治疗原发性肺癌的美乐托宁脂质体粉雾剂研究

Liposomal melatonin dry powder inhalers for the treatment of primary lung cancer

美乐托宁(melatonin, MLT)又称褪黑素,是人体内源性物质,大剂量给药时有抗肿瘤作用,但口服生物利用度低,体内半衰期短,成药性差。本文制备了美乐托宁脂质体粉雾剂(liposomal melatonin dry powder inhalers,LMD),经肺部给药治疗大鼠原发性肺癌。用乙醇注入法制备美乐托宁脂质体(liposomal melatonin, LM),包封率为98.9%,加入甘露醇冻干得到LMD,扫描电镜显示为类球形颗粒,加水复溶后粒径为65.15 nm, zeta电位为-14.2 mV。LMD的空气动力学粒径为6.73μm,微细粒子比例(fine particle fraction, FPF<8.06μm)为22.2%,适合肺部给药。在相同药物浓度时, LMD对A549肺癌细胞抑制作用显著高于MLT原料和吉西他滨,因此脂质体增强了MLT药效。大剂量LMD不影响人正常支气管细胞(BEAS-2B)生长,安全性好。用3-甲基胆蒽及N,N-二甲基亚硝胺经气管喷入大鼠肺中, 45天后得到原发性肺癌模型(动物实验经单位伦理委员会批准且实验均按照相关指导原则和规定进行)。将MLT、吉西他滨、LMD经气管喷入肺癌大鼠肺中,与模型组比较,治疗组均呈现明显少的肿瘤结节和炎性细胞数量,其中LMD的药效最强。治疗组NF-κB p65减少,以及Tunel检测表明细胞凋亡;丙二醛水平降低,其中LMD组的效果最强,与其他组有显著性差异。美乐托宁脂质体粉雾剂直接将药物递送至肺部肿瘤,是一种有前景的治疗肺癌的肺吸入给药剂型。

Melatonin(MLT) is an endogenous chemical that has antitumor effects at high doses. However, it shows low oral bioavailability and short in vivo half-life, leading to drug resistance. Here, liposomal melatonin dry powder inhalers(LMD) were prepared, and were used for treatment of primary rat lung cancer by pulmonary delivery. Liposomal melatonin(LM) was prepared by the ethanol injection method to achieve an entrapment efficiency of 98.89%. LMD was obtained by freeze-drying after LM was mixed with mannitol. LMD appeared as spherical particles under a scanning electron microscope. The rehydrated liposomes had a small size of 65.15 nm and the zeta potential of-14.2 mV without change inentrapment efficiency. LMD had an aerodynamic particle size of 6.73 ± 0.012 μm and a fine particle fraction(FPF<8.06 μm) of 22.2%, suitable for pulmonary delivery. When administered with the same dose, LMD showed much higher inhibition on A549 lung cancer cells than MLT and gemcitabine. LMD of a large dose had no effect on the growth of normal lung epithelial cells(BEAS-2 B). Rat lung cancer models were established after 45 days by instilling 3-methylcholanthrene(MCA) and N,N-dimethylni‐trosamine(DEN) into the rat lungs once(the experiments had been approved by the ethics committee and carried out in accordance with relevant guidelines and regulations). Decreases of tumor nodules and inflammatory cells in the tumor-bearing rat lungs were observed after treatment of MLT, gemcitabine and LMD by pulmonary delivery compared with the models, wherein LMD was most effective. The efficiencies of inhibition of NF-κB p65, increase of Tunel detection(indicating enhancement of apoptosis), and decrease of malondialdehyde corresponded to LMD being most effective. Therefore, given the fact that LMD can deliver the drug into the tumor tissues of lungs, and it presents as a promising pulmonary inhalable regiment for treatment of lung cancer.