Mammary Fibroblasts Secrete Damage Associated Molecular Patterns through Extracellular Vesicles in Response to Ionizing Radiation

Ionizing radiation (IR) is an integral component of cancer therapy. Cellular exposure to IR typically leads to major biological consequences including cell death and senescence. Furthermore, tissue injury in known to involve the release of damage-associated molecular patterns (DAMPs) into the extracellular space, which trigger inflammation and wound healing. However, DAMP release in the context of radiation injury remains to be fully characterized. Evidence suggests that extracellular vesicle (EV) secretion and associated cargo components are part of the cellular response to IR, but the mechanisms integrating cellular damage and EV secretion post-IR are largely unexplored. In this study, we show that acute IR-induced damage in mammary fibroblasts results in a senescence-like phenotype and substantially increased EV secretion. Quantitative proteomic analysis revealed that IR-induced EVs are enriched with extracellular and intracellular DAMPs, along with other pro-inflammatory mediators. We show that knockdown of the GTPase Rab27a abrogates IR-induced EV secretion and inhibits the enrichment of key DAMPs in EVs. By examining the integration of cellular damage and senescence with the release of inflammatory signals, this study elucidates a potentially critical role for EV-associated proteins in the radiation response.