Our data are also in line with previous ones demonstrating that in other tumors, TDO-derived Kyn activates AhR in an autocrine/paracrine manner to promote tumorigenesis of brain, breast, and bladder cancer cells (Opitz et al., 2011; Pham et al., 2018; Huang et al., 2020). This evidence concerns the gene TDO2 and urinary bladder carcinoma.