Transforming growth factor beta receptor 2 (TGFBR2) changes sialylation in the microsatellite unstable (MSI) Colorectal cancer cell line HCT116.

Abstract

Aberrant glycosylation is a common feature of many malignancies including colorectal cancers (CRCs). About 15% of CRC show the microsatellite instability (MSI) phenotype that is associated with a high frequency of biallelic frameshift mutations in the A10 coding mononucleotide microsatellite of the transforming growth factor beta receptor 2 (TGFBR2) gene. If and how impaired TGFBR2 signaling in MSI CRC cells affects cell surface glycan pattern is largely unexplored. Here, we used the TGFBR2-deficient MSI colon carcinoma cell line HCT116 as a model system. Stable clones conferring doxycycline (dox)-inducible expression of a single copy wildtype TGFBR2 transgene were generated by recombinase-mediated cassette exchange (RMCE). In two independent clones, dox-inducible expression of wildtype TGFBR2 protein and reconstitution of its signaling function was shown. Metabolic labeling experiments using the tritiated sialic acid precursor N-acetyl-D-mannosamine (ManNAc) revealed a significant decline (∼30%) of its incorporation into newly synthesized sialoglycoproteins in a TGFBR2-dependent manner. In particular, we detected a significant decrease of sialylated ß1-integrin upon reconstituted TGFBR2 signaling which did not influence ß1-integrin protein turnover. Notably, TGFBR2 reconstitution did not affect the transcript levels of any of the known human sialyltransferases when examined by real-time RT- PCR analysis. These results suggest that reconstituted TGFBR2 signaling in an isogenic MSI cell line model system can modulate sialylation of cell surface proteins like ß1-integrin. Moreover, our model system will be suitable to uncover the underlying molecular mechanisms of altered MSI tumor glycobiology.

• Authors: Jennifer Lee, Seda Ballikaya, Kai Schönig, Claudia R Ball, Hanno Glimm, Juergen Kopitz, Johannes Gebert
• Journal: PloS one (PLoS One) Vol. 8 Issue 2 Pg. e57074 ( 2013) ISSN: 1932-6203 [Electronic] United States
• PMID: 23468914 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Integrin beta1
• Polysaccharides
• Receptors, Transforming Growth Factor beta
• Protein Serine-Threonine Kinases
• Receptor, Transforming Growth Factor-beta Type II
• Doxycycline

Topics

• Base Sequence
• Colorectal Neoplasms (genetics, metabolism)
• Doxycycline (pharmacology)
• Gene Expression Regulation (drug effects)
• Gene Order
• Gene Targeting
• Genomic Instability
• HCT116 Cells
• Humans
• Integrin beta1 (metabolism)
• Microsatellite Repeats
• Polysaccharides (metabolism)
• Protein Serine-Threonine Kinases (genetics, metabolism)
• Receptor, Transforming Growth Factor-beta Type II
• Receptors, Transforming Growth Factor beta (genetics, metabolism)