Chemopreventive effects of Coltect, a novel dietary supplement, alone and in combination with 5-aminosalicylic acid in 1,2-dimethylhydrazine-induced colon cancer in rats.

OBJECTIVES: Coltect is a novel dietary supplement containing curcumin, green tea and selenomethionine. Previous reports have suggested that these agents can prevent colorectal cancer (CRC). The present study examined the chemopreventive effect of Coltect alone or combined with 5-aminosalicylic acid (5-ASA) using the 1,2-dimethylhydrazine (DMH) model in rats. METHODS: The effect of Coltect was examined on HT-29 CRC cells by growth inhibition assay. Apoptosis was determined by annexin V-FITC/PI staining. Male rats were injected with DMH in vivo and treated with Coltect 150 mg/kg, 5-ASA 50 mg/kg or their combination, by oral gavage. Aberrant crypt foci (ACF) were identified by methylene blue staining. RESULTS: HT-29 cells exhibited a dose-dependent response to Coltect. Part of the growth inhibition can be explained by the induction of mild-moderate apoptosis in cancer cells (28%) compared with the untreated cells (10%). In the in vivo model, the average number of ACF was divided into small (1-3 crypts) or large (≥4 crypts). The Coltect compound reduced the number of small and large ACF similarly to 5-ASA (40% reduction). This reduction was amplified by combining the two agents (70% reduction). CONCLUSION: Coltect inhibits the growth of colon cancer cells, induces apoptosis and inhibits ACF development. Furthermore, it augments the growth inhibitory effect of 5-ASA in vivo. This may be clinically important since this safe dietary supplement-drug combination can be administered as a chemopreventive regimen for the treatment of CRC.

Treatment of preestablished diet-induced fatty liver by oral fatty acid-bile acid conjugates in rodents.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in industrialized countries. It has no accepted medical therapy. Fatty acid-bile acid conjugates (FABACs) were proven to prevent diet-induced NAFLD in rodents. AIM: This study was undertaken to test whether oral FABACs are also effective in reducing liver fat in preestablished diet-induced NAFLD. METHODS: NAFLD was induced in mice and rats by a high-fat diet and maintained by various proportions thereof. The FABACs used were conjugates of cholic acid with either arachidic or stearic acids. RESULTS: FABAC therapy reduced liver fat in all four series of experiments. The rapidity of the effect was inversely proportional to the concentration of fat in the maintenance diet. In mice on a 25% maintenance diet FABACs decreased total liver lipids by about 30% in 4 weeks (P<0.03). Diglycerides (P<0.003) and triglycerides (P<0.01) were the main neutral liver lipids that decreased during FABAC therapy. Both FABACs tested reduced liver fat in NAFLD at doses of 25 and 150 mg/kg/day. High-fat diet increased, whereas FABAC therapy decreased plasma 16 : 1/(16 : 0+16 : 1) fatty acid ratio - a marker of stearoyl CoA desaturase activity. In HepG2 cells FABACs decreased de-novo fatty acid synthesis dose dependently. CONCLUSION: Oral FABAC therapy decreased liver fat in preestablished NAFLD in mice and rats. Inhibition of stearoyl CoA desaturase activity and fatty acid synthesis are mechanisms that may contribute to this decrease. FABACs may be potential therapeutic agents for human NAFLD.

Arginine uptake is attenuated, through post-translational regulation of cationic amino acid transporter-1, in hyperlipidemic rats.

Endothelial cell dysfunction (ECD) is a common feature of hypercholesterolemia. Defective nitric oxide (NO) generation due to decreased endothelial nitric oxide synthase (eNOS) activity is a crucial parameter characterizing ECD. L-arginine is the sole precursor for NO biosynthesis. Among several transporters that mediate L-arginine uptake, cationic amino acid transporter-1 (CAT-1) acts as a specific arginine transporter for eNOS. Our hypothesis implies that CAT-1 is a major determinant of eNOS activity in hypercholesterolemia. We studied aortic arginine uptake, CAT-1 and CAT-2 mRNA expression, and CAT-1, and PKC alpha protein in: (a) control, untreated animals (CTL), (b) rats fed with 4% cholesterol+1% cholate and 2% corn oil for 6 weeks (CHOL) and (c) rats with hypercholesterolemia treated orally with either atorvastatin (CHOL+ATORVA, 20mg/kg BW/day) or arginine 1% (CHOL+ARG) in the drinking water (modalities which have been shown to enhance CAT-1 activity and improve endothelial function). Serum cholesterol levels significantly increased in cholesterol fed animals, an increase which was blocked by atorvastatin (CTL: 66.8+/-15, CHOL: 133.9+/-22, CHOL+ARG: 128.2+/-20, CHOL+ATORVA: 77+/-15 mg/dl). Arginine transport was significantly decreased in CHOL. Treatment with neither arginine nor atorvastatin had an effect. Using RT-PCR, we found no change in aortic CAT-1 and CAT-2 mRNA expression in CHOL as well as following arginine or atorvastatin administration. The abundance of CAT-1 protein was significantly augmented in cholesterol fed rats and was not affected by arginine or atorvastatin. PKC alpha protein content, which was previously shown to regulate CAT-1 activity, increased significantly in CHOL and was neither affected by atorvastatin nor arginine. In conclusion, aortic arginine uptake is attenuated in hypercholesterolemia, through post-translational modulation of CAT-1 protein, possibly via upregulation of PKC alpha.