Steentoft C, Schjoldager KT, Cló E, Mandel U, Levery SB, Pedersen JW, Jensen K, Blixt O, Clausen H.
Glycoconj J. 2010 Aug;27(6):571-82.
Auto-antibodies induced by cancer represent promising sensitive biomarkers and probes to identify immunotherapeutic targets without immunological tolerance. Surprisingly few epitopes for such auto-antibodies have been identified to date. Recently, a cancer-specific syngeneic murine monoclonal antibody 237, developed to a spontaneous murine fibrosarcoma, was shown to be directed to murine podoplanin (OTS8) with truncated Tn O-glycans. Our understanding of such cancer-specific auto-antibodies to truncated glycoforms of glycoproteins is limited. Here we have investigated immunogenicity of a chemoenzymatically produced Tn-glycopeptide derived from the putative murine podoplanin O-glycopeptide epitope. We found that the Tn O-glycopeptide was highly immunogenic in mice and produced a Tn-glycoform specific response with no reactivity against unglycosylated peptides or the O-glycopeptide with extended O-glycan (STn and T glycoforms). The immunodominant epitope was strictly dependent on the peptide sequence, required Tn at a specific single Thr residue (Thr(77)), and antibodies to the epitope were not found in naive mice. We further tested a Tn O-glycopeptide library derived from human podoplanin by microarray analysis and demonstrated that the epitope was not conserved in man. We also tested human cancer sera for potential auto-antibodies to similar epitopes, but did not detect such antibodies to the Tn-library of podoplanin. The reagents and methods developed will be valuable for further studies of the nature and timing of induction of auto-antibodies to distinct O-glycopeptide epitopes induced by cancer. The results demonstrate that truncated O-glycopeptides constitute highly distinct antibody epitopes with great potential as targets for biomarkers and immunotherapeutics.http://www.springerlink.com/content/578834183832t410/
Department of Basic Sciences and Environment (IGM)-Bioorganic Chemistry, University of Copenhagen, Faculty of Life Sciences, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark.