MTDH与肿瘤酸性微环境相互作用对鼻咽癌紫杉醇化疗耐药的调控及分子机制研究

Acidic tumor microenvironment has been a hot spot in drug resistance of cancer chemotherapy. Our previous study has clearly demonstrated that: MTDH upregulation led to drug resistance of Paclitaxel in human nasopharyngeal carcinoma(NPC) cell line; Acidic extracellular pH could upregulate the expression of MTDH. These suggested that acidic tumor microenvironment might mediate drug resistance in NPC through the expression of MTDH. On the other hand, MTDH led to upregulation of V-ATPase which is essential in mediating acidic tumor microenvironment. Therefore, we hypothesize that interaction of MTDH and acidic tumor microenvironment may lead to drug resistance of chemotherapy in NPC. In the present study, NPC cells will be cultured in acidic medium, and that acidic tumor microenvironment induces drug resistance of Paclitaxel in NPC through mediating MTDH will be examed. Lentiviral vector plasmid will be used to mediate the expression of MTDH, and MTDH mediated drug resistance of Paclitaxel in NPC will also be measured. What’s more, the study will be further confirmed in vivo study. The accomplishment of this study will clarify MTDH lead to drug resistance of chemotherapy in NPC via interacting with acidic tumor microenvironment, which will provide novel theory and experimental data in the field of drug resistance in cancer chemotherapy.

肿瘤酸性微环境为肿瘤化疗耐药研究的热点。前期研究表明：MTDH表达增高后鼻咽癌细胞对紫杉醇的敏感性明显降低；酸性培养条件下，鼻咽癌细胞MTDH表达增高；这些提示肿瘤酸性微环境可能通过MTDH调控鼻咽癌化疗耐药。而上调鼻咽癌细胞的MTDH表达后，调节肿瘤酸性微环境的重要因子V-ATPase表达增加。据此，我们提出科学假设：肿瘤酸性微环境可上调MTDH的表达，而MTDH可反过来影响肿瘤酸性微环境，形成恶性循环，参与调控鼻咽癌细胞的紫杉醇敏感性。本项目用酸性培养基培养细胞，检测肿瘤酸性微环境通过MTDH调控鼻咽癌紫杉醇化疗耐药；采用慢病毒介导的质粒调控MTDH表达，检测MTDH对肿瘤酸性微环境的调控；建立裸鼠移植瘤模型体内实验验证体外实验结果。本项目的成功实施将阐明MTDH与肿瘤酸性微环境相互作用调控鼻咽癌细胞对紫杉醇的敏感性，为鼻咽癌及其他恶性肿瘤耐药机制研究提供新的理论依据和实验基础。

紫杉醇作为鼻咽癌的一线临床用药，其耐药性的产生严重影响着鼻咽癌患者的临床治疗效果、生存质量及预后。因此，紫杉醇耐药机理的研究对提高其临床效率意义重大。本项目研究，一方面，采用酸性培养基培养鼻咽癌细胞，检测酸性微环境对鼻咽癌细胞紫杉醇耐药的调控并探讨相关机制。结果表明：①酸性环境下鼻咽癌细胞对紫杉醇的敏感性降低；②酸性环境下鼻咽癌细胞发生上皮-间质转化（EMT）改变：细胞呈梭形改变，细胞间连接相对松散，E-钙粘蛋白（E-cadherin）表达降低、波形蛋白（vimentin）及N-钙粘蛋白（N-cadherin）表达增强；③MTDH表达增强；④酸性环境下沉默MTDH表达后，酸性环境引起的紫杉醇耐药及EMT改变得到逆转；这些说明酸性微环境可调控MTDH表达，并通过MTDH调控鼻咽癌对紫杉醇敏感性及EMT改变。另一方面，我们利用慢病毒介导的过表达和沉默载体，在鼻咽癌细胞中稳定过表达和沉默MTDH，观察MTDH对鼻咽癌细胞紫杉醇药物敏感性及肿瘤酸性微环境的影响。结果表明：①MTDH表达上调后鼻咽癌细胞对紫杉醇的敏感性降低，而沉默MTDH表达后鼻咽癌细胞对紫杉醇的敏感性升高，证实了MTDH对鼻咽癌细胞紫杉醇敏感性的调控；②MTDH上调后肿瘤酸性微环境重要相关蛋白V-ATPase、NHE1表达增强。综上所述，该项目基本按照研究计划进行，达到预期研究目的，初步阐明肿瘤酸性微环境及MTDH对鼻咽癌细胞紫杉醇耐药的调控，为鼻咽癌及其他恶性肿瘤耐药机制研究提供了新的理论依据和实验基础。