Abstract
The activity and expression of indoleamine 2,3-dioxygenase together with -tryptophan transport has been examined in cultured human breast cancer cells. MDA-MB-231 but not MCF-7 cells expressed mRNA for indoleamine 2,3-dioxygenase. Kynurenine production by MDA-MB-231 cells, which was taken as a measure of enzyme activity, was markedly stimulated by interferon-γ (1000 units/ml). Accordingly, -tryptophan utilization by MDA-MB-231 cells was enhanced by interferon-γ. 1-Methyl- -tryptophan (1 mM) inhibited interferon-γ induced kynurenine production by MBA-MB-231 cells. Kynurenine production by MCF-7 cells remained at basal levels when cultured in the presence of interferon-γ. -Tryptophan transport into MDA-MB-231 cells was via a Na+-independent, BCH-sensitive pathway. It appears that system L (LAT1/CD98) may be the only pathway for -tryptophan transport into these cells. 1-Methyl- , -tryptophan trans-stimulated -tryptophan efflux from MDA-MB-231 cells and thus appears to be a transported substrate of system L. The results suggest that system L plays an important role in providing indoleamine-2,3-dioxygenase with its main substrate, -tryptophan, and suggest a mechanism by which estrogen receptor-negative breast cancer cells may evade the attention of the immune system.
Original language | English |
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Pages (from-to) | 106-112 |
Number of pages | 6 |
Journal | BBA - Biomembranes |
Volume | 1661 |
Issue number | 1 |
DOIs | |
Publication status | Published - 10 Feb 2004 |
Keywords
- Indoleamine 2
- 3-dioxygenase
- tryptophan transport
- breast cancer