胆固醇内体-质膜转运调控HER2阳性胃癌曲妥珠单抗与化疗交叉耐药的研究

曲妥珠单抗是目前用于治疗HER2阳性胃癌唯一获批的靶向药物。然而，耐药性也是限制患者生存获益的首要障碍，且缺少针对性治疗方案。通过回顾HER2阳性胃癌临床研究，结合生信分析及预实验结果，我们发现并证实曲妥珠单抗与化疗存在跨类别交叉耐药的现象。进一步的预实验表明，质膜胆固醇富集是跨类别交叉耐药的关键环节；小GTPase介导的胆固醇内体-质膜转运是质膜胆固醇富集的主要途径；CDC42 GDP/GTP转换速率增加是转运的驱动力；联合靶向胆固醇内体-质膜转运可逆转化疗交叉耐药。由此，我们推测：CDC42驱动胆固醇内体-质膜转运促进质膜胆固醇富集，进而诱导曲妥珠单抗与化疗的交叉耐药。本研究拟通过3D耐药及类器官模型、亚细胞组分分离及荧光显微等体外模拟及可视化技术手段，探究胆固醇内体-质膜转运在曲妥珠单抗与化疗交叉耐药中的深层次机制，为优化HER2阳性胃癌患者曲妥珠单抗耐药后的用药策略提供理论支撑。

Trastuzumab is the only target drug to be approved as the first-line treatment of HER2-positive metastatic gastric cancer, but its ubiquitous resistance and the lack of efficient drugs for resistant patients decrease the therapeutic benefit. Reviewing clinical studies regarding HER2-positive gastric cancer, we observed a cross-resistance phenomenon across different classes of drugs, which was confirmed by our bioinformatics analysis and preliminary experiments. Further research has revealed that cholesterol redistribution, especially its enrichment in plasma membrane, plays a key role in the development of the cross-resistance between trastuzumab and chemotherapy. In addition, we identified the endosome-plasma membrane transport mediated by small GTPase CDC42 as the main source of plasma membrane cholesterol. Interestingly, it is the conversion rate of CDC42 GDP/GTP that determines its work efficiency. And blocking this transport route can reverse the paclitaxel resistance in vitro. Through this study, we intend to explore the mechanism underlying the cross-resistance between trastuzumab and chemotherapy by using experimental techniques such as PDOs construction, subcellular membrane components separation and visual fluorescence microscopy, thus providing new strategies for the treatment of trastuzumab-resistant HER2-positive gastric cancer patients.