Abstract A50: Comparative effects of DFMO, sulindac, and DFMO and sulindac on human colon polyp cells determined using pathway analysis
Authors: Elmore Eugene , Steele Vernon E. , Redpath John Leslie 
Published: June 2012

Cultures of the human colon polyp cell line, VACO 235, were individually treated with DFMO, sulindac, and both DFMO and sulindac to determine the comparative effects of individual agent exposures and the combined agent exposure on gene expression and pathway modifications. These agents were chosen based on their reported potential to prevent sporadic colorectal adenomas (Meyskens et al., Cancer Prev. Res., 1:32–38, 2008). Concentrations of agents were chosen to reflect clinically achievable levels. The exposures were continuous over a 96 hr with treatment and control media replenishment every 24 hr. The dosing frequency was similar to that in the Meyskens study. For the gene expression studies, five separate cultures were used to generate five separate microarrays for each control or treatment condition. Gene expression was assessed using Human gene 1.0 ST arrays from Affymetrix (Santa Clara, CA). The quality of the data from each array was assessed using the manufacturer's software and no outliers were found. Gene expression was assessed using Genespring 11.5.1 software (Agilent Technologies, Inc., Santa Clara, CA). Pathway analysis was done using Ariadne Genomics Pathway Studio 7.1 (Rockville, MD). The changes in pathway specific expression were compared to determine the effects of DFMO and sulindac alone and these changes compared to the effects found with the combined exposure. The ATM protein kinase, which plays an important role in protecting from DNA damage from various sources, phosphorylates a variety of proteins in the DNA damage response pathway. Sulindac and especially the combination of DFMO and sulindac induced many of the proteins modification target genes of ATM with p values of 0.044 and 0.023 respectively. Arachidonic acid metabolism showed no inhibition by DFMO with equal numbers of functional classes that were either induced or inhibited. Both sulindac alone and DFMO and sulindac increased the number of functional classes that were inhibited: however, the inhibition was the greatest with sulindac alone (∼76%). These findings are consistent with the known action of sulindac. Relative to DFMO alone, treatment with sulindac alone and DFMO and sulindac increased the inhibition of functional classes or cell processes that are known to be associated with the cell cycle. Changes in other pathways including the protein modification targets of CAMK (Ca++/calmodulin-kinase) and protein modification targets of matrix metalloproteinase showed significant changes only with the combined exposure of DFMO and sulindac, p values 0.0054 (CAMK) and 0.023 (MMP). The induced changes suggest that repeated exposures to low concentrations of agents were sufficient to induce changes in gene expression and that the combination treatment enhanced the overall effects. The induced changes by DFMO and sulindac would suggest the potential to reduce growth of the polyp cultures relative to the control cultures. Supported by NCI contract #N01-CN-43300

Citation Information: Cancer Prev Res 2011;4(10 Suppl):A50.