谷氨酰胺转运蛋白SLC1A5通过改造细胞外代谢微环境促进肿瘤相关巨噬细胞介导的肾癌耐药机制研究

The heavy exogenous L-glutamine addiction and aberrant glutamine-dependent reductive carboxylation pathway is the dominant alteration of metabolism patterns in clear-cell renal cell carcinoma (ccRCC). Exogenous L-glutamine uptake is mainly controlled by the Solute Carrier Family 1 Member 5 (SLC1A5) located on cell membrane, which can regulate ccRCC cells glutamine utilization and intracellular metabolites generation, as well as the formations and modulations of extracellular metabolic microenvironment, where the tumor associated macrophages (TAMs) reside and play significant protumoral roles. Hence ccRCC SLC1A5-mediated glutamine metabolism may regulate TAMs molecular phenotypes extensively and in this way promote tumor progression non-autonomously. Our preliminary results in this field have showed that, increased SLC1A5 expression levels in surgically resected ccRCC tumor tissues are higher than paired peritumor tissues, while the intratumoral SLC1A5 expressions correlated with clinical TNM stages, 10-year patient survivals, local macrophages infiltrations and their tumor-associated molecular phenotypes. Furthermore, the reduction of glutamine and accumulation of lactate detected extracellularly could induce secretions of IL-23 and arginase-1 from macrophages respectively. Based on these preliminary data, our current project proposal is designed to further elucidate the regulatory effect and functional significance of SLC1A5-mediated glutamine metabolism in ccRCC tumor progressions, especially its regulatory effect on TAMs phenotype activations through special extracellular metabolites, which is termed “Glutamine-metabolism associated microenvironment”. Our present research project will focus on the molecular mechanism and functional significance of the metabolism-immune crosstalk through metabolites such as glutamine/lactate and tumor-promoting factors such as IL-23/ arginase-1, which will establish an intrinsic model of molecular regulation pathways, advanced postsurgical survival evaluation algorithm and the therapeutic intervention of development and progression of ccRCC, which paves the way to clinical investigation and drug discovery based on molecular therapy targeting SLC1A5-mediated glutamine metabolism in ccRCC patients, and prime discussions of the significance and feasibility of glutamine addition-based PET/CT scan technology in early stage diagnose and pre-surgery evaluations, and hopefully, reveal attractive therapeutic targets to aid the treatment of everolimus, which also proved to target metabolic signals, in current clinical managements of high-risk ccRCC patients.

以对外源性谷氨酰胺的大量摄取和严重依赖为代表的细胞代谢改变是透明细胞性肾癌（ccRCC）的重要分子生物学特点之一。溶质运载体家族成员SLC1A5承担ccRCC细胞对谷氨酰胺的摄取功能，并可通过其异常代谢产物影响微环境中巨噬细胞的肿瘤免疫调控功能。我们前期研究发现，ccRCC患者肿瘤组织中SLC1A5表达水平与TNM临床分期、患者生存和瘤内巨噬细胞浸润程度、功能表型密切相关。本申请项目拟在前期实验基础上，进一步阐述肾癌细胞-巨噬细胞通过肿瘤代谢微环境和免疫细胞因子实现的相互调控作用和分子机制，以及它们在ccRCC发生发展和分子靶向药物治疗中的功能意义，建立ccRCC发生发展的代谢-免疫相关分子调控模型、术后生存评估模型，为发展以谷氨酰胺为基础的PET/CT影像诊断技术等临床应用提供理论支持，为开发针对相应异常分子信号通路和介导既有化疗药物依维莫司抵抗的相关分子的个体化靶向治疗药物提供方向。

在本项目资助下，项目负责人围绕巨噬细胞生物学方向，深入研究在肿瘤发生过程中异常巨噬细胞功能表型转化的分子机制及其功能意义，并取得一系列研究成果。以通讯作者在Journal for Immunotherapy of Cancer、European Urology、Oncoimmunology、European Journal of Cancer、International Journal of Cancer等免疫学领域国际权威期刊上发表SCI论文7篇，影响因子5以上论文7篇，其中包括影响因子10以上论文2篇。我们发现肿瘤细胞谷氨酰胺代谢异常或者肿瘤相关聚糖抗原改变，可通过诱导肿瘤相关巨噬细胞（TAM）功能表型从抗肿瘤的M1型转换为促肿瘤的M2型，分泌免疫抑制性细胞因子IL-23、IL-10等，促使肿瘤浸润CD8+T细胞表达免疫检查点分子和功能耗竭，形成肿瘤免疫抑制微环境从而促进肿瘤发生发展的分子机制。这些研究发现对于认识肿瘤相关巨噬细胞功能表型转化在诱导免疫逃逸形成过程中的作用和机制具有重要意义，同时也为开发靶向异常巨噬细胞功能表型转化的免疫治疗奠定基础。