Increased expression and possible role of chitinase 3-like-1 in a colitis-associated carcinoma model

Figure 1 Outline of the protocol in the murine model of colitis-associated carcinoma and chronic colitis. AOM (12 mg/kg) plus 3 cycles of DSS (3%) with or without caffeine (2.5 mmol/L) was introduced to animals in the CAC group (8 mice/group). Animals in the colitis group were administered 3 cycles of DSS with or without caffeine (5 mice/group). AOM: Azoxymethane; DSS: Dextran sulfate sodium; CAC: Colitis-associated carcinoma.

Figure 2 HT-29 cells do not express chitinase 3-like-1 constitutively. CHI3L1: Chitinase 3-like-1.

Figure 3 Chitinase 3-like-1 is up-regulated during the progression of carcinogenesis. A: Histological changes after AOM/DSS administration (HE staining, objective, 20 ×); B, C: CHI3L1 expression increased during the progression of colon carcinogenesis (B: Immunohistochemistry staining, objective, 40 ×). In Figure C, data represent mean ± SD. n = 3 at each time point. ^aP < 0.05 distal: day 56 vs day 0, 14, 28 and 42; ^bP < 0.01 distal: day 42 vs day 0, 14, 28; distal vs proximal. AOM: Azoxymethane; DSS: Dextran sulfate sodium; CAC: Colitis-associated carcinoma; CHI3L1: Chitinase 3-like-1.

Figure 4 Chitinase 3-like-1 inhibition may be one of the underlying mechanisms in the protective effect of caffeine. A: Caffeine suppresses CHI3L1 expression in both the CAC group and colitis group; B: Macroscopic overview of representative colonic samples from the CAC control group and the CAC + caffeine group; C: HE staining of colonic specimens from the colitis control group and caffeine-treated group (objective, 20 ×). CAC: Colitis-associated carcinoma; CHI3L1: Chitinase 3-like-1.

Figure 5 Immunofluorescence images of 8-hydroxyguanine expression in colon samples. Comparison of 8-OHdG expression in mice from the colitis control group and the colitis + caffeine group are shown (objective, 20 ×). 8-OHdG: 8-hydroxyguanine.

Figure 6 Recombinant chitinase 3-like-1 protein enhanced reactive oxygen species in HT29 cells. A, B: Flow cytometer results of ROS level in HT29 cells (A top: Without H₂O₂ challenge; A bottom: With H₂O₂ challenge). Data represent mean ± SD. ^aP < 0.05, 0 ng/mL + H₂O₂vs 0 ng/mL, 40 ng/mL + H₂O₂, 80 ng/mL + H₂O₂; ^bP < 0.01, 0 ng/mL vs 40 ng/mL + H₂O₂, 80 ng/mL + H₂O₂. ROS: Reactive oxygen species.