Abstract LB-129: Metastatic breast cancer cells promote anti-inflammatory MSC actions and release Lipocalin 2 to induce a tumor-supportive premetastatic lung microenvironment
Authors: Sanchez Francesca , Meade Kayla , Aguayo Analine , Nadeles Nathalie , Hamalian Sarkis , Uhlendorf Toni , Banner Lisa , Kelber Jonathan A. 
Published: August 2019

Abstract
Cancer metastasis is responsible for the vast majority of cancer-related deaths. Survival and proliferation of cancer cells within distant tissues requires that these foreign microenvironments acquire tumor-supportive characteristics. While it has been established that primary tumor cells can reprogram the molecular and cellular composition of the premetastatic niche by releasing soluble factors and extracellular vesicles, efforts to date have been limited by the use of in vivo models lacking a fully-functional immune system and/or the need for finely-tuned experiment end points to limit direct reprogramming effects of early-disseminating cells from the primary tumor. To address this need, we developed the immune-competent PyMT syngeneic murine model of breast cancer for elucidating events during premetastatic niche reprogramming in the absence of tumor cell allografting. We demonstrate that metastatic mouse PyMT breast cancer cells differentially influence the premetastatic lung and brain, selectively promoting a tumor-supportive lung microenvironment with increased CD73 expression and decreased TNFalpha expression. Using in vitro models of CD73-positive mesenchymal stem cells (MSCs) and monocytes/macrophages, we next tested whether MSCs can selectively mediate anti-inflammatory effects of metastatic breast cancer cells. Notably, conditioned media from metastatic Py230 cells reprogrammed MSCs to selectively increase anti-inflammatory CCL1 and MRC1 transcripts in monocytes/macrophages. In contrast, conditioned media from non-metastatic Py8119 cells reprogrammed MSCs to selectively increase pro-inflammatory IL23alpha and TNFalpha in monocytes/macrophages. Mining transcriptome data from Py8119 and Py230 cells revealed a lipocalin 2 (LCN2) axis that is selectively expressed in the metastatic Py230 cells and predicts poor breast cancer patient survival. Finally, we demonstrate that immunoneutralization of LCN2 in Py230 conditioned media renders it unable to reprogram the premetastatic lung microenvironment toward a tumor-supportive state. Taken together, these results establish the utility of a tumor cell-free in vivo model for interrogating breast cancer priming of the premetastatic niche, demonstrate that MSCs can mediate the anti-inflammatory state within the tumor microenvironment, and identify LCN2 as an important therapeutic target for blocking breast cancer progression.
Citation Format: Francesca Sanchez, Kayla Meade, Analine Aguayo, Nathalie Nadeles, Sarkis Hamalian, Toni Uhlendorf, Lisa Banner, Jonathan A. Kelber. Metastatic breast cancer cells promote anti-inflammatory MSC actions and release Lipocalin 2 to induce a tumor-supportive premetastatic lung microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-129.