Kanwal Simab, Abeysinghe Shalini, Srisaisup Monrudee, Boonserm Panadda
Institute of Molecular Biosciences, Mahidol University, Salaya, Phuttamonthon, Nakhon Pathom 73170, Thailand.
Toxins (Basel). 2021 Apr 19;13(4):288. doi: 10.3390/toxins13040288.
Binary toxin (Bin toxin), BinA and BinB, produced by has been used as a mosquito-control agent due to its high toxicity against the mosquito larvae. The crystal structures of Bin toxin and non-insecticidal but cytotoxic parasporin-2 toxin share some common structural features with those of the aerolysin-like toxin family, thus suggesting a common mechanism of pore formation of these toxins. Here we explored the possible cytotoxicity of Bin proteins (BinA, BinB and BinA + BinB) against Hs68 and HepG2 cell lines. The cytotoxicity of Bin proteins was evaluated using the trypan blue exclusion assay, MTT assay, morphological analysis and LDH efflux assay. The intracellular localization of Bin toxin in HepG2 cells was assessed by confocal laser scanning microscope. HepG2 cells treated with BinA and BinB (50 µg/mL) showed modified cell morphological features and reduced cell viability. Bin toxin showed no toxicity against Hs68 cells. The EC values against HepG2 at 24 h were 24 ng/mL for PS2 and 46.56 and 39.72 µg/mL for BinA and BinB, respectively. The induction of apoptosis in treated HepG2 cells was confirmed by upregulation of caspase levels. The results indicated that BinB mediates the translocation of BinA in HepG2 cells and subsequently associates with mitochondria. The study supports the possible development of Bin toxin as either an anticancer agent or a selective delivery vehicle of anticancer agents to target mitochondria of human cancer cells in the future.
由[具体产生菌]产生的二元毒素（Bin毒素），即BinA和BinB，因其对蚊虫幼虫具有高毒性，已被用作一种蚊虫控制剂。Bin毒素和非杀虫但具有细胞毒性的副孢子蛋白-2毒素的晶体结构与气单胞菌溶素样毒素家族的晶体结构具有一些共同的结构特征，因此表明这些毒素形成孔道的机制相同。在此，我们探究了Bin蛋白（BinA、BinB和BinA + BinB）对Hs68和HepG2细胞系可能的细胞毒性。使用台盼蓝排斥试验、MTT试验、形态学分析和乳酸脱氢酶外排试验评估Bin蛋白的细胞毒性。通过共聚焦激光扫描显微镜评估Bin毒素在HepG2细胞中的细胞内定位。用BinA和BinB（50 µg/mL）处理的HepG2细胞表现出细胞形态特征改变和细胞活力降低。Bin毒素对Hs68细胞无毒性。PS2在24小时时对HepG2的EC值为24 ng/mL，BinA和BinB分别为46.56和39.72 µg/mL。通过半胱天冬酶水平上调证实了处理后的HepG2细胞中凋亡的诱导。结果表明，BinB介导BinA在HepG2细胞中的转运，随后与线粒体结合。该研究支持未来有可能将Bin毒素开发为抗癌剂或作为抗癌剂向人类癌细胞线粒体靶向递送的载体。
