title: Transformation of kidney epithelial cells by a quinol thioether via inactivation of the tuberous sclerosis-2 tumor suppressor gene.
abstract: Although hydroquinone (HQ) is a rodent carcinogen, because of its lack of mutagenicity in standard bacterial mutagenicity assays it is generally considered a nongenotoxic carcinogen. 2,3,5-Tris-(glutathion-S-yl)HQ (TGHQ) is a potent nephrotoxic metabolite of HQ that may play an important role in HQ-mediated nephrocarcinogenicity. TGHQ mediates cell injury by generating reactive oxygen species and covalently binding to tissue macromolecules. We determined the ability of HQ and TGHQ to induce cell transformation in primary renal epithelial cells derived from the Eker rat. Eker rats possess a germline inactivation of one allele of the tuberous sclerosis-2 (Tsc-2) tumor suppressor gene that predisposes the animals to renal cell carcinoma. Treatment of primary Eker rat renal epithelial cells with HQ (25 and 50 microM) or TGHQ (100 and 300 microM) induced 2- to 4-fold and 6- to 20-fold increases in cell transformation, respectively. Subsequently, three cell lines (The QT-RRE 1, 2, and 3) were established from TGHQ-induced transformed colonies. The QT-RRE cell lines exhibited a broad range of numerical cytogenetic alterations, loss of heterozygosity at the Tsc-2 gene locus, and loss of expression of tuberin, the protein encoded by the Tsc-2 gene. Only heterozygous (Tsc-2(EK/+)) kidney epithelial cells were susceptible to transformation by HQ and TGHQ, as wild-type cells (Tsc-2(+/+)) showed no increase in transformation frequency over background levels following chemical exposure. These data indicate that TGHQ and HQ are capable of directly transforming rat renal epithelial cells and that the Tsc-2 tumor suppressor gene is an important target of TGHQ-mediated renal epithelial cell transformation.
authors.affiliation: Center for Molecular and Cellular Toxicology, Division of Pharmacology and Toxicology, College of Pharmacy, University of Texas at Austin, Texas, USA.
authors.forename: H S
authors.initials: HS
authors.lastname: Yoon
authors.forename: T J
authors.initials: TJ
authors.lastname: Monks
authors.forename: C L
authors.initials: CL
authors.lastname: Walker
authors.forename: S S
authors.initials: SS
authors.lastname: Lau
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002292:Carcinoma, Renal Cell / Q000235:genetics / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000187:drug effects* / Q000235:genetics; D020732:Cytogenetic Analysis; D017931:DNA Primers / Q000737:chemistry; D004847:Epithelial Cells / Q000187:drug effects; D020868:Gene Silencing / Q000187:drug effects*; D016147:Genes, Tumor Suppressor / Q000235:genetics*; D005978:Glutathione / Q000031:analogs & derivatives / Q000494:pharmacology*; D006873:Hydroquinones / Q000494:pharmacology*; D007668:Kidney / Q000187:drug effects*; D007680:Kidney Neoplasms / Q000235:genetics / Q000473:pathology*; D016133:Polymerase Chain Reaction; D051381:Rats; D011922:Rats, Mutant Strains; D012097:Repressor Proteins / Q000235:genetics*; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins
chemical_list: D017931:DNA Primers; D006873:Hydroquinones; D012097:Repressor Proteins; C000624655:Tsc2 protein, rat; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins; C078765:2,3,5-(triglutathion-S-yl)hydroquinone; D005978:Glutathione