缺氧诱导因子-1（HIF-1）与Notch信号通路在胰腺癌变中相互调控机制及靶向抑制剂联合治疗的研究

Pancreatic cancer is one of the most deadly malignancies with extremely poor prognosis. Drug resistance and patients’ intolerance to chemotherapeutics limited the effectiveness of current treatment. Multiple intracellular signaling pathways have been demonstrated to be abnormally activated during pancreatic tumorigenesis, thus making it possible to discover novel targeted inhibitors to treat this disease. It is known that hypoxia inducible factor-1 (HIF-1) and Notch signaling pathways were both hyper-activated during pancreatic tumorigenesis. Inhibitions of either HIF-1 or Notch pathway could decelerate pancreatic cancer progression. Our previous study found that HIF-1 and Notch pathways were simultaneously activated in both KrasG12D transgenic pancreatic cancer mouse model and human pancreatic cancer tissue samples. Pharmacological inhibition of Notch signaling in Kras mutant transgenic pancreatic cancer mouse not only suppressed Notch signaling activity, but also partially inhibited HIF-1 signaling activity. Based on that, HIF-1 and Notch pathways were activated at the same time during pancreatic tumorigenesis. It also provide potential therapeutic target for combined target therapy. This study aims to further evaluate the combination therapeutic effectiveness of both pathways’ inhibitors on Kras mutant transgenic pancreatic cancer mouse model. Furthermore, we also aim to study the molecular regulation mechanism and key regulatory molecules based on pancreatic cancer cell lines. In detail, the key molecules of HIF-1 and Notch pathways will be knocked down or over expressed, and the downstream molecules would be assayed. In conclusion, this study aims to providing experimental evidences for combined HIF-1 and Notch inhibition therapeutic strategy.

胰腺癌是一种死亡率高、预后差的恶性肿瘤；传统化疗易产生耐药性且耐受性差。胰腺癌变中多条信号通路发生异常活化，为靶向药物联合治疗的提供了可能。缺氧诱导因子-1（HIF-1）和Notch信号通路均在胰腺癌变过程中异常活化，分别单独抑制可减缓胰腺癌变进程。本组预实验基于已建立的Kras突变小鼠胰腺癌变模型、以及临床胰腺癌患者肿瘤组织标本，发现两条通路同步活化；小鼠模型单独使用Notch抑制剂可同时部分抑制两条信号通路；提示两条信号通路活化存在相关性，且为潜在靶向联合治疗靶点。本研究拟进一步在小鼠胰腺癌变模型进行在体实验，利用靶向药物干预研究两条信号通路联合抑制对胰腺癌的联合抑制效果。进一步，通过胰腺癌细胞系分别对两条信号的关键分子进行敲低和过表达实验，明确其相互调控机制及关键调控分子，并为联合用药策略提供实验依据。

胰腺癌致死性高、治疗效果差。本研究通过细胞系、转基因小鼠模型、胰腺癌患者标本等多个层面，研究缺氧诱导因子（HIF）信号和Notch信号两者在胰腺癌病变过程中的相互调节关系，为靶向药物联合治疗的提供理论依据。总体的研究结论与课题研究预期一致：即HIF信号和Notch信号在胰腺癌中起相互促进作用。①在胰腺癌细胞系层面：HIF信号胰腺癌细胞系本底表达较低，利用CoCl2药物诱导HIF信号活化，发现NOTCH信号下游HES1也随之活化；②在转基因小鼠模型方面：为了模拟实验胰腺癌变过程中HIF活化过程，构建KrasG12D, PDX1-Cre，VHL三阳性小鼠，即实验小鼠同时具有胰腺癌变最常见的KrasG12D突变和VHL杂合缺失。VHL是HIF上有的抑制因子，通过此构建HIF活化的胰腺癌变模型，从而分析HIF信号对胰腺癌变过程影响；③在胰腺癌患者水平，无论基于TCGA数据库公共数据分析，还是基于本项目开展的胰腺癌患者免疫组化染色，都提示胰腺癌中HIF信号及NOTCH信号通路的表达水平存在显著性正相关。以上三个层面均通过实验结果印证HIF和NOTCH信号在胰腺癌变中的关键调节作用。本研究进一步使用对NOTCH信号抑制剂DAPT，发现可同时抑制NOTCH和HIF信号表达，印证上述结果。