title: Compensation of loss of protein function in microsatellite-unstable colon cancer cells (HCT116): a gene-dependent effect on the cell surface glycan profile.
abstract: Tumors that display a high level of microsatellite instability (MSI-H) accumulate somatic frameshift mutations in several genes. The compensation of this loss of function by transfection represents a suitable approach to tie respective gene deficiency to alterations in cellular characteristics. In view of the emerging significance of cell surface glycans as biochemical signals for presentation/activity of various receptors/integrins and for susceptibility to adhesion/growth-regulatory tissue lectins, we examined the glycophenotype in the MSI-H colon cancer cell line HCT116 for activin type 2 receptor (ACVR2), absent in melanoma 2 (AIM2), and transforming growth factor beta-type 2 receptor (TGFBR2) known to be associated with MSI colorectal carcinogenesis. A panel of probes specific for functional carbohydrate epitopes including human lectins was used to trace changes in cell surface levels, thereby initiating glycan analysis related to MSI. In particular, the presence of core substitutions and branching in N-glycans, the sialylation status of N- and O-glycans, and the presence of Le(a/x)-epitopes were profiled. Transient transfection affected the glycophenotype, depending on the nature of the gene and the probe. The TGFBR2 presence reduced binding of probes specific for a core substitution and increased branch length in N-glycosylation, even reaching a P-value of 0.0016. ACVR2/AIM2 influenced core 1 mucin-type O-glycosylation differentially, upregulation by ACVR2, and downregulation by AIM2. These alterations of cell surface glycosylation by gene products that are not directly associated with the machinery for glycan generation direct attention to pursue analysis of glycosylation in MSI tumor cells on the level of target glycoproteins and open the way for functional studies.
authors.affiliation: Department of Applied Tumor Biology, Institute of Pathology, University Hospital Heidelberg, D-69120 Heidelberg, Germany.
authors.forename: Georgios
authors.initials: G
authors.lastname: Patsos
authors.forename: Sabine
authors.initials: S
authors.lastname: André
authors.forename: Nina
authors.initials: N
authors.lastname: Roeckel
authors.forename: Roland
authors.initials: R
authors.lastname: Gromes
authors.forename: Johannes
authors.initials: J
authors.lastname: Gebert
authors.forename: Jürgen
authors.initials: J
authors.lastname: Kopitz
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Gabius
mesh_terms: D030301:Activin Receptors, Type II / Q000235:genetics / Q000378:metabolism*; D003110:Colonic Neoplasms / Q000235:genetics* / Q000378:metabolism*; D004268:DNA-Binding Proteins; D006031:Glycosylation; D045325:HCT116 Cells; D006801:Humans; D037102:Lectins / Q000378:metabolism; D053842:Microsatellite Instability; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011134:Polysaccharides / Q000032:analysis*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*
chemical_list: C410167:AIM2 protein, human; D004268:DNA-Binding Proteins; D037102:Lectins; D009687:Nuclear Proteins; D011134:Polysaccharides; D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D030301:Activin Receptors, Type II; D000077294:Receptor, Transforming Growth Factor-beta Type II