Abstract 4272: Suppression of epigenetic regulator NURF leads to autophagy mediated chemo-and immune sensitization of triple negative breast cancer

Abstract

Dysregulation of the epigenome is implicated in initiation and progression of variety of cancers and their acquired resistance to chemotherapy. As such, targeting epigenetic regulators has the potential to modulate tumor cell biology and reestablish tumor cell sensitivity to chemotherapy and/or radiation. Our studies demonstrate that silencing of the epigenetic regulator Nucleosome Remodeling Factor (NURF) sensitizes breast tumor cells to chemotherapy and enhances the anti-tumor immune response. Compared to controls, NURF KD 4T1 breast tumor cells exposed to doxorubicin (Dox) show increased DNA damage (gamma H2AX staining) and autophagy (acridine orange staining) in vitro and enhanced growth inhibition both in vitro and in vivo. NURF KD also sensitizes 4T1 cells to doxorubicin stimulated Natural Killer (NK) cell antitumor activity ex vivo, which is associated with a cytokine/chemokine secreted by doxorubicin exposed NURF KD cells; potential candidates are CCL5, TNFa and CCL2. The importance of NK cells for the enhanced growth control of doxorubicin treated NURF KD cells was confirmed using a mAb depletion approach. Autophagy may be instrumental in NK cell activation and elimination of tumor cell targets by mediating cytokine secretion. Sensitization of NURF KD 4T1 cells to doxorubicin, both increased autophagy and enhanced NK cell activity, were also observed using a small molecule inhibitor of NURF, suggesting that NURF can also be targeted pharmacologically. Our studies suggest that enhanced doxorubicin induced DNA damage and autophagy (cell autonomous effects) and NK cell cytotoxic activity (cell non-autonomous affects) may be primary contributors to immune sensitization in NURF KD cells. Increased cell autonomous antitumor effects by doxorubicin in concert with increased cell non-autonomous immunogenicity could help to achieve tumor regression, reduce metastasis, and possibly promote long term remission in breast cancer. Citation Format: Liliya Tyutyunyk, David A. Gewirtz, Joseph Landry, Nga Dao. Suppression of epigenetic regulator NURF leads to autophagy mediated chemo-and immune sensitization of triple negative breast cancer [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 4272.