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.