ABSTRACT
Recent epidemiological studies have shown that moderate coffee consumption is associated with a lower risk of certain types of cancers, particularly colon cancer in postmenopausal women. To elucidate the molecular basis for the preventive action of coffee, we investigated the effect of coffee on estrogen sulfotransferase (SULT) because sulfation is the major pathway involved in the inactivation of estrogens. We found that coffee reduced SULT1E1 gene expression in human colon carcinoma Caco-2 cells. Treatment with 2.5% (v/v) coffee for 24 h resulted in a 60% reduction of the expression of the SULT1E1 gene in Caco-2 cells. Corresponding to reduced SULT1E1 gene expression, cytosolic estrogen SULT activity toward E(2) (20 nM) decreased by 25%. In addition, an accumulation of E(2) sulfates in the medium, which reflects cellular activity of estrogen SULT, decreased after the cells were treated with coffee. Major bioactive constituents in coffee such as caffeine, chlorogenic acid and caffeic acid did not show any effect. The inhibitory activity was extractable by using ethyl acetate. We also found that the inhibitory activity was produced by roasting the coffee beans. Mithramycin, an inhibitor of the transcription factor stimulating protein 1 (Sp1), was able to restore coffee-reduced SULT1E1 gene expression. Our data suggest that daily coffee consumption may reduce estrogen SULT activity, thereby enhancing estrogenic activity in the colon.
Subject(s)
Coffea , Gene Expression Regulation, Enzymologic/drug effects , Plant Extracts/pharmacology , Sulfotransferases/genetics , Caco-2 Cells , Cell Survival/drug effects , Coffee , Colonic Neoplasms/enzymology , Estradiol/metabolism , Humans , Nucleic Acid Synthesis Inhibitors/pharmacology , Plicamycin/pharmacology , Protein Synthesis Inhibitors/pharmacology , Sp1 Transcription Factor/antagonists & inhibitors , Sulfotransferases/metabolismABSTRACT
Coffee is a beverage that is consumed world-wide on a daily basis and is known to induce a series of metabolic and pharmacological effects, especially in the digestive tract. However, little is known concerning the effects of coffee on transporters in the gastrointestinal tract. To elucidate the effect of coffee on intestinal transporters, we investigated its effect on expression of the breast cancer resistance protein (BCRP/ABCG2) in a human colorectal cancer cell line, Caco-2. Coffee induced BCRP gene expression in Caco-2 cells in a coffee-dose dependent manner. Coffee treatment of Caco-2 cells also increased the level of BCRP protein, which corresponded to induction of gene expression, and also increased cellular efflux activity, as judged by Hoechst33342 accumulation. None of the major constituents of coffee tested could induce BCRP gene expression. The constituent of coffee that mediated this induction was extractable with ethyl acetate and was produced during the roasting process. Dehydromethylepoxyquinomicin (DHMEQ), an inhibitor of nuclear factor (NF)-κB, inhibited coffee-mediated induction of BCRP gene expression, suggesting involvement of NF-κB in this induction. Our data suggest that daily consumption of coffee might induce BCRP expression in the gastrointestinal tract and may affect the bioavailability of BCRP substrates.
Subject(s)
ATP-Binding Cassette Transporters/metabolism , Breast Neoplasms/metabolism , Coffee , Neoplasm Proteins/biosynthesis , Neoplasm Proteins/genetics , Plant Extracts/pharmacology , ATP Binding Cassette Transporter, Subfamily G, Member 2 , ATP-Binding Cassette Transporters/analysis , ATP-Binding Cassette Transporters/biosynthesis , ATP-Binding Cassette Transporters/genetics , Benzamides/pharmacology , Benzimidazoles/pharmacology , Breast Neoplasms/genetics , Caco-2 Cells , Cell Culture Techniques , Cyclohexanones/pharmacology , Dose-Response Relationship, Drug , Drug Evaluation, Preclinical , Female , Gene Expression/drug effects , Humans , Molecular Targeted Therapy , NF-kappa B/antagonists & inhibitors , NF-kappa B/genetics , Neoplasm Proteins/analysis , Neoplasm Proteins/metabolismABSTRACT
To investigate the possible effects of different beverages in the gastrointestinal tract on the sulfation of estrogen, which is a major hormone and prototype substrate for the human sulfotransferases (SULT), we analyzed the effects of these substances upon the sulfate conjugation of 17beta-estradiol (E2) in the human colon carcinoma cell line Caco-2. Sulfoconjugation activity toward E2 was measured by incubating 20 nM E2 with Caco-2 cells in the presence (5% (v/v)) of each beverage. Among the 35 beverages analyzed, four (aronia, blueberry, coffee, and peppermint) exhibited strong inhibitory effects on E2 sulfation within Caco-2 cells IC50 values ranging from 1.9 to 4.4% (v/v)). These active beverages also strongly inhibited the cytosolic estrogen SULT activity of Caco-2 cells in vitro (IC50 values ranging from 0.18 to 0.3% (v/v)). These inhibitory activities were extractable with ethyl acetate but not hexane or n-butanol, indicating that the molecules responsible are moderately lipophilic. Coffee was found to be the most potent inhibitor but the major constituents of this beverage, caffeic acid, caffeine, and chlorogenic acid, did not show any effects on estrogen SULT activity. Kinetic analyses further indicated that the mode of inhibition by coffee is competitive. A possible relationship between the inhibition of estrogen SULT activity by coffee in the gastrointestinal tract and the reported reduction of colon cancer incidence in women who consume coffee is discussed.
