Title : Differential N-glycosylation of
kallikrein 6 derived from ovarian cancer cells or the central nervous system
Abstract :
- Ovarian cancer causes more deaths than any other gynecological disorder
- Perturbed glycosylation is one of the hallmarks of this malignancy
- Kallikrein 6 ( KLK6 ) elevation in serum is a diagnostic and prognostic indicator in ovarian cancer
- The majority of ovarian carcinomas express high levels of KLK6 , which diffuses into the circulation
- Under physiological conditions, KLK6 is expressed highly in the central nervous system and found at high levels in cerebrospinal fluid from where it enters the circulation
- Our aim was to characterize and compare the N-glycosylation status of this protein in ovarian cancer ascites fluid and cerebrospinal fluid
- Anion-exchange chromatography was used to reveal different post-translational modifications on the two isoforms
- Mobility gel shift Western blot analysis coupled with glycosidase digestion showed that the molecular weight difference between the two isoforms was because of differential glycosylation patterns
- The presence of a single N-glycosylation site on KLK6 was confirmed by site-directed mutagenesis
- Using a Sambucus nigra agglutinin-monoclonal antibody sandwich enzyme-linked immunosorbent assay approach, it was shown that ovarian cancer-derived KLK6 was modified with alpha2-6-linked sialic acid.
- The structure and com position of glycans of both KLK6 isoforms was elucidated by glycopeptide monitoring with electrospray ionization-Orbitrap tandem mass spectrometry
- Therefore, the extensive and almost exclusive sialylation of KLK6 from ovarian cancer cells could lead to the development of an improved biomarker for the early diagnosis of ovarian carcinoma