Fig. 7 | Signal Transduction and Targeted Therapy

Fig. 7

From: Tobacco carcinogen induces tryptophan metabolism and immune suppression via induction of indoleamine 2,3-dioxygenase 1

Fig. 7

Mechanisms of action of tobacco smoke in promotion of tryptophan catabolism and immunosuppressive microenvironment. Tobacco smoke activates c-Jun through NNK-α7nAChR axis, leading to upregulation of IDO1 in tumor cells. IDO1 triggers catabolism of tryptophan and production of kynurenine, resulting in suppression of CD8+ T cells and accumulation of Tregs. These effects promote environmental lung carcinogenesis

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