外泌体源性CYP3A4在乳腺癌阿霉素耐药中的作用及机制研究

Doxorubicin has been the cornerstone of breast cancer chemotherapy. However the drug resistance and toxic side effects limited the clinical application of doxorubicin in breast cancer. CYP3A4 is an important activating enzyme for doxorubicin. Our previous study showed that the secretion of exosomes with doxorubicin was significantly increased, while the level of exosomes-CYP3A4 was significantly decreased in doxorubicin-resistant breast cancer cells. Therefore, we propose a hypothesis that low expression of CYP3A4 in exosomes of breast cancer cells may be important for inducing doxorubicin resistance; CYP3A4 specific over-expression in breast cancer cells by iRGD-CYP3A4-exosomes could increase chemosensitivity of doxorubicin. In order to prove this possibility, the research contents of this project include that: 1）to explore the correlation between exosomal CYP3A4 level and doxorubicin sensibility by analyzing the expression of exosomal CYP3A4 in doxorubicin-sensitive and doxorubicin-resistant breast cancer patients; 2）to investigate the process and mechanism of doxorubicin resistance mediated by exosomal CYP3A4 in cell experiments; 3）to clarify the chemotherapy sensitization effect of CYP3A4 specifically over-expressed in breast cancer cells by iRGD-CYP3A4-exosomes targeting systems in vivo and in vitro studies. This project will help to clarify the molecular mechanism of doxorubicin resistance mediated by exosomal CYP3A4, and provide new ideas for reversing doxorubicin resistance in breast cancer.

以阿霉素为基础的化疗方案一直是乳腺癌化疗的基石，但耐药和毒副反应限制了临床治疗。CYP3A4是阿霉素的重要活化酶，我们前期在诱导乳腺癌细胞阿霉素耐药过程中发现乳腺癌耐药细胞株外泌体分泌量增加伴随CYP3A4水平降低，然而在细胞水平上CYP3A4无显著变化。因此我们提出假设：乳腺癌细胞外泌体中CYP3A4低表达可能与细胞对阿霉素敏感性下降有关，通过iRGD-CYP3A4-外泌体靶向乳腺癌细胞能够增强肿瘤细胞对阿霉素的敏感性。本项目将在前期工作基础上进一步扩大临床样本，探讨乳腺癌阿霉素敏感组与耐药组患者外泌体中CYP3A4的表达差异；在细胞水平上探讨外泌体中CYP3A4参与阿霉素耐药的过程及分子调控机制；构建iRGD-CYP3A4-外泌体靶向传递系统，在阿霉素耐药细胞株和动物模型中明确其化疗增敏效果。本项目有助于明确外泌体介导阿霉素耐药的作用及分子机制，为提高化疗效果提供新的干预靶点。

以阿霉素为基础的化疗方案一直是乳腺癌化疗的基石，但耐药和毒副反应限制了临床治疗。CYP3A4是阿霉素的重要活化酶，我们前期在诱导乳腺癌细胞阿霉素耐药过程中发现乳腺癌耐药细胞株外泌体分泌量增加伴随CYP3A4水平降低，然而在细胞水平上CYP3A4无显著变化。因此我们提出假设：乳腺癌细胞外泌体中CYP3A4低表达可能与细胞对阿霉素敏感性下降有关，通过靶向提高乳腺癌细胞中CYP3A4水平能够增强肿瘤细胞对阿霉素的敏感性。通过临床新辅助化疗样本，发现敏感患者组织及血浆外泌体中CYP3A4的表达水平明显高于耐药患者；进一步构建iRGD-CYP3A4-外泌体靶向传递系统，证实外泌体中CYP3A4的表达降低是乳腺癌细胞阿霉素耐药性发生的原因之一，构建的肿瘤靶向肽iRGD和Lamp2b外泌体穿膜蛋白共修饰的双导向外泌体作为载体携载CYP3A4可以快速、高效、靶向的输送至乳腺癌细胞，在体外细胞模型和体内动物模型中明确了其化疗增敏效果，为提高化疗效果提供新的干预靶点。