Division of Immunology and Gnotobiology, Institute of Microbiology ASCR, v.v.i., Videnska 1083, 142 20 Prague 4, Czech Republic.
Curr Med Chem. 2013;20(38):4815-26. doi: 10.2174/09298673113206660281.
Treatment of murine EL4 T cell lymphoma with N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer conjugates of doxorubicin (Dox) leads to complete tumor regression and to the development of therapy-dependent longlasting cancer resistance. This phenomenon occurs with two types of Dox conjugates tested, despite differences in the covalent linkage of Dox to the polymer carrier. Such a cancer resistance cannot fully express in conventional treatment with free Dox, due to substantial immunotoxicity of the treatment, which was not observed in the polymer conjugates. In this study, calreticulin (CRT) translocation and high mobility group box-1 protein (HMGB1) release was observed in EL4 cells treated with a conjugate releasing Dox by a pH-dependent manner. As a result, the treated tumor cells were engulfed by dendritic cells (DC) in vitro, and induced their expression of CD80, CD86, and MHC II maturation markers. Conjugates with Dox bound via an amide bond only increased translocation of HSPs to the membrane, which led to an elevated phagocytosis but was not sufficient to induce increase of the maturation markers on DCs in vitro. Both types of conjugates induced engulfment of the target tumor cells in vivo, that was more intense than that seen with free Dox. It means that the induction of anti-tumor immunity documented upon treatment of EL4 lymphoma with HPMA-bound Dox conjugates does not rely solely on CRT-mediated cell death, but involves multiple mechanisms.
用 N-(2-羟丙基)甲基丙烯酰胺（HPMA）聚合物偶联阿霉素（Dox）治疗小鼠 EL4 T 细胞淋巴瘤导致完全肿瘤消退，并产生治疗依赖性的持久抗癌作用。尽管测试的两种 Dox 缀合物的共价键连接方式不同，但都出现了这种抗癌作用。由于治疗的免疫毒性很大，在常规的游离 Dox 治疗中，这种抗癌作用无法完全表达，而在聚合物缀合物中则没有观察到这种情况。在这项研究中，用 pH 依赖性方式释放 Dox 的缀合物处理 EL4 细胞后，观察到钙网蛋白（CRT）易位和高迁移率族蛋白 B1（HMGB1）释放。结果，处理过的肿瘤细胞被树突状细胞（DC）体外吞噬，并诱导其表达 CD80、CD86 和 MHC II 成熟标志物。只有通过酰胺键结合 Dox 的缀合物增加 HSP 向膜的易位，从而导致吞噬作用增加，但不足以诱导体外 DC 上成熟标志物的增加。两种类型的缀合物都能诱导体内靶肿瘤细胞的吞噬作用，其强度大于游离 Dox。这意味着，用 HPMA 结合的 Dox 缀合物治疗 EL4 淋巴瘤时所证明的抗肿瘤免疫的诱导不仅依赖于 CRT 介导的细胞死亡，还涉及多种机制。
