Abstract 1495: Lipocalin-2 promotes breast cancer metastasis via tumor cell intrinsic and extrinsic mechanisms

Abstract While metastasis is the primary factor predicting poor outcomes in solid tumors, survival is lowest in patients initially diagnosed with a localized malignancy that then progresses to metastatic disease. Notably, nearly 25% of early-stage breast cancers (BCs) metastasize during treatment or following an initial positive response to therapeutic intervention. To define the molecular and cellular factors that contribute to metastatic progression of BC, we previously developed the Py230-C57Bl/6 syngeneic experimental metastasis model for interrogating mechanisms by which soluble factors condition premetastatic lung tissue to potentiate BC cell seeding/expansion. Using this model and the TCGA, we identified lipocalin-2 (Lcn2) as a molecular candidate that is upregulated in lung-tropic Py230 cells and other human triple-negative breast cancer (TNBC) cells, and that predicts poor outcomes in human BCs. While Lcn2 has been previously reported to mediate BC progression in genetically engineered mouse models, its mechanism(s) of action remain undefined. Here, we demonstrate that Py230 cell-secreted Lcn2 is necessary for optimal reprogramming of the premetastatic lung during metastatic progression. In agreement with these data, we defined a cell intrinsic role for Lcn2 in BC cell organoid assembly/invasion and expression of proinflammatory factors. To define BC cell extrinsic roles for Lcn2 in remodeling the premetastatic lung, we collected global transcriptome and single-cell spatial proteome data for lung tissue from C57Bl/6 mice systemically educated with mock media or media conditioned with Py8119 (Lcn2low) or Py230 (Lcn2hi) BC cells. Mice receiving Py230 conditioned media treatments were further divided between two groups – one receiving an isotype control IgG and the other receiving an Lcn2 immunoneutralizing antibody. Global transcriptome data was used to determine novel gene set enrichment signatures and clinically relevant interactomes – notable candidates predicted to cooperate with Lcn2 in decreasing patient survival were affiliated with cilia biogenesis and function. Single-cell spatial proteome data were analyzed for 28 different cell populations within the premetastatic lung. Interestingly, Py230 cell-derived Lcn2 did not affect the percentage of ciliated epithelial cells indicating that the global transcriptome data referenced above represent a real increase in expression of cilia-related genes and not an increase in cilia-positive cell types. Notably, we identified that Lcn2 increased the percentage of CD45neg/Despos mechanomodulatory cells and proliferating CD45pos/CD3pos/CD4neg/CD8pos cytotoxic T cells in the premetastatic lung. Taken together, these data define new targets around which new therapeutic strategies can be developed to improve BC patient outcomes. Citation Format: Joshua Gamez, Francesca Sanchez, Gabriela Ortiz-Soto, Jane Cox, Amir Gerami, Jonathan A. Kelber. Lipocalin-2 promotes breast cancer metastasis via tumor cell intrinsic and extrinsic mechanisms [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1495.