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Effects of phenylethyl isothiocyanate on early molecular events in N-nitrosomethylbenzylamine-induced cytotoxicity in rat esophagus.

ABSTRACT: There is little information on early molecular events in the development of N-nitrosomethylbenzylamine (NMBA)-induced rat 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 cotreatment with phenylethyl isothiocyanate (PEITC). Rats were fed AIN-76A diet or AIN-76A diet containing PEITC for 3 weeks. During the 3rd week of dietary treatment, they were administered three s.c. doses of NMBA (0.5 mg/kg body weight). Rats were sacrificed 24 h after the last treatment; esophagi were excised and processed for histologic grading, microarray and real-time PCR analysis. Histopathologic analysis showed that treatment of rats with PEITC had a protective effect on NMBA-induced preneoplastic lesions in the rat esophagus. We identified 2,261 genes that were differentially expressed in the NMBA-treated versus control esophagi and 1,936 genes in the PEITC + NMBA versus NMBA-treated esophagi. The intersection of these two sets resulted in the identification of 1,323 genes in NMBA-treated esophagus, the vast majority of which were modulated by PEITC to near-normal levels of expression. Measured changes in the expression levels of eight selected genes were validated using real-time PCR. Results from 12 microarrays indicated that PEITC treatment had a genome-wide modulating effect on NMBA-induced gene expression. Samples obtained from animals treated with PEITC alone or cotreated with PEITC + NMBA were more similar to controls than to samples treated with NMBA alone.

SUBMITTER: Reen RK

PROVIDER: S-EPMC3016711 | biostudies-literature | 2007 Jul

REPOSITORIES: biostudies-literature

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Effects of phenylethyl isothiocyanate on early molecular events in N-nitrosomethylbenzylamine-induced cytotoxicity in rat esophagus.

Reen Rashmeet K RK Dombkowski Alan A AA Kresty Laura A LA Cukovic Daniela D Mele Jennifer M JM Salagrama Sridevi S Nines Ronald R Stoner Gary D GD

Cancer research 20070701 13

There is little information on early molecular events in the development of N-nitrosomethylbenzylamine (NMBA)-induced rat 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 cotreatment with phenylethyl isothiocyanate (PEITC). Rats were fed AIN-76A diet or AIN-76A diet containing PEITC for 3 weeks. During the 3rd week ...[more]

PMID: 17616710

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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:Background: Earthworms are essential for a healthy soil ecosystem, performing key functions such as bioturbation. The soil ecosystem can be challenged by natural toxins such as isothiocyanates (ITC), secondary metabolites produced by many commercial crops. This study investigated the effects of the natural toxin, 2-phenylethyl isothiocyanate on the earthworm Eisenia andrei using an ecotoxicogenomics approach that combined standardised ecotoxicological testing with gene expression analyses. Results and discussion: Exposure to 2-Phenylethyl ITC reduced both survival and reproduction of E. andrei in a dose-dependent manner, with an EC50 (reproduction) value of 556 nmol/g soil. Cross-species comparative genomic hybridisation validated the applicability of an existing 4x44k E. fetida microarray to E. andrei. Gene expression profiles revealed the importance of metallothionein (mt) as an early warning signal when E. andrei is exposed to low concentrations of 2-phenylethyl ITC. Allignment of these mt genes with the mt-2 gene of Lumbricus rubellus showed that there must at least have 2 mt genes in the Eisenia sp. genome. At high exposure concentrations of 2-phenylethyl ITC gene expression was mainly affected by inhibiting chitinase activities, inducing an oxidative stress response, and stimulating energy metabolism. KEGG pathway analysis, furthermore, implied that the high concentration may cause impaired light sensitivity, angiogenesis (e.g. wound healing), olfactory perception (olfaction), learning and memory. Conclusions: Increased levels of isothiocyanates may be found in the field in the near future. Risks of such compounds should be carefully investigated before allowing them to enter the soil on a large scale. This is the first study to investigate the effects of an isothiocyanate on an earthworm both on the ecotoxicological and genomic level. Three-exposure experiment; Acetone control vs.EC10 vs.EC50 exposed animals. Biological replicates: 4 replicates for each exposure. Technical replicates: 2 replicates for each exposure

Dataset Information

Effects of phenylethyl isothiocyanate on early molecular events in N-nitrosomethylbenzylamine-induced cytotoxicity in rat esophagus.

Publications

Effects of phenylethyl isothiocyanate on early molecular events in N-nitrosomethylbenzylamine-induced cytotoxicity in rat esophagus.

Similar Datasets

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