Transcriptomic responses of cancerous and noncancerous human colon cells to sulforaphane and selenium

Diets enriched with bioactive food components trigger molecular changes in cells that may contribute to either health-promoting or adverse effects. Recent technological advances in high-throughput data generation allow for observing systems-wide molecular responses to cellular perturbations with nontoxic and dietary-relevant doses while considering the intrinsic differences between cancerous and noncancerous cells. In this chemical profile, we compared molecular responses of the colon cancer cell line HT29 and a noncancerous colon epithelial cell line (HCEC) to two widely encountered food components, sulforaphane and selenium. We conducted this comparison by generating new transcriptome data by microarray gene-expression profiling, analyzing them statistically on the single gene, network, and functional pathway levels, and integrating them with protein expression data. Sulforaphane and selenium, at doses that did not inhibit the growth of the tested cells, induced or repressed the transcription of a limited number of genes in a manner distinctly dependent on the chemical and the cell type. The genes that most strongly responded in cancer cells were observed after treatment with sulforaphane and were members of the aldo-keto reductase (AKR) superfamily. These genes were in high agreement in terms of fold change with their corresponding proteins (correlation coefficient r(2) = 0.98, p = 0.01). Conversely, selenium had little influence on the cancer cells. In contrast, in noncancerous cells, selenium induced numerous genes involved in apoptotic, angiogenic, or tumor proliferation pathways, whereas the influence of sulforaphane was very limited. These findings contribute to defining the significance of cell type in interpreting human cellular transcriptome-level responses to exposures to natural components of the diet.