水通道蛋白（AQP）1胞浆表达作为乳腺癌蒽环类化疗药物疗效标志物的研究及其分子机制

Anthracycline-based therapies are part of the standard of care in first line treatment of metastatic breast cancer and their clinical use is widespread. Chemoresistance of anthracycline is the important problem to be overcome in clinic at present and screening anthracycline sensitive biomarkers is urgently needed. Our group has been focused on research of AQP (water channels) family, especially the function of AQP1 in breast cancer development. Our previous reports firstly discovered the cytoplasmic expression of AQP1 in breast cancer and disclaimed that high expression of AQP1 was negatively associated with prognosis of breast cancer patients for the first time. Furthermore, our resent work found that (1) patients with high expression of AQP1 have better prognosis in CEF regimens than those who were treated with CMF regimens. It indicated that AQP1 was associated with the anthracycline-based therapies. (2) AQP1 could have co-localization and interaction with β-catenin in cytoplasm. (3) Expression of AQP1 was positively associated with β-catenin in breast cancer patients and only patients with both high expression of AQP1 and β-catenin had best outcome among patients with CEF regimens. Therefore, our group demonstrated the new hypothesis that expression of AQP1 in cytoplasm may be biomarker of anthracycline-based therapies and it probably enhance the therapeutic effect of anthracycline through β-catenin signaling, we will confirm the hypothesis by this project. The present project is the continuous research work of our previous NSFC projects.

蒽环类药物是乳腺癌化疗一线药物，其耐药是困扰临床应用的重要问题，筛选其敏感性标志物具有显著临床意义。课题组长期专注水通道蛋白（AQP），尤其是AQP1在乳腺癌中的作用。我们前期明确了AQP1在乳腺癌中的胞浆表达，首次报道AQP1胞浆表达与乳腺癌患者预后显著负相关。深入研究又发现（1）AQP1胞浆高表达患者可从CEF方案中获益，不能从CMF方案中获益，提示AQP1胞浆表达与蒽环类药物疗效密切相关；（2）AQP1与β-catenin在乳腺癌细胞胞浆中共定位并相互作用；（3）乳腺癌患者中AQP1与β-catenin二者胞浆表达正相关；接受CEF方案患者中二者均胞浆高表达患者预后最好。据此课题组提出AQP1胞浆表达可作为乳腺癌蒽环类药物疗效的标志物，AQP1胞浆高表达可通过β-catenin信号通路增加蒽环类药物疗效的原创性假说并进行验证，是前期国家自然科学基金青年项目和面上项目的延续和深入研究。

乳腺癌是女性最常见的恶性肿瘤类型。蒽环类药物是广泛应用于乳腺癌治疗的常规一线化疗药物，而蒽环类药物耐药是我们面临的重要临床问题。因此，筛选出蒽环类药物敏感性的可靠标志物，对于乳腺癌病人个体化治疗和改善患者生存将具有很高的临床价值。.课题组在前期工作的基础上，通过生物信息学分析，乳腺癌原代细胞药物敏感性检测，免疫组织化学实验，免疫荧光实验，免疫共沉淀实验，细胞ATP活力检测实验，泛素化实验，胞浆/胞核提取物的制备和亚细胞分离实验，TOP/FOP Flash双荧光素酶报告基因实验和TopoGen活性检测等实验研究发现与低表达AQP1的患者相比，高表达AQP1的乳腺癌患者可以从含有蒽环类药物的化疗方案治疗中获得更好的临床效果，AQP1可以和糖原合酶激酶3β（GSK3β）竞争性结合β-catenin的12个ARM重复基序结构域，进而抑制β-catenin的降解，导致其在胞浆中积累和入核。入核的β-catenin可以与TopoIIα相互作用从而增强TopoIIα活性，进而增强乳腺癌细胞对蒽环类药物的敏感性。此外，我们还发现miR-320a-3p可以抑制AQP1的表达，从而削弱乳腺癌细胞对蒽环类药物的化学敏感性。.根据以上结果，我们得出结论：AQP1的表达水平可以作为临床上蒽环类化疗药物治疗乳腺癌的敏感性标志物，高表达AQP1的患者可从蒽环类化疗药物治疗中获益，而AQP1低表达的患者不能获益。以上结果将为乳腺癌患者临床个体化治疗及新治疗方法的开发与研究提供新的方向与思路。