Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, ON M5S 3M2, Canada.
Breast Cancer Res Treat. 2010 Jun;121(2):323-33. doi: 10.1007/s10549-009-0473-3. Epub 2009 Jul 18.
Multidrug resistance (MDR) is one of the main challenges in the treatment of breast cancer. A new microsphere formulation able to generate reactive oxygen species (ROS) locally was thus investigated for circumventing MDR in breast cancer cells in this work. Glucose oxidase (GOX) was encapsulated in alginate/chitosan hydrogel microspheres (ACMS-GOX). The in vitro cytotoxicity of ACMS-GOX to murine breast cancer EMT6/AR1.0 cells, which overexpress P-glycoprotein (P-gp), was evaluated by a clonogenic assay. The mechanism of the cytotoxicity of ACMS-GOX was investigated by using various extracellular and intracellular ROS scavengers and antioxidant enzyme inhibitors. The effect of lipid peroxidation and cellular uptake of GOX was also evaluated. ACMS-GOX exhibited similar dose and time-dependent cytotoxicity to EMT6/AR1.0 cells as to their wild-type EMT6/WT parent cells, in effect circumventing the MDR phenotype of EMT6/AR1.0 cells. Extracellular H(2)O(2) and intracellular hydroxyl radical were found to play critical roles in the cytotoxicity of ACMS-GOX. Cellular uptake of GOX was negligible and thus not responsible for intracellular ROS generation. Combining ACMS-GOX with intracellular antioxidant inhibitors-enhanced cytoxicity. This work demonstrates that the ACMS-GOX are effective in circumventing P-gp-mediated MDR in breast cancer cells.
多药耐药性（MDR）是乳腺癌治疗的主要挑战之一。在这项工作中，为了克服乳腺癌细胞中的 MDR，研究了一种能够局部产生活性氧（ROS）的新的微球制剂。葡萄糖氧化酶（GOX）被包裹在海藻酸钠/壳聚糖水凝胶微球（ACMS-GOX）中。通过集落形成试验评估了 ACMS-GOX 对过表达 P 糖蛋白（P-gp）的鼠乳腺癌 EMT6/AR1.0 细胞的体外细胞毒性。通过使用各种细胞外和细胞内 ROS 清除剂和抗氧化酶抑制剂研究了 ACMS-GOX 的细胞毒性机制。还评估了 GOX 的脂质过氧化和细胞摄取的影响。ACMS-GOX 对 EMT6/AR1.0 细胞的剂量和时间依赖性细胞毒性与 EMT6/WT 亲代细胞相似，有效地克服了 EMT6/AR1.0 细胞的 MDR 表型。发现细胞外 H2O2 和细胞内羟基自由基在 ACMS-GOX 的细胞毒性中起关键作用。GOX 的细胞摄取可以忽略不计，因此不会导致细胞内 ROS 的产生。将 ACMS-GOX 与细胞内抗氧化抑制剂结合使用可增强细胞毒性。这项工作表明，ACMS-GOX 可有效克服乳腺癌细胞中的 P 糖蛋白介导的 MDR。
