Dataset Information

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.

SUBMITTER: Lee J

PROVIDER: S-EPMC3584148 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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

Lee Jennifer J Ballikaya Seda S Schönig Kai K Ball Claudia R CR Glimm Hanno H Kopitz Juergen J Gebert Johannes J

PloS one 20130227 2

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-defi ...[more]

PMID: 23468914

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Project description:Colorectal cancers (CRCs) that lack DNA mismatch repair function exhibit the microsatellite unstable (MSI) phenotype and are characterized by the accumulation of frameshift mutations at short repetitive DNA sequences (microsatellites). These tumors recurrently show inactivating frameshift mutations in the tumor suppressor Transforming Growth Factor Beta Receptor Type 2 (TGFBR2) thereby abrogating downstream signaling. How altered TGFBR2 signaling affects exosome-mediated communication between MSI tumor cells and their environment has not been resolved. Here, we report on molecular alterations of exosomes shed by MSI cells and the biological response evoked in recipient cells.Exosomes were isolated and characterized by electron microscopy, nanoparticle tracking, and western blot analysis. TGFBR2-dependent effects on the cargo and functions of exosomes were studied in a MSI CRC model cell line enabling reconstituted and inducible TGFBR2 expression and signaling. Microsatellite frameshift mutations in exosomal and cellular DNA were examined by PCR-based DNA fragment analysis and exosomal protein profiles were identified by mass spectrometry. Uptake of fluorescent-labeled exosomes by hepatoma recipient cells was monitored by confocal microscopy. TGFBR2-dependent exosomal effects on secreted cytokine levels of recipient cells were analyzed by Luminex technology and ELISA.Frameshift mutation patterns in microsatellite stretches of TGFBR2 and other MSI target genes were found to be reflected in the cargo of MSI CRC-derived exosomes. At the proteome level, reconstituted TGFBR2 expression and signaling uncovered two protein subsets exclusively occurring in exosomes derived from TGFBR2-deficient (14 proteins) or TGFBR2-proficient (five proteins) MSI donor cells. Uptake of these exosomes by recipient cells caused increased secretion (2-6 fold) of specific cytokines (Interleukin-4, Stem Cell Factor, Platelet-derived Growth Factor-B), depending on the TGFBR2 expression status of the tumor cell.Our results indicate that the coding MSI phenotype of DNA mismatch repair-deficient CRC cells is maintained in their exosomal DNA. Moreover, we uncovered that a recurrent MSI tumor driver mutation like TGFBR2 can reprogram the protein content of MSI cell-derived exosomes and in turn modulate the cytokine secretion profile of recipient cells. Apart from its diagnostic potential, these TGFBR2-dependent exosomal molecular and proteomic signatures might help to understand the signaling routes used by MSI tumors. Fricke et al. uncovered coding microsatellite instability-associated mutations of colorectal tumor driver genes like TGFBR2 in MSI tumor cellderived exosomes. Depending on the TGFBR2 expression status of their donor cells, shed exosomes show distinct proteomic signatures and promote altered cytokine secretion profiles in recipient cells.

Project description:Colorectal cancer, one of the most frequent types of malignancy in the Western world, develops through a multi-step process. The main pathways establishing transformation of normal mucosa to invasive carcinoma include chromosomal instability (CIN), microsatellite instability (MSI) or epigenetic silencing through the CpG Island Methylator Phenotype (CIMP). These pathways have distinct clinical, pathological and genetic characteristics. In general, altered cell surface glycosylation has been linked to colorectal cancer progression, however the impact of MSI-specific pathways on the glycosylation machinery of MSI colon cancer cells has not been investigated yet. In a recent study (Patsos et al., 2009) we have shown that MSI-specific mutations induce marked alterations in cell surface glycosylation, indicating specific changes in the expression of glyco-genes. Therefore the purpose of our experiment is to define these changes by glyco-gene chip analysis. Biallelic mutational inactivation of MSI target genes is believed to drive MSI tumorigenesis. TGFBR2, ACVR2 and AIM2 are among the most frequently mutated genes in MSI colorectal adenomas and carcinomas and functional studies indicate their contribution to MSI-carcinogenesis. A first general screening approach by lectin FACS analysis indicated a correlation between functional inactivation of these genes and cell surface glycosylation of the MSI colon cell line HCT116 (Patsos et al., 2009). For detailed analysis of the altered glycosylation pattern and the underlying molecular mechanisms we have established HCT116 double stable transfectants that allow doxycycline-inducible expression of the three MSI target genes TGFBR2, ACVR2 and AIM2 in a reversible manner. Thus we can experimentally control the expression of the MSI-genes and analyze short and long-term effects on different cell functions, including glycosylation. From the application of the glyco-gene chip for analysis of the transfectants we expect to gain seminal information on the influence of MSI-target genes on glycan expression and function in MSI tumor cells. Correlating loss-of-function of MSI target genes not yet linked with glycosylation to the regulation of the glycophenotype is a novel approach to investigate the glycobiology of tumor cells. In addition it is also suitable to detect new MSI-(glyco)markers for clinical applications, including diagnostic tumor markers and specific targets for immunotherapies.

Dataset Information

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

Publications

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

Similar Datasets

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