X线靶向激发的光动力学化疗逆转肿瘤耐药

Chemotherapy drug tolerance could be one of the most common reasons for the failure of tumor treatment, which severely impacts survival time and life quality of cancer patients. Massive reports have revealed[7] that transferrin/ transferrin receptor system may transport chemotherapeutic agents targetedly into maglignant cells, however the cytotoxicity is greatly impaired for that chemotherapeutic agents fail to escape from endosome trapping. Our previous results revealed that some kinds of photosensitiser may physically disrupt endosomal membrane to faciliate releasing trapped biomacromolecules under excitation of specific wavelength of visible light, its efficiency is far higher than other release facilitating methods. In this proposal, we utilize photosensitizer to faciliate releasing of transferrin mediated transportation of chemotherapeutic agents, and cojugate X-ray excitable nanoparticle with matching photosensitizer to realize external radiation excite photosensitizer to help release the transferrin mediated internalized and accumulated chemotherapeutic agents, with the concept that accumulation and storage of drugs, and subsequent targeted burst releasing of high load of drugs into cytoplasm of malignant cells to reverse drug tolerance. By this means, under therapeutic dose of X-irradiation and photosensitizer concentration, it can establish a new method with low toxicity and high efficiency to remedy advanced and refractory solid tumor by combination of radiotherapy, chemotherapy and photodynamic treatment.

化疗耐受是恶性肿瘤治疗失败复发的常见原因，严重影响了肿瘤病人的生存期和生活质量。大量的研究表明[7]，转铁蛋白/转铁蛋白受体系统能极有效率地向肿瘤细胞内靶向性转导化疗药物，但其细胞毒效果却受限于化疗药物难以逃离内涵体的圈陷而未能达到预期，我们前期的研究表明光敏剂在特定波长的光照下可以物理破坏内涵体膜而释放包含的生物大分子，其效率远远高于其它辅助释放的方法，在本课题中我们拟利用光敏剂的这一优点释放经转铁蛋白转导的化疗药物，并将X线可激发特定波长发光的纳米颗粒与相应的光敏剂化学连结以实现外照射（X线）激发光敏剂，增强释放经转铁蛋白导入肿瘤细胞并富集的化疗药物，以达到转铁蛋白先富集、贮存，外照射靶向激发高浓度化疗药物瞬间释放入胞的方式逆转化疗耐药，在治疗剂量的X线与光敏剂浓度的情况下，可以实现晚期复发难治的实体肿瘤靶向性的集放疗、化疗和光动力学治疗三位一体的低毒、高效的新型治疗方法。

化疗耐受是恶性肿瘤治疗失败复发的常见原因，严重影响了肿瘤病人的生存期和生活质量。我们利用光敏剂在特定波长的光照下可以物理破坏内涵体膜而释放包含的生物大分子，其效率远远高于其它辅助释放的方法，在本课题中我们利用光敏剂的这一优点释放经转铁蛋白转导的化疗药物，并将X线可激发特定波长发光的纳米颗粒与相应的光敏剂化学连结以实现外照射（X线）激发光敏剂，增强释放经转铁蛋白导入肿瘤细胞并富集的化疗药物，以达到转铁蛋白先富集、贮存，外照射靶向激发高浓度化疗药物瞬间释放入胞的方式逆转化疗耐药。首先我们采用基于二硫键的化学构建方法连接光敏剂（TOAP）和X线激发纳米颗粒（Cds）以及化疗药物（ADM），最后连接上Tf蛋白形成靶向转导光动力化疗纳米复合体，并经过Superdex 200层析柱纯化。我们将荧光染料AF488取代化疗药物用于验证纳米复合体的入胞实验。入胞后复合体和AF488染料在光照（X线照射）前聚集在内涵体颗粒里，光照后立即均匀分布在胞浆和胞核中。纯化后的复合体与化疗耐药的肝癌细胞株Hep-G2-ADM孵育，与单纯化疗组相比，纳米复合体处理后的细胞抑制率和克隆形成率明显低于单纯化疗组（p＜0.05）。动物实验也表明，纳米复合体组的肿瘤退缩率明显高于同当量的单纯化疗组（p＜0.05）。实验证实，光敏化疗纳米复合体有望实现晚期复发难治的实体肿瘤靶向性治疗，是集放疗、化疗和光动力学治疗三位一体的低毒、高效的新型治疗方法。