TDO2 and neoplasm: In addition, elevated expression of TDO2 in the prostate cancer cell lines LNCaP and VCaP promoted Trp metabolism, and tumor cells enhanced the transport of Trp transport proteins through the activation of the NF-κB-dependent AhR/C-Myc/ABC-SLC transport protein signaling pathway, which further promoted Trp metabolism catalyzed by TDO2 in prostate cancer cells and promoted Trp metabolism in an AhR/c-Myc-dependent manner to promote chemotherapy resistance in prostate cancer (Li et al., 2021).