title: Glycoproteomic identification of potential glycoprotein biomarkers in ovarian cancer proximal fluids.
abstract: BACKGROUND
  Ovarian cancer is the leading cause of death among all gynecological disorders. Aberrant glycosylation, or more specifically, increased sialylation of proteins has been observed in ovarian cancer. Several sialyltransferase genes have been shown to be up-regulated at both the mRNA and protein levels in a number of cancers, including that of the ovary. ST6GAL1 (β-galactosamide α2,6-sialyltranferase 1) gene expression has previously been shown to be upregulated in ovarian cancers of all major subtypes.
  
  
  METHODS
  We have identified the sialome (i.e., sialic acid containing glycoproteins) of biological fluids from ovarian cancer patients and ovarian cancer cell lines utilizing tandem mass spectrometry as a potential pool of novel biomarker candidates. The sialoglycopeptides from four ovarian cancer cell lines, pooled ascites (n=13) and ovarian cyst (n=14) fluids from ovarian cancer patients were enriched utilizing affinity to agarose-immobilized Elderberry lectin (Sambucus nigra agglutinin) and magnetic hydrazide beads folowing periodate-mediated oxidation of sialic acids. Benign ovarian cyst (n=10) and peritoneal effusion (n=20) fluids were analyzed in the same fashion to serve as controls. PNGase F deglycosylated peptides were identified using electrospray ionization-LTQ Orbitrap tandem mass spectrometry.
  
  
  RESULTS
  In all of the samples analyzed in the glycoproteomic portion of the study, we have identified 579 glycosylation sites on 333 proteins. Of these, 13 were exclusively identified in biological fluids from ovarian cancer patients, and another eight were common to these fluids and the ovarian cancer cell line supernatants.
  
  
  CONCLUSIONS
  The proteins identified in the present study could form the basis for future studies examining and quantifying their sialylation status as biomarkers of ovarian cancer.
authors.affiliation: Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Uros
authors.initials: U
authors.lastname: Kuzmanov
authors.forename: Natasha
authors.initials: N
authors.lastname: Musrap
authors.forename: Hari
authors.initials: H
authors.lastname: Kosanam
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Smith
authors.forename: Ihor
authors.initials: I
authors.lastname: Batruch
authors.forename: Apostolos
authors.initials: A
authors.lastname: Dimitromanolakis
authors.forename: Eleftherios P
authors.initials: EP
authors.lastname: Diamandis
mesh_terms: D018262:Adenocarcinoma, Clear Cell / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D002288:Adenocarcinoma, Mucinous / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D000328:Adult; D000595:Amino Acid Sequence; D014408:Biomarkers, Tumor / Q000235:genetics / Q000302:isolation & purification*; D016022:Case-Control Studies; D045744:Cell Line, Tumor; D018284:Cystadenocarcinoma, Serous / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D005260:Female; D006023:Glycoproteins / Q000235:genetics / Q000302:isolation & purification*; D006031:Glycosylation; D006801:Humans; D037102:Lectins / Q000737:chemistry; D008875:Middle Aged; D058977:Molecular Sequence Annotation; D008969:Molecular Sequence Data; D010051:Ovarian Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D040901:Proteomics; D012799:Sialyltransferases / Q000235:genetics / Q000302:isolation & purification*; D053719:Tandem Mass Spectrometry
chemical_list: D014408:Biomarkers, Tumor; D006023:Glycoproteins; D037102:Lectins; D012799:Sialyltransferases