Department of Radiology, Molecular Imaging Program at Stanford (MIPS), Stanford University, CA, U.S.A.
Stanford Center for Innovation in In vivo Imaging (SCi 3 ) at Porter, Canary Center for Cancer Early Detection, Stanford University, CA, U.S.A.
Theranostics. 2023 Mar 13;13(6):1745-1758. doi: 10.7150/thno.79342. eCollection 2023.
As a cancer, Glioblastoma (GBM) is a highly lethal and difficult-to-treat. With the aim of improving therapies to GBM, we developed novel and target-specific theranostic nanoparticles (TNPs) that can be selectively cleaved by cathepsin B (Cat B) to release the potent toxin monomethyl auristatin E (MMAE). We synthesized TNPs composed of a ferumoxytol-based nanoparticle carrier and a peptide prodrug with a Cat-B-responsive linker and the tubulin inhibitor MMAE. We hypothesized that intratumoral Cat B can cleave our TNPs and release MMAE to kill GBM cells. The ferumoxytol core enables drug tracking with magnetic resonance imaging (MRI). We incubated U87-MG GBM cells with TNPs or ferumoxytol and evaluated the TNP content in the cells with transmission electron microscopy and Prussian blue staining. In addition, we stereotaxically implanted 6- to 8-week-old nude mice with U87-MG with U87-MG GBM cells that express a fusion protein of Green Fluorescence Protein and firefly Luciferase (U87-MG/GFP-fLuc). We then treated the animals with an intravenous dose of TNPs (25 mg/kg of ferumoxytol, 0.3 mg/kg of MMAE) or control. We also evaluated the combination of TNP treatment with radiation therapy. We performed MRI before and after TNP injection. We compared the results for tumor and normal brain tissue between the TNP and control groups. We also monitored tumor growth for a period of 21 days. We successfully synthesized TNPs with a hydrodynamic size of 41 ± 5 nm and a zeta potential of 6 ± 3 mV. TNP-treated cells demonstrated a significantly higher iron content than ferumoxytol-treated cells (98 ± 1% vs. 3 ± 1% of cells were iron-positive, respectively). We also found significantly fewer live attached cells in the TNP-treated group (3.8 ± 2.0 px) than in the ferumoxytol-treated group (80.0 ± 14.5 px, p < 0001). MRI studies demonstrated a decline in the tumor signal after TNP (T= 28 ms) but not control (T= 32 ms) injections. When TNP injection was combined with radiation therapy, the tumor signals dropped further (T = 24 ms). The combination therapy of radiation therapy and TNPs extended the median survival from 14.5 days for the control group to 45 days for the combination therapy group. The new cleavable TNPs reported in this work accumulate in GBM, cause tumor cell death, and have synergistic effects with radiation therapy.
作为一种癌症，神经胶质瘤（GBM）是一种高度致命且难以治疗的疾病。为了改善对 GBM 的治疗方法，我们开发了新型的、针对特定靶点的治疗性纳米颗粒（TNPs），这些纳米颗粒可以被组织蛋白酶 B（Cat B）选择性切割，从而释放出有效的毒素单甲基奥瑞他汀 E（MMAE）。我们合成了由基于 ferumoxytol 的纳米颗粒载体和具有 Cat-B 响应性连接体和微管抑制剂 MMAE 的肽前药组成的 TNPs。我们假设肿瘤内的 Cat B 可以切割我们的 TNPs 并释放 MMAE 来杀死 GBM 细胞。ferumoxytol 核心使药物能够通过磁共振成像（MRI）进行跟踪。我们用 TNPs 或 ferumoxytol 孵育 U87-MG GBM 细胞，并通过透射电子显微镜和普鲁士蓝染色评估细胞中的 TNP 含量。此外，我们将表达绿色荧光蛋白和萤火虫荧光素酶融合蛋白的 U87-MG GBM 细胞（U87-MG/GFP-fLuc）立体定向植入 6-8 周龄裸鼠的 U87-MG 中。然后，我们用静脉注射 25 mg/kg ferumoxytol（0.3 mg/kg MMAE）的 TNPs 或对照物处理动物。我们还评估了 TNP 治疗与放射治疗的联合应用。我们在 TNP 注射前后进行 MRI 检查。我们比较了 TNP 组和对照组之间肿瘤和正常脑组织的结果。我们还监测了 21 天的肿瘤生长情况。我们成功合成了具有 41 ± 5nm 水动力直径和 6 ± 3mV 的 Zeta 电位的 TNPs。与 ferumoxytol 处理的细胞相比，TNP 处理的细胞显示出显著更高的铁含量（分别为 98 ± 1%和 3 ± 1%的细胞为铁阳性）。我们还发现 TNP 处理组的活附着细胞明显少于 ferumoxytol 处理组（3.8 ± 2.0 px）（p < 0001）。MRI 研究表明，TNP（T=28 ms）注射后肿瘤信号下降，但对照物（T=32 ms）注射后信号未下降。当 TNP 注射与放射治疗联合应用时，肿瘤信号进一步下降（T=24 ms）。放射治疗和 TNPs 的联合治疗将对照组的中位生存期从 14.5 天延长至联合治疗组的 45 天。本工作报道的新型可切割 TNPs 在 GBM 中积累，导致肿瘤细胞死亡，并与放射治疗具有协同作用。
