| Lung cancer is one of the most malignant tumors, which occurs mostly in bronchial epithelial cells. Gemcitabine(GEM) is a common anti-tumor drug used in the first-line chemotherapy for advanced non-small cell lung cancer. Due to its short half-life period Gemcitabine must be applied in high-dose that results accumulation of the toxicities.This study aims to design a new drug transfer system to increase the concentration of Gemcitabine in tumor cells and decrease the side effects for normal tissues. As artificial double phospholipids, liposome is able to extend the half-life period of drug in vivo. Together with estrogen receptors(ER), which are widely overexpressed on non-small cell lung cancer cells and act as a potential target for cancer targeted therapy, the modified drug loaded liposomes could specifically target tumor cells and further release chemotherapeutic drugs.Four types of Gemcitabine loaded liposomes(GEM loaded conventional liposomes L-GEM, GEM loaded targeted liposomes ES-L-GEM, GEM loaded sterically stabilized liposomes SSL-GEM and GEM loaded sterically stabilized and targeted liposomes ES-SSL-GEM) were prepared via thin film hydration method.The physicochemical characteristics of these four GEM loaded liposomes were investigated, including the morphological examination, particle size, zeta potential,encapsulation efficiency, drug-loading capacity and the stability at 4°C and 25°C. To evaluate the in vivo target effect, the fluorescence intensity of lung cancer cells A579 treated with Rhodamine B(Rh B) loaded liposomes was measured by fluorescence microscope. By adding different inhibitory agents of endocytosis including sucrose,genistein, amiloride hydrochlorid and ES, the mechanism of cellular uptake wasdetermined. Furthermore, the in vitro anti-tumor efficacy of GEM and the prepared GEM-loaded liposomes was investigated via MTT assay.We observed that, the successfully prepared four types of GEM loaded liposomes obtained average particle sizes in the range of 120nm~140nm and PDI in the range of 0.1~0.2. The zeta potentials of the liposomes showed negative. After storing at 4°C for 48 h SSL-GEM and especially ES-SSL-GEM were obviously more stabile than other liposomes. The in vitro targeting test revealed that,ES-L-Rh B and ES-SSL-Rh B were able to active target A549 cells, and that ES-SSL-Rh B showed sustained release effect. The result of inhibition assay of cellular uptake confirmed that, the cellular uptake of liposomes mainly depended on caveolin endocytosis and estrogen receptor-mediated endocytosis. Compare to Gemcitabine and other GEM-modified liposomes, ES-SSL-GEM, which benefited from its sterical stability and ER targeting speciality, obtained the greatest in vitro anti-tumor efficacy, In vivo experiments can be seen that the ES-SSL-GEM ’s anti-tumor effect is the best one.In this study, we designed and successfully prepared a new type of Gemcitabine loaded sterically stabilized and ES-modified liposome ES-SSL-GEM, which was able to specifically target the non-small cell lung cancer cells and showed high anti-tumor efficiency. We expect that, in the near future this new Gemcitabine loaded liposome could be applied to clinical treatment and support the lung cancer therapy. |
