PET Imaging of Glutamine Metabolism and Glutamate Transport to Guide Metabolically Targeted Therapy in Triple-Negative Breast Cancer

谷氨酰胺分解是谷氨酰胺的一种重要代谢途径 治疗侵袭性癌症和耐药癌症，包括许多三阴性乳腺癌 癌症(TNBCs)。人们普遍认为，谷氨酰胺通过 线粒体谷氨酰胺酶(GLS)为TAC循环提供能量和 生物合成的前体。新出现的数据揭示了一个不太被认识但很重要的问题 谷氨酰胺分解在介导活性内源性氧化应激中的作用 侵袭性癌细胞的生长以及包括化疗在内的外部治疗 和免疫疗法。靶向GLS抑制剂阻断谷氨酰胺分解是一种治疗方法 该策略已经在乳腺癌和其他癌症的临床试验中进行了测试，可以接受 毒性，但疗效有限，很大程度上是由于缺乏临床标志物来指导患者 选择和评估目标影响。我们实验室的初步数据显示， 靶向GLS和质膜谷氨酸转运蛋白XCT(SLC7A11)， 导致耐药的TNBC对化疗显著增敏。我们提出三个建议 以一个总体主题为基础的目标是制定一个非代谢的动力学框架 氨基酸模拟PET示踪剂测量细胞池大小作为指示 分解代谢和细胞运输。具体地说，我们将(1)验证数量标记 来自动态[18F]Fluciclovine PET的细胞谷氨酰胺池大小；(2)开发和验证 用4-(3-[18F]氟丙基)-L测定胞质谷氨酸池的大小和转运 谷氨酸([18F]FSPG)PET，以及(3)测定结合[18F]氟西洛韦的效用 和[18F]FSPG PET用于预测和测量双靶向治疗的反应 旨在使TNBC对化疗敏感。作为这项工作的一部分，我们将解决 细胞质谷氨酸从线粒体池转运的机制问题 以及细胞外液的去向和去向，以指导解释PET示踪动力学。我们会 还要测试针对TNBC代谢漏洞的方法，特别是 PET方法指导下的谷氨酰胺依赖代谢和谷氨酸转运 我们在我们的临床前TNBC模型中开发和验证。拟议的工作将导致 更深入地了解谷氨酰胺分解和氧化还原之间的相互作用 癌细胞的动态平衡，将产生准备好的定量成像方法 转到诊所去。

Glutaminolysis, the cellular catabolism of glutamine, is an important metabolic pathway for aggressive and treatment-resistant cancers, including many triple-negative breast cancers (TNBCs). It is well accepted that glutamate produced from glutamine by mitochondrial glutaminase (GLS) fuels the TAC cycle, which provides energy and precursors for biosynthesis. Emerging data have revealed a less recognized but important contribution of glutaminolysis in mediating oxidative stress introduced internally by active growth of aggressive cancer cells and externally by treatments including chemotherapy and immunotherapy. Targeting inhibitors of GLS to block glutaminolysis is a therapeutic strategy that has been tested in clinical trials of breast and other cancers with acceptable toxicity, but limited efficacy, owing in good part to a lack of clinical markers to guide patient selection and assess target impact. Preliminary data from our lab have shown that dual targeting of GLS and the plasma membrane glutamate transporter, xCT (SLC7A11), resulted in dramatic sensitization of resistant TNBC to chemotherapy. We propose three aims based upon an overall theme to develop a kinetic framework for non-metabolized amino acid analog PET tracers to measure cellular pool sizes as an indicator of catabolism and cellular transport. Specifically, we will (1) validate quantitative markers for cellular glutamine pool size from dynamic [18F]fluciclovine PET; (2) develop and validate markers for cytosolic glutamate pool size and transport using 4-(3-[18F]fluoropropyl)-L- glutamic acid ([18F]FSPG) PET, and (3) determine the utility of combined [18F]fluciclovine and [18F]FSPG PET for predicting and measuring response to dual-targeted treatment designed to sensitize TNBC to chemotherapy. As part of this work, we will address mechanistic questions regarding cytosolic glutamate transport from mitochondrial pools and to/from extracellular fluid to guide the interpretation of PET tracer kinetics. We will also test approaches to target TNBC metabolic vulnerabilities, specifically the dependence glutamine metabolism and glutamate transport, guided by the PET methods we develop and validate in our pre-clinical TNBC models. The proposed work will lead to a deeper understanding of the mutual engagement between glutaminolysis and redox homeostasis of cancer cells and will yield quantitative imaging methodologies ready to translate to the clinic.