选择性自噬在IBP促进乳腺癌紫杉醇耐药中的作用及机制研究

Paclitaxel has become one of the first-line drugs commonly used in clinical breast cancer chemotherapy. However, post-treatment breast cancer patients often show resistant to chemotherapy drugs. For that reason, investigating the mechanism of paclitaxel-resistant breast cancer cells is significant to improve the effect of chemotherapy. It has been confirmed that IBP(Interferon regulatory factor-4 binding protein) can inhibit breast cancer cells autophagy by activating mTORC2(mammalian target of Rapamycin complex 2)/Akt(protein kinase B )/Foxo3a (Forkhead family of transcription factors )pathway in our pre-experiment as well as Foxo3a can regulate selective autophagy via transcription levels, so the function of IBP that could inhibit selective autophagy degradation pathway is possible. Our recent study found that IBP is able to promote the drug resistance and the expressing of resistance protein P-gp(p-glycoprotein) . Moreover, evidence shows that down regulating the expression of multidrug resistance protein P-gp in selective autophagy pathway can reduce the drug resistance . It is assumed that IBP’s function of promoting breast cancer cells resistance to paclitaxel is acquired by inhibiting selective autophagy in breast cancer cells and then inhibiting the degradation P-gp.This study, from the levels of cell and animal model, will try to identify the relationships between the selective autophagy and the role of IBP promoting breast cancer cells resistant to paclitaxel and investigate the possible molecular mechanisms of it.This project aims at improving the understanding of the correlation between the selective autophagy and the resistance mechanisms in breast cance in order to provide some new therapeutic targets in the treatment of metastatic breast cancer.

乳腺癌患者治疗后期往往会对化疗药物产生耐药，探讨乳腺癌化疗一线药物紫杉醇的耐药机制，对于提高乳腺癌化疗效果具有十分重要的意义。我们已证实IBP可通过激活mTORC2/Akt/Foxo3a通路抑制乳腺癌自噬，而Foxo3a可从转录水平调节选择性自噬，故IBP可能具有抑制选择性自噬降解途径的功能。前期预实验发现：IBP 具有促进乳腺癌细胞紫杉醇耐药及促进多药耐药蛋白P-gp表达的作用，并且有研究发现促进选择性自噬能促进耐药蛋白P-gp降解从而降低细胞的耐药性。因此我们推测IBP可能是通过抑制选择性自噬进而抑制乳腺癌细胞P-gp降解，从而促进乳腺癌细胞对紫杉醇耐药。本研究拟从细胞及动物水平，明确选择性自噬与IBP促进乳腺癌紫杉醇耐药的关系，并探讨选择性自噬在IBP促进乳腺癌紫杉醇耐药中的可能分子机制，本项目将有助于完善选择性自噬与乳腺癌耐药机制的认识，为临床转移性乳腺癌的化疗提供新的思路及靶点。

乳腺癌是女性常见恶性肿瘤之一，手术结合放化疗为主的综合治疗是其主要治疗方法。紫杉醇（PTX）作为一种可与纺锤体微管结合从而导致有丝分裂阻滞及细胞死亡的强化疗药物，目前已成为临床常用的乳腺癌化疗的一线药物之一，尤其对转移性乳腺癌有突出疗效。然而，乳腺癌患者治疗的后期往往会对化疗药物产生耐药，这使得紫杉醇的有效率仅达 30%～70%，且效果往往不长久，一般只能持续 6～10 个月，其他抗癌药物亦存在耐药问题，因此，对化疗药物的获得性耐药是乳腺癌治疗失败的主要原因之一，探讨乳腺癌紫杉醇耐药机制，对于提高乳腺癌化疗效果具有十分重要的意义。本课题研究了分子伴侣自噬作为一种选择性自噬在乳腺癌紫杉醇耐药中的作用和分子机制。.本项目通过shRNA慢病毒感染和瞬时转染过表达质粒技术，构建了CMA水平不同的MDA-MB-231和MDA-MB-468乳腺癌细胞株。间接免疫荧光法观察LAMP2A高低表达不同乳腺癌细胞株的CMA活性。采用MTT检测，观察了分子伴侣自噬作为一种选择性自噬对紫杉醇耐药性的影响，发现分子伴侣自噬作为一种选择性自噬可以促进乳腺癌细胞紫杉醇耐药。采用基因芯片、qRT-PCR和Western Blot方法验证与分析子伴侣自噬作为一种选择性自噬促进乳腺癌细胞紫杉醇耐药性的可能机制，发现分子伴侣自噬作为一种选择性自噬促进乳腺癌细胞紫杉醇耐药性的可能是由于促进了乳腺癌细胞的糖酵解过程。.通过细胞模型（MTT检测、克隆形成实验、伤痕愈合实验和小室侵袭实验）、动物模型（裸鼠皮下接种）和乳腺癌临床标本，观察了分子伴侣自噬作为一种选择性自噬与乳腺癌细胞增殖转移的关系及其可能分子机制，发现分子伴侣自噬作为一种选择性自噬可以促进乳腺癌增殖转移，其可能分子机制是通过Atg5调控大自噬的发生。本项目有助于完善选择性自噬与乳腺癌耐药机制的认识，为临床转移性乳腺癌的化疗提供新的思路及靶点。