State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa, Macao, China.
Centre of Reproduction, Development and Aging (CRDA), Faculty of Health Sciences, University of Macau, Taipa, Macao, China.
J Adv Res. 2023 Apr;46:149-158. doi: 10.1016/j.jare.2022.06.011. Epub 2022 Jun 29.
The anti-cancer effect of high concentrations of ascorbic acid (AA) has been well established while its underlying mechanisms remain unclear. The association between iron and AA has attracted great attention but was still controversial due to the complicated roles of iron in tumors.
Our study aims to explore the anti-cancer mechanisms of AA and the interaction between AA and iron in cancer.
The MTT and ATP assays were used to evaluate the cytotoxicity of AA. Reactive oxygen species (ROS) generation, calcium (Ca), and lipid peroxidation were monitored with flow cytometry. Mitochondrial dysfunction was assessed by mitochondrial membrane potential (MMP) detection with JC-1 or tetramethylrhodamine methyl ester (TMRM) staining. Mitochondrial swelling was monitored with MitoTracker Green probe. FeSO (Fe), FeCl (Fe), Ferric ammonium citrate (Fe), hemin chloride (Fe) were used as an iron donor to investigate the effects of iron on AA's anti-tumor activity. The in vivo effects of AA and iron were analyzed in xenograft zebrafish and allograft mouse models.
High concentrations of AA exhibited cytotoxicity in a panel of cancer cells. AA triggered ROS-dependent non-apoptotic cell death. AA-induced cell death was essentially mediated by the accumulated intracellular Ca, which was partly originated from endoplasmic reticulum (ER). Surprisingly, exogenous iron could significantly reverse AA-induced ROS generation, Ca overloaded, and cell death. Especially, the iron supplements significantly impaired the in vivo anti-tumor activity of AA.
Our study elucidated the protective roles of iron in ROS/Ca mediated necrosis triggered by AA both in vitro and in vivo, which might shed novel insight into the anti-cancer mechanisms and provide clinical application strategies for AA in cancer treatment.
高浓度抗坏血酸（AA）的抗癌作用已得到充分证实，但其潜在机制尚不清楚。铁与 AA 的关联引起了极大关注，但由于铁在肿瘤中的复杂作用，其仍然存在争议。
本研究旨在探讨 AA 的抗癌机制以及 AA 和铁在癌症中的相互作用。
使用 MTT 和 ATP 测定法评估 AA 的细胞毒性。通过流式细胞术监测活性氧（ROS）生成、钙（Ca）和脂质过氧化。通过 JC-1 或四甲基罗丹明甲酯（TMRM）染色检测线粒体膜电位（MMP）评估线粒体功能障碍。通过 MitoTracker Green 探针监测线粒体肿胀。使用 FeSO（Fe）、FeCl（Fe）、柠檬酸铁铵（Fe）、氯化血红素（Fe）作为铁供体，研究铁对 AA 抗癌活性的影响。在异种移植斑马鱼和同种异体小鼠模型中分析 AA 和铁的体内作用。
高浓度 AA 在一系列癌细胞中表现出细胞毒性。AA 触发了依赖 ROS 的非凋亡性细胞死亡。AA 诱导的细胞死亡主要是由累积的细胞内 Ca 介导的，其中部分源自内质网（ER）。令人惊讶的是，外源性铁可以显著逆转 AA 诱导的 ROS 生成、Ca 过载和细胞死亡。特别是，铁补充剂显著损害了 AA 在体内的抗肿瘤活性。
本研究阐明了铁在 AA 诱导的 ROS/Ca 介导的坏死中的保护作用，无论是在体外还是体内，这可能为 AA 的抗癌机制提供新的见解，并为 AA 在癌症治疗中的临床应用策略提供依据。
