Fig. 2: IL-11⁺ Fibroblasts appear in tumor tissues in the absence of colitis.

a Elevated Il11 and Egfp expression in colon tumors from Apc^Min/+;Il11-Egfp reporter mice. Experiments were performed using tumor and nontumor tissues from the colons of Apc^Min/+;Il11-Egfp reporter mice. Il11 and Egfp mRNA expression was determined by qPCR. Results are mean ± SEM (n = 5 mice). Results are representative of two independent experiments. b Colon tissue sections from Apc^Min/+;Il11-Egfp reporter mice were stained with H&E (upper panels) or anti-GFP antibody (lower panels) (n = 2 mice). Middle and right panels, respectively, show enlargements of the black and red boxes from the left panels. Red arrowheads indicate tumor cells. Scale bar, 100 μm. c, d The majority of IL-11⁺ cells express stromal cell markers, and a few IL-11⁺ cells express epithelial cell markers. Colonic cells were prepared from tumors of Apc^Min/+;Il11-Egfp reporter mice, stained with the indicated antibodies, and analyzed by flow cytometry. Percentages of IL-11⁺ cells were determined (c). Results are mean ± SEM (n = 3 mice). A representative dot plot from four independent experiments shows the percentages of EGFP⁺ cells expressing each marker (d). Results are mean ± SEM (n = 5 mice). e–h Characterization of IL-11⁺ cells by IHC. Colon tumor sections from Apc^Min/+;Il11-Egfp reporter mice were stained with the indicated antibodies and anti-GFP antibody (e–h) (n = 4 mice). White arrowheads indicate EGFP⁺ cells expressing E-cadherin (e). The right-hand panels show enlarged images of white boxes from the left-hand panels. Scale bar, 100 μm. Numbers of Ki67⁺ EGFP⁺ cells and EGFP⁺ cells were calculated, and percentages of Ki67⁺ cells among EGFP⁺ cells are shown (g) (n = 4 mice). i, j Deletion of the Il11 gene attenuated tumor development in the colon and small intestine of Apc^Min/+ mice. Numbers and areas of tumors in colon and small intestine of 20- to 24-week-old mice of the indicated genotypes were calculated and are plotted. n = 17 (Apc^Min/+;Il11^+/−) or 8 (Apc^Min/+;Il11^−/−) mice; pooled data from seven independent experiments. Statistical significance was determined by using the two-tailed unpaired Student’s t-test (a, c, i, j). Source data are provided as a Source Data file.