Krinick N L, Sun Y, Joyner D, Spikes J D, Straight R C, Kopecek J
Department of Bioengineering, University of Utah, Salt Lake City 84112.
J Biomater Sci Polym Ed. 1994;5(4):303-24. doi: 10.1163/156856294x00040.
Three water soluble copolymers based on N-(2-hydroxypropyl)methacrylamide were prepared. Copolymer I contains adriamycin, a chemotherapeutic agent, attached via enzymatically degradable oligopeptide (glycylphenylalanylleucylglycine; G-F-L-G) side chains. The other two copolymers contained the photosensitizer, meso-chlorin e6 monoethylene diamine disodium salt (Mce6). In Copolymer II, the chlorin is attached via the degradable G-F-L-G sequence, and it was bound by the nondegradable glycyl spacer in Copolymer III. Initially, the copolymers were characterized separately in vitro and in vivo. Combinations of the copolymer bound chemotherapeutic agent and each of the copolymer bound photosensitizers were then assessed for antitumor effect in vivo. Localization/retention studies (A/J mice; Neuro 2A neuroblastoma solid tumor) were performed with the two copolymers containing Mce6 as well as the free drug. Results of these experiments demonstrated a very different tumor uptake profile for the two copolymers. While the free drug was rapidly cleared from tumor tissue, the copolymer containing Mce6 attached via the non-degradable bond was retained for an extended period; drug concentrations in the tumor were high even after 5 days. On the other hand, a high concentration of the copolymer containing Mce6 bound via the degradable sequence was taken up by the tumor, yet its concentration in the tumor was substantially diminished at 48 h after administration. This shows indirect evidence of in vivo cleavage of Mce6 from the copolymer in the lysosomal compartment which is supported by direct evidence of cleavage by cathepsin B (a lysosomal enzyme) in vitro. Antitumor effects were assessed on Neuro 2A neuroblastoma induced in A/J mice for all three copolymers. Photodynamic therapy (PDT) proved the copolymer with Mce6 bound via the degradable oligopeptide sequence to be a more effective photosensitizer in vivo than the other chlorin containing copolymer. The difference in activity was consistent with the results obtained by photophysical analyses in which the free drug had a higher quantum yield of singlet oxygen generation than the polymer bound drug in buffer. The quantum yield of singlet oxygen generation increased with the enzymatic cleavage of the chlorin from the copolymer. Conditions were subsequently determined for which chemotherapy or PDT would show some antitumor effect, yet be incapable of curing tumors. Finally, combination therapy experiments were performed in which the copolymer bound adriamycin was mixed with either of the copolymer bound chlorin compounds and injected intravenously (i.v.) into the tail veins of mice.(ABSTRACT TRUNCATED AT 400 WORDS)
制备了三种基于N-(2-羟丙基)甲基丙烯酰胺的水溶性共聚物。共聚物I含有通过可酶解的寡肽（甘氨酰苯丙氨酰亮氨酰甘氨酸；G-F-L-G）侧链连接的化疗药物阿霉素。另外两种共聚物含有光敏剂中-氯代卟啉e6单乙二胺二钠盐（Mce6）。在共聚物II中，卟啉通过可降解的G-F-L-G序列连接，而在共聚物III中它通过不可降解的甘氨酰间隔基连接。最初，分别在体外和体内对共聚物进行了表征。然后评估了与共聚物结合的化疗药物和每种与共聚物结合的光敏剂的组合在体内的抗肿瘤效果。使用含有Mce6的两种共聚物以及游离药物进行了定位/滞留研究（A/J小鼠；Neuro 2A神经母细胞瘤实体瘤）。这些实验的结果表明，两种共聚物的肿瘤摄取情况非常不同。游离药物迅速从肿瘤组织中清除，而通过不可降解键连接Mce6的共聚物则能长时间滞留；即使在5天后肿瘤中的药物浓度仍很高。另一方面，通过可降解序列连接Mce6的共聚物在给药后48小时肿瘤摄取量高，但其在肿瘤中的浓度已大幅降低。这间接证明了Mce6在溶酶体区室中从共聚物上的体内裂解，体外组织蛋白酶B（一种溶酶体酶）的裂解直接证据也支持了这一点。对A/J小鼠诱导的Neuro 2A神经母细胞瘤评估了所有三种共聚物的抗肿瘤效果。光动力疗法（PDT）证明，通过可降解寡肽序列连接Mce6的共聚物在体内比另一种含卟啉的共聚物是更有效的光敏剂。活性差异与光物理分析结果一致，在缓冲液中游离药物产生单线态氧的量子产率高于聚合物结合药物。随着卟啉从共聚物上的酶解，单线态氧产生的量子产率增加。随后确定了化疗或PDT显示出一定抗肿瘤效果但无法治愈肿瘤的条件。最后，进行了联合治疗实验，将与共聚物结合的阿霉素与两种与共聚物结合的卟啉化合物之一混合，并静脉注射到小鼠尾静脉中。（摘要截断于400字）
