Effect of usnic acid on malignant behavior of gastric cancer cells investigated based on CCL2-CCR2 signal axis
Objective:To investigate impacts of usnic acid(UA)on malignant behavior of gastric cancer cells by regulating the chemokine(C-C motif)ligand 2(CCL2)-CCL2 receptor(CCR2)signal axis.Methods:SGC-7901 cells,a well growing human gastric cancer cell line,were treated with different concentrations of UA,which were grouped into low concentration(UA-L)group(62.5 μmol/L UA),medium concentration(UA-M)group(125 μmol/L UA)and high concentration(UA-H)group(250 μmol/L UA);meantime,the cells were transfected with CCL2 overexpression vector(pc DNA3.1 CCL2),empty vector(pc DNA3.1),silenced CCL2(si CCL2)and negative control(si control),and SGC-7901 cells were treated with 250 μmol/L UA,labeled as UA-H+pc DNA3.1 CCL2 group,UA-H+pc DNA3.1 group,UA-H+si control group and UA-H+si CCL2 group,another untreated SGC-7901 cells were taken as the control group.Flow cytometry,MTT and qRT-PCR were applied to detect cell apoptosis,proliferation,and expres-sion levels of CCL2 and CCR2 mRNA;Western blot was applied to detect expression levels of PD-L1,apoptotic protein(Bax),proli-ferative protein(CyclinD1,CCL2,CCR2)and immune escape related protein(B7H1);after co-culturing with CD8+T cells isolated and cultured in vitro,ELISA was applied to detect levels of IL-4,IFN-γ and IL-10 in the supernatant.Gastric cancer cells in each group were co-cultured with activated peripheral blood mononuclear cell(PBMC)1∶1 for 72 hours,and the sensitivity of gastric can-cer cells in each group to T-cell-mediated killing was compared.Results:Compared with control group,cell proliferation rate,IL-10 level,CyclinD1,PD-L1,CCL2,CCR2 and B7H1 protein and mRNA expressions,cell counts after co-culturing with activated PBMC 1∶1 for 72 hours in UA-L group,UA-M group and UA-H group were obviously reduced,while apoptosis rate,IL-4 and IFN-γ levels,Bax protein expression were obviously increased(P<0.05);compared with UA-H+pc DNA3.1 group,cell proliferation rate,IL-10 level,CyclinD1,PD-L1,CCL2,CCR2 protein and mRNA expressions,cell counts after co-culturing with activated PBMC 1∶1 for 72 hours in UA-H+pc DNA3.1 CCL2 group were obviously increased,while apoptosis rate,IL-4 and IFN-γ levels,and Bax protein ex-pression were obviously reduced(P<0.05);compared with UA-H+si control group,cell proliferation rate,IL-10 level,CyclinD1,PD-L1,CCL2,CCR2 and B7H1 protein and mRNA expressions,cell counts after co-culturing with activated PBMC 1∶1 for 72 hours in UA-H+si CCL2 group were obviously reduced,while apoptosis rate,IL-4 and IFN-γ levels and Bax protein expression were obviously increased(P<0.05).Conclusion:UA can inhibit gastric cancer cells proliferation,immune escape,and induce apoptosis,which may be related to the inhibition of the CCL2-CCR2 signaling axis.
Usnic acidCCL2-CCR2 signal axisGastric cancer cellsProliferationApoptosisImmune escape
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