Increase in Kyn and IS in plasma of mice with colon cancer xenografts. (A) Increase in Kyn level in the plasma of animals injected with the colon cancer xenograft. Plasma obtained from athymic mice with HT-29 xenografts (N = 8, as described in Figure 1A) before IVC occlusion were examined for Kyn levels. The uninjected athymic mice served as controls (N = 8). An average of 2 independent determinations in plasma of the mice from Figure 1D is shown. A Student t test was performed. Error bars = SEM. P < .001. (B) Increased IS in plasma of animals with colon cancer xenografts. Plasma obtained from athymic mice with HT-29 xenografts before IVC occlusion was examined for IS levels as noted earlier. Average of 2 independent determinations in plasma of the mice from Figure 1D is shown. A Student t test was performed. Error bars = SEM. P = .03. (C) Correlation of Kyn levels with clot weights. Kyn levels recorded in a total of 16 mice from both groups (xenograft-bearing and control, as described in Figure 1A) were correlated with the clot weights. Pearson’s correlation analysis was performed. Line represents a linear regression performed to obtain the P value. (D) Correlation of IS levels with the clot weight. IS levels obtained from 16 mice from both groups (xenograft-bearing and control) were correlated with clot weights. Pearson’s correlation and linear regression analysis were performed. (E) Kyn production by HT-29 cells. HT-29 cells were cultured for 48 hours in the presence or absence of 10% serum and/or tryptophan (Tryp). The harvested media were analyzed for Kyn by using LC/MS, and values were subtracted from the levels in the basal medium (nonsupplemented). The box plots are representative of Kyn levels analyzed in quadruplets. The line within the box corresponds to the median, the borders represent the 25th and 75th percentiles, and the whiskers represent the highest and the lowest values. *P = .014 and **P = .03. ns, not significant.