CHOP调控糖酵解逆转脑胶质瘤替莫唑胺耐药的机制研究

Glioblastoma is the the most popular tumor in brain, which is difficult to be resected completely in surgery. As a result, radiotherapy and chemotherapy are necessary to increase the survival time of patients. Unfortunately however,temozolomide (TMZ),the most effective chemotherapy agents for glioblastoma, is reported the acquired chemoresistance in clinical. It becomes the key issue in glioblastoma how to overcome temozolomide resistance. In our previous studies, we have figured that CHOP would impact on temozolomide resistance. Combination of temozolomide and tunicamycine, would inhibit the proliferation of glioblastoma, and also glycolysis. These effects were attenuated obviously when CHOP was inactive by CHOP-specific siRNA. Here, we will employ the glioma cell lines and orthotopic glioma models to understand whether CHOP overcome temozolomide resistance by modifying glycolysis, and thereby make an approach to the clinical treatment for glioblastoma.

脑胶质瘤是最常见的颅内肿瘤，临床上很难通过手术对肿瘤进行彻底切除，手术后的放、化疗是延长患者生存时间的重要方式。替莫唑胺是治疗脑胶质瘤的最有效药物，但其耐药性严重制约了治疗效果。有效逆转脑胶质瘤的替莫唑胺耐药性，是当前亟待解决的问题。目前国内外尚缺乏有效的逆转替莫唑胺耐药策略，我们前期研究发现内质网应激诱导分子Tunicamycine与替莫唑胺（TMZ）对胶质瘤细胞的增殖抑制有协同作用；同时，联合给药能抑制胶质瘤细胞的糖酵解；而这些作用在内质网应激标志蛋白-CHOP基因被沉默后分别被减弱和阻断。因此，CHOP可能是实现逆转脑胶质瘤替莫唑胺耐药的潜在治疗靶标，作用机制可能与其调控糖酵解限速酶基因表达，影响代谢重塑有关。本课题组拟在胶质瘤细胞系和裸鼠原位胶质瘤模型上研究CHOP对于替莫唑胺抗肿瘤的增敏作用和逆转其耐药作用，帮助临床发现对胶质瘤细胞替莫唑胺耐药性的治疗策略。

本课题组成功构建了人神经胶质瘤耐替莫唑胺细胞株U251/TR，证实内质网应激诱导剂tunicamycine(Tm)、2-脱氧-D-葡萄糖( 2-Deoxy-D-glucose，2-DG)、质粒转染上调CHOP表达等预处理胶质瘤细胞后，替莫唑胺（TMZ）对U251/ TR细胞的增殖抑制、凋亡诱导现象加强，表现出对TMZ抗肿瘤作用的增敏作用；而通过RNA干扰技术沉默CHOP表达后，TMZ对U251/ TR细胞的增殖抑制、凋亡诱导现象被削弱。进一步研究证实2-DG、Tm、质粒转染上调CHOP表达等预处理U251/ TR细胞后，U251/TR细胞糖酵解水平被明显抑制，同时对TMZ抗肿瘤的增敏作用亦产生抑制作用；而沉默CHOP表达后，U251/TR细胞糖酵解水平升高，同时对TMZ抗肿瘤的增敏作用产生抑制作用，证实CHOP通过糖酵解影响对TMZ抗肿瘤的增敏作用。建立大鼠原位胶质瘤模型，分别给予TMZ、2-DG，以及联合给药两周，结果发现2-DG和TMZ联合用药对肿瘤生长抑制作用优于单药应用，生存期延长，同时HE染色发现联合给药组相较于对照组可见瘤细胞较为稀疏，凋亡的细胞变圆变小，细胞核故所、碎裂。而转染了si-CHOP的胶质瘤细胞成瘤率、生存期、HE染色与对照组无明显差异。本研究首次阐明了CHOP、糖酵解与胶质瘤替莫唑胺耐药的相关性，为解决胶质瘤对替莫唑胺耐药性这一临床难题提供理论和实践依据。