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Alterations in expression and synthesis of glycolipid antigens in human colonic tumor cell lines
Abstract:
Incubation of human intestinal SW1116 tumor cells in serum-free medium containing butyric acid reduced their capacity to synthesize gastrointestinal carcinoma-associated (GICA) glycolipid antigen 4- to 8-fold as determined by a radioimmunobinding assay using anti-GICA monoclonal antibody:high-performance thin-layer chromatography; autoradiography; and densitometry. The structure of GICA has been described as a sialylated Lea glycolipid (J. L. Magnani, B. Nilsson, M. Brockhaus, D. Zopf, Z. Steplewski, A. Koprowski, and V. Ginsburg. J. Biol. Chem., 257: 14365-14369, 1982). Tritiated fucose incorporation into GICA was reduced per cell (7-fold), per mg protein (5-fold), and per mg lipid (4-fold). A purified organically soluble glycolipid fraction from control SW1116 cells contained more Lewis antigen than did butyrate-treated cells as determined by the high-performance thin-layer chromatography radioimmunobinding assay. Incorporation of radioactivity from [3H]fucose and guanosine diphosphate [14C]fucose into Lewis antigens in butyrate-treated cells was 2- to 3-fold lower than in control cells. HT29 cells carry the blood type of the original donor, Blood Group A. Isotope incorporation into A glycolipid antigen was reduced 2- to 8-fold upon exposure to butyrate. Commensurate with these results was a dramatic reduction in cell population-doubling rate. We propose that synthesis of these fucolipid antigens is associated more with dividing, undifferentiated tumor cell populations. The diminution in antigen levels may derive from diminished cells' capacity for fucosylation in the presence of butyrate.
Insights
Butyric acid significantly reduced the synthesis of gastrointestinal carcinoma-associated (GICA) glycolipid antigens in human intestinal tumor cells. This suggests fucolipid antigen production is linked to cell division and differentiation.
Area of Science:
- Oncology
- Glycobiology
- Biochemistry
Background:
- Gastrointestinal carcinoma-associated (GICA) glycolipid antigens are biomarkers for certain cancers.
- Butyric acid is a short-chain fatty acid with known effects on cell differentiation and proliferation.
Purpose of the Study:
- To investigate the effect of butyric acid on the synthesis of GICA glycolipid antigens in human intestinal tumor cells.
- To explore the relationship between fucolipid antigen expression and tumor cell proliferation.
Main Methods:
- Human intestinal SW1116 tumor cells were incubated with butyric acid in serum-free medium.
- GICA glycolipid antigen synthesis was quantified using radioimmunobinding assays, high-performance thin-layer chromatography, autoradiography, and densitometry.
- Tritiated fucose and guanosine diphosphate [14C]fucose incorporation assays were used to measure Lewis and A glycolipid antigen synthesis.
Main Results:
- Butyric acid treatment reduced GICA glycolipid antigen synthesis 4- to 8-fold in SW1116 cells.
- Incorporation of [3H]fucose into GICA was reduced 7-fold per cell.
- Butyrate treatment also decreased Lewis and Blood Group A glycolipid antigen synthesis and significantly reduced cell population-doubling rates.
Conclusions:
- Butyric acid diminishes the synthesis of fucolipid antigens in human intestinal tumor cells.
- The production of these antigens appears to be associated with actively dividing, undifferentiated tumor cells.
- Reduced antigen levels may result from butyrate-induced inhibition of cellular fucosylation capacity.