Abstract Body: Cancer survivors face a substantially increased risk of cardiovascular disease driven by genotoxic stress from chemotherapy and radiotherapy. These treatments induce persistent epigenetic remodeling, including DNA methylation and dysregulation of long noncoding RNAs (lncRNAs), that alter endothelial cell fate and vascular integrity. However, the lncRNAs that mediate adaptive versus maladaptive endothelial responses to genotoxic injury remain poorly defined.
DNA methylation profiling of irradiated human umbilical vein endothelial cells identified the conserved lncRNA DIO3OS as the top candidate, exhibiting promoter hypomethylation. Doxorubicin increased DIO3OS expression by ~80% compared with vehicle (n = 6, p = 0.0171), consistent with an adaptive stress response. While DIO3OS has been studied in other pathological contexts, its role in vascular dysfunction remains unclear. We tested the hypothesis that DIO3OS is adaptively induced by genotoxic stress as an epigenetically regulated lncRNA that preserves endothelial homeostasis, and that loss of DIO3OS promotes maladaptive endothelial dysfunction.
Loss of DIO3OS induced a maladaptive endothelial phenotype that phenocopied canonical doxorubicin-associated injury. DIO3OS knockdown increased apoptosis by ~270% (n = 4, p = 0.0016), γH2AX foci formation by 130% (n = 3, p = 0.0185), while reducing proliferation by 34% (n = 4, p = 0.0405). Endothelial migration was reduced by 67% (n = 3, p = 0.0146), and angiogenic capacity was markedly impaired by 84% (n = 5, p = 0.0185).
Transcriptomic analyses revealed activation of inflammatory and immune-response pathways, with interleukin-8 increased by 130% (n = 4, p = 0.0531) and interleukin-6 by 25% (n = 4, p = 0.0068), alongside downregulation of extracellular matrix organization and cell-adhesion pathways. Consistent with maladaptive metabolic stress, DIO3OS loss reduced mitochondrial membrane potential by 23% (n = 5, p = 0.0024), oxygen consumption by 41% (n = 4, p = 0.0294), and ATP levels by 34% (n = 5, p = 0.0339).
Altogether, these findings identify DIO3OS as an epigenetically regulated lncRNA that is adaptively induced by genotoxic stress to preserve endothelial integrity. Loss of DIO3OS converts this adaptive response into maladaptive endothelial dysfunction. Targeting DIO3OS may represent a novel strategy to mitigate cardiovascular toxicity associated with anthracycline-based cancer therapies.