Volume 2 Supplement 3
ONO-AE3-208 inhibits myeloid derived suppressor cells and glioma growth
© Kohanbash et al.; licensee BioMed Central Ltd. 2014
Published: 6 November 2014
Myeloid Derived Suppressor Cells (MDSCs) heavily infiltrate in a variety of solid tumors and suppress anti-tumor T-cell activity. Our recent studies have demonstrated the ability of monocytic, Ly6C+ MDSCs to promote glioma growth through the activation of cyclooxygenase (COX)-2 pathway, which is responsible for prostaglandin-synthesis. ONO-AE3-208 is an antagonist of the prostaglandin E (EP)-4 receptor, which is an important positive feedback regulator of the COX-2 pathway. We thus examined the ability of ONO-AE3-208 to suppress MDSC activity in gliomas. ONO-AE3-208 treatment in mice bearing established GL261-quad glioma in the brain resulted in complete and persistent rejection of the tumors. Flow cytometric analysis revealed that gliomas in the ONO-AE3-208-treated mice were infiltrated by fewer numbers of Ly6C+ MDSCs compared with non-treated animals. We subsequently isolated glioma-infiltrating Ly6C+ MDSCs by flow-sorting to address their functions. RT-PCR analysis revealed that the Ly6C+ MDSCs derived from ONO-AE3-208 treated mice expressed lower levels of the Arg1 and Cox2 expression compared to control animals. Consistently, brain infiltrating leukocytes in ONO-AE3-208 treated tumor-bearing mice demonstrated enhanced IFN-g expression compared with control mice, suggestive of enhanced T-cell activity. Importantly, ONO-AE3-208 inhibited glioma growth and promoted immune activity in 2 additional murine glioma models: the Sleeping Beauty de novo glioma model and the SB28 glioma cell line model. Our data demonstrate that ONO-AE3-208 may be useful in the treatment of glioma patients to suppress Ly6C+ MDSCs and promote anti-tumor immunity.
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.