Di(2-ethylhexyl)phthalate Induces Hepatocellular Adenoma in Transgenic Mice Carrying a Human Prototype c-Ha-ras Gene in a 26-Week Carcinogenicity Study

Abstract

To evaluate the transgenic mouse carrying a human prototype c-Ha-ras gene (rasH2 mouse) as a model for 26-week carcinogenicity tests, Di(2-ethylhexyl)phthalate (DEHP), a peroxisome proliferator, was administered to 15 rasH2 mice/sex/group at concentrations of 1,500, 3,000 or 6,000 ppm, and to 15 wild-type (non-Tg) mice/sex/group at a concentration of 6,000 ppm in their diets for 26 weeks. Survival rates and food consumption in the groups treated with DEHP and in the control group were similar. Body weight gain in rasH2 and non-Tg mice at 6,000 ppm in the terminal week decreased about 10% as compared to the control group. Common findings related to treatment with DEHP in rasH2 and non-Tg mice included hypertrophy with coarse granules and deposit of pigment in the liver, hydronephrosi s and tubular regeneration in the kidney, focal atrophy in the testis, and increased eosinophilic body in the nasal cavity. Hepatocellular adenoma was induced by treatment with DEHP, and was confined to male rasH2; mice the incidence being 7%(1/15), 13%(2/15), and 27%(4/15) in the 1,500-, 3,000-, and 6,000-ppm group, respectively. Point mutation was not detected in codon 12 and 61 of human c-Ha-ras transgene upon DNA analyses on frozen samples taken from these hepatocellular adenomas. From the results obtained in this 26-week carcinogenicity study, it is concluded that DEHP is a hepato-carcinogen for transgenic mouse carrying a human prototype c-Ha-ras gene.

Keywords

Human prototype c-Ha-ras transgenic mice rasH2 mice Di(2-ethylhexyl)phthalate (DEHP)peroxisome proliferator rodent carcinogen 26-week carcinogenicity study transgenic mouse model alternatives to carcinogenicity testing.

References

Ando K. , Saitoh A. , Hino O. , Takahashi R. , Kimura M. , Katsuki M. (1992). Chemically induced forestomach papillomas in transgenic mice carrying mutant human c-Ha-ras transgenes. Cancer Res 52: 978—982.

Dahl GA , Miller EC , Miller JA (1980). Comparative carcinogenicities and mutagenicities of vinyl carbamate, ethyl carbamate, and ethyl N-hydroxycarbamate. Cancer Res 40: 1194—1203.

Grasso P. (1993). Hepatic changes associated with peroxisome proliferation . In: Peroxisomes: Biology and Importance in Toxicology and Medicine, Gibson G and Lake B (eds). Taylor and Francis Ltd , London, pp 639— 651.

Hayashi S. , Mori I. , Nonoyama T. , Mitsumori K. (1998). Point mutation of the c-Ha-ras gene in spontaneous liver tumors of transgenic mice carrying the human c-Ha-ras gene. Toxicol Pathol 26: 556—561.

Huber WW , Grasl-Kraupp B. , Schulte-Hermann R. (1996). Hepatocarcinogenic potential of di(2-ethylhexyl)phthalate in rodents and its implications on human risk. Crit Rev Toxicol 26: 365—481.

International Agency for Research on Cancer ( 1978). N-Nitrosodiethylamine. In: IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemical s to Humans Vol.17, Some N-Nitroso Compounds, International Agency for Research on Cancer, Lyon, France, pp 83—124.

Kluwe WM , Haseman JK , Douglas JF , Huff JE ( 1982). The carcinogenicity of dietary di(2-ethylhexyl)phthalate (DEHP) in Fischer 344 rats and B6C3F1 mice. J Toxicol Environ Health 10: 797—815.

Mitsumori K. , Wakana S. , Yamamoto S. , Kodama Y. , Yasuhara K. , Nomura T. , Hayashi Y. , Maronpot RR (1997). Susceptibility of transgenic mice carrying human prototype c-Ha-ras gene in a short-term carcinogenicity study of vinyl carbamate and ras gene analyses on the induced tumors. Mol Carcinog 20: 298—307.

Mitsumori K. , Koizumi H. , Nomura T. , Yamamoto S. (1998). Pathological features of spontaneous and induced tumors in transgenic mice carrying a human prototype c-Ha-ras gene used for six-month carcinogenicity studies. Toxicol Pathol 26: 520—531.

10.

National Cancer Institute/National Toxicology Program (1981). NTP Technical Report on the Carcinogenesis Assay of Di(2-ethyl hexyl)phthalate. CAS No. 117-81-7, NTP-80-37. DHHS Publication No. (NIH) 81—1773.

11.

National Toxicology Program ( 1993a). TR-47 Bioassay of 4,4'-thiodianiline for possible carcinogenicity (CAS:139-65-1). Environ Health Perspect 101(suppl.1): 30.

12.

National Toxicology Program ( 1993b). TR-80 Bioassay of 1,4-dioxane for possible carcinogenicity (CAS:123-91-1). Environ Health Perspect 101(suppl.1): 50.

13.

National Toxicology Program ( 1993c). TR-142 Bioassay of p-cresidine for possible carcinogenicity (CAS:120-71-8). Environ Health Perspect 101(suppl.1): 81—82.

14.

National Toxicology Program ( 1993d). Toxicology and carcinogenesi s studies of furfural (CAS:98-01-1) in F344/N rats and B6C3F1 mice (gavage studies). Environ Health Perspect 101 (suppl 1): 260—261.

15.

National Toxicology Program ( 1993e). Toxicology and carcinogenesi s studies of ethylene thiourea (CAS:96-45-7) in F344 rats and B6C3F1 mice (feed studies). Environ Health Perspect 101 (suppl 1): 264—266.

16.

Reddy JK , Lalwani ND (1983). Carcinogenesi s by hepatic peroxisome proliferators: Evaluation of the risk of hypolipidemi c drugs and industrial plasticizers to human. Crit Rev Toxicol 12: 1—58.

17.

Saitoh A. , Kimura M. , Takahashi R. , Yokoyama M. , Nomura T. , Izawa M. , Sekiya T. , Nishimura S. , Katsuki M. (1990). Most tumors in transgenic mice with human c-Ha-ras gene contained somatically activated transgenes. Oncogene 5: 1195—1200.

18.

Ward JM , Diwan BA , Ohshima M. , Hu H. , Schuller HM , Rice JM ( 1986). Tumor-initiating and promoting activities of di(2-ethylhexyl)phthalate in vivo and in vitro. Environ Health Perspect 65: 279—291.

19.

Ward JM , Peter JM , Perella CM , Gonzalez FJ (1998). Receptor and Nonreceptor-mediated organ-specific toxicity of di(2-ethylhexyl)phthalate (DEHP) in peroxisome proliferator- activated receptor α-null mice. Toxicol Pathol 26: 240—246.

20.

Yamamoto S. , Mitsumori K. , Kodama Y. , Matsunuma N. , Manabe S. , Okamiya H. , Suzuki H. , Fukuda T. , Sakamaki Y. , Sunaga M. , Nomura G. , Hioki K. , Wakana S. , Nomura T. , Hayashi Y. (1996). Rapid induction of more malignant tumors by various genotoxic carcinogens in transgenic mice harboring human prototype c-Ha-ras gene than in control nontransgenic mice. Carcinogenesis 17: 2455—2461.

21.

Yamamoto S. , Hayashi Y. , Mitsumori K. , Nomura T. (1997). Rapid carcinogenicity testing system with transgenic mice harboring human prototype c-Ha-ras gene . Lab Anim Sci 47: 121—126.

22.

Yamamoto S. , Urano K. , Koizumi H. , Wakana S. , Hioki K. , Mitsumori K. , Kurokawa K. , Hayashi Y. , Nomura T. (1998). Validation of transgenic mice carrying the human prototype c-Ha-ras gene as a bioassay model for rapid carcinogenicity testing. Environ Health Perspect 106 (suppl 1): 57—69.