title: Subchronic exposure to arsenic through drinking water alters expression of cancer-related genes in rat liver.
abstract: Although arsenic exposure causes liver disease and/or hepatoma, little is known about molecular mechanisms of arsenic-induced liver toxicity or carcinogenesis. We investigated the effects of arsenic on expression of cancer-related genes in a rat liver following subchronic exposure to sodium arsenate (1, 10, 100 ppm in drinking water), by using real-time quantitative RT-PCR and immunohistochemical analyses. Arsenic accumulated in the rat liver dose-dependently and caused hepatic histopathological changes, such as disruption of hepatic cords, sinusoidal dilation, and fatty infiltration. A 1-month exposure to arsenic significantly increased hepatic mRNA levels of cyclin D1 (10 ppm), ILK (1 ppm), and p27(Kip1) (10 ppm), whereas it reduced mRNA levels of PTEN (1 ppm) and beta-catenin (100 ppm). In contrast, a 4-month arsenic exposure showed increased mRNA expression of cyclin D1 (100 ppm), ILK (1 ppm), and p27(Kip1) (1 and 10 ppm), and decreased expression of both PTEN and beta-catenin at all 3 doses. An immunohistochemical study revealed that each protein expression accords closely with each gene expression of mRNA level. In conclusion, subchronic exposure to inorganic arsenate caused pathological changes and altered expression of cyclin D1, p27(Kip1), ILK, PTEN, and beta-catenin in the liver. This implies that arsenic liver toxicity involves disturbances of some cancer-related molecules.
authors.affiliation: Environmental Health Sciences Division, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. xing.cui@nies.go.jp
authors.forename: Xing
authors.initials: X
authors.lastname: Cui
authors.forename: Song
authors.initials: S
authors.lastname: Li
authors.forename: Amjad
authors.initials: A
authors.lastname: Shraim
authors.forename: Yayoi
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Toru
authors.initials: T
authors.lastname: Hayakawa
authors.forename: Sanae
authors.initials: S
authors.lastname: Kanno
authors.forename: Megumi
authors.initials: M
authors.lastname: Yamamoto
authors.forename: Seishiro
authors.initials: S
authors.lastname: Hirano
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001149:Arsenates / Q000008:administration & dosage / Q000633:toxicity*; D002273:Carcinogens / Q000008:administration & dosage / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004326:Drinking; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D007124:Immunoenzyme Techniques; D008099:Liver / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008113:Liver Neoplasms / Q000235:genetics*; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis; D012334:RNA, Neoplasm / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014881:Water Supply
chemical_list: D001149:Arsenates; D002273:Carcinogens; D012334:RNA, Neoplasm; C009277:sodium arsenate