Proteins Involved in Focal Cell Adhesion and Podosome Formation Are Differentially Expressed during Colorectal Tumorigenesis in AOM-Treated Rats

Simple Summary Colon cancer first involves the development of small clusters of abnormal cells. The purpose of our study was to determine changes in protein expression in such abnormal cells as they grow after being triggered to form due to exposure to a carcinogen using rats as a model. We were able to identify a number of proteins that were very differently expressed when comparing early abnormal cells to more mature cell clusters. Many of these proteins are involved in regulating cell-to-cell interactions and cell shape, among other activities in the cells. Our findings help us better understand the biology of intestinal cancer and may be useful in developing biomarkers for detecting colon cancer. This information also helps us lay a foundation for future studies aimed at better understanding the how intestinal cancers develop and grow under different intestinal conditions. Abstract Colorectal tumorigenesis involves the development of aberrant crypt foci (ACF) or preneoplastic lesions, representing the earliest morphological lesion visible in colon cancer. The purpose of this study was to determine changes in protein expression in carcinogen-induced ACF as they mature and transform into adenomas. Protein expression profiles of azoxymethane (AOM)-induced F344 rat colon ACF and adenomas were compared at four time points, 4 (control), 8, 16, and 24 weeks post AOM administration (n = 9/group), with time points correlating with induction and transformation events. At each time point, micro-dissected ACF and/or adenoma tissues were analyzed across multiple quantitative two-dimensional (2D-DIGE) gels using a Cy-dye labeling technique and a pooled internal standard to quantify expression changes with statistical confidence. Western blot and subsequent network pathway mapping were used to confirm and elucidate differentially expressed (p ≤ 0.05) proteins, including changes in vinculin (Vcl; p = 0.007), scinderin (Scin; p = 0.02), and profilin (Pfn1; p = 0.01), By determining protein expression changes in ACF as they mature and transform into adenomas, a “baseline” of altered regulatory proteins associated with adenocarcinoma development in this model has been elucidated. These data will enable future studies aimed at biomarker identification and understanding the molecular biology of intestinal tumorigenesis and adenocarcinoma maturation under varying intestinal conditions.