The Effect And Mechanism Of CXCL7/CXCR2 Axis On The Occurrence And Development Of Lung Cancer

Objective:In the process of tumor evolution,the interaction between tumor cells and immune cells has attracted much attention.Tumor-associated macrophages,which are abundant in lung cancer,have become a new target for the study of tumorigenesis,development and treatment.The signal axis formed by ELR+chemokines and CXCR2(CXCLs-CXCR axis),as an important mediator of the interaction between tumor cells and surrounding stromal cells,plays an important role in the early diagnosis,development,invasion and metastasis,treatment,and drug resistance of lung cancer.Our previous study found that PGE2 can induce the activation of macrophages to highly express CXCL7.This study clarified the effect of the CXCL7/CXCR2 axis on the proliferation,invasion and migration of lung cancer cells and the possible mechanism through the bidirectional regulation of the expression of the receptor CXCR2 in lung cancer cell lines..And by detecting the expression level of CXCL7 in lung cancer tissue specimens,the relationship between CXCL7 and adverse clinicopathological factors in lung cancer was clarified.Methods:(1)Using cytokine chip to screen the cytokine differentially secreted by macrophages Raw264.7 after PGE2 stimulation,and confirm CXCL7 as the research factor.(2)Western blotting(WB)was used to detect the expression of CXCL7 receptor CXCR2 on six lung cancer cells:A549,H2122,H226,SK-MES-1,XLA-07 and XLA-JT.(3)The CCK8 experiment detects the effect of CXCL7 on the proliferation of lung cancer cells with different expression levels of CXCR2;the cell scratch test and the Transwell experiment are used to evaluate the changes of CXCL7 on the invasion and migration ability of lung cancer cells with different expression levels of CXCR2.(4)WB detects the expression differences of COX2 and EMT-related proteins,AKT and p-AKT in lung cancer cells after CXCL7 stimulation;(5)Select lung cancer cell lines with high expression of CXCR2 and low expression of CXCR2,and use lentivirus transfection cell technology to construct respectively The CXCR2 interference stable transgenic strain and the CXCR2 overexpression stable transfected strain were verified by fluorescence quantitative PCR and WB to verify the transfection efficiency;CCK8 experiment,cell scratch test and Trans well experiment further verified the changes in the proliferation,invasion and migration functions of the stable transfected strain under the stimulation of CXCL7;(6)Detect the expression level of CXCL7 in lung cancer tissue specimens,and analyze the relationship between CXCL7 and adverse clinicopathological factors in lung cancer.Results:(1).PGE2 induces the high expression of chemokine CXCL7 in macrophages Raw264.7:Gene chip results show that there are 6 cytokines whose expression of macrophages Raw264.7 is up-regulated(≥1.5 times)after PGE2 stimulation;the expression is down-regulated(≤0.67)Fold)there are 12 cytokines.Among them,the expression of chemokine CXCL7 is significantly up-regulated,so it was selected as a research factor to explore its influence on the biological function of lung cancer and its possible mechanism.(2).How high is CXCL7 expressed in lung cancer,and it is related to adverse clinicopathological factors.The immunohistochemical results of 75 lung cancer tissue specimens showed that CXCL7 was mostly positively expressed in lung adenocarcinoma(73.68%)and lung squamous cell carcinoma(70.59%);and the expression of CXCL7 was related to the TNM staging of lung cancer patients and lymph node metastasis It is positively correlated with distant metastasis.(3).The six non-small cell lung cancer cell lines all have CXCR2 protein expression.Among them,A549,H2122,SK-MES-1 and XLA-JT cells highly expressed CXCR2,while XLA-07 and H226 expressed low CXCR2.(4).The CXCL7/CXCR2 axis can promote the invasion and migration of lung cancer cells without promoting proliferation:CCK8 results show that the proliferation ability of A549 cells with high expression of CXCR2 and XLA-07 cells with low expression of CXCR2 have no significant changes under the action of various concentrations of CXCL7;Cell scratch test and Transwell test results show that CXCL7 can promote the invasion and migration of CXCR2 high-expressing cell A549,but has no obvious effect on CXCR2 low-expressing cell XLA-07.Consistent results were observed in A549 and XLA-07 cells that bidirectionally regulate CXCR2 expression.(5).The CXCL7/CXCR2 axis promotes the expression of COX2 in lung cancer cells and induces the occurrence of EMT to promote the invasion and migration of lung cancer cells:Western blot experiments show that CXCL7 can regulate the expression of EMT-related proteins E-Cad and N-Cad to promote high-expressing CXCR2 cells Invasion and migration of A549,but no obvious promotion effect on XLA-07 cells with low expression of CXCR2.(6).The CXCL7/CXCR2 axis affects the invasion and migration of lung cancer cells by promoting the AKT pathway:A549 lung cancer cells with high expression of CXCR2 significantly increase the expression of p-AKT under the action of CXCL7,while the expression of p-AKT in XLA-07 lung cancer cells with low expression of CXCR2 is not See obvious changes.Conclusion(s):PGE2 secreted by tumor cells can stimulate macrophages to highly express chemokine CXCL7;CXCL7/CXCR2 axis feeds back to promote lung cancer progression,but it has no obvious relationship with its proliferation;and it may induce the EMT process of lung cancer cells by activating the AKT pathway,thereby promoting the development of lung cancer cells.Invasion and migration.