高迁移率族蛋白1介导骨肉瘤化疗抵抗的分子机制研究

Osteosarcoma is the most commonly occurring bone cancer in children and adolescents. Unfortunately, treatment failures are common due to the development of chemoresistance, for which the underlying molecular mechanisms remain unclear. Cisplatin, doxorubicin and methotrexate are commonly used anti-cancer drugs in osteosarcoma. Our recent study published on Cancer Research and Autophagy demonstrated that high mobility group box 1 protein (HMGB1)-mediated autophagy is a significant contributor to these drugs resistance in osteosarcoma cells. Inhibition of both HMGB1 and autophagy increase the drug sensitivity of osteosarcoma cells in vivo and in vitro. In current study, we will continue to expand these findings and explore the mechanism of upregulation of HMGB1 in response to osteosarcoma, and how HMGB1-mediated autophagy regulates mitochondria and endoplasmic reticulum apoptotic pathway. This project will provide novel potential targets for the treatment of osteosarcoma.

骨肉瘤是好发于青少年的原发性恶性骨肿瘤，化疗的敏感性对其预后有着重要的影响，而耐药形成是临床化疗失败中的常见原因。项目组最近在《Cancer Research》和《Autophagy》上首次报道高迁移率族蛋白1（HMGB1）促进了骨肉瘤细胞自噬和化疗耐药的形成。本项目在此基础之上进一步研究HMGB1介导骨肉瘤化疗抵抗的分子机制，拟采用各种转基因细胞和突变体，通过基因转染、RNA干扰、Western blot、免疫共沉淀、免疫荧光和免疫电镜等方法，在整体、细胞和分子水平，研究HMGB1转录表达和释放异常的分子机制以及HMGB1介导的细胞自噬如何调控内质网与线粒体凋亡信号通路。开展本项目可望揭示自噬与凋亡相互作用的新机制，为肿瘤化疗的研究开辟新的领域，为寻找基于HMGB1为靶点的骨肉瘤治疗药物和手段提供新的思路与实验线索。

为了阐明HMGB1参与骨肉瘤细胞多药化疗耐药的分子机制，采用一系列相应的研究方法，首先初步探讨了化疗药物上调骨肉瘤细胞中HMGB1蛋白表达的分子机制，证实转录因子Kruppel-like factor 4(KLF-4)直接结合HMGB1基因启动子中的-456到-240序列而上调HMGB1蛋白的表达。同时，我们观察到化疗药物促进骨肉瘤细胞分泌HMGB1蛋白，揭示了骨肉瘤细胞分泌的外源性HMGB1蛋白通过与膜受体RAGE结合，上调骨肉瘤细胞的自噬水平而参与骨肉瘤细胞对多种化疗药物耐药；在研究外源性HMBG1蛋白介导的骨肉瘤细胞多种化疗药物耐药的基础上，进一步研究了内质网应激在骨肉瘤对顺铂耐药的分子机制，阐明了NF-κB通路参与了骨肉瘤细胞对顺铂的化疗耐药机制，较为圆满的完成课题计划。