title: Influencing factors on the NMP-22 urine assay: an experimental model.
abstract: BACKGROUND
  The commercial NMP-22 urine assays for bladder cancer (BCa) detect nuclear mitotic apparatus protein 1 (NUMA1) using monoclonal antibodies. It remains unclear whether these assays are monitoring a tumor antigen or some other phenomenon associated with the disease state. In this study, we investigated the influence of urinary cellular and protein concentration, and hematuria on the performance of the NMP-22 tests in an experimental model.
  
  
  METHODS
  Pooled urine from healthy subjects were spiked with varying concentrations of benign (UROtsa) cells, cancer cells (RT4, T24, KU-7 and UM-UC-14), whole blood or serum, prior to analysis with both NMP22® Bladder Cancer ELISA test and the NMP22® BladderChek® point-of-care test.
  
  
  RESULTS
  Urines from control subjects were negative for NMP-22. The addition of whole blood at 50ul/10 ml, but not serum, resulted in a false-positive result. Furthermore, the addition of a high concentration of benign urothelial cells (10(6)) or the cell lysate from these cells (306 μg protein) resulted in a false-positive result. High concentrations of pooled-cancer cells (10(6)) or cell lysate (30.6 μg and above) resulted in a positive NMP-22 assay. Concordance between the NMP-22 ELISA assay and the NMP-22 point of care assay was >90%.
  
  
  CONCLUSIONS
  Rather than detecting a specific tumor antigen, urinary NMP-22 assays may be measuring the cellularity or amount of cell turnover that may be introduced into the urine by a variety of conditions, including surface shedding from bladder tumors. The absence of significant urinary cellularity in some cases due to lesion characteristics or the timing of sampling may result in false-negative NMP-2 assays.
authors.affiliation: Cancer Research Institute, MD Anderson Cancer Center Orlando, Orlando, FL 32827, USA.
authors.forename: Makito
authors.initials: M
authors.lastname: Miyake
authors.forename: Steve
authors.initials: S
authors.lastname: Goodison
authors.forename: Evan Gomes
authors.initials: EG
authors.lastname: Giacoia
authors.forename: Wasia
authors.initials: W
authors.lastname: Rizwani
authors.forename: Shanti
authors.initials: S
authors.lastname: Ross
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Rosser
mesh_terms: D015415:Biomarkers / Q000652:urine; D014408:Biomarkers, Tumor / Q000652:urine*; D045744:Cell Line, Tumor; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005189:False Positive Reactions; D006801:Humans; D008297:Male; D009687:Nuclear Proteins / Q000652:urine*; D001749:Urinary Bladder Neoplasms / Q000175:diagnosis / Q000652:urine
chemical_list: D015415:Biomarkers; D014408:Biomarkers, Tumor; D009687:Nuclear Proteins; C100379:nuclear matrix protein 22