| Head and neck squamous cell carcinoma(HNSCC)was defined as a kind of immunosuppressive disease,being infiltrated with a rather large amount of immunosuppressive cells,including myeloid-derived suppressor cells(MDSCs),tumor-associated macrophages(TAMs),regulatory T cells(Tregs),and exhausted T cells.This special immunosuppressive microenvironment protected the tumor cells from recognition and elimination by immune system,promoting the progression and metastasis of cancer cells.Hence,the discovery of effective immunotherapeutic target of HNSCC is urgently needed.Cancer immunotherapy has been listed as one of top ten scientific breakthroughs of the year in 2013.The immune checkpoint based immunotherapies,such as anti-CTLA-4 or anti-PD-1,exerted inspiring anti-tumor effects in many cancers.However,cancer cells take advantage of multiple and unexpected mechanism to suppress the anti-tumor effects of the immune system.On of such mechanism is hypoxia-adenosinergic pathway.The hypoxic status elevates the expression of adenosine generator CD39 and CD73 on both tumor cells and tumors infiltrated immune cells,causing the excessive accumulation of extracellular adenosine within the tumor microenvironment.As a consequence,extracellular adenosine weakens the recruitment,expansion and anti-tumor effects of the effector T cells and enhances the expansion and immunosuppressive functions of immunosuppressive cells through the adenosine receptors A2AR and A2BR.On the basis of these,targeting hypoxia-adenosinergic pathway is probably a promising immunotherapeutic target in many cancers including HNSCC.Part IBlockade of CD73 enhances the anti-tumor effect of T cells in head and neck squamous cell carcinomaObjective:This part was aimed to investigate the expression of the adenosine generator CD73 in human head and neck squamous cell carcinoma(HNSCC)tissues and the immunosuppressive function of CD73 in immunocompetent genetically modified HNSCC mouse model.Methods:Immunohistochemical staining analysis was used to evaluate the expression level of CD73 in human HNSCC tissues.In-vivo treatment of specific monoclonal antibody(mAb)of CD73 in Tgfbrl/Pten conditional knockout mice was used to assess the anti-tumor effect of CD73 blockade.Flow cytometry was used to quantify the population of CD4+ and CD8+ T cells,and the expression of CD73,CTLA-4 and PD-1 on their surface.The expression of CTLA-4 and LAG-3 on regulatory cells(Tregs)was also detected by Flow cytometry.Results:The expression of CD73 was up-regulated in the stroma of human HNSCC tissues(P<0.05).Meanwhile,CD73 expression was a prognostic factor for poor outcome in our cohort(P<0.05).Further,immune profiling analysis showed the expression of CD73 on CD4+ and CD8+ T cells was associated with "exhausted"phenotype in immunocompetent transgenic HNSCC mouse model.Study with CD73 specific antibody significantly blunted the tumor growth(P<0.001).And the blockade of CD73 altered the "exhausted" phenotype of CD4+ and CD8+ T cells through down regulating total expression of PD-1 and CTLA-4 on T cells.Whereas the population of CD4+ CD73hi/CD8+ CD73hi T cells expressed higher CTLA-4 and PD-1 than untreated counterpart.Moreover,anti-CD73 mAb treatment down-regulated the expression of LAG-3 on regulatory T cells(Tregs)to enhance anti-tumor immunity.Conclusion:This part highlighted the immunoregulatory role of CD73 in the development of HNSCC and proposed that CD73 may be a promising immunotherapeutic approach for the treatment of HNSCC.Part ?Blockade of A2AR enhances the anti-tumor effect in head and neck squamous cell carcinomaObjective:This chapter was aimed to explore the expression of A2AR in primary human HNSCC,recurrence HNSCC,and HNSCC with inductive TPF chemotherapies.Additionally,in this part,we aimed to discover the immunosuppressive function of A2AR in HNSCC and the mechanism of the anti-tumor effect of A2AR blockade.Methods:Immunohistochemical staining analysis was used to detect the expression level of A2AR in HNSCC.Pearson correlation analysis was used to determine the correlation among A2AR,HIF-1?,CD73,Foxp3 and CD8.Treatment of specific antagonist of A2AR in Tgfbrl/Pten conditional knockout mice was used to evaluate the anti-tumor effect of A2AR blockade.The anti-tumor effects was detected by flow cytometry.Results:Immunostaining of HNSCC tissue samples revealed that increased expression of A2AR on tumor infiltrating immune cells(P<0.001)correlated with advanced pathological grade(P<0.001),larger tumor size(P<0.01),positive lymph node metastasis status(P<0.001)and unfavorable prognosis(P<0.05).Elevated A2AR expression was also detected in recurrent HNSCC(P<0.05)and HNSCC tissues with induction chemotherapy(P<0.05).The expression of A2AR was found to be significantly correlated with HIF-1 a(P<0.001,r=0.4364),CD73(P<0.001,r=0.2433),CD8(P<0.05,r=-0.1894)and Foxp3(P<0.05,r=0.1918).Furthermore,the increased population of CD4+ Foxp3+ regulatory T cells(Tregs),which partially expressed A2AR,was observed in an immune sufficient mouse model that spontaneously develops HNSCC.Pharmacological blockade of A2AR by SCH58261 delayed the tumor growth in the HNSCC mouse model(P<0.001).Meanwhile,A2AR blockade significantly reduced the population of CD4+ Foxp3+ Tregs and enhanced the anti-tumor response of CD8+ T cells.Conclusion:These results offered a preclinical proof for the administration of A2AR inhibitor on experimental therapy of HNSCC,suggesting that A2AR blockade is a potential novel strategy for HNSCC immunotherapy. |
PDF Full Text Request