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

IL-1β induced senescence characterized by G0/G1 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.