Fig. 5: STEAP4 promotes colitis-associated colon tumorigenesis.

a Western blot analysis of colon tissue lysates from mice treated with DSS water for indicated days. b Analysis of XIAP shift on colon tissue lysates from mice treated with DSS water for indicated days. c Construction of STEAP4 floxed/floxed allele. d Copper and iron contents of colons from WT and colonic epithelial cell-specific knockout mice (Steap4^CKO) treated with DSS. n = 5 mice. *P = 0.0281 and **P = 0.0061 for Cu measurement; *P = 0.0186 and **P = 0.0063 for Fe measurement by two-tailed Student’s t test. e Copper and iron contents in the cytosol fraction and mitochondrial fraction from the DSS-treated Steap4 WT and KO colon tissue. n = 5 mice. *P = 0.0107 for right panel; **P = 0.0097 for left panel by two-tailed Student’s t test. f Macroscopic view of longitudinally opened colon from control (WT) and colon epithelial cells-specific knockout mice. g Tumor numbers and tumor incidence from WT and Steap4^CKO mice on AOM-DSS-induced colon cancer model. n = 8 mice. **P = 0.0084 by two-tailed Student’s t test. h H&E staining and immunostaining for Ki67 and cleaved caspase-3 (cCasp3) from paraffin sections of tumors of the indicated genotypes. Scale bar, 100 µm. n = 5 biologically independent tissues. *P = 0.0239 for Ki67; *P = 0.0454 for cCasp3 by two-tailed Student’s t test. i Treatment schedule of TTM. j, k Tumor burden for TTM- or vehicle-treated Steap4 WT mice on AOM-DSS model. *P = 0.0232 for panel (j) (n = 7 mice); *P = 0.0241 for panel (k) (n = 3) by two-tailed Student’s t test. l Immunostaining of Ki67 and cleaved Caspase-3 from TTM- or vehicle-treated colon tissue. n = 5 biologically independent tissues. *P = 0.0265 for cCasp3; **P = 0.0012 for Ki67 by two-tailed Student’s t test. Scale bar, 100 µm. All data were shown as mean ± SEM. All experiments were repeated twice with consistent results. Data were not pooled.