Proteomic analysis of tumor and adjacent non‐tumor intestinal tissue and tumor burden after iron supplementation in Apc Min/+ mice

Abstract

To determine the effect of excess dietary iron on intestinal tumorigenesis, proteomic changes between tumors from intestines of ApcMin/+ mice fed adequate and excess iron (45 vs. 450 mg iron/kg AIN‐93M[M] diet) were analyzed using 2D‐DIGE and LTQ LCMS. In addition, tumor burden was measured and proteins differentially expressed in tumor and non‐tumor intestinal tissues were analyzed. There was a 2‐fold increase in tumor burden with excess iron. Of 980 analyzed protein spots, 78 spots were differentially expressed among normal and tumor tissues (adequate vs. excess iron (p<0.05; ANOVA, then Tukey's test)). Among these spots, 36 changed in tumor vs. normal tissue (12↓; 24↑) and 18 differed between tumors in mice fed adequate vs. excess iron (5↓; 13↑). Findings reveal that some of these proteins are involved in generation or reduction of reactive oxygen species (ROS), such as, by gene name, SOD1, SOD2, PRDX1, ITGB1 and ALB. Others are involved in protein degradation, such as ANPEP, DPP7, PSMA1, PSMA2, PSMA3, SERPINB1, HSPA5, HSPA9, PSMA4, and PEPD. Using Ingenuity Pathways Analysis (IPA), we found 4 highly significant functional networks in tumor as compared to normal tissue and 2 in tumors from mice fed adequate as compared to excess iron. Notably, the top network in both cases was associated with functions implicated in cancer and cell death. Supported in part by grants IRG‐91‐022 from ACS (to JS) and P30CA43703 from NIH.