TLR4促进脂筏相关的HIF-1α的高活性在宫颈癌中的作用及机制

The growing out of control of cervical cancer is related to the high activity of HIF-1α. Nowadays, the mechanism of high expression of HIF-1 α in cancer cells under normoxic condition is not clear. The former studies have confirmed that lipid rafts related and NADPH oxidase derived reactive oxygen species( lipid raft redox signaling ) can maintain the high activity of HIF-1α in cancer cells under normoxic condition. The study group has also found that high expression of HIF-1α has a positive correlation with TLR4 signaling pathway in cervical cancer cells. Studies have reported that TLR4 signaling up-regulated the expression of HIF-1α by activating NF-κB.We also found that inhibition of the combination of TLR4 and the ligand could inhibit lipid raft redox signaling and reduced the activity of HIF-1α, but the inhibition of NF-κB could not inhibited lipid raft redox signaling though it inhibits the HIF-αslightly. Thus, it can be speculated that TLR4 signaling transduction may promote the activity of HIF-1α mainly by means of activation of lipid raft redox signaling. This project aims to study the changes of lipid raft redox signaling, TLR4 signaling, HIF-1α activity, the growth of cervical cancer cells after the intervention ofTLR4 signaling transduction and lipid rafts function by pharmacological or molecular biological means, trying to explore the mechanism of the promotive action that TLR4 signal does on the lipid raft redox signaling, and to find a new pathway to inhibit the occurrence and development of cervical cancer, which may provide new ideas for clinical treatment of cervical cancer.

宫颈癌的生长失控与HIF-1α的高活性有关，目前常氧状态下HIF-1α高表达的机制不清，我们前期已证实脂筏氧化还原信号是维持宫颈癌常氧状态下HIF-1α高活性的关键因素；宫颈癌组织中TLR4与HIF-1α的表达呈正相关。文献报道TLR4信号通过活化NF-κB上调HIF-1α的表达。而我们发现干扰脂筏功能可抑制TLR4信号发生，抑制TLR4和其配体结合可抑制脂筏氧化还原信号、降低HIF-1α活性，但抑制NF-κB活性不能抑制脂筏氧化还原信号。故推测TLR4信号主要通过激发脂筏氧化还原信号、而非依赖NF-κB的活化来促进HIF-1α的活性。所以本项目拟在体内外通过药理和分子生物学手段干预TLR4信号和脂筏功能，观察脂筏氧化还原信号、TLR4信号、HIF-1α含量、宫颈癌细胞生长的变化，阐明TLR4信号促进HIF-1α活性的作用和机制，探讨抑制宫颈癌发生发展的新路径，为防治宫颈癌提供研究基础。

宫颈癌细胞的生长失控与宫颈癌细胞内一个重要的转录因子-低氧诱导因子-1ɑ（hypoxia inducible factor-1α, HIF-1α）的过度激活密切相关。前期已证实脂筏氧化还原信号是维持宫颈癌常氧状态下HIF-1α高活性的关键因素。宫颈癌细胞中TLR4与HIF-1α表达呈正相关。本研究选用宫颈癌Siha细胞系，采用体外进行药物和分子干预，分别检测HIF-1α表达、ROS含量、NADPH氧化酶含量以及宫颈癌细胞的生物学行为变化，研究结果发现TLR4 可通过核因子-κB (NF-κB) 信号途径促进宫颈癌的发生和发展，NADPH 氧化酶参与TLR4 维持细胞内HIF-1α 高活性，此过程与NF-κB 信号活化无关，并进一步发现TLR4信号可能通过激活脂筏，刺激NADPH氧化酶的氧化还原信号，产生活性氧来维持宫颈癌细胞HIF-1α高活性。并进一步加以体内实验验证，将不同干预措施处理的宫颈癌细胞接种裸鼠，对比不同组裸鼠实体瘤的大小，得到与细胞水平相似的结果。以上研究结果显示脂筏-NADPH氧化酶在TLR4促进HIF-1α高活性的重要作用，脂筏作为新的药物靶点治疗具有可行性，这为研究宫颈癌的发生发展机制提供新的思路。