Abstract
Abstract The major challenges for breast cancer includes therapy resistance and metastasis to distant organs. Chronic inflammation has been intimately linked with these processes. We have observed increased level of CXCR2 ligands, inflammatory immunosuppressive microenvironment, and increased metastasis in chemotherapy resistant cells. CXCR2 and its ligands have been shown to be the primary mechanism for neutrophils recruitment to the sites of primary tumors and metastases. However, their precise roles in therapy resistance and metastasis remains unclear. The aim of this project is to investigate the role of neutrophils in chemotherapy resistance and metastasis in breast cancer. In this report, we investigated the mechanisms and putative role of neutrophils in chemotherapy resistance and metastasis. We evaluated the expression level of the factors critical for neutrophil recruitments, such as interleukin (IL)-17 and its receptors (IL-17R), granulocyte colony stimulating factor (GCSF), CXCR2 and its ligands in primary tumors and metastases established from parents and chemotherapy resistant cells. The frequency of neutrophils and T-helper 17 (Th17) cells were analyzed using immunohistochemistry. Chemotherapy-resistant cell lines express higher levels of GCSF, IL-17, and IL-17R compared to Cl66 parent cells. We observed higher expression of IL-17R, CXCR2, and CXCR2 ligands in metastatic lesions compared to primary tumors. Furthermore, there were more recruitments of neutrophils and Th17 cells in resistant tumors than parent tumors. In addition, treatment of tumor cells with IL-17 significantly increased cellular proliferation together with CXCL1 and CXCL5 expression in a concentration-dependent manner. Moreover, we observed higher expression of TGFβ 2 and Th17 cell priming factors, IL-6 and IL-23, in neutrophils co-cultured with therapy resistant cells compared to the control suggesting a feed forward loop. In addition, we observed that IL17 treatment of tumor cells did not increase their tolerance to chemotherapy drug, indicating its role in establishing immune suppressive microenvironments. Together our data demonstrate an IL17-CXCR2 ligands axis induces protumorigenic inflammation, facilitating therapy resistance and metastasis through recruited neutrophils. Citation Format: Lingyun Wu, Bhawna Sharma, Rakesh K. Singh. Role of IL-17-CXCR2 axis in neutrophil recruitment facilitating breast cancer metastasis and therapy resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 132.
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