IDO1 and breast carcinoma: lncRNA HULC, which is highly expressed in HCC, downregulates p18 in liver cirrhosis to affect Treg differentiation.130 In gastric cancer, lncRNA POU3F3 promotes the distribution of Tregs among surrounding T cells by recruiting TGF-β and activating the TGF-β pathway.131 lncRNA SNHG1 regulates Treg differentiation by targeting miR-448/IDO in breast cancer.96