title: Apoptosis-related deregulation of proteolytic activities and high serum levels of circulating nucleosomes and DNA in blood correlate with breast cancer progression.
abstract: BACKGROUND
  As cell-free circulating DNA exists predominantly as mono- and oligonucleosomes, the focus of the current study was to examine the interplay of circulating nucleosomes, DNA, proteases and caspases in blood of patients with benign and malignant breast diseases.
  
  
  METHODS
  The concentrations of cell-free DNA and nucleosomes as well as the protease and caspase activities were measured in serum of patients with benign breast disease (n = 20), primary breast cancer (M0, n = 31), metastatic breast cancer (M1, n = 32), and healthy individuals (n = 28) by PicoGreen, Cell Death Detection ELISA, Protease Fluorescent Detection Kit and Caspase-Glo®3/7 Assay, respectively.
  
  
  RESULTS
  Patients with benign and malignant tumors had significantly higher levels of circulating nucleic acids in their blood than healthy individuals (p = 0.001, p = 0.0001), whereas these levels could not discriminate between benign and malignant lesions. Our analyses of all serum samples revealed significant correlations of circulating nucleosome with DNA concentrations (p = 0.001), nucleosome concentrations with caspase activities (p = 0.008), and caspase with protease activities (p = 0.0001). High serum levels of protease and caspase activities associated with advanced tumor stages (p = 0.009). Patients with lymph node-positive breast cancer had significantly higher nucleosome levels in their blood than node-negative patients (p = 0.004). The presence of distant metastases associated with a significant increase in serum nucleosome (p = 0.01) and DNA levels (p = 0.04), and protease activities (p = 0.008).
  
  
  CONCLUSIONS
  Our findings demonstrate that high circulating nucleic acid concentrations in blood are no indicators of a malignant breast tumor. However, the observed changes in apoptosis-related deregulation of proteolytic activities along with the elevated serum levels of nucleosomes and DNA in blood are linked to breast cancer progression.
authors.affiliation: Institute of Tumor Biology, University Medical Center Hamburg-Eppendorf, Germany.
authors.forename: Carina
authors.initials: C
authors.lastname: Roth
authors.forename: Klaus
authors.initials: K
authors.lastname: Pantel
authors.forename: Volkmar
authors.initials: V
authors.lastname: Müller
authors.forename: Brigitte
authors.initials: B
authors.lastname: Rack
authors.forename: Sabine
authors.initials: S
authors.lastname: Kasimir-Bauer
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Janni
authors.forename: Heidi
authors.initials: H
authors.lastname: Schwarzenbach
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis; D001943:Breast Neoplasms / Q000097:blood* / Q000473:pathology; D053148:Caspase 3 / Q000097:blood / Q000378:metabolism; D053179:Caspase 7 / Q000097:blood / Q000378:metabolism; D004273:DNA, Neoplasm / Q000097:blood*; D018450:Disease Progression; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008875:Middle Aged; D009707:Nucleosomes / Q000378:metabolism; D010447:Peptide Hydrolases / Q000097:blood* / Q000378:metabolism; D055815:Young Adult
chemical_list: D004273:DNA, Neoplasm; D009707:Nucleosomes; D010447:Peptide Hydrolases; D053148:Caspase 3; D053179:Caspase 7