The Xc− inhibitor sulfasalazine improves the anti-cancer effect of pharmacological vitamin C in prostate cancer cells via a glutathione-dependent mechanism

作者：Zijie Zheng, Ganhua Luo, Xinchong Shi, Yali Long, Wanqing Shen, Zhoulei Li, Xiangsong Zhang · 发表于：Cellular Oncology · 年份：2019 · DOI：10.1007/s13402-019-00474-8 · 被引用次数：35 · 研究领域：Vitamin C and Antioxidants Research、Sulfur Compounds in Biology、Trace Elements in Health

Traditional treatment regimens for advanced prostate cancer, especially castration-resistant prostate cancer, result in low survival times with severe side effects. Therefore, new treatment options are required. Vitamin C (VC) has been identified as a promising anti-cancer agent of which the effects depend on the accumulation of H 2 O 2 that is produced through autoxidation. Sulfasalazine (SAS), a cystine transporter (X c − ) inhibitor, is known to suppress cellular glutathione (GSH) biosynthesis. Here, we hypothesized that targeting the X c − transporter via SAS may improve the anti-cancer activity of VC through regulating GSH biosynthesis, which in turn may result in the accumulation of reactive oxygen species (ROS). The anti-cancer effect of VC and/or SAS on prostate cancer cells was assessed using WST-8, colony formation and annexin V-FITC/PI FACS assays. Changes in cellular ROS and GSH levels were determined to verify our hypothesis. Finally, BALB/c nude mice bearing prostate cancer xenografts were used to assess the anti-cancer effects of single or combined VC and SAS therapies. We found that SAS could potentiate the short- and long-term cytotoxicity of VC in prostate cancer cells. We also found that the synergistic effect of SAS and VC led to significant cellular GSH depletion, resulting in increased ROS accumulation. This synergistic effect could be reversed by the antioxidant N-acetyl-L-cysteine (NAC). The synergistic effect of SAS and VC was also noted in prostate c...