Gene expression of indoleamine and tryptophan dioxygenases and three long non-coding RNAs in breast cancer.

Abstract The kynurenine pathway (KP) has a principal role in the metabolism of tryptophan. This pathway is also involved in the pathogenesis of cancer. We evaluated expression of two rate limiting enzymes from this pathway (IDO1 and TDO2) as well as three long non-coding RNAs (lncRNAs) that have been predicted to alter expression of IDO1 (ITGB2-AS1, HCP5 and MIR155HG) in 82 breast cancer tissues and their adjacent non-cancerous tissues (ANCTs). While IDO1 expression levels were not significantly different between malignant tissues and ANCTs (expression ratio = 0.56, P = .21), TDO2 was significantly down-regulated in malignant tissues compared with ANCTs (Expression ratio = 0.001, P