| Objectives:This article mainly explores the mechanism of FGL1 regulating EMT and metastasis in NSCLC,which is expected to provide scientific evidence for screening potential clinical biomarkers in evaluation of early metastasis risk and therapeutic response in NSCLC.Method:(1)Public database analysis:Analyze the relationship between FGL1 expression level and DFS and OS in NSCLC patients.(2)Clinical specimen verification:Ten patients diagnosed with NSCLC who received standardized first-line therapy were enrolled in this present study.Peripheral blood samples were collected dynamically at the 0,2,4,and 6 cycles of treatment.A total of 40 samples were collected.Preliminary analysis of the relationship between FGL1~+CTC and therapeutic response.(3)Tumor cell line biological behavior verification:Analyze the relationship between FGL1 expression and epithelial mesenchymal phenotype.(4)Research on the experimental mechanism of cell lines:Si RNA was used to knockdown the FGL1 gene in NSCLC cell lines,explore the role of FGL1 in mediating EMT in NSCLC cells.NSCLC cells were stimulated with IL-6 for 24H.Western Blot was used to detect FGL1 up-regulation and the EMT phenotype changes of NSCLC cells after IL-6 treatment.NSCLC cells were treated with STAT3 inhibitor Stattic for 2H,and the changes of FGL1expression level and EMT marker expression were compared,and to clarify the molecular mechanism by which IL-6 regulated FGL1 expression and mediated lung cancer cell metastasis.Results:(1)TCGA and STARBASE database analysis indicated the expression level of FGL1 was correlated with tumor stage(P=0.0312),and was correlated with the patient’s DFS(HR=1.4,P=0.0073).(2)The dynamic changes of FGL1~+CTC might be related to the therapeutic response in NSCLC patients.(3)Western Blot and Transwell showed that in four different lung adenocarcinoma cell lines,the expression level of FGL1 was consistent with the change trend of interstitial markers and migration abilities.(4)After knocking down the FGL1gene,cells EMT phenotype reversed and migration abilities decreased,and the clone formation abilities decreased as well(P<0.05),which indicated that FGL1 mediated the EMT process in NSCLC cells.(5)After treatment with IL-6 in H1299 and H1975,the expression of FGL1increased and EMT Promoted,indicating that IL-6 could up-regulating FGL1 and promote EMT process in NSCLC cells.(6)IL-6 regulated FGL1 expression may be related to the activation of STAT3 and AKT signaling pathways.(7)Stattic could inhibit the expression of FGL1 regulated by IL-6 and inhibited the occurrence of EMT in H1299 and H1975 cells,which indicated that IL-6 mediated the development of EMT in NSCLC cells by up-regulating STAT3 expression and its pathway activation in regulation of FGL1 expression.Conclusion:(1).The expression level of FGL1 is associated with the stage and prognosis in non-small cell lung cancer patients based on public databases analysis.(2).The expression level of FGL1 is correlated with the epithelial mesenchymal phenotype in non-small cell lung cancer cells.(3).FGL1 mediates the EMT process in non-small cell lung cancer cells.(4).IL-6 up-regulates the expression of FGL1 in non-small cell lung cancer cells and promotes the process of EMT.(5).IL-6 up-regulates the expression of FGL1 by activating the STAT3 pathway,thereby enhancing the migration ability of non-small cell lung cancer cells. |
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