Cholesterol inhibits glutamine metabolism in LLC WRC256 tumour cells but does not affect it in lymphocytes: possible implications for tumour cell proliferation
✍ Scribed by A. Lescano-De-Souza JR.; R. Curi
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 93 KB
- Volume
- 17
- Category
- Article
- ISSN
- 0263-6484
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✦ Synopsis
The eect of cholesterol on proliferation and glutamine metabolism of lymphocytes and tumour cells was investigated. The addition of cholesterol to the culture medium did not cause a signi®cant eect on [2-14 C]-thymidine incorporation in lymphocytes. In the presence of concanavalin A, lymphocyte proliferation was increased by cholesterol ( from 0 . 013 up to 1 . 3 mM). At high concentrations (234 and 468 mM), however, a marked inhibition of lymphocyte proliferation occurred. The same inhibitory eect was observed in the presence of lipopolysaccharides. Cholesterol also caused a marked decrease of LLC WRC256 tumour cell growth at 117 and 234 mM. The same ®ndings were obtained by the measurement of [2-14 C]-thymidine incorporation in these cells. The eect of cholesterol on phosphate-dependent glutaminase activity was then tested in cultured lymphocytes and LLC WRC256 tumour cells. Cholesterol at concentrations of 117 and 234 mM did not alter this enzyme activity in lymphocytes. However, this sterol, already at 26 mM, caused a 44 per cent reduction in glutaminase activity. Similar to the changes observed for glutaminase, cholesterol reduced glutamine oxidation in LLC WRC256 tumour cells, whereas no eect was observed on lymphocytes. Therefore, cholesterol might control lymphocyte and tumour cells proliferation by dierent mechanisms. The signi®cance of these ®ndings for the immune function in tumour-bearing patients remains to be investigated.