Blocking pro-invasive signaling and inflammatory activation in triple-negative breast cancer with nucleic-acid scavengers (NASs).

Abstract

e13096 Background: Breast cancers remain the most lethal malignancies amongst women worldwide and the second leading cause of cancer-related mortalities in the US. Subtype heterogeneity and aggressive invasive potential are believed to be the major contributors of these outcomes. Triple-negative breast cancer (TNBC) are notoriously aggressive, difficult-to-treat, and metastatic. Inflammation-driven tumorigenesis has been shown to correlate with cell-free DNA (cfDNA) and other damage-associated molecular patterns (DAMPs) in cancer patient sera. We showed that nucleic-acid scavengers (NAS) can block pro-inflammatory signals elicited by DAMP-activation of innate immune sensors (e.g. toll-like receptors). Treatment with the NAS PAMAM-G3 drastically reduced liver metastatic burden in an immunocompetent murine model of pancreatic cancer. Methods: TNBC cells lines were treated with a cocktail of standard-of-care chemotherapeutic agents and the conditioned media (CM) from these cells served as an in vitro DAMP source. Downstream function of TLR activation was tested via a HEK293-TLR reporter cell line measuring absorbance at 655nm. The in vitro invasive phenotype was tested and quantified using a Transwell-Matrigel invasion assay. Cytokine secretion was measured using a BioLegend cytokine array. Results: TNBC CM greatly increased TNBC cell invasion in vitro and that treatment with the NAS PAMAM-G3 significantly inhibits this effect. Treatment of human monocytes (THP-1) with TNBC CM elicited a strong pro-inflammatory response with elevated levels of IL-8, IL-6, CCL2, and IL-1β. Other biologically immune responders including human PBMCs will be tested to determine the potential impact on the tumor immune microenvironment during tumorigenesis and treatment. Conclusions: To elucidate the mechanism by which this NAS works in these tumor settings, our lab has developed several PAMAM-G3 derivatives, including biotin, IR-, and near-IR fluorophore labeled molecules. These molecules will allow us to capture and characterize DAMPs and do in vivo live imaging experiments to gain insight into NAS PK/PD properties. This insight into NAS capabilities will enhance our understanding of metastatic progression and its interplay with the immune system. Moreover, these principles will aid in the development of novel of anti-metastatic therapies to improve TNBC patient outcomes.