Function Of Flt-1 In Lung Cancer Migration Through BBB

PurposeBrain metastases are a source of significant morbidity and mortality and herald a poor prognosis in patients with lung cancer. Patients with small cell lung cancer (SCLC) have an incidence of brain metastases of 10% at diagnosis and 80% after two years, Metastases occur in complicate and sequential steps that include invasion of cancer cells from the primary site to blood vessels or the lymphatic system, survival in the circulation, intravascular transfer to distant organs, attachment to endothelial cells, extravasation into the parenchyma, and outgrowth into secondary tumor with neovascularization because Sclc have the a-bility to migrate to specific organs, moreover, Studies reported that leukocytes and breast cancer cells migration through the endothelium cell monolayer was associated with TJ disruption. thus the precise molecular mechanism of SCLC cells penetrating the BBB is extremely significant in clinic.Researches indicate that Flt - 1 have effect on angiogenesis binding to VEGF, Vascular endothelial growth factor (VEGF) also called vascular permeability factor (VPF) , expression has been observed in several malignant tumors, including lung cancer. VEGF is a potent angiogenic mediator, and angiogenesis has important effects. Expression of VEGF may therefore be an indicator for the angiogenic potential and biological aggressiveness of a tumor. The known responses of VEGF are mediated through VEGF receptors in endothelial cells. Including : vascular endothelial growth factor receptor - 1 (VEGFR - 1;flt - 1;fms - like tyrosine kinase) , VEGFR - 2 ( flk - 1;KDR;kinase - insert - do-main - containing receptor) , VEGFR - 3 and neuropilin - 1 expressed on endo-thelial cells.Fit -1 is highly similar to other receptors and contains an extracellular domain carrying seven immunoglobulin - like sequences and a cytoplasmic TK domain with a long kinase insert. Fit - 1 is expressed as a full - length tyrosine ki-nase receptor and in some cases as a soluble form, which carries only the extracellular domain. Biochemically, Fit - 1 shows an affinity to VEGF that is at least 10 -fold higher than that of KDR/Flk - 1, but its TK activities;10 -fold weaker than that of KDR/Flk - 1, moreover Fit - 1 also specially binds to PL-GF.Recent studies show that VEGF/flt - 1 signaling pathway is characterized as one of the most important endothelial regulators in tumor invasion and metastasis , so we presume that Fit - 1 should be a mediator in the course of Sclc migration through BBB. the aim of research was to investigate how Fit -1 work on the course that Sclc migrate BBB by the way of establishing a model between Sclc and HBMEC in vitro. Thereafter whether or not we can provide a new theoretical basis to treat brain metastases of small cell lung cancer by impacting on Fit -1.Methods1 Culture of NCI - H209 cells and HBMEC cells2 Transendothelial migration assay of NCI - H209 cells2. 1 Establishment of in vitro model of blood brain barrier;culture and propagation of human brain microvascular endothelial cells ( HBMEC) to form the monolayer cells and tight junctions2. 2 Interaction of NCI - H209 cells and HBMEC cells3 Western Blot assay of the expression of fit - 14 Immunofluorescence assay of the expression of F - actin and ZO - 1Results1 NCI - H209 cells Transendothelial migration is associated with TJ disruption and cytoskeleton rearrangement in HBMECs.2 Fit - 1 plays a important role in NCI - H209 cells transendothelial migration.2. 1 Expression of Fit - 1 in HBMEC increases because time increases in the transendothelial migration of NCI - H209 cells, that is, a time - and dose -dependent increase.2. 2 More Expression of Fit - 1 in HBMEC mainly is caused by PLGF from NCI-H209.2. 3 Inhabition of NCI - H209 cells transendothelial migration by Fit - 1 neutralization antibody.ConclusionThe research find that Fit - 1 receptor participate in NCI - H209 cells migration through the HBMEC, the studies in vitro indicate that Fit - 1 receptor may have relation with Sclc migration through BBB.