Deregulating cellular energetics by reprogramming metabolic pathways, including arginine metabolism, is critical for cancer cell onset and survival. Drugs that target the specific metabolic requirements of cancer cells have emerged as promising targeted cancer therapeutics. In this study, we investigate the therapeutic potential of targeting colon cancer cells using arginine deprivation induced by a pegylated cobalt-substituted recombinant human Arginase I [HuArgI (Co)-PEG5000]. Four colon cancer cell lines were tested for their sensitivity to [HuArgI (Co)-PEG5000] as well as for their mechanism of cell death following arginine deprivation. All four cell lines were sensitive to arginine deprivation induced by [HuArgI (Co)-PEG5000]. All cells expressed ASS1 and were rescued from arginine deprivation-induced cytotoxicity by the addition of excess L-citrulline, indicating they are partially auxotrophic for arginine. Mechanistically, cells treated with [HuArgI (Co)-PEG5000] were negative for AnnexinV and lacked caspase activation. Further investigation revealed that arginine deprivation leads to a marked and prolonged activation of autophagy in both Caco-2 and T84 cell lines. Finally, we show that [HuArgI (Co)-PEG5000] causes cell death by sustained activation of autophagy as evidenced by the decrease in cell cytotoxicity upon treatment with chloroquine, an autophagy inhibitor. Altogether, these data demonstrate that colon cancer cells are partially auxotrophic for arginine and sensitive to [HuArgI (Co)-PEG5000]-induced arginine deprivation. They also show that the activation of autophagy does not play protective roles but rather, induces cytotoxicity and leads to cell death.

中文翻译：

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[HuArgI (Co)-PEG5000] 诱导的精氨酸剥夺后自噬的激活介导结肠癌细胞中的细胞死亡。

通过重新编程代谢途径（包括精氨酸代谢）来解除对细胞能量的调节对于癌细胞的发作和存活至关重要。针对癌细胞特定代谢需求的药物已成为有希望的靶向癌症治疗药物。在这项研究中，我们研究了使用由聚乙二醇化钴取代的重组人精氨酸酶 I [HuArgI (Co)-PEG5000] 诱导的精氨酸剥夺来靶向结肠癌细胞的治疗潜力。测试了四种结肠癌细胞系对 [HuArgI (Co)-PEG5000] 的敏感性以及它们在精氨酸剥夺后的细胞死亡机制。所有四种细胞系都对 [HuArgI (Co)-PEG5000] 诱导的精氨酸剥夺敏感。所有细胞都表达 ASS1，并通过添加过量的 L-瓜氨酸从精氨酸剥夺诱导的细胞毒性中解救出来，表明它们对精氨酸是部分营养缺陷型的。从机制上讲，用 [HuArgI (Co)-PEG5000] 处理的细胞对 AnnexinV 呈阴性并且缺乏半胱天冬酶活化。进一步的研究表明，精氨酸剥夺导致 Caco-2 和 T84 细胞系中自噬的显着和延长激活。最后，我们发现 [HuArgI (Co)-PEG5000] 通过持续激活自噬导致细胞死亡，这可以通过自噬抑制剂氯喹治疗后细胞毒性降低来证明。总之，这些数据表明结肠癌细胞对精氨酸具有部分营养缺陷性，并且对 [HuArgI (Co)-PEG5000] 诱导的精氨酸剥夺敏感。