多功能维生素E衍生物纳米乳：共传递线粒体靶点药物和克服肿瘤多药耐药

Multidrug resistance (MDR) in tumor cells is a significant obstacle for successful cancer chemotherapy. Multidrug resistance of cancer may come from many factors including cancer cell membrane-related drug resistance due to overexpression of ATP binding cassette (ABC) transporters and the mitochondria-related drug resistance involved in the overall resistance to chemotherapy. Inhibitors of P-gp such as Verapamil can be used to overcome MDR. But, clinical applications were limited because of toxicity or lack of reversal efficacy. In previous study we found that TS as a mitocan could suppress the overexpression of P-gp and Bcl-2 family proteins at the same time.MNEs could overcome MDR by targeting to mitochondria and inhibiting P-gp. Since the mitochondria plays a pivotal role in cell-death, a mitochondria-targeted treatment strategy could be promising for treating resistant cancers. We proposed here a strategy that co-deliver mitochondria-targeted drugs by Vitamin E derivative based nanoemulsions as well as overcoming multidrug resistance in cancer. In addition, Vitamin E derivative, Vitamin E succinate (TS), as a mitochondrial targeting molecule, has been used as carrier in MNEs which could induce apoptosis of different cells and improve the sensitivity of tumor cells to drug. In previous studies, it has been shown that VE and TS could inhibit P-gp to overcome MDR. And MNEs have been prepared with a high drug loading efficiency for PTX. In the present study, we will study drug release, cell toxicity and antitumor efficacy and distribution of the MNEs loaded PTX drug delivery systems, especially the mechanism of MNEs to overcome multidrug resistance in cancer by mitochondrial targeting and the inhibition of P-gp. Anticancer drugs associate with MNES would provide a potential strategy to treat the resistant cancers by inducing apoptosis via mitochondria signaling pathway and inhibiting P-gp.

肿瘤多药耐药（MDR）是肿瘤化疗失败的主要原因。产生多药耐药的主要原因是外排转运蛋白（如P-gp）和抗凋亡蛋白（Bcl-2）等过表达。常用克服MDR的方法是使用P-gp抑制剂，但由于毒副作用大等原因限制了临床应用。本研究采用多功能维生素E（VE）及衍生物纳米乳（MNEs）为载体，共传递线粒体靶点药物紫杉醇，克服MDR。我们前期已发现VE和VE琥珀酸酯（TS）可抑制P-gp，TS可阻滞Bcl-2蛋白的过表达，提高肿瘤细胞对药物的敏感性，TS可通过线粒体途径介导多种肿瘤细胞凋亡。因此MNEs可通过抑制Bcl-2和P-gp及线粒体途径诱导凋亡协同作用克服MDR。前期研究中我们已制备了MNEs，对紫杉醇有高载药效率。我们将研究载药MNEs的理化性质、抗肿瘤药效等，特别是通过线粒体靶向和P-gp抑制克服MDR的机制。本研究将为以MNEs作为载体通过线粒体靶向和P-gp抑制协同克服MDR提供理论依据。

肿瘤细胞对化疗药物产生的耐药性，严重影响着临床化疗的效果。我们发现VE和V E琥珀酸酯（TS）可抑制P-gp，TS可阻滞Bcl-2蛋白的过表达，提高肿瘤细胞对药物的敏感性，TS可通过线粒体途径介导多种肿瘤细胞凋亡。本项目制备了MNEs-PTX，并对MNEs的理化性质及通过线粒体靶向和P-gp抑制克服MDR的机制进行了研究。. 本研究通过乳化蒸发法制备了MNEs-PTX，α-TOS-NE，并对其理化性质、抗肿瘤作用、药动学以及通过线粒体靶向和P-gp抑制克服MDR的机制进行了考察。体外实验表明紫杉醇多功能纳米乳能够缓慢的释放药物，且释放较完全，具有良好的缓释性能。采用卵巢癌细胞A2780/Taxol对MNEs-PTX的毒性以及摄取进行了研究。结果表明MNEs-PTX对A2780/Taxol细胞的抑制作用最强，MNEs-PTX在肿瘤细胞中分布较多，能够增加药物在细胞中的积累。MNEs能够携带药物进入细胞，提高细胞内药物浓度，从而使得PTX更好的发挥作用。通过激光共聚焦显微镜观察MNEs-PTX对细胞线粒体膜电位的影响，采用Western blot法考察了MNEs-PTX对A2780/Taxol细胞Bcl-2和Bax蛋白表达的影响。证明了MNEs及MNEs-PTX能够抑制抗凋亡蛋白Bcl-2的表达，同时上调促凋亡蛋白Bax的表达，从而抑制耐药性的产生，恢复细胞药物的敏感性。在对α-TOS-NE制剂的研究中，药动学及MTT/JC-1实验不仅表明维生素E衍生物α-生育酚琥珀酸酯（α-TOS）具有抗肿瘤作用而且也进一步证明了α-TOS可以通过线粒体途径诱导细胞凋亡，从而克服多药耐药。