RGD肽介导的载蟾毒灵多功能纳米胶束抑制结肠癌多药耐药的机制研究

Multidrug resistance is the major reason for the failure of chemotherapy in colorectal cancer. Bufalin is one of the most effective antitumor active constituents in Venenum Bufonis. Our previous study found that BUF can effectively treat colon cancer and reverse P-gp mediated multidrug resistance. However, the clinical application of BUF is limited due to its low solubility in water and high toxicity. This project designed loading bufalin BUF/VES-g-CSO/TPGS-RGD multifunctional nano micelle delivery system, which is based on TPGS and RGD peptide; The CSO can improve the solubility of BUF in water and reduce its toxicity; using the specific combination of RGD and integrin receptor to target tumor tissues; thought the inhibition of P-gp to reverse multidrug resistance; using the role of inducing apoptosis by VES. This project based on the completion of preparation of bufalin loaded nanomicelle and the study of its vitro antitumor activity , from the targeting for tumor,inducing apoptosis, inhibition of P-gp to implore the mechanism of reversing multidrug resistance. This study will provide a new treatment method based on BUF for drug resistant colon cancer in clinic application.

多药耐药性是导致结肠癌化疗失败的主要原因。蟾毒灵(BUF)是蟾酥中抗肿瘤活性最强的有效成分之一，本课题组前期研究发现BUF能有效治疗结肠癌并逆转P-糖蛋白(P-gp)介导的多药耐药，但因其水溶性低，毒性大而限制了其应用。本项目基于聚乙二醇维生素E琥珀酸酯(TPGS)与RGD肽构建载蟾毒灵的BUF/VES-g-CSO/TPGS-RGD多功能纳米胶束递送系统。通过疏水性内核的包裹与壳寡糖(CSO)的作用，提高BUF的溶解度；利用RGD肽与整合素受体特异性结合达到肿瘤组织的靶向；通过TPGS对P-gp的抑制实现多药耐药的逆转；发挥维生素E琥珀酸酯(VES)诱导肿瘤细胞凋亡的优势。本项目在完成载蟾毒灵纳米胶束的制备及体外抗结肠癌研究的基础上，从靶向肿瘤、诱导凋亡及抑制P-gp介导的药物外排等方面探讨纳米胶束抑制结肠癌多药耐药的机制，本研究为临床应用蟾毒灵治疗耐药性结肠癌提供新的治疗方法与思路。

多药耐药性是导致结肠癌化疗失败的主要原因。蟾毒灵(BU)是蟾酥中抗肿瘤活性最强的有效成分之一，本课题组前期研究发现BUF能有效治疗结肠癌并逆转P-糖蛋白(P-gp)介导的多药耐药，但因其水溶性低，毒性大而限制了其应用。本项目基于聚乙二醇维生素E琥珀酸酯(TPGS)与RGD肽构建载蟾毒灵的BU@VES-g-CSO/TPGS-RGD多功能纳米胶束递送系统。BU@VES-g-CSO/TPGS-RGD纳米胶束粒径均一，球形良好，能有效提高蟾毒灵的溶解度，延缓体外释放，增加细胞摄取率，并且能增强其对结肠癌耐药细胞株的抑制率。进一步的机制研究表明，BU@VES-g-CSO/TPGS-RGD纳米胶束逆转结肠癌多药耐药的机制涉及诱导肿瘤细胞凋亡，抑制P-gp的表达等。此外，本项目构建了结肠癌裸鼠移植瘤模型，实验结果证实，BU@VES-g-CSO/TPGS-RGD纳米胶束能有效提高蟾毒灵对耐药性结肠癌小鼠的抑瘤率，原因包括延长体内滞留时间，改善药动学性质，增加其肿瘤靶向性与降低毒性。本研究为临床应用蟾毒灵治疗耐药性结肠癌提供新的治疗方法与思路。