title: Independent validation of candidate breast cancer serum biomarkers identified by mass spectrometry.
abstract: BACKGROUND
  We previously selected a panel of 3 breast cancer biomarkers (BC1, BC2, and BC3) from serum samples collected at a single hospital based on their collective contribution to the optimal separation of breast cancer patients and noncancer controls by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS). The identities and general applicability of these markers, however, were unknown. In this study, we performed protein expression profiling on samples obtained from a second hospital, included a greater number of ductal carcinoma in situ (DCIS) cases, and performed purification and identification of the 2 confirmed markers.
  
  
  METHODS
  Using a case-control study design, we performed protein expression profiling on serum samples from the National Cancer Institute (Milan, Italy). The validation sample cohort consisted of 61 women with locally invasive breast cancer, 32 with DCIS, 37 with various benign breast diseases (including 13 atypical), and 46 age-matched apparently healthy women (age range, 44-68 years). Validated biomarkers were purified and identified with serial chromatography, 1-dimensional gel electrophoresis, in-gel ASP-N digestion, peptide mass fingerprinting, and tandem mass peptide sequencing.
  
  
  RESULTS
  The BC3 and BC2 expression patterns in this sample set were consistent with the first study sample set. BC3 and BC2 were identified to be complement component C3a(desArg) and a C-terminal-truncated form of C3a(desArg), respectively.
  
  
  CONCLUSIONS
  Evaluation of biomarkers in independent sample sets can help determine the broader utility of candidate markers, and protein identification permits understanding of their molecular basis. C3a(desArg) appears to lack specificity among patients with benign diseases, limiting its utility as a stand-alone tumor marker, but it may still be useful in a multimarker panel for early detection of breast cancer.
authors.affiliation: Department of Pathology, Johns Hopkins Medical Institutions, Baltimore, MD 21231, USA.
authors.forename: Jinong
authors.initials: J
authors.lastname: Li
authors.forename: Rosaria
authors.initials: R
authors.lastname: Orlandi
authors.forename: C Nicole
authors.initials: CN
authors.lastname: White
authors.forename: Jason
authors.initials: J
authors.lastname: Rosenzweig
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.forename: Ettore
authors.initials: E
authors.lastname: Seregni
authors.forename: Daniele
authors.initials: D
authors.lastname: Morelli
authors.forename: Yinhua
authors.initials: Y
authors.lastname: Yu
authors.forename: Xiao-Ying
authors.initials: XY
authors.lastname: Meng
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhang
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Davidson
authors.forename: Eric T
authors.initials: ET
authors.lastname: Fung
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Chan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood* / Q000737:chemistry*; D001943:Breast Neoplasms / Q000097:blood*; D005260:Female; D006801:Humans; D007118:Immunoassay; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000097:blood* / Q000737:chemistry*; D015203:Reproducibility of Results; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins