An investigation into the effects of Glucosinolates and their degradation products on human colorectal Adenocarcinoma cells

Abstract

Cruciferous vegetables are unique in that they are rich sources of glucosinolates, sulfur-containing compounds that are responsible for their pungent aromas and spicy taste. Many commonly consumed cruciferous vegetables come from the Brassica genus, including broccoli, cabbage, cauliflower, cramp, and turnip, and have been widely regarded as potentially cancer-preventative. The hydrolysis of glucosinolates by the plant enzyme myrosinase results in the formation of biologically active compounds, including indoles and isothiocyanates. Epidemiological studies indicate that human exposure to isothiocyanates and indoles through consumption of cruciferous vegetables may decrease cancer risk. A strong relationship between tight junction proteins and cancer development has been established. Loss or suppression of cell-cell adhesiveness is a crucial step that may trigger the release of cancer cells from the primary cancer nest and confer invasive properties to the tumor. Therefore, the disruption of tight junctions leads to loss of organization, invasiveness and lack of differentiation, thereby promoting tumorigenesis. Both an increase and decrease in claudin proteins expression have been shown to be associated with tumorigenesis. In this study we chose 6 different seeds of cruciferous vegetables from which we extracted glucosinolates and tested their effects and the effects of their degradation products following myrosinase hydrolysis on Caco-2 cells. Viability and proliferation tests were done for each of the seeds' purified glucosinolates and their corresponding degradation products. These tests were followed by measurement of Transepithelial Electrical Resistance of Caco-2 cell monolayers that were formed on filters in the presence of glucosinolates. Results obtained indeed proved an extract-dependent effect, first on viability and second on Transepithelial Electrical Resistance across the Caco-2 cell membranes, suggesting an alteration in the organization of tight junctions.