Inhibition of N-acetyltransferase activity and gene expression in human colon cancer cell lines by diallyl sulfide.
ABSTRACT Diallyl sulfide (DAS) is one of the major components of garlic (Allium sativum) and is widely used in the world for food. In this study, DAS was selected for testing the inhibition of arylamine N-acetyltransferase (NAT) activity (N-acetylation of 2-aminofluorene) and gene expression (mRNA NAT) in human colon cancer cell lines (colo 205, colo 320 DM and colo 320 HSR). The NAT activity was examined by high performance liquid chromatography and indicated that a 24 h DAS treatment decreases N-acetylation of 2-aminofluorene in three colon (colo 205, 320 DM and colo 320 HSR) cancer cell lines. The NAT enzymes (protein) were analyzed by western blotting and flow cytometry and it indicated that DAS decreased the levels of NAT in three colon (colo 205, 320 DM and colo 320 HSR) cancer cell lines. The gene expression of NAT (mRNAT NAT) was determined by polymerase chain reaction (PCR), it was shown that DAS affect mRNA NAT expression in examined human colon cancer cell lines. This report is the first to demonstrate that DAS does inhibit human colon cancer cell NAT activity and gene expression.
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ABSTRACT: Garlic (Allium sativum L.) with the food supplement material and medicine was used traditionally in Asia and Europe. Epidemiological studies revealed that the intake of garlic reduced incidences of various cancer including digestive system. The present study was designed to investigate the effect of garlic ethanol extract on the development of colonic aberrant crypt foci (ACF) induced by 1,2-dimethylhydrazine (DMH) in male F344 rats. Five-week-old rats were given four times for two weeks to subcutaneous injections by DMH (30 mg/kg body weight) to induce ACF. The animals were divided into groups that fed diet containing garlic ethanol extract at five different doses (0.1, 0.2, 0.5, 2, 5%), respectively, animals were evaluated for the total number of ACF and total aberrant crypts (AC) per colon detected from methylene blue-stained rat colon. ACF were formed in animals in DMH-treated group. The feeding suppressed potently the appearance ACF in the colon of rats. Especially, fed diet containing garlic ethanol extract at intermediate dose (0.5%) significantly reduced the number of ACF and AC per colon (p < 0.05). Garlic ethanol extract inhibited DMH-induced overexpression of Activator Protein-1 (AP-1) and genes related to cell proliferation that also upregulated the expression of p21Waf1/Cip1 mRNA, a cell cycle-regulating gene. These results suggested that garlic ethanol extract may inhibit ACF formation, gene as the early preneoplastic marker of malignant potential in the process of colon carcinogenesis.Toxicological Research. 12/2007; 23(4).
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ABSTRACT: To explore how to calculate the effect of solanine on the Michaelis constant and the maximum reaction rate of NAT, high performance liquid chromatography (HPLC) was used, with 2-AF as substrate, and the rate at which 2-AF is acetylated into 2-AAF in intact HepG2 cells or in the cytoplasm of HepG2 cells as the reaction rate. The double reciprocal plot was made, with 1/S (reciprocal of the concentration of the substrate 2-AF) plotted against 1/V (reciprocal of the reaction rate), to yield a regression equation for calculating Km and Vmax. With intact HepG2 cells, the Km and Vmax for the negative control are 2.37times10-3plusmn8.37times10-5 mM and 9.16times10-4plusmn7.54times10-5 nmol/106 cells, respectively, and that the Km and Vmax for the solanine group are 2.22times10-3plusmn9.05times10-5 mM and 5.14times10-4plusmn 3.72times10-5 nmol/106 cells, respectively.For the cytoplasm of HepG2 cells, the Km and Vmax for the negative control are 8.95times10-3plusmn2.61times10-4 mM and 2.55times10-6plusmn1.92times10-8 nmol/ minldrmg protein, respectively, and the Km and Vmax of the solanine group are 9.48times10-3plusmn3.63times10-4 Mm and 2.43times10-6plusmn1.32times10-8 nmol/minldrmg protein. Statistical analysis showed that, for both intact HepG2 cells and cytoplasm of HepG2 cells, Km does not differ significantly between the negative control and the solanine groups, but Vmax does differ significantly for these groups (PAdvanced Materials Research. 05/2008; 282-283.
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ABSTRACT: Garlic has been reported to have chemopreventive effects against a variety of cancers. However, different garlic preparations contain different constituents. We investigated the chemopreventive effect of aged garlic extract (AGE), an odorless product from prolonged extraction of fresh garlic, on colon carcinogenesis and cell proliferation in 1,2- dimethylhydrazine (DMH)-induced colon neoplastic rats. Rats were given weekly subcutaneous injections of DMH (20mg/kg) for 20 wk, and fed either a basal diet or one containing 4% AGE. Serum from AGE-treated rats contained detectable S-allylcysteine. The AGE diet significantly reduced the number of colon tumors and aberrant crypt foci compared to the basal diet. Cell proliferation of normal-appearing colonic mucosa was assessed by MIB-5 immunohistochemistry. AGE treatment significantly decreased the mean MIB-5-labeling index. These findings suggest AGE has a chemopreventive effect on colon carcinogenesis through suppression of cell proliferation. J. Nutr. 136: 847S-851S, 2006.