甲硫氨酸代谢异常调控胶质瘤干细胞“干性”的甲基化机制研究

Glioma stem cells (GSCs) are the origin of glioma carcinogenesis. Epigenetic modifications are essential for sustaining the stemness of GSCs. It is well known that metabolic abnormalities and reprogramming play important roles on carcinogenesis and cancer development. Recent studies show that metabolic abnormalities have important impacts on epigenetic modifications in cancer cells. In preliminary studies, we found that methionine metabolism pathway is extremely active in human glioma tissues and primary GSCs, and methionine deprivation stress significantly decreased neurosphere formation of GSCs. Based on the fact that methyls produced in methionine cycle provides important methyl donors for a variety of biological reactions, we propose that methionine metabolism pathway regulates the stemness of GSCs by methylation mechanism. To confirm this hypothesis, in this study we will investigate the effect of methionine metabolism pathway on the stemness of GSCs in vitro and in vivo, and study the the regulation mechnasims of methionine metabolism pathway on the stemness of GSCs by Chip assay, DNA promoter methylation analysis, histone methylation detection and etc. The study will enrich the theory that metabolic reprogramming regulates carcinogenesis and cancer development, and provide new insights and potential molecular targets for glioma therapy.

胶质瘤干细胞是胶质瘤难治的根源，表观遗传学修饰在肿瘤干细胞“干性”维持中必不可少。代谢异常与肿瘤发生发展关系密切，近年研究表明细胞代谢方式的改变对表观遗传学修饰有重要影响。申请者在前期研究中发现，甲硫氨酸代谢通路在人脑胶质瘤组织及原代胶质瘤干细胞内异常活跃，且甲硫氨酸应激对胶质瘤干细胞的成球能力有显著影响。基于甲硫氨酸循环是体内生物反应中甲基的重要供体，申请者推测甲硫氨酸代谢通路可能通过甲基化机制调控胶质瘤干细胞的“干性”。为证实这一假说，本课题将在体外和体内水平研究甲硫氨酸代谢通路相关分子对胶质瘤干细胞“干性”的影响，采用Chip assay, DNA启动子甲基化分析、组蛋白甲基化检测等技术研究甲硫氨酸代谢通路调控胶质瘤干细胞“干性”的甲基化机制，明确甲硫氨酸代谢通路在胶质瘤干细胞“干性”维持中的作用及意义，丰富代谢重编程调控肿瘤发生发展的理论，为胶质瘤分子靶向治疗提供新的思路和靶点。

胶质瘤是颅内最常见的脑恶性肿瘤，致死和致残率极高，目前尚未有根治的治疗方法。代谢异常与肿瘤发生发展关系密切，甲硫氨酸代谢异常与胶质瘤的发生发展关系密切，但是分子机制尚待进一步挖掘。本课题通过一系列研究发现甲硫氨酸和胱氨酸剥夺在体内外抑制U87，U251胶质瘤细胞的增殖，其分子机制是通过依赖ROS激活和自噬来实现的；并且两者一起剥夺在抑制胶质瘤细胞增殖，激活自噬和ROS具有协同的生物学作用；更为重要的是抑制自噬能促进甲硫氨酸与胱氨酸剥夺对肿瘤细胞增殖的抑制。同时申请者根据新发现的线索修改了部分研究计划，发现微小核苷酸MiR-212-3p与SGK3在胶质瘤组织中的表达呈负相关，MiR-212-3p通过直接靶向调控SGK3的表达抑制胶质瘤细胞增殖的分子机制。总之，在本项目的支持下本项目取得了多个具有原创性和前沿性的结果。