title: Detection of colorectal disease by stool defensin assay: an exploratory study.
abstract: OBJECTIVE
  Alpha-defensins 1-3 (human neutrophil peptides [HNP]1-3), reported to be elevated in tumor tissue and serum of patients with colorectal cancer (CRC), have not been studied in stool. We evaluated the neoplasm specificity of HPN1-3 and their discriminant value as stool markers for CRC.
  
  
  METHODS
  Protein and mRNA expression of HPN1-3 were assayed in CRC cell lines, microdissected CRC and normal epithelium, and white blood cells. HNP1-3 proteins in stools were quantified in blinded fashion from 30 normal subjects, 20 patients with CRC, 10 with a large colorectal adenoma, 10 with upper gastrointestinal cancer, and 10 with IBD. Stool lactoferrin was also quantified.
  
  
  RESULTS
  HPN1-3 proteins were not detected in CRC cell lines but were high (>4000 ng/mL) in white blood cells. mRNA levels of HPN1-3 were comparably low in CRC cell lines, microdissected CRC, and normal colon epithelium, but they were >1000-fold and >30,000-fold higher in white blood cells and neutrophils, respectively. Mean stool HPN1-3 levels were 17 ng/mL with normals, 125 ng/mL with CRC, 62 ng/mL with adenoma, 63 ng/mL with upper gastrointestinal cancer, and 231 ng/mL with IBD (P < .01 for each patient group vs normals). HPN1-3 levels in IBD were higher than in CRC (P = .04). At 90% specificity, sensitivity of stool defensins was 35% for CRC, 40% for adenoma, 40% for upper gastrointestinal cancers, and 80% for IBD. Stool defensins and lactoferrin levels correlated (R2 = 0.70, P < .001).
  
  
  CONCLUSIONS
  Alpha-defensins 1-3 levels are nonspecifically elevated in stools from patients with colorectal neoplasia and likely originate from white blood cells. Alpha-defensins 1-3 in stool might serve as markers of inflammatory bowel conditions.
authors.affiliation: Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota 55905, USA.
authors.forename: Hongzhi
authors.initials: H
authors.lastname: Zou
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Harrington
authors.forename: Aravind
authors.initials: A
authors.lastname: Sugumar
authors.forename: Kristie K
authors.initials: KK
authors.lastname: Klatt
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Smyrk
authors.forename: David A
authors.initials: DA
authors.lastname: Ahlquist
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000032:analysis; D002478:Cells, Cultured; D003108:Colonic Diseases / Q000175:diagnosis* / Q000378:metabolism; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay; D005243:Feces / Q000737:chemistry*; D005260:Female; D015870:Gene Expression; D006801:Humans; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000235:genetics; D012002:Rectal Diseases / Q000175:diagnosis* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D023084:alpha-Defensins / Q000032:analysis* / Q000235:genetics
chemical_list: D015415:Biomarkers; D012333:RNA, Messenger; D023084:alpha-Defensins; C406413:human neutrophil peptide 1; C406416:human neutrophil peptide 2; C406427:human neutrophil peptide 3