疗常以最大限度切除瘤体为主要目标，缺乏针对性，易导致脑功能的损害。本项目通过多体素氢质子磁共振波谱分析（1H-MRS）定位胆碱/肌酸（Cho/Cr）代谢显著差异区域，术中神经导航辅助下准确获取代谢差异区域组织；利用相关实验方法明确Cho/Cr高代谢与胶质瘤干细胞富集的相关性，并通过细胞、分子及动物实验等阐明胆碱激酶ɑ调控胶质瘤及胶质瘤干细胞功能的分子机制。通过本项目的研究，证实Cho/Cr高代谢区域为胶质瘤干细胞富集区；胆碱激酶ɑ在胶质瘤干细胞中高表达，并可能通过影响Kennedy代谢通路调控干细胞的增殖与凋亡；胆碱激酶ɑ在高级别胶质瘤中高表达，并且低表达患者较高表达患者生存期长；CHKA可能通过调控PI3K-Akt信号通路影响胶质瘤细胞的增殖、凋亡、侵袭及迁移等功能。本课题将临床影像检查与基础研究相结合，使完全切除胶质瘤具有一定的可能性，同时还可以减少复发和术中盲目切除肿瘤对脑功能的损害，术后针对性的靶向治疗则可进一步提高胶质瘤的治疗效果。将胶质瘤及胶质瘤干细胞的基础研究成果转化为临床诊疗的理论依据和实际指导，这将对胶质瘤的标准化治疗提供新的思路和方向，实现临床治疗的个体化、精准治疗目标，减少术后并发症，提高患者生存率。课题针对胶质瘤、胶质瘤干细胞、功能代谢影像的研究是国际学界的热点，符合脑计划研究的内容。研究成果有望对自治区重点专科宁医大总院神经外科起到科技支撑作用，符合自治区“十三五”科学技术发展规划，也是宁夏神经科学界迫切需要开展的交叉学科研究领域，有利于学科发展和人才培养，最终惠及胶质瘤病人和家属。