College of Pharmaceutical Science, Zhejiang University, Hangzhou, People’s Republic of China.
Int J Nanomedicine. 2011;6:3499-508. doi: 10.2147/IJN.S26670. Epub 2011 Dec 21.
Solid tumors need new blood vessels to feed and nourish them as well as to allow tumor cells to escape into the circulation and lodge in other organs, which is termed "angiogenesis." Some tumor cells within solid tumors can overexpress integrins α(v)β(3) and α(v)β(5), which can specifically recognize the peptide motif Arg-Gly-Asp (RGD). Thus, the targeting of RGD-modified micelles to tumor vasculature is a promising strategy for tumor-targeting treatment.
RGD peptide (GSSSGRGDSPA) was coupled to poly(ethylene glycol)-modified stearic acid-grafted chitosan (PEG-CS-SA) micelles via chemical reaction in the presence of N,N'-Disuccinimidyl carbonate. The critical micelle concentration of the polymeric micelles was determined by measuring the fluorescence intensity of pyrene as a fluorescent probe. The micelle size, size distribution, and zeta potential were measured by light scattering and electrophoretic mobility. Doxorubicin (DOX) was chosen as a model anticancer drug to investigate the drug entrapment efficiency, in vitro drug-release profile, and in vitro antitumor activities of drug-loaded RGD-PEG-CS-SA micelles in cells that overexpress integrins (α(ν)β(3) and α(ν)β(5)) and integrin-deficient cells.
Using DOX as a model drug, the drug encapsulation efficiency could reach 90%, and the in vitro drug-release profiles suggested that the micelles could be used as a controlled-release carrier for the hydrophobic drug. Qualitative and quantitative analysis of cellular uptake indicated that RGD-modified micelles could significantly increase the DOX concentration in integrin-overexpressing human hepatocellular carcinoma cell line (BEL-7402), but not in human epithelial carcinoma cell line (Hela). The competitive cellular-uptake test showed that the cellular uptake of RGD-modified micelles in BEL-7402 cells was significantly inhibited in the presence of excess free RGD peptides. In vitro cytotoxicity tests demonstrated DOX-loaded RGD-modified micelles could specifically enhance the cytotoxicity against BEL-7402 compared with DOX-loaded PEG-CS-SA and doxorubicin hydrochlorate.
This study suggests that RGD-modified PEG-CS-SA micelles are promising drug carriers for integrin-overexpressing tumor active targeting therapy.
实体瘤需要新的血管来滋养它们，并允许肿瘤细胞逃入循环系统并在其他器官中定植，这被称为“血管生成”。一些实体瘤中的肿瘤细胞可以过度表达整合素α(v)β(3)和α(v)β(5)，它们可以特异性识别肽基序 Arg-Gly-Asp (RGD)。因此，将 RGD 修饰的胶束靶向肿瘤血管是一种很有前途的肿瘤靶向治疗策略。
通过化学反应，在 N,N'-二琥珀酰亚胺基碳酸酯的存在下，将 RGD 肽(GSSSGRGDSPA)偶联到聚乙二醇修饰的硬脂酸接枝壳聚糖(PEG-CS-SA)胶束上。通过作为荧光探针的芘的荧光强度来测定聚合物胶束的临界胶束浓度。用光散射和电泳迁移率测定胶束的粒径、粒径分布和 zeta 电位。选择阿霉素(DOX)作为模型抗癌药物，研究载药 RGD-PEG-CS-SA 胶束在整合素过度表达(α(v)β(3)和α(v)β(5))和整合素缺陷细胞中的药物包封效率、体外药物释放特性和体外抗肿瘤活性。
以 DOX 为模型药物，药物包封效率可达 90%，体外药物释放曲线表明，该胶束可用作疏水性药物的控释载体。细胞摄取的定性和定量分析表明，RGD 修饰的胶束可以显著增加整合素过度表达的人肝癌细胞系(BEL-7402)中 DOX 的浓度，但对人上皮癌细胞系(Hela)没有影响。竞争细胞摄取试验表明，在过量游离 RGD 肽存在的情况下，RGD 修饰胶束在 BEL-7402 细胞中的摄取明显受到抑制。体外细胞毒性试验表明，与载 DOX 的 PEG-CS-SA 和盐酸多柔比星相比，载 DOX 的 RGD 修饰胶束对 BEL-7402 具有更强的细胞毒性。
本研究表明，RGD 修饰的 PEG-CS-SA 胶束是一种很有前途的整合素过度表达肿瘤主动靶向治疗的药物载体。
