Alteration of fecal tryptophan metabolism correlates with shifted microbiota and may be involved in pathogenesis of colorectal cancer

Figure 1 Levels of Zonula occludens-1 and indoleamine 2,3-dioxygenase 1 mRNA in colon tissue and their correlations with fecal tryptophan metabolites. A: The relative Zonula occludens-1 (ZO-1) mRNA levels in colorectal adenoma and colorectal cancer (CRC) were significantly lower than those in controls (P < 0.001); B: The relative indoleamine 2,3-dioxygenase 1 (IDO1) mRNA levels in ARA and CRC were higher than those in controls (P =0.04 and P = 0.035, respectively); C: Fecal kynurenine/tryptophan (Trp) ratio was positively correlated with the level of IDO1 mRNA in all subjects; D: There was a positive correlation between fecal indoles/Trp ratio and ZO-1 mRNA level in all subjects. KYN: Kynurenine; Trp: Tryptophan; HC: Healthy control; ADA: Colorectal adenoma; CRC: Colorectal cancer; ZO-1: Zonula occludens-1; IDO1: Indoleamine 2,3-dioxygenase 1.