Background: Pancreatic ductal adenocarcinoma (PDAC) is an insidious, rapidly progressing malignancy of the gastrointestinal tract. Due to its dense fibrous stroma and complex tumor microenvironment, neither of which is sensitive to radiotherapy, pancreatic adenocarcinoma is one of the malignancies with the poorest prognosis. Therefore, detailed elucidation of the inhibitory microenvironment of PDAC is essential for the development of novel therapeutic strategies./nMethods: We analyzed the association between cancer-associated fibroblasts (CAFs) and resistance to ferroptosis in PDAC using conditioned CAF medium and co-culture of pancreatic cancer cells. Abnormal cysteine metabolism was observed in CAFs using non-targeted metabolomics analysis with liquid chromatography-tandem mass spectrometry (LC-MS/MS). The regulatory effects of cysteine were investigated in PDAC cells through measurement of cell cloning, cell death, cell function, and EdU assays. The effects of exogenous cysteine intake were examined in a mouse xenograft model and the effects of the cysteine pathway on ferroptosis in PDAC were investigated by western blotting, measurement of glutathione and reactive oxygen species levels, among others./nResults: It was found that CAFs played a critical role in PDAC metabolism by secreting cysteine, which could increase tumor resistance to ferroptosis. A previously unrecognized function of the sulfur transfer pathway in CAFs was identified, which increased the extracellular supply of cysteine to support glutathione synthesis and thus inducing ferroptosis resistance. Cysteine secretion by CAFs was found to be mediated by the TGF-β/SMAD3/ATF4 signaling axis./nConclusion: Taken together, the findings demonstrate a novel metabolic relationship between CAFs and cancer cells, in which cysteine generated by CAFs acts as a substrate in the prevention of oxidative damage in PDAC and thus suggests new therapeutic targets for PDAC.

中文翻译：

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癌症相关成纤维细胞重新编程半胱氨酸代谢以增加胰腺癌中肿瘤对铁死亡的抵抗力

背景：胰腺导管腺癌（PDAC）是一种隐匿、进展迅速的胃肠道恶性肿瘤。由于其致密的纤维间质和复杂的肿瘤微环境，且对放疗不敏感，胰腺腺癌是预后最差的恶性肿瘤之一。因此，详细阐明 PDAC 的抑制性微环境对于开发新的治疗策略至关重要。/n方法：我们使用条件 CAF 培养基和共培养分析了 PDAC 中癌症相关成纤维细胞 (CAF) 与铁死亡抗性之间的关联胰腺癌细胞。使用液相色谱-串联质谱 (LC-MS/MS) 进行非靶向代谢组学分析，在 CAF 中观察到半胱氨酸代谢异常。通过测量细胞克隆、细胞死亡、细胞功能和 EdU 测定，研究了半胱氨酸在 PDAC 细胞中的调节作用。在小鼠异种移植模型中检查了外源半胱氨酸摄入的影响，并通过蛋白质印迹、谷胱甘肽和活性氧水平的测量等研究了半胱氨酸途径对 PDAC 铁死亡的影响。/n 结果：发现CAF 通过分泌半胱氨酸在 PDAC 代谢中发挥关键作用，半胱氨酸可以增强肿瘤对铁死亡的抵抗力。发现了 CAF 中硫转移途径的一个以前未被识别的功能，该功能增加了细胞外半胱氨酸的供应以支持谷胱甘肽的合成，从而诱导铁死亡抗性。研究发现 CAF 分泌的半胱氨酸是由 TGF-β/SMAD3/ATF4 信号轴介导的。/n结论：综上所述，这些发现证明了 CAF 与癌细胞之间存在一种新的代谢关系，其中 CAF 产生的半胱氨酸充当预防 PDAC 氧化损伤的底物，从而为 PDAC 提出了新的治疗靶点。