LepR调控胶质瘤干细胞分化为血管周细胞的作用机制及治疗意义

Glioblastoma (GBM) is featured by the pericyte-enriched neovessels which contribute to low vascular permeability and poor effusion of drugs. The majority of pericytes in GBM are derived from glioma stem cells (GSCs) whereas the underlying mechanism and therapeutic significance of GSCs differentiation into pericytes remain largely unknown. Herein, our preliminary results revealed that pericytes in GBM expressed higher leptin receptor (LepR) than pericytes in tumor-adjacent brain tissue, and its ligand leptin was enriched in GBM perivascular niche. In vitro experiment showed that leptin activated LepR on GSCs and thus increased the proportion of cells with pericyte phenotype differentiated from GSCs. Based on the above results, we hypothesize that the binding of leptin to LepR on GSCs may activate downstream signaling pathways to promote the differentiation of GSCs into pericytes. Blocking LepR may suppress the differentiation process of GSCs and decrease the number of pericytes, thus promote the effusion of drugs. In this project, we will address the roles of LepR in promoting the differentiation of GSCs into pericytes and its therapeutic value by performing tumor sample analyses, cell-lineage tracing experiments, in vitro functional assays and in vivo therapeutic experiments. The findings of this study will provide rationale for the development of new therapeutic strategy by targeting GSC-derived pericytes to improve the efficacy of chemotherapy.

富含周细胞的新生血管是胶质母细胞瘤（GBM）的突出特征和化疗药物渗透性低、疗效不佳的重要原因。胶质瘤干细胞（GSC）分化是GBM周细胞的重要来源，但GSC向周细胞分化的调控机制及治疗意义尚不清楚。我们前期发现，与瘤周脑组织中周细胞相比，GBM中周细胞高表达瘦素受体（LepR），且GBM血管周微环境中富含其配体Leptin；外源性Leptin活化GSC表面 LepR后，GSC分化为周细胞表型的细胞比例显著增加。我们据此推测，GBM中Leptin结合GSC表面LepR，活化下游相关信号通路，促进GSC分化为周细胞；阻断LepR活化有望抑制该分化过程，降低周细胞数量，提升化疗效果。本课题将通过临床样本检测、细胞谱系追踪、体外功能实验和动物治疗实验等手段，阐明LepR调控GSC分化为周细胞的作用、分子机制及治疗意义，为靶向GSC来源周细胞提升化疗效果的治疗新策略研发提供依据。

胶质母细胞瘤（GBM）异型血管富含血管周细胞，后者是GBM化疗疗效不佳的重要原因。我们发现LepR是促进胶质瘤干细胞向血管周细胞转分化的关键分子并在本项目支持下开展了临床样本分析、体外功能机制实验以及体内异种移植瘤实验。研究发现：（1）人GBM中周细胞普遍特异性高表达LepR，而对照正常脑组织周细胞低表达LepR。GBM周细胞数量越多，GBM患者对化疗的反应及预后均越差；（2）和非GSCs肿瘤细胞（NSTCs）对比，LepR配体Leptin在GSCs中高表达；（3）胶质瘤干细胞表达LepR，神经祖细胞不表达LepR；（4）与胶质瘤干细胞相比，胶质瘤干细胞衍生的周细胞高表达LepR；（5）使用体内原位移植瘤实验和周细胞转分化荧光示踪载体证明在LepR在胶质瘤干细胞（GSCs）来源的周细胞中显著高表达；（6）体外荧光示踪和蛋白免疫印迹实验证实Leptin处理促进GSCs向周细胞转分化；（7）体外敲低LepR发现，下调LepR阻碍GSCs来源周细胞维持；（8）敲低LepR降低胶质瘤小鼠原位移植瘤周细胞覆盖率，延长荷瘤小鼠生存期；（9）Leptin处理活化GSCs中p38、Stat3等信号通路；（10）阻断p38信号通路活化抑制Leptin介导的GSCs向周细胞转分化；（11）SMLA抑制Leptin介导的通路活化和周细胞表型转化。本研究首次揭示了LepR调控胶质瘤干细胞向血管周细胞转分化的作用，阐明了相关分子机制，并明确了靶向LepR抑制胶质瘤干细胞向血管周细胞转分化和GBM进展的治疗学意义。