title: Surveying proteolytic processes in human cancer microenvironments by microdialysis and activity-based mass spectrometry.
abstract: OBJECTIVE
  We present a strategy to survey proteolytic processes that occur in human cancer microenvironments.
  
  
  METHODS
  In situ microdialysis during oral cancer surgery was combined with mass spectrometry-based proteomics to analyze interstitial fluid surrounding tumors and anatomically matched normal sites. Protease activity-based (18)O-profiling was utilized to reveal peptides that were processed by co-collected proteases ex vivo.
  
  
  RESULTS
  We demonstrated for the first time the use of microdialysis in humans to collect interstitial fluid from cancer microenvironments. Proteomic profiling identified proteases and inhibitors in the microdialysis samples. A subset of peptides displayed characteristic (18)O-isotope patterns that indicated processing by endogenous proteases.
  
  
  CONCLUSIONS
  The presented approach provides unprecedented views of in vivo targets of proteases without disrupting the cancer or surrounding tissue. The methodology can be broadly adapted to other physiological conditions in which proteolytic mediators are involved (e.g. arthritic joints, inflamed muscle, other types of cancer) and where a comparison of normal and pathological tissue is sought.
authors.affiliation: Boston Biomedical Research Institute, Watertown, MA, USA. hardt@bbri.org
authors.forename: Markus
authors.initials: M
authors.lastname: Hardt
authors.forename: David K
authors.initials: DK
authors.lastname: Lam
authors.forename: John C
authors.initials: JC
authors.lastname: Dolan
authors.forename: Brian L
authors.initials: BL
authors.lastname: Schmidt
mesh_terms: D000595:Amino Acid Sequence; D002294:Carcinoma, Squamous Cell / Q000378:metabolism / Q000473:pathology; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D017551:Microdialysis / Q000379:methods*; D008969:Molecular Sequence Data; D009062:Mouth Neoplasms / Q000378:metabolism / Q000473:pathology; D059748:Proteolysis; D059016:Tumor Microenvironment