Gene expression data from colitis-associated colonic tumors of WT vs. MDR1A KO mice. Mus musculus

Human Ulcerative colitis (UC) is characterized by chronic colonic inflammation and has been associated with an increased risk of colorectal carcinoma. Gene and protein expression profiles of ABCB1/MDR1 have been shown to be dysregulated in UC and sporadic colorectal cancer. We demonstrated that in a murine model of colitis-associated tumorigenesis, MDR1A KO mice showed reduced tumor load when compared to wildtype (WT) mice. The aim of this study was to identify gene alterations in colitis-associated tumors in the context of MDR1A deficiency. We used microarrays to assess gene expression profiles of colitis-associated colonic tumors from WT or MDR1A KO mice. Overall design: We used the azoxymethane (AOM) / dextran sulfate sodium (DSS) – model to study the development of colitis-associated colorectal cancer in WT and MDR1A KO mice. AOM was administered once (10mg/kg body weight) to 6-week-old male mice, followed by treatments with 2.5% DSS (mol wt, 36,000-50,000) for 7 days in drinking water starting on day 0, 21 and 42, respectively. Mice were sacrificed at the experimental endpoint (day 84). At that time the entire colon and rectum were excised, cut longitudinally, and rinsed in ice-cold Hank’s Balanced Salt Solution. During gross examination, tumors were macroscopically visualized by 1% alcian blue staining and excised. Total RNA was extracted from tumor samples. All extracted RNA samples (one tumor per individual mouse; 4 mice per group (WT vs. MDR1A KO); i.e. 4 tumor samples (rep) per group) were analyzed independently. Microarray processing was performed at an Affymetrix Service Provider and Core Facility, “KFB - Center of Excellence for Fluorescent Bioanalytics” (Regensburg, Germany).