βig-h3调控内质网应激介导胶质瘤多药耐药的机制研究

Multidrug resistance (MDR) is the key reason for the ineffectiveness of chemotherapy in glioma; however, the molecular mechanisms remain poorly understood. βig-h3 is highly expressed in extracellular matrix in glioma. In our previous study, we found that down-regulation of βig-h3 can increase the susceptibilities of glioma cells to Temozolomide, and this indicated that βig-h3 participates in the regulation of drug resistance. We know that endoplasmic reticulum stress (ERS) has played an important role in MDR, and disequilibrium of calcium homeostasis is an important mechanism to induce ERS. It has reported that βig-h3 is involved in the regulation of calcium homeostasis. But so far there has not been published that βig-h3 regulates MDR via Ca2+-ERS signal pathway. After βig-h3 expression regulation, some experiment were performed to investigate the variation of molecules of ERS, MDR, apoptosis and cell cycle, and to discuss whether βig-h3 regulates MDR via Ca2+-ERS signal pathway in glioma. If we elucidate the molecular mechanism of βig-h3 regulating MDR, it will provide new drug targets for chemotherapy in glioma.

胶质瘤产生多药耐药是化疗失败的重要原因，然而其机制尚不清楚。βig-h3高表达于胶质瘤细胞外基质。我们的研究发现抑制βig-h3表达可提高胶质瘤细胞对替莫唑胺的敏感性，提示βig-h3参与胶质瘤耐药过程。内质网应激在肿瘤多药耐药中发挥重要作用。Ca2+稳态改变是诱发细胞内质网应激的重要因素。研究证实βig-h3参与调控细胞Ca2+水平。然而βig-h3是否通过调控Ca2+稳态，诱发胶质瘤细胞内质网应激并介导多药耐药，尚未见报道。本项目拟通过调控βig-h3表达，检测胶质瘤细胞内质网应激、多药耐药、细胞凋亡及细胞周期等相关分子的变化，在体内、体外探讨βig-h3可否通过激活Integrin-FAK-PI3K-IP3-IP3R-Ca2+通路诱发胶质瘤细胞内质网应激，进而介导胶质瘤多药耐药过程。本研究旨在揭示βig-h3调控胶质瘤多药耐药的分子机制，为提高胶质瘤化疗疗效提供新靶点。

胶质瘤是最常见的颅内肿瘤。由于呈浸润性生长，它与周围正常脑组织无明显边界，手术很难做到完全切除。因此，胶质瘤的术后化疗具有极其重要的意义。然而胶质瘤产生多药耐药是化疗失败的重要原因，并且其机制尚不清楚。这就需要我们就此进行深入研究。已知βig-h3高表达于胶质瘤细胞外基质。我们发现抑制βig-h3表达可提高胶质瘤细胞对替莫唑胺的敏感性，提示βig-h3参与胶质瘤耐药过程。内质网应激（ERS）在肿瘤多药耐药中发挥重要作用，并且Ca2+稳态改变是诱发细胞内质网应激的重要因素。研究证实βig-h3通过下游钙调蛋白calpain-2，参与调控细胞Ca2+水平。然而βig-h3是否通过调控Ca2+稳态，诱发胶质瘤细胞内质网应激并介导多药耐药，尚未见报道。在本研究中，我们通过调控βig-h3表达，发现βig-h3分子可以通过激活Integrin-FAK-PI3K-IP3-IP3R-Ca2+通路诱发胶质瘤细胞内质网应激，进而介导胶质瘤多药耐药过程。并且发现βig-h3可以调控ERS相关分子Grp78、CHOP、ATF6、IRE1、PERK，多药耐药分子TopoⅡ、p-gp，细胞凋亡相关分子Bcl-2，Bax，Bim，细胞周期相关分子CyclinD1、CDK4、CDK6、P21、P27、P53蛋白和mRNA的表达；明确了βig-h3参与胶质瘤细胞ERS、多药耐药、细胞凋亡及细胞周期的调控。并且我们还发现βig-h3可以通过调控自噬影响胶质瘤的多药耐药过程，且自噬过程和ERS互相影响，相互作用。本研究旨在揭示βig-h3调控胶质瘤多药耐药的分子机制，为提高胶质瘤化疗疗效提供新靶点，并且将课题进一步延伸和细化。