Targeting DNA Polymerase Epsilon Leads to Tumor Clearance and Activation of an NF-κB mediated inflammatory response in Triple Negative Breast Cancer

Breast cancer remains the second leading cause of cancer-related mortality among women, with triple-negative breast cancer (TNBC) exhibiting a particularly poor five-year prognosis. Here, we demonstrate that among genetic and pharmacological perturbations targeting DNA replication, suppression of DNA polymerase epsilon (POLE) in TNBC, induces a potent, TNBC-specific gene expression signature enriched in inflammatory cytokines that are transcriptional targets of NF-KB. TNBC cells exhibit markedly higher levels of DNA damage and canonical NF-KB activation compared to luminal breast cancer cells. Notably, NF-KB activation in this context depends on the canonical component RELA, but not the non-canonical component RELB. Mechanistically, ATM, STING, and RIG-I each contribute to NF-KB activation following POLE suppression. In vivo, POLE suppression in a murine TNBC model leads to cancer cell-intrinsic elimination of tumor burden and increased immune cell infiltration. Together, these findings support a model in which replication stress from POLE inhibition triggers robust NF-KB-mediated inflammation and immune microenvironment remodeling in TNBC and can independently trigger tumor eradication. These results suggest a potential therapeutic avenue for targeting POLE in TNBC.