Dysregulated Glutamate Transporter SLC1A1 Propels Cystine Uptake via Xc− for Glutathione Synthesis in Lung Cancer

作者：Wenzheng Guo, Kaimi Li, Beibei Sun, Dongliang Xu, Lingfeng Tong, Huijing Yin, Yueling Liao, Hongyong Song, Tong Wang, Bo Jing, Min Hu, Shuli Liu, Yanbin Kuang, Ling Jing, Qi Li, Yadi Wu, Qi Wang, Feng Yao, Binhua P. Zhou, Shuhai Lin, Jiong Deng · 发表于：Cancer Research · 年份：2020 · DOI：10.1158/0008-5472.can-20-0617 · 被引用次数：104 · 研究领域：Amino Acid Enzymes and Metabolism、Sulfur Compounds in Biology、Epigenetics and DNA Methylation

Abstract Cancer cells need to generate large amounts of glutathione (GSH) to buffer oxidative stress during tumor development. A rate-limiting step for GSH biosynthesis is cystine uptake via a cystine/glutamate antiporter Xc−. Xc− is a sodium-independent antiporter passively driven by concentration gradients from extracellular cystine and intracellular glutamate across the cell membrane. Increased uptake of cystine via Xc− in cancer cells increases the level of extracellular glutamate, which would subsequently restrain cystine uptake via Xc−. Cancer cells must therefore evolve a mechanism to overcome this negative feedback regulation. In this study, we report that glutamate transporters, in particular SLC1A1, are tightly intertwined with cystine uptake and GSH biosynthesis in lung cancer cells. Dysregulated SLC1A1, a sodium-dependent glutamate carrier, actively recycled extracellular glutamate into cells, which enhanced the efficiency of cystine uptake via Xc− and GSH biosynthesis as measured by stable isotope-assisted metabolomics. Conversely, depletion of glutamate transporter SLC1A1 increased extracellular glutamate, which inhibited cystine uptake, blocked GSH synthesis, and induced oxidative stress-mediated cell death or growth inhibition. Moreover, glutamate transporters were frequently upregulated in tissue samples of patients with non–small cell lung cancer. Taken together, active uptake of glutamate via SLC1A1 propels cystine uptake via Xc− for GSH biosynthesis in lun...