title: Haptoglobin-alpha subunit as potential serum biomarker in ovarian cancer: identification and characterization using proteomic profiling and mass spectrometry.
abstract: OBJECTIVE
  The objective of this study was to identify and characterize new serum biomarkers in ovarian cancer patients using mass spectrometric protein profiling and specific immunological assays.
  
  
  METHODS
  Serum samples from 80 cancer patients and 91 healthy women were analyzed by surface enhanced laser desorption and ionization-mass spectrometry (MS) profiling. A candidate biomarker was purified by affinity chromatography, and its sequence was determined by liquid chromatography-tandem MS. An antibody was generated from the synthesized peptide for quantitative validation in the cases and controls. CA125 was determined and compared with the same set of specimens.
  
  
  RESULTS
  Using surface enhanced laser desorption and ionization, we found a serum biomarker at approximately 11700 Da, which had peak intensity significantly higher in cases (1.366) compared with controls (0.208, P = 0.002), and subsequently identified this as the alpha chain of haptoglobin. ELISA indicated that Hp-alpha was </=2-fold higher in cancer serum compared with normal, benign tumor, and other gynecological cancers (P < 0.05) and had 64% sensitivity at 90% specificity alone and 91% sensitivity and 95% specificity if combined with CA125.
  
  
  CONCLUSIONS
  Haptoglobin-derived alpha subunit is a potential marker for ovarian cancer that is complementary to CA125. MS-based protein profiling is a valuable tool for screening protein markers and useful to detect post-translational modification of tumor-associated proteins or abnormal metabolic products. However, confirmation of protein identity with specific antibodies is crucial for clinical application and functional studies.
authors.affiliation: Department of Obstetrics & Gynecology, Brigham and Women's Hospital, Dana-Farber Cancer Institute, Dana-Farber Harvard Cancer Center, Boston, MA 02115, USA. Bin-Ye@hms.harvard.edu
authors.forename: Bin
authors.initials: B
authors.lastname: Ye
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Cramer
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Skates
authors.forename: Steven P
authors.initials: SP
authors.lastname: Gygi
authors.forename: Vanessa
authors.initials: V
authors.lastname: Pratomo
authors.forename: Lanfei
authors.initials: L
authors.lastname: Fu
authors.forename: Nora K
authors.initials: NK
authors.lastname: Horick
authors.forename: Larry J
authors.initials: LJ
authors.lastname: Licklider
authors.forename: John O
authors.initials: JO
authors.lastname: Schorge
authors.forename: Ross S
authors.initials: RS
authors.lastname: Berkowitz
authors.forename: Samuel C
authors.initials: SC
authors.lastname: Mok
mesh_terms: D000595:Amino Acid Sequence; D014408:Biomarkers, Tumor / Q000097:blood*; D001710:Biotin / Q000378:metabolism; D015153:Blotting, Western; D018394:CA-125 Antigen / Q000097:blood; D019281:Dimerization; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005833:Genital Neoplasms, Female / Q000097:blood; D006242:Haptoglobins / Q000096:biosynthesis*; D006801:Humans; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D010051:Ovarian Neoplasms / Q000097:blood* / Q000175:diagnosis*; D010455:Peptides / Q000737:chemistry; D040901:Proteomics / Q000379:methods; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013997:Time Factors
chemical_list: D014408:Biomarkers, Tumor; D018394:CA-125 Antigen; C485359:HP protein, human; D006242:Haptoglobins; D010455:Peptides; D001710:Biotin