Human Cancer Biology Increased Ectonucleotidase Expression and Activity in Regulatory T Cells of Patients with Head and Neck Cancer

Purpose: Regulatory T cell (Treg) frequency and activity are increased in cancer patients and play a major role in tumor escape. Although disease progression is favored by the presence of Treg, mechanisms used by Treg to suppress antitumor immunity are unknown. The ectonucleotidases CD39 and CD73 are expressed in Treg and convert ATP into immunosuppressive adenosine. In this study, the involvement of the adenosinergic pathway in Treg-mediated suppression in head and neck squamous cell carcinoma (HNSCC) patients was evaluated. Experimental Design: HNSCC patients with an active disease (n = 19) and patients with no evident disease after therapy (n = 14) were studied. Ectonucleotidase expression on CD4 T cells andCD4CD25Tregwasevaluatedby flowcytometryandcomparedwithnormal controls. Ectonucleotidase activity was also compared within these three groups. The data were analyzed for associations of ectonucleotidase expression/function with disease stage. Results: The percentages and expression levels of CD39 and CD73 in CD4 T cells and Treg were greater in HNSCC than in normal controls and highest in patients with no evident disease. Patients' Treg hydrolyzed ATP at higher rates and produced higher levels of adenosine than normal controls' Treg. The increased frequency and enzymatic activity of CD4CD39 cells corresponded to increased adenosine-mediated suppression of effector T cells, which was partly inhibited by ARL67156, an ectonucleotidase inhibitor, and by ZM241385, a selective A2a/A2b receptor antagonist. Conclusions: CD39 Treg frequency and adenosine-mediated suppression are significantly increased in HNSCC patients. The adenosinergic pathway is involved in Treg-mediated immunosuppression in cancer and its attenuation could be a promising immunotherapeutic strategy for patients with HNSCC. (Clin Cancer Res 2009;15(20):6348–57) Head and neck squamous cell carcinoma (HNSCC), arising from the mucosal epithelium, is the fifth most common type of cancer worldwide and the sixth most common cause of cancerrelated mortality (1, 2). Although advances in surgical methods, chemotherapy, and radiation have improved patients' treatment and quality of life, the overall outcome and survival rate among patients with this disease have not notably improved (3). Therefore, novel therapeutic strategies are necessary for the treatment of HNSCC. Recent studies have focused on the dynamic interplay and coevolution of antitumor immune responses and tumor progression in HNSCC (4, 5). These studies have shown that T lymphocytes play a major albeit contradictory role in local tumor expansion, metastasis, and neoangiogenesis. In most human cancers, regulatory T cells (Treg), a small subset of CD4 T cells, are significantly increased in the peripheral blood as well as in the tumor microenvironment (6–8). Treg are phenotypically defined as CD4 CD25FOXP3 and modulate immune responses by suppressing functions of other T cells. To date, at least two types of Treg are known to exist in man: (a) naturally occurring Treg, which develop in the thymus and are responsible for maintaining peripheral tolerance using cell contact–dependent or cell contact–independent suppression (9, 10), and (b) inducible Treg (Tr1), which arise in the periphery on antigen exposure and Authors' Affiliations: University of Pittsburgh Cancer Institute and Depart‐ ments of Pathology, Pharmacology, Otolaryngology, and Biostatistics, University of Pittsburgh, Pittsburgh, Pennsylvania and Department of Otorhinolaryngology, University of Duisburg-Essen, Essen, Germany Received 5/5/09; revised 6/25/09; accepted 6/26/09; published OnlineFirst 10/13/09. Grant support: NIH grant PO1 CA109688 (T.L. Whiteside) and Department of Defense award BCO51720 (E. Gorelik); Harry Lloyd Charitable Trust and Hillman Foundation (E. Gorelik), National Heart, Lung, and Blood Institute contract HB-37-165 (M. Szajnik), and Philip Morris International and IFORES Program (M. Mandapathil). The costs of publication of this articlewere defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Note: Supplementary data for this article are available at Clinical Cancer Research Online (http://clincancerres.aacrjournals.org/). Requests for reprints: Theresa L. Whiteside, University of Pittsburgh Cancer Institute, Research Pavilion at the Hillman Cancer Center, 5117 Centre Avenue, Suite 1.27, Pittsburgh, PA 15213-1863. Phone: 412-624-0096; Fax: 412-624-0264; E-mail: [email protected]. F 2009 American Association for Cancer Research. doi:10.1158/1078-0432.CCR-09-1143 6348 Clin Cancer Res 2009;15(20) October 15, 2009 www.aacrjournals.org Published Online First on October 13, 2009 as 10.1158/1078-0432.CCR-09-1143 Research. on July 14, 2017. © 2009 American Association for Cancer clincancerres.aacrjournals.org Downloaded from Published OnlineFirst October 13, 2009; DOI: 10.1158/1078-0432.CCR-09-1143