Abstract 7: Modeling cell-cell crosstalk in TNBC brain metastasis

Abstract

Abstract Brain metastasis (BrM) is a difficult clinical problem in triple-negative breast cancer (TNBC) patients: it occurs in 25% to 40% of metastatic patients while two-year survival rate stubbornly remains a single digit. TNBC usually spreads to the brain rapidly at earlier stages or before the diagnosis of primary cancer. The shorter development time of BrM in TNBC and shorter survival time after BrM diagnosis may indicate a unique innate ability of TNBC tumor cells in adapting to the brain. Indeed, emerging data including ours indicates that TNBC tumor cells have intrinsic brain-like traits resulting in brain-tropism metastasis. Our preliminary studies identified enriched and diverse expressions of receptors and transporters of various neuro-active substances in brain metastatic TNBC cells, including neurotransmitters, gliotransmitters, neurotrophic factors and neural cytokines. By immunopanning astrocytes and microglia/macrophages from mouse brains bearing TNBC brain metastatic tumors at day 3 post tumor cell injection through left cardiac ventricle, and use the CCCExplorer software in modeling the interactions among tumor cells, astrocytes, and microglia/macrophage with cell-type specific RNAseq data, we identified several novel crosstalk signaling, including tumor autocrine TPH1-HTR2, astrocyte→tumor PCDH7-EGFR, IL6-IL6R, CCL5-CCR5 and VGF-C3AR1, and microglia/macrophage→tumor ARTN-GFAR3. Functional experiments demonstrated that cell type-specific depletion of the secreted neuro-active substances deactivated the activities of corresponding receptor and downstream signaling in co-cultured BrM tumor cells. Given that more complex paracrine/autocrine signaling network may dynamically evolve during BrM development, we are characterizing the spatiotemporal cell-cell crosstalk in the BrM metastatic niche that will have important implications for novel therapeutics development. Citation Format: Hong Zhao, Xin Wang, Nikola Liu, Jianting Sheng, Stephen Wong. Modeling cell-cell crosstalk in TNBC brain metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 7.