Tryptophan-degrading enzymes in tumoral immune resistance.
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van Baren N, Van den Eynde BJ
Tryptophan-degrading enzymes in tumoral immune resistance.
Front Immunol. 2015 Feb 3;6:34. doi: 10.3389/fimmu.2015.00034. eCollection 2015.
- PubMed ID
- 25691885 [ View in PubMed]
- Abstract
Tryptophan is required for T lymphocyte effector functions. Its degradation is one of the mechanisms selected by tumors to resist immune destruction. Two enzymes, tryptophan-2,3-dioxygenase and indoleamine 2,3-dioxygenase 1, control tryptophan degradation through the kynurenine pathway. A third protein, indoleamine 2,3-dioxygenase 2, was identified more recently. All three enzymes were reported to be expressed in tumors, and are candidate targets for pharmacological inhibition aimed at restoring effective anti-tumoral immunity. In this review, we compare these three enzymes in terms of structure, activity, regulation, and expression in healthy and cancerous tissues, in order to appreciate their relevance to tumoral immune resistance.