A novel redox-sensitive system for co-delivering hydrophobic drugs and hydrophilic siRNA or shRNA was developed by conjugating gambogic acid (GA) with poly(amido amine)s (PAAs) through amide bonds, which is called GA-conjugated PAAs (PAG). PAG can self-assemble into micelles as amphiphilic block copolymers, which exhibits an excellent loading ability for the co-delivery of docetaxel (DTX) and MMP-9 shRNA with adjustable dosing ratios. In addition, confocal microscopy, flow cytometry and in vitro transfection analyses demonstrated more efficient cellular internalization of DTX and MMP-9 shRNA after incubation with PAG/DTX- MMP-9 shRNA micelles (PAG/DTX-shRNA) than with free drugs. Unlike traditional amphiphilic copolymer micelles, GA conjugated in PAG possesses an intrinsic anticancer efficacy. The presence of disulfide bonds in PAAs enables rapid disassembly of PAG micelles in response to reducing agents, inducing the release of loaded drugs (DTX, GA and MMP-9 shRNA). In vitro cellular assays revealed that PAG/DTX-shRNA micelles inhibited MCF-7 cell proliferation more efficiently than the single drug or single drug-loaded micelles. In vivo biodistribution and anti-tumor effect studies using an MCF-7 breast cancer xenograft mouse model have indicated that PAG/DTX-shRNA micelles can enhance drug accumulation compared with the free drug, thereby sustaining the therapeutic effect on tumors. Additionally, PAG/DTX-shRNA micelles displayed a greater anti-tumor efficacy than Taxotere^® and PAG-shRNA micelles. These results suggest that the redox-sensitive PAG platform is a promising co-delivery system for combining drugs and gene therapy for the treatment of cancer.

Statement of Significance

The PAG micelles were designed by conjugating gambogic acid (GA) with poly(amido amine)s (PAAs), which would serve dual purposes as both gene and drugs co-delivery carrier and an anti-tumor prodrug. Unlike traditional amphiphilic micelles, GA conjugated in PAG could exert its intrinsic efficacy and provide synergistic antiproliferative effects with docetaxel (DTX) on MCF-7 cells. Disulfide bonds in PAG enables a rapid disassembly of PAG micelles in response to reducing agents and to release all loaded drugs (DTX, GA and MMP-9 shRNA) at tumor sites. PAG/DTX-shRNA micelles displayed greater anti-tumor efficacy than that of Taxotere^® , indicating the design concept for PAG works well. And the strategy for PAG could be used to develop a series of similar co-delivery systems through conjugations of other small-molecule drugs with PAAs, such as doxorubicin, methotrexate and other drugs with carboxy groups in their structure.

中文翻译：

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通过将藤黄酸与可生物还原的聚（酰胺胺）缀合以形成多西他赛和MMP-9 shRNA共同形成的氧化还原反应性聚合物胶束

通过将藤黄酸（GA）与聚（酰胺胺）（PAA）通过酰胺键共轭，开发了一种共递送疏水性药物和亲水性siRNA或shRNA的新型氧化还原敏感系统，称为GA共轭PAA（PAG） 。PAG可以以两亲性嵌段共聚物的形式自组装成胶束，对于多西他赛（DTX）和MMP-9 shRNA的共递送显示出优异的负载能力，且剂量比可调。另外，共聚焦显微镜，流式细胞术和体外转染分析表明，与游离药物孵育后，与PAG / DTX- MMP-9 shRNA胶束（PAG / DTX-shRNA）孵育后，DTX和MMP-9 shRNA的细胞内化作用更加有效。与传统的两亲共聚物胶束不同，PAG中缀合的GA具有固有的抗癌功效。PAA中二硫键的存在使PAG胶束响应还原剂快速分解，从而诱导了负载药物（DTX，GA和MMP-9 shRNA）的释放。体外细胞分析显示，PAG / DTX-shRNA胶束比单药或单药装载的胶束更有效地抑制MCF-7细胞增殖。体内使用MCF-7乳腺癌异种移植小鼠模型进行的生物分布和抗肿瘤作用研究表明，与游离药物相比，PAG / DTX-shRNA胶束可以增强药物蓄积，从而维持对肿瘤的治疗作用。此外，PAG / DTX-shRNA的胶束显示更大的抗肿瘤功效比泰索帝^®和PAG-shRNA的胶束。这些结果表明，氧化还原敏感的PAG平台是将药物和基因治疗相结合以治疗癌症的有希望的共同交付系统。

重要声明

PAG胶束是通过将藤黄酸（GA）与聚（酰胺基胺）（PAA）结合而设计的，这将同时具有基因和药物共同递送载体以及抗肿瘤前药的双重作用。与传统的两亲胶束不同，PAG中缀合的GA可以发挥其固有功效，并与多西他赛（DTX）对MCF-7细胞提供协同的抗增殖作用。PAG中的二硫键能够响应还原剂快速分解PAG胶束，并在肿瘤部位释放所有负载的药物（DTX，GA和MMP-9 shRNA）。PAG / DTX-shRNA的胶束显示更大的抗肿瘤功效比泰索帝^®，表明PAG的设计理念效果很好。通过将其他小分子药物与PAA（例如阿霉素，甲氨蝶呤和其他结构上带有羧基的药物）结合，PAG的策略可用于开发一系列相似的共递送系统。