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细胞催化剂，是一种重要的代谢途径 对于侵袭性和耐药性癌症，包括许多三阴性乳腺癌， 癌症（TNBC）。公认的是，谷氨酸是由谷氨酰胺产生的， 线粒体谷氨酰胺酶（GLS）为TAC循环提供燃料，TAC循环提供能量， 生物合成的前体。新出现的数据揭示了一个不太被认可但重要的 在介导由活性物质内部引入的氧化应激中， 侵袭性癌细胞的生长和外部治疗，包括化疗 和免疫疗法。靶向GLS抑制剂以阻断多巴胺分解是一种治疗方法， 该策略已在乳腺癌和其他癌症的临床试验中进行了测试， 毒性，但疗效有限，这在很大程度上是由于缺乏临床标志物来指导患者 选择和评估目标的影响。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TNBC对化疗的显著敏感性。我们提出了三 目标是基于一个总体主题，为非代谢性疾病建立一个动力学框架， 氨基酸类似物PET示踪剂，以测量细胞池大小作为 催化剂和细胞运输。具体而言，我们将（1）验证定量标记物， 动态[18 F]氟草胺PET的细胞谷氨酰胺池大小;（2）开发和验证 使用4-（3-[18F]氟丙基）-L- 谷氨酸（[18F] FSPG）PET，和（3）确定组合的[18F]氟鹿草碱的效用 和[18 F] FSPG PET用于预测和测量对双靶向治疗的反应 旨在使TNBC对化疗敏感。作为这项工作的一部分，我们将 关于从线粒体库转运胞质谷氨酸的机制问题 和从/到细胞外液，以指导PET示踪剂动力学的解释。我们将 还测试针对TNBC代谢脆弱性的方法，特别是 依赖谷氨酰胺代谢和谷氨酸转运，由PET方法指导 我们在临床前TNBC模型中开发和验证。拟议的工作将导致 更深入地了解氨解和氧化还原之间的相互作用 癌细胞的体内平衡，并将产生定量成像方法， 翻译到诊所。

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.