title: Novel serum protein biomarker panel revealed by mass spectrometry and its prognostic value in breast cancer.
abstract: BACKGROUND
  Serum profiling using proteomic techniques has great potential to detect biomarkers that might improve diagnosis and predict outcome for breast cancer patients (BC). This study used surface-enhanced laser desorption/ionization time-of-flight (SELDI-TOF) mass spectrometry (MS) to identify differentially expressed proteins in sera from BC and healthy volunteers (HV), with the goal of developing a new prognostic biomarker panel.
  
  
  METHODS
  Training set serum samples from 99 BC and 51 HV subjects were applied to four adsorptive chip surfaces (anion-exchange, cation-exchange, hydrophobic, and metal affinity) and analyzed by time-of-flight MS. For validation, 100 independent BC serum samples and 70 HV samples were analyzed similarly. Cluster analysis of protein spectra was performed to identify protein patterns related to BC and HV groups. Univariate and multivariate statistical analyses were used to develop a protein panel to distinguish breast cancer sera from healthy sera, and its prognostic potential was evaluated.
  
  
  RESULTS
  From 51 protein peaks that were significantly up- or downregulated in BC patients by univariate analysis, binary logistic regression yielded five protein peaks that together classified BC and HV with a receiver operating characteristic (ROC) area-under-the-curve value of 0.961. Validation on an independent patient cohort confirmed the five-protein parameter (ROC value 0.939). The five-protein parameter showed positive association with large tumor size (P = 0.018) and lymph node involvement (P = 0.016). By matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS, immunoprecipitation and western blotting the proteins were identified as a fragment of apolipoprotein H (ApoH), ApoCI, complement C3a, transthyretin, and ApoAI. Kaplan-Meier analysis on 181 subjects after median follow-up of >5 years demonstrated that the panel significantly predicted disease-free survival (P = 0.005), its efficacy apparently greater in women with estrogen receptor (ER)-negative tumors (n = 50, P = 0.003) compared to ER-positive (n = 131, P = 0.161), although the influence of ER status needs to be confirmed after longer follow-up.
  
  
  CONCLUSIONS
  Protein mass profiling by MS has revealed five serum proteins which, in combination, can distinguish between serum from women with breast cancer and healthy control subjects with high sensitivity and specificity. The five-protein panel significantly predicts recurrence-free survival in women with ER-negative tumors and may have value in the management of these patients.
authors.forename: Liping
authors.initials: L
authors.lastname: Chung
authors.forename: Katrina
authors.initials: K
authors.lastname: Moore
authors.forename: Leo
authors.initials: L
authors.lastname: Phillips
authors.forename: Frances M
authors.initials: FM
authors.lastname: Boyle
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Marsh
authors.forename: Robert C
authors.initials: RC
authors.lastname: Baxter
mesh_terms: D016632:Apolipoprotein A-I / Q000097:blood; D053302:Apolipoprotein C-I / Q000097:blood; D014408:Biomarkers, Tumor / Q000097:blood*; D001798:Blood Proteins / Q000032:analysis*; D001943:Breast Neoplasms / Q000097:blood* / Q000175:diagnosis / Q000401:mortality; D015926:Complement C3a / Q000032:analysis; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008875:Middle Aged; D011228:Prealbumin / Q000032:analysis; D011960:Receptors, Estrogen / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053482:beta 2-Glycoprotein I / Q000097:blood
chemical_list: D016632:Apolipoprotein A-I; D053302:Apolipoprotein C-I; D014408:Biomarkers, Tumor; D001798:Blood Proteins; D011228:Prealbumin; D011960:Receptors, Estrogen; D053482:beta 2-Glycoprotein I; D015926:Complement C3a