Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy.
Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy; Program in Physiology & Experimental Biology, Hospital for Sick Children, Toronto, Canada.
Biochim Biophys Acta Gen Subj. 2017 Apr;1861(4):860-870. doi: 10.1016/j.bbagen.2017.01.015. Epub 2017 Jan 15.
Liposomes, used to improve the therapeutic index of new and established drugs, have advanced with the insertion of active targeting. The lectin from Lotus tetragonolobus (LTL), which binds glycans containing alpha-1,2-linked fucose, reveals surface regionalized glycoepitopes in highly proliferative cells not detectable in normally growing cells. In contrast, other lectins localize the corresponding glycoepitopes all over the cell surface. LTL also proved able to penetrate the cells by an unconventional uptake mechanism.
We used confocal laser microscopy to detect and localize LTL-positive glycoepitopes and lectin uptake in two cancer cell lines. We then constructed doxorubicin-loaded liposomes functionalized with LTL. Intracellular delivery of the drug was determined in vitro and in vivo by confocal and electron microscopy.
We confirmed the specific localization of Lotus binding sites and the lectin uptake mechanism in the two cell lines and determined that LTL-functionalized liposomes loaded with doxorubicin greatly increased intracellular delivery of the drug, compared to unmodified doxorubicin-loaded liposomes. The LTL-Dox-L mechanism of entry and drug delivery was different to that of Dox-L and other liposomal preparations. LTL-Dox-L entered the cells one by one in tiny tubules that never fused with lysosomes. LTL-Dox-L injected in mice with melanoma specifically delivered loaded Dox to the cytoplasm of tumor cells.
Liposome functionalization with LTL promises to broaden the therapeutic potential of liposomal doxorubicin treatment, decreasing non-specific toxicity.
Doxorubicin-LTL functionalized liposomes promise to be useful in the development of new cancer chemotherapy protocols.
脂质体可用于提高新的和已建立药物的治疗指数，随着主动靶向的插入而得到了发展。来自荷花（Lotus tetragonolobus）的凝集素（LTL）与含有α-1,2-连接岩藻糖的聚糖结合，揭示了在高度增殖的细胞中表面区域性糖基化表位，而在正常生长的细胞中则无法检测到。相比之下，其他凝集素将相应的糖基化表位定位在整个细胞表面。LTL 还被证明能够通过非传统的摄取机制穿透细胞。
我们使用共聚焦激光显微镜检测和定位两种癌细胞系中的 LTL 阳性糖基化表位和凝集素摄取。然后，我们构建了用 LTL 功能化的阿霉素负载脂质体。通过共聚焦和电子显微镜在体外和体内测定药物的细胞内递送。
我们证实了在两种细胞系中莲花结合位点的特异性定位和凝集素摄取机制，并确定与未修饰的阿霉素负载脂质体相比，用 LTL 功能化的负载阿霉素的脂质体大大增加了药物的细胞内递送。LTL-Dox-L 的进入和药物递送机制与 Dox-L 和其他脂质体制剂不同。LTL-Dox-L 以小的小管进入细胞，这些小管从不与溶酶体融合。在患有黑色素瘤的小鼠中注射的 LTL-Dox-L 特异性地将负载的 Dox 递送到肿瘤细胞的细胞质中。
脂质体用 LTL 功能化有望扩大脂质体阿霉素治疗的治疗潜力，降低非特异性毒性。
用 Doxorubicin-LTL 功能化的脂质体有望在开发新的癌症化疗方案中发挥作用。
