Myeloid-Derived Suppressor Cells in the Tumor Microenvironment: Current Knowledge and Future Perspectives
The current knowledge on tumor-infiltrating myeloid-derived suppressor cells (MDSCs) is based mainly on the extensive work performed in murine models. Data obtained for human counterparts are generated on the basis of tumor analysis from patient samples. Both sources of information led to determination of the main suppressive mechanisms used by these cell subsets in tumor-bearing hosts. As a result of the identification of protein targets responsible for MDSCs suppressive activity, different therapeutics agents have been used to eliminate/reduce their adverse effect. In the present work, we review the current knowledge on suppressive mechanisms of MDSCs and therapeutic treatments that interfere with their differentiation, expansion or activity. Based on the accumulation of new evidences supporting their importance for tumor progression and metastasis, the interest in these cell types is increasing. We revise the methods of MDSC generation/differentiation ex vivo that may help in overcoming problems associated with limited numbers of cells available from animals and patients for their study.
KeywordsMyeloid-derived suppressor cells (MDSCs) Immunosuppression Myeloid regulatory cells Tumor progression Metastasis Immunotherapy
This work was partially supported by a crowdfunding project by FECYT (Spain), a CAIXA grant, a BIOEF grant (Government of the Basque Country), a FIS grant (PI14/00579) from the Instituto de Salud Carlos III, and a grant from the Government of Navarre (BMED 033-2014), Spain. We thank SARAY foundation (Navarra, Spain) and Sandra Ibarra foundation (Spain) for their financial support. M. Gato is funded by a PhD fellowship granted by the Government of Navarre. M. Zuazo is funded by a fellowship granted by Universidad Publica de Navarra (UPNA), Spain. M. Ibáñez-Vea is funded by a Sara Borrel Fellowship. D. Escors is funded by a Miguel Servet Fellowship (CP12/03114) awarded by the Instituto de Salud Carlos III (Spain).
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