Description
Aryl hydrocarbon receptor (AHR) activation by tryptophan (Trp) catabolites enhances tumor malignancy and suppresses anti-tumor immunity. Hitherto, indoleamine-2,3-dioxygenase 1 (IDO1) or tryptophan- 2, 3-dioxygenase (TDO2) are recognized as the main Trp-catabolizing enzymes (TCEs) responsible for the generation of AHR agonists. Here, the ability of the aromatic L-amino acid oxidase, interleukin 4 induced 1 (IL4I1), to activate the AHR was investigated using IL4I1 knockout CAS-1 glioblastoma cells.