Case study

An evaluation of the human relevance of the synthetic pyrethroid metofluthrin-induced liver tumors in rats based on mode of action

Tomoya Yamada, Satoshi Uwagawa, Yasuyoshi Okuno, Samuel Monroe Cohen, Hideo Kaneko

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

In recent years, mode of action (MOA) frameworks have been developed through the International Life Sciences Institute Risk Science Institute and the International Programme on Chemical Safety, including an evaluation of the human relevance of the animal MOA data. In the present paper, the MOA for rat liver tumors induced by Metofluthrin is first analyzed through this framework based on data from studies on Metofluthrin and information on related chemicals from the literature. The human relevance of the rat liver carcinogenic response is then discussed based upon the human relevance framework. Two-year treatment with high dose of Metofluthrin produced hepatocellular tumors in both sexes of the Wistar rats. Metofluthrin induced CYP2B (increased smooth endoplasmic reticulum), resulted in increased liver weights which were associated with centrilobular hepatocyte hypertrophy, and induction of increased hepatocellular DNA replications. The above parameters related to the key events in Metofluthrin-induced liver tumors were observed at or below tumorigenic dose levels. Furthermore, CYP2B induction by Metofluthrin was shown to involve activation of the constitutive androstane receptor in rat hepatocytes. Based on the evidence, including a comparison with the results with another chemical, phenobarbital, acting by a similar MOA, it is reasonable to conclude that Metofluthrin will not have any hepatocarcinogenic activity in humans.

Original languageEnglish (US)
Pages (from-to)59-68
Number of pages10
JournalToxicological Sciences
Volume108
Issue number1
DOIs
StatePublished - Mar 4 2009

Fingerprint

Pyrethrins
Liver
Rats
Tumors
Neoplasms
Hepatocytes
Chemical Safety
Smooth Endoplasmic Reticulum
Biological Science Disciplines
Phenobarbital
(2,3,5,6-tetrafluoro-4-methoxymethylphenyl)methyl-2,2-dimethyl-3-(1-propenyl)cyclopropanecarboxylate
DNA Replication
Human Activities
Hypertrophy
Wistar Rats
Animals
Chemical activation
Weights and Measures
DNA

Keywords

  • Chemical carcinogenesis
  • Conceptual framework
  • Dose-response relationships
  • Phenobarbital
  • Risk assessment

ASJC Scopus subject areas

  • Toxicology

Cite this

Case study : An evaluation of the human relevance of the synthetic pyrethroid metofluthrin-induced liver tumors in rats based on mode of action. / Yamada, Tomoya; Uwagawa, Satoshi; Okuno, Yasuyoshi; Cohen, Samuel Monroe; Kaneko, Hideo.

In: Toxicological Sciences, Vol. 108, No. 1, 04.03.2009, p. 59-68.

Research output: Contribution to journalArticle

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