title: Hypersusceptibility to cisplatin carcinogenicity in metallothionein-I/II double knockout mice: production of hepatocellular carcinoma at clinically relevant doses.
abstract: Metallothionein (MT) is a high-affinity metal binding protein thought to mitigate the toxicity of various metals. Cisplatin is a widely used cancer chemotherapeutic that is a rodent carcinogen and may have carcinogenic potential in humans. MT seems to reduce cisplatin toxicity by binding the metal compound but how MT deficiency might impact the carcinogenic effects of cisplatin is unknown. Thus, groups (n = 25) of male MT-I/II double knockout (MT-null) or MT wild-type (WT) mice were exposed to a single treatment of cisplatin (5 or 10 mg/kg, i.p.), or left untreated (control) and observed over the next 104 weeks. The doses of cisplatin used equate to only a fraction of the total dose used typically in clinical settings. In cisplatin-treated MT-null mice, a dose-related increase in hepatocellular carcinoma (HCC) occurred (control, 0%; 5 mg/kg, 17%; 10 mg/kg, 36%) that was not seen in WT mice. Similarly, liver carcinoma multiplicity (HCC/liver) was increased markedly by cisplatin but only in MT-null mice, indicating the formation of multiple primaries in MT deficient mice. Harderian gland carcinoma incidence was also increased by cisplatin treatment in MT-null mice but not WT mice. Our results indicate that MT-null mice are hypersusceptible to the hepatocarcinogenic effects of cisplatin, and poor MT expression may be a predisposing factor for cisplatin-induced secondary tumors after chemotherapy.
authors.affiliation: Inorganic Carcinogenesis Section, Laboratory of Comparative Carcinogenesis, National Cancer Institute at the National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA. waalkes@niehs.nih.gov
authors.forename: Michael P
authors.initials: MP
authors.lastname: Waalkes
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Kazimierz S
authors.initials: KS
authors.lastname: Kasprzak
authors.forename: Bhalchandra A
authors.initials: BA
authors.lastname: Diwan
mesh_terms: D000818:Animals; D002273:Carcinogens / Q000008:administration & dosage; D006528:Carcinoma, Hepatocellular / Q000139:chemically induced*; D002945:Cisplatin / Q000008:administration & dosage / Q000009:adverse effects*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D008113:Liver Neoplasms / Q000139:chemically induced*; D008297:Male; D008668:Metallothionein / Q000235:genetics*; D051379:Mice; D018345:Mice, Knockout; D009378:Neoplasms, Multiple Primary / Q000139:chemically induced*
chemical_list: D002273:Carcinogens; D008668:Metallothionein; D002945:Cisplatin