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Effects of Phenylethyl Isothiocyanate on N-Nitrosomethylbenzylamine-induced Cytotoxicity in Rat Esophagus

ABSTRACT: To date, there is little information on early molecular events in the development of N-nitrosomethylbenzylamine (NMBA) induced esophageal tumorigenesis and of the effects of chemopreventive agents on these events. In this study, we identified genes in rat esophagus that were differentially expressed in response to short–term NMBA-treatment and modulated by co-treatment with phenethylisothiocyanate (PEITC). Rats were fed AIN-76A diet or AIN-76A diet containing PEITC for three weeks. During the third week of dietary treatment, they were administered three s.c. doses of NMBA (0.5 mg/kg b.w.). Rats were sacrificed 24 h after the last treatment, esophagi excised and processed for histological grading, microarray and real-time PCR analysis. Our histopathological data showed that treatment of rats with PEITC had protective effect on NMBA-induced preneoplastic lesions in the rat esophagus. We identified 2261 genes that were differentially expressed in the NMBA-treated vs. control esophagi and 1936 genes in the NMBA+PEITC- vs. NMBA-treated esophagi. The intersection of these two sets resulted in the identification of 1323 genes in NMBA-treated esophagus that were modulated by PEITC to near-normal levels of expression. The measured changes in the expression levels of 10 selected genes were validated using real-time PCR. Principle components analysis (PCA) was applied to all twelve microarrays in the study, which suggested that in terms of global gene expression, PEITC treatment had a genome-wide modulating effect on NMBA-induced gene expression. Samples obtained from animals treated with PEITC alone or co-treated with NMBA were more similar to controls than they were to NMBA treatment alone. Keywords: Toxicogenomics,reference design

ORGANISM(S): Rattus norvegicus

PROVIDER: GSE6917 | GEO | 2007/07/18

SECONDARY ACCESSION(S): PRJNA98131

REPOSITORIES: GEO

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Project description:To date, there is little information on early molecular events in the development of N-nitrosomethylbenzylamine (NMBA) induced esophageal tumorigenesis and of the effects of chemopreventive agents on these events. In this study, we identified genes in rat esophagus that were differentially expressed in response to shortâ??term NMBA-treatment and modulated by co-treatment with phenethylisothiocyanate (PEITC). Rats were fed AIN-76A diet or AIN-76A diet containing PEITC for three weeks. During the third week of dietary treatment, they were administered three s.c. doses of NMBA (0.5 mg/kg b.w.). Rats were sacrificed 24 h after the last treatment, esophagi excised and processed for histological grading, microarray and real-time PCR analysis. Our histopathological data showed that treatment of rats with PEITC had protective effect on NMBA-induced preneoplastic lesions in the rat esophagus. We identified 2261 genes that were differentially expressed in the NMBA-treated vs. control esophagi and 1936 genes in the NMBA+PEITC- vs. NMBA-treated esophagi. The intersection of these two sets resulted in the identification of 1323 genes in NMBA-treated esophagus that were modulated by PEITC to near-normal levels of expression. The measured changes in the expression levels of 10 selected genes were validated using real-time PCR. Principle components analysis (PCA) was applied to all twelve microarrays in the study, which suggested that in terms of global gene expression, PEITC treatment had a genome-wide modulating effect on NMBA-induced gene expression. Samples obtained from animals treated with PEITC alone or co-treated with NMBA were more similar to controls than they were to NMBA treatment alone. Experiment Overall Design: For each treatment we used a pooling strategy to enable the inclusion of samples from numerous animals. Three replicate microarrays were completed for each of the four treatments (control, PEITC, NMBA and NMBA+PEITC) for a total of twelve microarrays. Each microarray was hybridized using a pooled RNA sample, and each pool was created from equal amounts of total RNA from two or three independent RNA samples, representing individual animals. Each of these samples was obtained from a different animal, and no sample was included in more than one pool. In total, samples from nine animals per group were pooled for control, NMBA, PEITC and NMBA+PEITC microarrays. To facilitate comparisons of gene expression across all treatments, we utilized a reference design in which each microarray was co-hybridized with a common reference sample labeled with Cy3, and RNA from the treatment pool was labeled with Cy5. Stratageneâ??s Universal Rat reference RNA (Stratagene, La Jolla, CA) was used as the common reference in all microarrays.

Project description:Inflammatory Bowel Disease (IBD) is a term describing a collection of conditions characterised by chronic inflammatory disorder of the gastrointestinal tract involving an inappropriate immune response to commensal microorganisms in a genetically susceptible host. Four kiwifruit extracts, aqueous and ethyl acetate extracts of gold kiwifruit (Actinidia chinensis) or green kiwifruit (A. deliciosa), have previously demonstrated anti-inflammatory activity using in vitro models of IBD. This study examined whether these kiwifruit extracts had immune modulating effects in vivo against inflammatory processes known to be increased in patients with IBD. KFEs were used as a dietary intervention in Il10-/- mice (an in vivo model of IBD) and the C57BL/6J background strain in a 3 x 2 factorial design. While all Il10-/- mice developed significant colonic inflammation compared to the C57BL/6J mice, this was not affected by the inclusion of KFE in the diet. Whole genome gene and protein expression level profiling indicated that KFEs influenced immune signalling pathways and metabolic processes within the colonic tissue; however, the effects were subtle. In particular, adaptive immune pathways were reduced by three out of four kiwifruit extracts, with greater reduction seen in the C57BL/6J mice. This suggests that while immune-modulating activity was present in vivo, KFEs did not reduce inflammatory processes relevant to IBD. Experimental design. Two experiments were conducted, one using extracts from gold kiwifruit and one using extracts from green kiwifruit. Within each experiment, both Il10-/- and C57 mice were randomly divided into three diet treatment groups, to ive the following 12 treatments: 1) Gold Kiwifruit Experiment, C57BL/6J mice, Control diet (AIN-76A), 2) Gold Kiwifruit Experiment, C57BL/6J mice, Aqueous Kiwifruit Extract Supplemented Diet (AIN-76A + 5% Aqueous KFE) 3) Gold Kiwifruit Experiment, C57BL/6J mice, Ethyl Acetate Kiwifruit Extract Supplemented Diet (AIN-76A + 0.11% Ethyl Acetate KFE) 4) Gold Kiwifruit Experiment, Il10-/- mice, Control diet (AIN-76A), 5) Gold Kiwifruit Experiment, Il10-/- mice, Aqueous Kiwifruit Extract Supplemented Diet (AIN-76A + 5% Aqueous KFE) 6) Gold Kiwifruit Experiment, Il10-/- mice, Ethyl Acetate Kiwifruit Extract Supplemented Diet (AIN-76A + 0.11% Ethyl Acetate KFE) 7) Green Kiwifruit Experiment, C57BL/6J mice, Control diet (AIN-76A), 8) Green Kiwifruit Experiment, C57BL/6J mice, Aqueous Kiwifruit Extract Supplemented Diet (AIN-76A + 5% Aqueous KFE) 9) Green Kiwifruit Experiment, C57BL/6J mice, Ethyl Acetate Kiwifruit Extract Supplemented Diet (AIN-76A + 0.11% Ethyl Acetate KFE) 10) Green Kiwifruit Experiment, Il10-/- mice, Control diet (AIN-76A), 11) Green Kiwifruit Experiment, Il10-/- mice, Aqueous Kiwifruit Extract Supplemented Diet (AIN-76A + 5% Aqueous KFE) 12) Green Kiwifruit Experiment, Il10-/- mice, Ethyl Acetate Kiwifruit Extract Supplemented Diet (AIN-76A + 0.11% Ethyl Acetate KFE) Six biological replicates were analysed from each treatment group, except for groups 3 and 7 where five replicates were analysed due to array quality issues with the sixth replicate. Each replicate contained mRNA from one mouse. A reference design was used, where each slide was hybridised with mRNA from one sample (green channel) and mRNA from a common reference pool (red channel).

Project description:Dietary n-3 polyunsaturated fatty acids can reduce inflammation via a range of mechanisms. This study tested the effect of dietary eicosapentaenoic acid (EPA) on intestinal inflammation using interleukin-10 gene-deficient (Il10-/-) mice. Methods: At 35 days of age, 12 weaned Il10-/- and 12 C57 mice were randomly assigned to one of two modified AIN-76A diets, supplemented with 3.7% purified ethyl esters of either EPA (n-3) or oleic acid (OA, control). To identify genes relevant to colon inflammation, transcription profiling (microarrays and qRT-PCR) and bioinformatic analyses were used. Results: In this study, dietary EPA reversed the decrease in colon fatty acid Î²-oxidation gene expression observed in OA-fed Il10-/- compared to C57 mice. Il10-/- mice fed the OA diet showed decreased expression of antioxidant enzyme genes, as well as those involved in detoxification of xenobiotics, compared to C57 mice on the same diet. In contrast, dietary EPA increased the expression of these genes in Il10-/- mice. Conclusions: These data indicate that dietary EPA induced endogenous lipid oxidation which might have a potential anti-inflammatory effect on colon tissue. This is supported by the activation of the Ppara gene that regulates the expression of pro-inflammatory and immunomodulatory genes and proteins. Experiment Overall Design: The diet abbreviations EPA, OA, AA and CO used in the sample records Experiment Overall Design: refer to the following : Experiment Overall Design: CO : AIN-76A (control) Experiment Overall Design: OA : AIN-76A (fat-free) + 1% corn oil + 3.7% oleic acid Experiment Overall Design: EPA : AIN-76A (fat-free) + 1% corn oil + 3.7% eicosapentaenoic acid Experiment Overall Design: AA : AIN-76A (fat-free) + 1% corn oil + 3.7% arachidonic acid Experiment Overall Design: Corn oil was supplemented with purified linoleic and alpha-linolenic acid to meet the nutritional requirements of mice for these essential fatty acids. Diets fed for 6 weeks.

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Effects of Phenylethyl Isothiocyanate on N-Nitrosomethylbenzylamine-induced Cytotoxicity in Rat Esophagus

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