ObjectiveTo study the relationship between hypoxia and the hypoxia inducible factor-1α (HIF-1α) from lung cancer cells,to reveal the possible mechanism of brain metastases of lung cancer. MethodsThe hypoxia model of A549 lung cancer cells was established. After hypoxia culture of A549 cells for 0.5,2,4,8,12 and 24 h (normal oxygen culture at the same time point was set as the control group),the mass concentration of HIF-1α in A549 lung cancer cell culture medium were determined by ELISA. Transwell chamber was used to construct anin vitroblood brain barrier model,was treated with A549 lung cancer cell culture medium after different time points of hypoxia,Tran endothelial resistance (TER) change of blood-brain barrier model in instrument,to reflect the changes of blood-brain barrier permeabilityin vitro; A549 lung cancer cells in the culture medium were counted under Transwell room. A549 lung cancer cells with hypoxia at different time points injected into Wistar rats via tail vein,Western blot method was used to menstruate expression of tight junction associated protein Claudin-5 in the brain tissues,Evans blue to detect the change of blood brain barrier permeability in rats. ResultsCompared with the control group,the HIF-1α mass concentration in the cell culture solution of A549 increased,thein vitroblood-brain barrier model TER decreased,and the cell number of A549 that passed through transwell into the lower chamber increased (allPPin vivoexperiment of rats,compared with the control group,the mass percent of Evans blue in rat brain tissues increased after A549 cell culture solution with hypoxia 2 h was injected via caudal vein,meaning increased the permeability of rat blood brain barrier,while the expression of Claudin-5 protein in rat brain tissues decreased (allPP
