EPR-effect driven tumor delivery of multifunctional boron nanomedicine for neutron capture therapy

我们合成了一种水溶性胶束药物，称为苯乙烯马来酸（SMA）共聚物共轭氨基葡萄糖和硼酸（SGB-complex）。在体外及多种小鼠肿瘤模型中均表现出基于EPR效应的肿瘤选择性蓄积，具有良好的杀瘤活性。然而，sgb -复合物的精确化学结构和在没有中子辐照的情况下细胞毒性的详细作用方式尚不清楚。FY2022期间，我重点研究了sgb -复合物的分子结构，包括UV-vis、IR、NMR、液相色谱质谱等。我们证实了sma -聚合物通过酰胺键与氨基葡萄糖结合，硼酸通过二醇键与氨基葡萄糖结合（我们在ACS Applied Biomaterials杂志上报道了这项工作）。接下来，我们试图找出sgb复合物体外细胞毒性的可能机制。我们推测sgb复合体可能在轻度缺氧状态下诱导内质网或线粒体应激。为了支持我们的假设，我们测量了内质酰胺应激标志物磷酸化真核起始因子2 α (p-eIF2)、C/-EBP同源蛋白（CHOP）以及治疗后Caspase 3和7的表达。有趣的是，我们发现sgb复合物显著增加了各种内质网应激标志物，这证实了我们的药物在适应缺氧的癌细胞中诱导内质网应激。我们还测量了我们的药物治疗后的线粒体膜电位，数据显示，与未治疗组相比，发生的变化非常小。TEM图像将能够确认是否有线粒体损伤发生。

We synthesized a water-soluble micellar drug called styrene maleic acid (SMA) copolymer conjugated glucosamine and boric acid (SGB-complex). It showed tumor selective accumulation based on EPR effect and excellent tumoricidal activity in vitro as well as various mouse tumor models. However, the precise chemical structure of SGB-complex and the detailed mode of action of cytotoxicity without neutron irradiation was not understood.During FY2022 period, I focused on the determination of molecular structure of SGB-complex by UV-vis, IR, NMR spectroscopy and liquid chromatography mass spectroscopy. We confirmed that the SMA-polymer bound to the glucosamine via amide bond and the boric acid was attached to glucosamine by di-ol bond (This works we reported at ACS Applied Biomaterials journal). Next, we try to find out the possible mechanism of in vitro cytotoxicity of SGB-complex. We hypothesized that SGB-complex might induce ER or mitochondrial stress in mild-hypoxia state. To support our hypothesis, we measure the ER stress marker phosphorylated eukaryotic initiation factor 2 alpha (p-eIF2), C/-EBP homologous protein (CHOP), and Caspase 3 and 7 expressions after treating of our drug. Interestingly, we found the SGB-complex significantly increased various ER stress markers that confirmed our drug induces ER stress in hypoxia adapted cancer cells. We also measured the mitochondrial membrane potential after treatment of our drug, and data showed very less changes occurred compare to non-treated group. TEM image will be able to confirm whether any mitochondrial damage occur or not.