Comparison of the Effects of Phenethyl Isothiocyanate and Sulforaphane on Gene Expression in Breast Cancer and Normal Mammary Epithelial Cells

Phenethyl isothiocyanate (PEITC) and sulforaphane (SF) exhibit tumor preventive activity in lung, prostate, breast and colon cancers. Our objective was to examine the effect of these two isothiocyanates on estrogen receptor-related genes, and genes related to apoptosis and cell cycle in the estrogen-dependent breast cancer cell line MCF7 and in normal human epithelial breast (HME) cells. We treated cells with 0.3 μM or 3.0 μM concentrations of PEITC or SF. In HME cells, gene expression was significantly altered for 23 genes by PEITC at a concentration of 0.3 μM and 4 genes at 3.0 μM. SF altered the expression of 16 genes at a concentration of 0.3 μM and 2 genes at 3.0 μM. In HME cells, genes altered by both PEITC and SF exhibited changes in gene expression that were similar in extent as well as direction of change. In MCF-7 cells, PEITC did not produce any significant changes in the gene expression at both treatment levels. SF produced significant changes in 7 genes, but only at the higher treatment level of 3.0 μM. Normal mammary cells exhibited more changes in the expression of estrogen receptor related genes than did breast cancer cells, and significantly these changes occurred predominantly at the low concentration of 0.3 μM, a concentration achievable by dietary input of isothiocyanates. Novel findings were the upregulation of the pro-apoptotic gene BAD and estrogen receptor beta gene in normal human mammary cells. These gene alterations observed, along with upregulation of tumor suppressors p21 and p27, may provide a protective effect to mammary cells against breast cancer.