Fig. 5

NNK upregulates IDO1 expression and promotes Trp metabolism in an α7nAChR/c-Jun-dependent manner. a Luciferase activity driven by the IDO1 promoter in A549 cells treated with 25 μM NNK for 48 h. b c-Jun binding site in the IDO1 promoter. TSS, transcription start site. c, d The cells were transfected with siCHRNA7 (c) or pretreated with α-BGT (d) and then treated with 25 μM NNK for 72 h. The cells were lysed for western blotting using the indicated antibodies. e A549 cells expressing pGL-IDO1 promoter-luciferase were transfected with si-c-Jun, treated with 25 μM NNK for 72 h, and lysed for analysis of luciferase activity. f A549 and LLC cells were treated with or without NNK and lysed, chromatin immunoprecipitation assays were performed using IgG or an anti-c-Jun antibody, and the precipitated DNA was used to detect the expression of IDO1 by qRT-PCR. g The cells were transfected with sic-Jun, treated with 25 μM NNK for 72 h, lysed and subjected to western blotting using indicated antibodies. h The cells were transfected with sic-Jun and treated with 25 μM NNK for 72 h, the concentrations of Trp and Kyn in the supernatants were measured, and the Trp/Kyn ratio was calculated. P values, Student’s t test. Error bars, sd