title: Toxicogenomic assessment of liver responses following subchronic exposure to furan in Fischer F344 rats.
abstract: Furan is a widely used industrial chemical and a contaminant in heated foods. Chronic furan exposure causes cholangiocarcinoma and hepatocellular tumors in rats at doses of 2 mg/kg bw/day or greater, with gender differences in frequency and severity. The hepatic transcriptional alterations induced by low doses of furan (doses below those previously tested for induction of liver tumors) and the potential mechanisms underlying gender differences are largely unexplored. We used DNA microarrays to examine the global hepatic mRNA and microRNA transcriptional profiles of male and female rats exposed to 0, 0.03, 0.12, 0.5 or 2 mg/kg bw/day furan over 90 days. Marked gender differences in gene expression responses to furan were observed, with many more altered genes in exposed males than females, confirming the increased sensitivity of males even at the low doses. Pathway analysis supported that key events in furan-induced liver tumors in males include gene expression changes related to oxidative stress, apoptosis and inflammatory response, while pathway changes in females were consistent with primarily adaptive responses. Pathway benchmark doses (BMDs) were estimated and compared to relevant apical endpoints. Transcriptional pathway BMDs could only be examined in males. These median BMDs ranged from 0.08 to 1.43 mg/kg bw/day and approximated those derived from traditional histopathology. MiR-34a (a P53 target) was the only microRNA significantly increased at the 2 mg/kg bw/day, providing evidence to support the importance of apoptosis and cell proliferation in furan hepatotoxicity. Overall, this study demonstrates the use of transcriptional profiling to discern mode of action and mechanisms involved in gender differences.
authors.affiliation: Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, K1A 0K9, Canada.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Dong
authors.affiliation: Bureau of Chemical Safety, Health Canada, Ottawa, ON, K1A 0K9, Canada.
authors.forename: Santokh
authors.initials: S
authors.lastname: Gill
authors.affiliation: Bureau of Chemical Safety, Health Canada, Ottawa, ON, K1A 0K9, Canada.
authors.forename: Ivan H
authors.initials: IH
authors.lastname: Curran
authors.affiliation: Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, K1A 0K9, Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Williams
authors.affiliation: Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, K1A 0K9, Canada.
authors.forename: Byron
authors.initials: B
authors.lastname: Kuo
authors.affiliation: Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, K1A 0K9, Canada.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Wade
authors.affiliation: Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, ON, K1A 0K9, Canada. carole.yauk@hc-sc.gc.ca.
authors.forename: Carole L
authors.initials: CL
authors.lastname: Yauk
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D002274:Carcinogens, Environmental / Q000633:toxicity*; D049109:Cell Proliferation / Q000187:drug effects; D016000:Cluster Analysis; D004305:Dose-Response Relationship, Drug; D005260:Female; D005506:Food Contamination; D005663:Furans / Q000633:toxicity*; D008099:Liver / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008297:Male; D035683:MicroRNAs / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000235:genetics*; D011916:Rats, Inbred F344; D012737:Sex Factors; D043922:Toxicogenetics; D014158:Transcription, Genetic / Q000187:drug effects*; D059467:Transcriptome / Q000187:drug effects*
chemical_list: D002274:Carcinogens, Environmental; D005663:Furans; D035683:MicroRNAs; D012333:RNA, Messenger; C039281:furan
keywords: Gender differences; Low dose furan; Pathway benchmark dose; Rat liver; Thryoid hormone; miRNA