| Background&ObjectivesOral squamous cell carcinoma(OSCC)is the most common malignant tumor in the head and neck.Conventional treatment includes surgical resection and chemoradiotherapy.In recent years,the rise of immune checkpoint inhibitor therapy has brought new hope for patients with OSCC.However,there was no significant improvement in survival due to the heterogeneity of patients’ response to immune checkpoint drugs.Therefore,it is of great significance for the diagnosis and treatment of oral squamous cell carcinoma to search for more effective molecular markers.CD24 is a newly discovered "don’t eat me" signal,which is overexpressed in a variety of tumors.It has been reported that it is related to the occurrence and development of tumors.Previous study demonstrated that CD24 expressed in tumor cells can interact with inhibitory receptor Siglec-10 on tumor-associated macrophages(TAMs)to achieve the purpose of anti-phagocytosis.However,the role of CD24 in OSCC is poorly understood.This study aims to preliminarily verify the relationship between CD24 expression level and patient prognosis using oral squamous cell carcinoma tissue microarrays,and determine whether blocking CD24 enhances immune response by inhibiting tumor-related macrophages in vivo,providing a potential candidate target for clinical treatment of oral squamous cell carcinoma.Methods56 cases of human oral squamous cell carcinoma and 20 cases of paracancer normal mucosal tissue were obtained by surgical operation to make tissue microarrays.The expressions of CD24 and CD68 were analyzed by immunohistochemical staining.Further,CD24 was inhibited in an allograft squamous cell carcinoma(SCC)related mouse model with CD24mAb to determine the tumor volume and weight.Changes of immune cells including TAMs and T cells in the tumor microenvironment(TME)were analyzed by Flow cytometry.The expressions of CD4 and CD8 were analyzed via immunohistochemical and immunofluorescence staining.The changes of cell proliferation marker Ki67 were detected by immunohistochemical staining.And the inhibition effect of CD24 was confirmed by Western blot and immunohistochemical stainingResults1.The present study confirmed the high expression of CD24 in human oral squamous cell carcinoma by immunohistochemical staining of tissue microarrays(p<0.05).Survival analysis showed that the overall survival time of patients with high CD24 expression was shortened(p<0.05),indicating a poor prognosis in patients with high CD24 expression.The expression of CD24 was not correlated with tumor size,invasion depth and lymph node metastasis stage,suggesting that CD24 played a role throughout the tumor whole development.2.It was confirmed that CD24 was positively correlated with CD68,a marker of TAMs,in human oral squamous cell carcinoma(p<0.05),suggesting a correlation between CD24 and TAMs.3.In vivo CD24 blocking experiments confirmed that the tumor growth was delayed after blocking CD24,indicating that CD24 promotes tumor development in oral squamous cell carcinoma.Flow cytometry of tumor tissue showed that the number of TAMs decreased(p<0.05)and CD4 and CD8 T lymphocytes were up-regulated(p<0.01;p<0.05),suggesting that CD24 affects T lymphocyte infiltration through TAMs.The changes of T cells were again verified by immunohistochemical staining of CD4 and CD8.Immunohistochemical staining of Ki67 showed that blocking CD24 could reduce the proliferation of oral squamous cell carcinoma(p<0.01),suggesting that CD24 promoted the proliferation of oral squamous cell carcinoma.ConclusionsIn summary,CD24 is significantly high expressed in oral squamous cell carcinoma and affects the survival of patients,preliminarily confirming that CD24 is a potential prognostic marker for oral squamous cell carcinoma.Targeting and blocking CD24 in oral squamous cell carcinoma with CD24 monoclonal antibody can enhance the antitumor effect of T lymphocytes by down-regulating TAMs,while weakening the proliferation ability of tumor cells.It provides a theoretical basis for CD24 to be a potential target in the clinical diagnosis and treatment of oral squamous cell carcinoma... |
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