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Abstract: Selenium (Se) has been shown to be protective against cancers in animal models at concentrations exceeding those considered essential for normal nutritional requirements. Organic forms of Se provided as dairy proteins were obtained from cows fed diets supplemented with yeast Se. The casein extracted from milk was found to contain approximately half the Se of the Se-enriched milk. This casein was included in a semi-purified AIN rodent diet so as to provide 1 ppm Se and 25% protein and was compared with AIN diets containing no added Se (control, 0.05 ppm), 1 ppm and 4 ppm Se as selenised yeast (Sel-Plex®) Their influence on colon tumor expression was examined in rats induced with azoxymethane, the diets being introduced post-induction. The selenised casein diet at this concentration was effective in reducing colon tumor incidence (by 29%) and burden (decreased 52%, P < 0.05) relative to the control in rats 26 wk post-induction. Selenised yeast, when added at similar (1 ppm) and increased Se concentration (4 ppm), did not influence significantly colon tumor expression. However, in a second study, with Se yeast providing Se at 1 ppm, 4 ppm, and 8 ppm throughout the experiment, a significant reduction in tumors was observed with 8 ppm Se (colon tumor incidence was 15% lower and colon tumor burden was 35% lower, P < 0.05). However this was associated with a significantly lower body weight in the rats (down 10.5%, P < 0.05) indicating a possible disturbance with normal energy intake or metabolism. The form in which Se is presented in the diet may influence significantly its bioavailability and/or anticancer potential at given concentrations within a safe range. The efficacy of selenised casein and indeed other potential dietary sources deserve further investigation with regard to their ability to prevent colon tumors at concentrations considered safe in the diet. [ABSTRACT FROM AUTHOR]

The anticancer properties of zerumbone (2,6,9 humulatriene-8-one, a sesquiterpenoid) from Zingiber aromaticum were compared with those of curcumin from Curcuma longa in an in vitro MTT tetrazolium salt assay using HT-29, CaCo-2, and MCF-7 cancer cells and in an azoxymethane (AOM)-induced animal model of colon cancer using aberrant crypt foci (ACFs) as a preneoplastic marker. The IC50 of zerumbone was approximately 10 μM and that of curcumin was 25 μM. Cell cycle arrest in HT-29 cells was observed at G0/G1 for 10 and 12.5 mM and G2/M for 25 μM after 24 h at concentrations of 10-25 μM of zerumbone, and a concentration-dependent increase in apoptosis (2-6% of viable cells) was observed after 48 h using the same concentration range. Male Sprague-Dawley rats were fed extracts in an AIN diet prepared from the equivalent of 4% by weight of dried rhizomes of Z. aromaticum and C. longa. ACFs were induced by two doses (15 mg/kg body weight) subcutaneously of AOM 1 wk apart, the rats were killed 10 wk later, and the ACFs were assessed in the colon. Total ACFs were significantly reduced by Z. aromaticum extract (down 21%, P < 0.05) relative to control, the effect being most evident with large ACFs (≥3 aberrant crypts per focus). Similar reductions were observed with 4% C. longa extract in the diet (down 24%, P < 0.01) and with 2,000 ppm curcumin, the effect being particularly evident with large ACFs. The concentration of zerumbone in the Z. aromaticum extract diet was assayed at 300 ppm and of curcumin in the C. longa extract diet was also 300 ppm, i.e., the extract of C. longa was as effective at one-seventh the concentration of curcumin as the positive control. Zerumbone is effective as an anticancer agent, possibly by its apoptosis-inducing and antiproliferative influences. This latter possibility is currently being investigated. [ABSTRACT FROM AUTHOR]

Abstract: Butyrate has been proposed as an antineoplastic agent, leading to the inhibition of tumorigenesis. The purpose of this study was to examine butyrate, supplied as tributyrin (Tbn) or as a natural component of anhydrous milk fat (AMF), on the development of nitrosomethylurea-induced mammary tumors in female Sprague-Dawley rats. Diets were 1) semipurified rodent diet (AIN-93) with high fat [20% sunflower seed oil (SSO), control], 2) SSO diet with Tbn added at 1%, 3) SSO diet with Tbn added at 3%, and 4) 19% AMF with 1% SSO diet, which contained butyrate equivalent to the 1% Tbn diet. These diets were fed ad libitum from weaning at 21 days of age, and at 24 days of age each rat was injected with nitrosomethylurea (50 mg/kg body wt ip). At any one period, there was a relative risk increase of 88% (p <> . [ABSTRACT FROM AUTHOR]

Abstract: Probiotic bacteria strains were examined for their influence on 1,2-dimethylhydrazine (DMH)-induced intestinal tumors in 100 male Sprague-Dawley rats. Lactobacillus acidophilus (Detvo Pro LA-1), Lactobacillus rhamnosus (GG), Bifidobacterium animalis (CSCC1941), and Streptococcus thermophilus (DD145) strains were examined for their influence when added as freeze-dried bacteria to an experimental diet based on a high-fat semipurified (AIN-93) rodent diet. Four bacterial treatments were compared: L. acidophilus, L. acidophilus + B. animalis, L. rhamnosus, and S. thermophilus, the bacteria being added daily at 1% freeze-dried weight (10[sup 10] colony-forming units/g) to the diet. Trends were observed in the incidence of rats with large intestinal tumors for three treatments: 25% lower than control for L. acidophilus, 20% lower for L. acidophilus + B. animalis and L. rhamnosus treatments, and 10% lower for S. thermophilus. Large intestinal tumor burden was significantly lower for treated rats with L. acidophilus than for the control group (10 and 3 tumors/treatment group, respectively, p = 0.05). Large intestinal tumor mass index was also lower for the L. acidophilus treatment than for control (1.70 and 0.10, respectively, p < 0.05). Other treatments showed no statistically significant change from control for these indexes of tumorigenesis. For rats fed L. acidophilus, no adenocarcinomas were present in the colons. Pulsed-field gel electrophoresis of bacterial chromosomal DNA fragments was used to differentiate introduced (exogenous) bacterial strains from indigenous bacteria of the same genera present in the feces. Survival during gut passage and displacement of indigenous lactobacilli occurred with introduced L. acidophilus and L. rhamnosus GG during the probiotic treatment period. However, introduced strains of B. animalis and S. thermophilus were not able to be isolated from feces. It is concluded that this strain of L. acidophilus supplied as freeze-dr... [ABSTRACT FROM AUTHOR]