2:26 PM Abstract No. 99 - Cancer associated extracellular DNA traps in human plasma may predispose to venous thrombosis

Abstract

Purpose Recent evidence from animal models shows neutrophil extracellular traps (NETs), which are comprised of genomic DNA and histones, to be highly thrombogenic predisposing to venous thrombosis (VT). Our aim was to: 1) investigate whether increased NETs in plasma was associated with human cancer patients vs the control, non-cancer patients, 2) determine whether human tumor tissue may be a source of circulating NETs and 3) analyze human VT tissue for NETs and determine whether nucleases can break down NETs in situ. Materials and Methods Following IRB approval, plasma was collected from 19 cancer patients and age-matched 27 non-cancer patients. Extracellular NETs and circulating DNA were quantitated using an ELISA assay and dsDNA PicoGreen assay, respectively. Tumor tissues and human VT tissues were immunostained for NETs using the monoclonal anti-H2A/H2B/DNA complex antibody. To demonstrate the specificity of the antibody to detect NETs, the adjacent tissue section was pretreated with 10 units of DNase prior to NETs immunostaining. DNase-1 levels in plasma (n=46) were quantitated using Western blot analysis. Results Plasma samples from cancer patients demonstrated higher levels of both NETs and dsDNA than those from patients without cancer (p Conclusion Cancer creates a state of increased circulating NETs, which may be in part due to decreased levels of DNase-1 and marked levels of NETs in cancer tissue. Since in situ DNase treatment decreased NETs in human VT, systemic DNAse treatment may decrease circulating chromatin and potentially modulate the risk for thrombotic events in cancer patients.