Hara Hirokazu, Sueyoshi Sayako, Taniguchi Miko, Kamiya Tetsuro, Adachi Tetsuo
a Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University , Gifu , Japan.
Free Radic Res. 2017 Mar;51(3):306-315. doi: 10.1080/10715762.2017.1309527. Epub 2017 Apr 9.
There is growing evidence that plasma-activated medium (PAM), which is prepared by non-thermal plasma (NTP) irradiation of cell-free medium, is a beneficial tool for cancer therapy. PAM has been reported to preferentially kill cancer cells; however, its mechanism is not fully understood. Since PAM contains reactive oxygen species (ROS) and reactive nitrogen species, the anti-cancer effects of PAM are thought to be attributed to oxidative stress induced by these reactive molecules. Oxidative stress has been shown to release zinc (Zn) from intracellular Zn stores and provoke Zn-dependent cell death. We have previously demonstrated that intracellular free Zn plays a critical role in PAM-induced cell death in human neuroblastoma SH-SY5Y cells. In this study, we found that normal human fibroblasts were less susceptible to PAM cytotoxicity compared with SH-SY5Y cells. PAM decreased intracellular NAD levels in both cells, whereas the depletion of ATP and mitochondrial ROS generation was hardly observed in fibroblasts. Intracellular mobile Zn contents of fibroblasts were lower than those of SH-SY5Y cells. PAM suppressed the activity of aconitase, which is a tricarboxylic acid cycle enzyme, only in SH-SY5Y cells, and N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), a Zn chelator, counteracted the suppression. The combination treatment with PAM and Zn augmented PAM-induced ATP depletion, mitochondrial ROS generation, and cytotoxicity in fibroblasts. These findings suggest the possibility that cells with high intracellular mobile Zn are susceptible to PAM cytotoxicity. Therefore, we concluded that the differences in mobile Zn levels affect PAM-induced cellular responses.
越来越多的证据表明，通过对无细胞培养基进行非热等离子体（NTP）照射制备的等离子体活化培养基（PAM）是一种用于癌症治疗的有益工具。据报道，PAM能优先杀死癌细胞；然而，其机制尚未完全明确。由于PAM含有活性氧（ROS）和活性氮，PAM的抗癌作用被认为归因于这些活性分子诱导的氧化应激。氧化应激已被证明可从细胞内锌储存中释放锌（Zn）并引发锌依赖性细胞死亡。我们之前已经证明，细胞内游离锌在人神经母细胞瘤SH-SY5Y细胞中PAM诱导的细胞死亡中起关键作用。在本研究中，我们发现与SH-SY5Y细胞相比，正常人成纤维细胞对PAM细胞毒性的敏感性较低。PAM降低了两种细胞内的NAD水平，而在成纤维细胞中几乎未观察到ATP的消耗和线粒体ROS的产生。成纤维细胞的细胞内可移动锌含量低于SH-SY5Y细胞。PAM仅在SH-SY5Y细胞中抑制了三羧酸循环酶乌头酸酶的活性，而锌螯合剂N,N,N',N'-四（2-吡啶甲基）乙二胺（TPEN）可抵消这种抑制作用。PAM与锌的联合处理增强了PAM诱导的成纤维细胞中的ATP消耗、线粒体ROS产生和细胞毒性。这些发现表明，细胞内可移动锌含量高的细胞可能对PAM细胞毒性敏感。因此，我们得出结论，可移动锌水平的差异影响PAM诱导的细胞反应。
