Downregulation Of FOXP3 In Neutrophils By IL-8 Promotes The Progression Of Oral Squamous Cell Carcinoma

Purposes: Numerous studies have confirmed that FOXP3(forkhead box P3)is expressed in various tumor cells,and FOXP3 expressed in different tumor cells plays a different role in tumor progression.Neutrophils,as common immune cells in the tumor microenvironment,play different roles in tumor progression.Whether FOXP3 is expressed in neutrophils and whether its expression plays a role in tumor growth has not been reported so far.The aim of this study was to investigate the effects of the transcription factor FOXP3 in neutrophils on the progression of oral squamous cell carcinoma(OSCC).Methods: 1.SCC-9,a human tongue carcinoma cell line,was cocultured with neutrophils in 96-well plates and treated with human recombinant interleukin-8(IL-8).After 24 hours,the proliferation of SCC-9 cells was measured using the Cell Counting Kit 8(CCK-8)assay.2.Neutrophils were treated with IL-8.After 12 hours,the expression of FOXP3 mRNA in neutrophils was analyzed by real-time quantitative PCR(RT-qPCR).3.SCC-9cells were cocultured with neutrophils in 96-well plates and the FOXP3 protein were inhibited with P60(an inhibitor of FOXP3).After 24 hours,theproliferation of SCC-9 cells was determined using the CCK-8 assay.4.Immunofluorescence was used to detect the expression of FOXP3 protein in neutrophils in the OSCC cancer tissues and the relationship between the expression of FOXP3 protein in neutrophils and the clinical stage of OSCC patients was analyzed.5.Immunofluorescence was used to detect the expression of IL-8 protein in the OSCC cancer tissues.Results: 1.Neutrophils and IL-8 promoted the proliferation of SCC-9 cells.2.IL-8 downregulated the expression of FOXP3 mRNA in neutrophils.3.Neutrophils promoted SCC-9 cell proliferation after FOXP3 protein was inhibited by P60(an inhibitor of FOXP3).4.In patients with OSCC,the expression of FOXP3 protein in neutrophils of the stage ? group was significantly lower as compared with the stage ? group(P = 0.001)and the stage ? group(P = 0.008).5.The expression of IL-8 protein was higher in cancer tissues than in paracarcinoma tissues.Conclusion: IL-8,in the tumor microenvironment,may recruit neutrophils,and downregulation of FOXP3 in neutrophils by IL-8 may promote the progression of OSCC.