Rogers Leonard C, Zhou Jing, Baker Adriana, Schutt Charles R, Panda Prashanta K, Van Tine Brian A
Division of Medical Oncology, Washington University in St. Louis, St. Louis, Missouri, 63110, USA.
The First Affiliated Hospital of Nanchang University, Nanchang, 330006, Jiangxi, China.
Cancer Metab. 2021 Jan 21;9(1):4. doi: 10.1186/s40170-021-00238-9.
Many cancers silence the metabolic enzyme argininosuccinate synthetase 1 (ASS1), the rate-limiting enzyme for arginine biosynthesis within the urea cycle. Consequently, ASS1-negative cells are susceptible to depletion of extracellular arginine by PEGylated arginine deiminase (ADI-PEG20), an agent currently being developed in clinical trials. As the primary mechanism of resistance to arginine depletion is re-expression of ASS1, we sought a tool to understand the temporal emergence of the resistance phenotype at the single-cell level.
A real-time, single-cell florescence biosensor was developed to monitor arginine-dependent protein translation. The versatile, protein-based sensor provides temporal information about the metabolic adaptation of cells, as it is able to quantify and track individual cells over time.
Every ASS1-deficient cell analyzed was found to respond to arginine deprivation by decreased expression of the sensor, indicating an absence of resistance in the naïve cell population. However, the temporal recovery and emergence of resistance varied widely amongst cells, suggesting a heterogeneous metabolic response. The sensor also enabled determination of a minimal arginine concentration required for its optimal translation.
The translation-dependent sensor developed here is able to accurately track the development of resistance in ASS1-deficient cells treated with ADI-PEG20. Its ability to track single cells over time allowed the determination that resistance is not present in the naïve population, as well as elucidating the heterogeneity of the timing and extent of resistance. This tool represents a useful advance in the study of arginine deprivation, while its design has potential to be adapted to other amino acids.
许多癌症会使代谢酶精氨琥珀酸合成酶1（ASS1）沉默，ASS1是尿素循环中精氨酸生物合成的限速酶。因此，ASS1阴性细胞易受聚乙二醇化精氨酸脱亚氨酶（ADI-PEG20）耗尽细胞外精氨酸的影响，ADI-PEG20是一种目前正在临床试验中开发的药物。由于对精氨酸耗竭的主要耐药机制是ASS1的重新表达，我们寻求一种工具来在单细胞水平上了解耐药表型的时间出现情况。
开发了一种实时单细胞荧光生物传感器来监测精氨酸依赖性蛋白质翻译。这种多功能的基于蛋白质的传感器能够随着时间推移对单个细胞进行量化和追踪，从而提供有关细胞代谢适应的时间信息。
分析的每个ASS1缺陷细胞都被发现通过传感器表达降低来响应精氨酸剥夺，这表明原始细胞群体中不存在耐药性。然而，细胞之间耐药性的时间恢复和出现差异很大，这表明存在异质性代谢反应。该传感器还能够确定其最佳翻译所需的最低精氨酸浓度。
此处开发的依赖翻译的传感器能够准确追踪用ADI-PEG20处理的ASS1缺陷细胞中耐药性的发展。它随时间追踪单个细胞的能力使得能够确定原始群体中不存在耐药性，并阐明耐药性出现的时间和程度的异质性。这个工具代表了精氨酸剥夺研究中的一项有用进展，同时其设计有可能适用于其他氨基酸。
