Introduction: As high cholesterol level has been reported to be associated with cancer cell growth and cholesterol is vulnerable to oxidation, the conventional liposomes including cholesterol in the formulation seem to be challenged. Timosaponin AIII (TAIII), as a steroid saponin from Anemarrhena asphodeloides Bunge, possesses a similar structure with cholesterol and exhibits a wide range of antitumor activities, making it possible to develop a TAIII-based liposome where TAIII could potentially stabilize the phospholipid bilayer as a substitution of cholesterol and work as a chemotherapeutic drug as well. Meanwhile, TAIII could enhance the uptake of doxorubicin hydrochloride (DOX) in human hepatocellular carcinoma (HCC) cells and exhibit synergistic effect. Thus, we designed a novel thermally sensitive multifunctional liposomal system composed of TAIII and lipids to deliver DOX for enhanced HCC treatment.
Methods: The synergistic effects of DOX and TAIII were explored on HCC cells and the tumor inhibition rate of TAIII-based liposomes carrying DOX was evaluated on both subcutaneous and orthotopic transplantation tumor models. TAIII-based multifunctional liposomes were characterized.
Results: Synergistic HCC cytotoxicity was achieved at molar ratios of 1:1, 1:2 and 1:4 of DOX/TAIII. TAIII-based liposomes carrying a low DOX dose of 2 mg/kg exhibited significantly enhanced antitumor activity than 5 mg/kg of DOX without detected cardiotoxicity on both subcutaneous and orthotopic transplantation tumor models. TAIII-based liposomes were characterized with smaller size than cholesterol liposomes but exhibited favorable stability. Mild hyperthermia generated by laser irradiation accelerated the release of DOX and TAIII from liposomes at tumor site, and cell permeability of TAIII enhanced uptake of DOX in HCC cells.
Conclusion: The innovative application of TAIII working as bilayer stabilizer and chemotherapeutic drug affords a stable multifunctional liposomal delivery system for synergistic therapy against HCC, which may be referred for the development of other types of saponins with similar property.

Keywords: doxorubicin, timosaponin AIII, liposomes, hepatocellular carcinoma, cholesterol


中文翻译：

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新型基于知母皂苷 AIII 的多功能脂质体递送系统用于肝细胞癌的协同治疗

引言：据报道，高胆固醇水平与癌细胞生长有关，而且胆固醇容易被氧化，因此配方中包含胆固醇的传统脂质体似乎受到了挑战。Timosaponin AIII (TAIII)，作为来自知母的类固醇皂苷Bunge 具有与胆固醇相似的结构并表现出广泛的抗肿瘤活性，这使得开发基于 TAIII 的脂质体成为可能，其中 TAIII 可能稳定磷脂双分子层作为胆固醇的替代物，并作为化疗药物发挥作用。同时，TAIII可以增强人肝细胞癌（HCC）细胞对盐酸阿霉素（DOX）的摄取并表现出协同作用。因此，我们设计了一种由 TAIII 和脂质组成的新型热敏多功能脂质体系统，以提供 DOX 以增强 HCC 治疗。
方法：探索了 DOX 和 TAIII 对 HCC 细胞的协同作用，并在皮下和原位移植肿瘤模型上评估了携带 DOX 的基于 TAIII 的脂质体的肿瘤抑制率。表征了基于TAIII的多功能脂质体。
结果：在 DOX/TAIII 的摩尔比为 1:1、1:2 和 1:4 时实现了协同 HCC 细胞毒性。携带 2 mg/kg 低 DOX 剂量的基于 TAIII 的脂质体表现出比 5 mg/kg DOX 显着增强的抗肿瘤活性，而在皮下和原位移植肿瘤模型中未检测到心脏毒性。基于 TAIII 的脂质体的特点是尺寸小于胆固醇脂质体，但表现出良好的稳定性。激光照射产生的轻度热疗加速了肿瘤部位脂质体中 DOX 和 TAIII 的释放，TAIII 的细胞通透性增强了 HCC 细胞对 DOX 的摄取。
结论：TAIII作为双层稳定剂和化疗药物的创新应用为肝癌的协同治疗提供了稳定的多功能脂质体递送系统，可用于开发其他类似性质的皂苷。

关键词：阿霉素，知母皂苷AIII，脂质体，肝细胞癌，胆固醇