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Mammary carcinoma: enzymatic block in disialoganglioside biosynthesis
Abstract:
The sialyl transferase of disialoganglioside formation is depressed in mammary tumors induced in the rat by 7,12-dimethylbenz[a]anthracene. Specific activities of other glycosyltransferases of the pathway ceramide to monosialo-ganglioside are unchanged or elevated so that the ganglioside GM(1) accumulates and higher gangliosides are depressed. These findings with a solid tumor are critical to an involvement of gangliosides in the cell-surface changes of tumorigenesis.
Insights
Sialyl transferase activity is reduced in rat mammary tumors, leading to GM(1) ganglioside accumulation and decreased higher gangliosides. This suggests gangliosides play a role in tumor cell surface changes during tumorigenesis.
Area of Science:
- Biochemistry
- Cancer Biology
- Glycobiology
Background:
- Gangliosides are complex glycosphingolipids found in cell membranes.
- Alterations in ganglioside metabolism are associated with tumorigenesis.
- The specific role of sialyl transferases in tumor development requires further investigation.
Purpose of the Study:
- To investigate the activity of sialyl transferase in mammary tumors induced by 7,12-dimethylbenz[a]anthracene in rats.
- To determine the impact of altered sialyl transferase activity on ganglioside profiles in these tumors.
- To explore the potential involvement of gangliosides in the cell-surface changes associated with tumorigenesis.
Main Methods:
- Induction of mammary tumors in rats using 7,12-dimethylbenz[a]anthracene.
- Measurement of specific activities of various glycosyltransferases involved in ganglioside biosynthesis.
- Analysis of ganglioside composition in tumor tissues.
Main Results:
- A significant depression in the sialyl transferase activity responsible for disialoganglioside formation was observed in mammary tumors.
- Specific activities of other glycosyltransferases in the pathway from ceramide to monosialo-ganglioside remained unchanged or were elevated.
- Accumulation of ganglioside GM(1) and a decrease in higher gangliosides were noted in the tumor tissues.
Conclusions:
- The depressed sialyl transferase activity is a key finding in 7,12-dimethylbenz[a]anthracene-induced rat mammary tumors.
- Ganglioside GM(1) accumulation and reduced higher gangliosides suggest a specific metabolic shift during tumorigenesis.
- These findings support the critical involvement of altered ganglioside metabolism in the cell-surface modifications characteristic of cancer development.