Polymer-drug conjugates has significantly improved the anti-tumor efficacy of chemotherapeutic drugs and alleviated their side effects. N-(1,3-dihydroxypropan-2-yl) methacrylamide (DHPMA) copolymer was synthesized via RAFT polymerization and polymer-doxorubicin (DOX) (diblock pDHPMA-DOX) were formed by conjugation, resulting in a self-aggregation-induced nanoprodrug with a favorable size of 21 nm and great stability. The nanoprodrug with a molecular weight (MW) of 95 kDa released drugs in response to tumor microenvironmental pH variations and they were enzymatically hydrolyzed into low MW segments (45 kDa). The nanoprodrug was transported through the endolysosomal pathway, released the drug into the cytoplasm and some was localized in the mitochondria, resulting in disruption of the cellular actin cytoskeleton. Cellular apoptosis was also associated with reduction in the mitochondrial potential caused by the nanoprodrug. Notably, the nanoprodrug had a significantly prolonged blood circulation time with an elimination half time of 9.8 h, displayed high accumulation within tumors, and improved the in vivo therapeutic efficacy against 4T1 xenograft tumors compared to free DOX. The tumor xenograft immunohistochemistry study clearly indicated tumor inhibition was through the inhibition of cell proliferation and antiangiogenic effects. Our studies demonstrated that the diblock pDHPMA-DOX nanoprodrug with a controlled molecular structure is promising to alleviate adverse effects of free DOX and have a great potential as an efficient anticancer agent. STATEMENT OF SIGNIFICANCE: In this work, we prepared a biodegradable diblock DHPMA polymer-doxorubicin conjugate via one-pot of RAFT polymerization and conjugate chemistry. The conjugate-based nanoprodrug was internalized by endocytosis to intracellularly release DOX and further induce disruption of mitochondrial functions, actin cytoskeleton alterations and cellular apoptosis. The nanoprodrug with a high molecular weight (MW) (95 kDa) showed a long blood circulation time and achieved high accumulation into tumors. The nanoprodrug was degraded into low MW (∼45 kDa) products below the renal threshold, which ensured its biosafety. Additionally, the multi-stimuli-responsive nanoprodrug demonstrated an enhanced antitumor efficacy against 4T1 breast tumors and alleviated side effects, showing a great potential as an efficient and safe anticancer agent.

中文翻译：

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刺激反应性聚合物-阿霉素结合物：抗肿瘤机制和作为纳米前药的潜力。

聚合物-药物缀合物显着改善了化学治疗药物的抗肿瘤功效，并减轻了其副作用。通过RAFT聚合合成N-（1,3-二羟基丙-2-基）甲基丙烯酰胺（DHPMA）共聚物，并通过共轭形成聚合物-阿霉素（diblock pDHPMA-DOX），从而产生自聚集诱导的纳米前药。具有21 nm的有利尺寸和出色的稳定性。分子量（MW）为95 kDa的纳米前药响应于肿瘤微环境pH的变化而释放药物，并被酶水解为低MW片段（45 kDa）。纳米前药通过内溶酶体途径运输，将药物释放到细胞质中，有些位于线粒体中，导致细胞肌动蛋白细胞骨架的破坏。细胞凋亡也与由纳米前药引起的线粒体电位降低有关。值得注意的是，与游离DOX相比，纳米前药具有显着延长的血液循环时间和9.8 h的消除半衰期，显示出在肿瘤内的高积累，并提高了对4T1异种移植肿瘤的体内治疗功效。肿瘤异种移植物的免疫组织化学研究清楚地表明，肿瘤抑制作用是通过抑制细胞增殖和抗血管生成作用来实现的。我们的研究表明，具有受控分子结构的二嵌段pDHPMA-DOX纳米前药有望缓解游离DOX的不利影响，并具有作为有效抗癌剂的巨大潜力。意义声明：在这项工作中，我们通过一锅RAFT聚合反应和结合物化学制备了可生物降解的二嵌段DHPMA聚合物-阿霉素结合物。基于缀合物的纳米前药通过内吞作用被内在化，以在细胞内释放DOX，并进一步诱导线粒体功能破坏，肌动蛋白细胞骨架改变和细胞凋亡。具有高分子量（MW）（95 kDa）的纳米前药显示出长的血液循环时间，并在肿瘤中高度积累。纳米前药被降解为低于肾阈值的低分子量（〜45 kDa）产品，从而确保了其生物安全性。另外，多刺激响应的纳米前药显示出对4T1乳腺肿瘤的增强的抗肿瘤功效并减轻了副作用，显示出作为有效和安全的抗癌剂的巨大潜力。