Abstract 3980: Ly6G+ neutrophils and polymorphonuclear myeloid derived suppressor cells promote the survival of tumor cells

Abstract

Abstract A heterogeneous group of immature myeloid cells which suppress the immune system are termed myeloid derived suppressor cells (MDSC). Collectively a MDSC population is comprised of monocyte-like MDSC and polymorphonuclear MDSC (PMN-MDSC). MDSC are increased in the presence of a number of different tumors. We previously demonstrated that PMN-MDSC represent the majority of MDSC in tumor-bearing mice. In a mouse model of multiple myeloma (MM) depletion of myeloid cells in vivo results in increased survival. Direct co-culture of neutrophils (CD11b+Gr1+ cells from tumor-free mice) or PMN-MDSC (CD11b+Gr1+ cells from tumor-bearing mice) and MM cells increases the survival of the MM cells from chemotherapeutic-induced death. Cell-cell contact is not necessary for the protective effect. Neutrophil and PMN-MDSC supernatants protect MM cells from cell death, suggesting the factor protecting tumor cells is soluble. Results in the mouse were confirmed using human MM cells and replicated on breast cancer cells with neutrophils or PMN-MDSC. Several cytokines and growth factors, such as IL-6 and fibroblast growth factor, are implicated in chemoresistance. The role of these neutrophil and PMN-MDSC soluble factors and the identification of novel contributors to chemoresistance are under investigation. Citation Format: Sarah Herlihy, Cindy Lin, Maria Ozeriva, Alfred Garfall, Dan Vogl, Dmitry Gabrilovich, Yulia Nefedova. Ly6G+ neutrophils and polymorphonuclear myeloid derived suppressor cells promote the survival of tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3980. doi:10.1158/1538-7445.AM2017-3980