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Epidemiological studies have associated diets rich in broccoli with reduction in risk of cancer. This protective effect has been attributed to the bioactivity of isothiocyanates and indoles, both of which are degradation products of glucosinolates that accumulate in broccoli.

Broccoli provides two major isothiocyanates, sulforaphane (4-methylsulfinylbutyl isothiocyanate, SF), which is the predominant ITC in heading broccoli (‘calabrese’) and iberin (3-methylsulphinyl propyl isothiocyanate), which is the predominant ITC in purple sprouting broccoli. While there have been many studies on the biological activity of SF, there are few studies on iberin, despite it being an important component in broccoli. Moreover, the majority of these studies have been undertaken with transformed cells that have cancerous phenotypes, despite the epidemiological evidence being associated with reduction in cancer risk. Thus, in this study, we seek to compare the response of primary prostatic epithelial and fibroblast cells to both SF and iberin obtained from benign prostate tissue.

Epithelial and fibroblast primary cell lines were derived from the same sample of benign prostate tissue, obtained by transurethral resection of the prostate. The cells were treated in triplicate, in the exponential phase of growth, with 15μM SF, 15μM iberin or an equal amount of DMSO for 24 hours. RNA extracted from the samples was hybridised to whole genome Affymetrix U133Plus 2.0 arrays.

In epithelial cells, more genes were changed in expression on exposure to SF compared to iberin, whereas in fibroblasts the opposite occurred. Moreover, the genes altered in epithelial cells by either SF or iberin were different from those altered in fibroblasts. GenMAPP software was used to further analyse these changes in gene expression. Whereas there were some similarities between the pathways modified in epithelial cells exposed to SF and iberin, there were no pathways in common between fibroblasts exposed to SF and iberin. Thus, in conclusion, SF and iberin have overlapping activities in epithelial cells, but contrasting activities in fibroblast cells.

98th AACR Annual Meeting-- Apr 14-18, 2007; Los Angeles, CA