IL-1β/IL-6 inflammatory crosstalk drives DNA methylation and histone remodeling associated with cytokine induced senescence in luminal breast cancer

BACKGROUND: Chronic inflammation exerts paradoxical effects in breast cancer, inducing growth arrest while sustaining tumor progression. However, how autocrine and paracrine inflammatory cytokine induced senescence integrates with tumor-promoting behaviour remains unclear. Here, we identify a reciprocal IL-1β/IL-6 circuit that links inflammatory cues, epigenetic remodeling and cytokine induced senescence in luminal breast cancer cells. METHODS: Following treatment with IL-1β and IL-6, MCF-7 cells were examined using cell-cycle, apoptosis, reactive oxygen species flow cytometry assays, and senescence assays; RNA sequencing; global DNA methylation quantification; methylation-specific PCR; ChIP-qPCR for histone marks; cytokine ELISA; and western blotting for DNMTs and STAT3/AKT/NF-κB signaling proteins. The kinetics of IL-1β and IL-6 signaling were examined using receptor antagonism and pharmacological inhibition. RESULTS: arrest, elevated SA-β-gal activity, ROS accumulation and absence of apoptosis. Transcriptomic profiling revealed cell-cycle regulator repression, enrichment of senescence-associated signatures and a pro-inflammatory secretory phenotype. Mechanistically, IL-1β induced increased DNMT1 and DNMT3A expression, elevated global DNA methylation, induced promoter-specific DNA methylation (IL-15, HMGB2) and histone mark remodeling (IL-6, IL1RN, BCL2,BAX) at inflammatory, senescence, and apoptotic loci. IL-1 receptor antagonism attenuated these effects. IL-6 induced downstream of IL-1β, in turn activated STAT3, increased DNMT1 and DNMT3B expression, amplified IL-1β expression and tumor-promoting phenotypes, while sustaining the IL-1β induced senescence state. IL-6R blockade disrupted this axis and reduced tumor-promoting effects. CONCLUSION: An IL-1β/IL-6 inflammatory loop drives epigenetic remodeling associated with cytokine induced senescence while promoting tumor-supportive signaling. IL-1β initiates the senescence program, whereas IL-6 reinforces and sustains this state through STAT3/DNMT signaling, highlighting inflammatory cytokine signaling pathways as potential therapeutic targets for breast cancer therapy.