Blockade of adenosine A2A receptor enhances CD8+ T cells response and decreases regulatory T cells in head and neck squamous cell carcinoma

Mol Cancer. 2017 Jun 7;16(1):99. doi: 10.1186/s12943-017-0665-0.


Background: Cancer immunotherapy offers a promising approach in cancer treatment. The adenosine A2A receptor (A2AR) could protect cancerous tissues from immune clearance via inhibiting T cells response. To date, the role of A2AR in head and neck squamous cell carcinoma (HNSCC) has not been investigated. Here, we sought to explore the expression and immunotherapeutic value of A2AR blockade in HNSCC.

Methods: The expression of A2AR was evaluated by immunostaining in 43 normal mucosae, 48 dysplasia and 165 primary HNSCC tissues. The immunotherapeutic value of A2AR blockade was assessed in vivo in genetically defined immunocompetent HNSCC mouse model.

Results: Immunostaining of HNSCC tissue samples revealed that increased expression of A2AR on tumor infiltrating immune cells correlated with advanced pathological grade, larger tumor size and positive lymph node status. Elevated A2AR expression was also detected in recurrent HNSCC and HNSCC tissues with induction chemotherapy. The expression of A2AR was found to be significantly correlated with HIF-1α, CD73, CD8 and Foxp3. Furthermore, the increased population of CD4+Foxp3+ regulatory T cells (Tregs), which partially expressed A2AR, was observed in an immunocompetent mouse model that spontaneously develops HNSCC. Pharmacological blockade of A2AR by SCH58261 delayed the tumor growth in the HNSCC mouse model. Meanwhile, A2AR blockade significantly reduced the population of CD4+ Foxp3+ Tregs and enhanced the anti-tumor response of CD8+ T cells.

Conclusions: These results offer a preclinical proof for the administration of A2AR inhibitor on prophylactic experimental therapy of HNSCC and suggest that A2AR blockade can be a potential novel strategy for HNSCC immunotherapy.

Keywords: Adenosine A2A receptor; Anti-tumor response; Head and neck squamous cell carcinoma; Immunotherapy; Regulatory T cells.

MeSH terms

  • 5'-Nucleotidase / metabolism
  • Adenosine A2 Receptor Antagonists / pharmacology
  • Adult
  • Aged
  • Animals
  • Biomarkers
  • CD8-Positive T-Lymphocytes / immunology*
  • CD8-Positive T-Lymphocytes / metabolism*
  • Carcinoma, Squamous Cell / genetics
  • Carcinoma, Squamous Cell / immunology*
  • Carcinoma, Squamous Cell / metabolism*
  • Carcinoma, Squamous Cell / pathology
  • Cytokines / metabolism
  • Disease Models, Animal
  • Forkhead Transcription Factors / metabolism
  • Gene Expression
  • Head and Neck Neoplasms / genetics
  • Head and Neck Neoplasms / immunology*
  • Head and Neck Neoplasms / metabolism*
  • Head and Neck Neoplasms / pathology
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism
  • Immunohistochemistry
  • Immunomodulation*
  • Induction Chemotherapy
  • Lymphocyte Count
  • Mice
  • Mice, Transgenic
  • Middle Aged
  • Neoplasm Grading
  • Neoplasm Metastasis
  • PTEN Phosphohydrolase / genetics
  • Protein Serine-Threonine Kinases / metabolism
  • Receptor, Adenosine A2A / genetics
  • Receptor, Adenosine A2A / metabolism*
  • Receptor, Transforming Growth Factor-beta Type I
  • Receptors, Transforming Growth Factor beta / metabolism
  • Recurrence
  • Squamous Cell Carcinoma of Head and Neck
  • T-Lymphocytes, Regulatory / immunology*
  • T-Lymphocytes, Regulatory / metabolism*
  • Tumor Burden / drug effects
  • Xenograft Model Antitumor Assays


  • Adenosine A2 Receptor Antagonists
  • Biomarkers
  • Cytokines
  • FOXP3 protein, human
  • Forkhead Transcription Factors
  • HIF1A protein, human
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Receptor, Adenosine A2A
  • Receptors, Transforming Growth Factor beta
  • Protein Serine-Threonine Kinases
  • Receptor, Transforming Growth Factor-beta Type I
  • 5'-Nucleotidase
  • PTEN Phosphohydrolase