The plant defensin NaD1 induces tumor cell death via a non-apoptotic, membranolytic process.
The plant defensin NaD1 induces tumor cell death via a non-apoptotic, membranolytic process.
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该植物通过非凋亡的膜液化过程来防御NAD1的NAD1诱导肿瘤细胞死亡。
DOI：
10.1038/cddiscovery.2016.102
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发表时间：
2017
影响因子：
7
通讯作者：
Hulett MD
中科院分区：
文献类型：
--
作者：
Baxter AA;Poon IK;Hulett MD
阳离子抗菌肽(CAPS)在宿主对细菌、真菌等病原体的天然防御中发挥着重要作用。包括防御素在内的许多CAPS还通过凋亡和非凋亡过程对哺乳动物细胞显示出选择性的细胞毒活性，并被作为潜在的抗癌药物进行研究。来自观赏烟草的抗真菌植物防御素1(NAD1)最近被证明在10 M的浓度下，在30 μ分钟内诱导多种类型的肿瘤细胞死亡。在这些实验参数中，NAD1介导的细胞死亡是通过与靶细胞的质膜磷脂酰肌醇4，5-二磷酸(PIP2)结合来促进膜的不稳定和随后的溶解而发生的。关于NaD1是否也能诱导肿瘤细胞凋亡的报道尚未见报道。本研究采用亚急性(~lt；10 μM)浓度的NaD16-24 h处理MM170(黑色素瘤)和Jurkat T细胞(白血病)，以确定NaD1a是否可通过诱导细胞凋亡来诱导细胞死亡。在亚急性浓度下，NaD_1在30 分钟内不能有效地诱导细胞膜通透性，但在24 小时内显著降低细胞存活率。与其他已被证明通过激活caspase诱导细胞凋亡的CAP不同，濒死细胞对pancaspase抑制剂不敏感，在24 h处理时间内也不显示caspase活性或DNA片段化。此外，在24 h期间，细胞出现坏死表型，并屈从于膜通透性。这些结果表明，亚急性浓度的NaD1的细胞毒性机制是膜溶解的，而不是凋亡的，也可能是通过PIP2靶向的细胞裂解途径介导的。
Cationic anti-microbial peptides (CAPs) have an important role in host innate defense against pathogens such as bacteria and fungi. Many CAPs including defensins also exhibit selective cytotoxic activity towards mammalian cells via both apoptotic and non-apoptotic processes, and are being investigated as potential anticancer agents. The anti-fungal plant defensin from ornamental tobacco, Nicotiana alata Defensin 1 (NaD1), was recently shown to induce necrotic-like cell death in a number of tumor cell types within 30 min of treatment, at a concentration of 10 μM. NaD1-mediated cell killing within these experimental parameters has been shown to occur via binding to the plasma membrane phosphatidylinositol 4,5-bisphosphate (PIP2) in target cells to facilitate membrane destabilization and subsequent lysis. Whether NaD1 is also capable of inducing apoptosis in tumor cells has not been reported previously. In this study, treatment of MM170 (melanoma) and Jurkat T (leukemia) cells with subacute (<10 μM) concentrations of NaD1 over 6–24 h was investigated to determine whether NaD1 could induce cell death via apoptosis. At subacute concentrations, NaD1 did not efficiently induce membrane permeabilization within 30 min, but markedly reduced cell viability over 24 h. In contrast to other CAPs that have been shown to induce apoptosis through caspase activation, dying cells were not sensitive to a pancaspase inhibitor nor did they display caspase activity or DNA fragmentation over the 24 h treatment time. Furthermore, over the 24 h period, cells exhibited necrotic phenotypes and succumbed to membrane permeabilization. These results indicate that the cytotoxic mechanism of NaD1 at subacute concentrations is membranolytic rather than apoptotic and is also likely to be mediated through a PIP2-targeting cell lytic pathway.