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J Cancer Res Clin Oncol. 2003 Jun;129(6):335-40. Epub 2003 May 13.

High susceptibility of nullizygous p53 knockout mice to colorectal tumor induction by 1,2-dimethylhydrazine.

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Division of Oncological Pathology, Aichi Cancer Center Research Institute, Kanokoden, Chikusa-ku, 464-8681 Nagoya, Japan.



The susceptibility of male p53 nullizygote (-/-), heterozygote (+/-), and wild-type (+/+) mice to 1,2-dimethylhydrazine (DMH) induction of colon carcinogenesis was investigated.


In a preliminary short-term experiment, male mice of three genotypes were given s.c. of 20 mg/kg DMH once weekly for 5 weeks. In a medium-term experiment, mice were given weekly s.c. of DMH for 15 weeks. In a long-term experiment, male p53 (+/-) and (+/+) mice were given weekly injections of DMH for 15 weeks, and killed at week 30.


In the medium-term experiment, carcinomas were observed in 70% of p53 (-/-) mice, although there were no carcinomas in p53 (+/+) and (+/-) mice. In the long-term experiment, there was no significant difference in incidences of adenomas and carcinomas between p53 (+/+) and (+/-) mice. PCR-single strand conformation polymorphism analysis of exons 5-8 of p53 gene revealed four mutations in one focal atypia, one adenoma, and two carcinomas, out of 56 colonic proliferative lesions in the medium- and long-term experiments.


These results suggest that p53 might not be a direct target of DMH but complete loss of p53 might elevate susceptibility to DMH-induced colorectal carcinogenesis.

[Indexed for MEDLINE]

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