@misc{oai:repo.qst.go.jp:00061537,
 author = {Imaoka, Tatsuhiko and Okamoto, Mieko and Nishimura, Mayumi and Kakinuma, Shizuko and Shimada, Yoshiya and 今岡 達彦 and 西村 まゆみ and 柿沼 志津子 and 島田 義也},
 month = {Jun},
 note = {The ApcMin/+ (Min) mouse is a genetically predisposed model of both intestinal and mammary tumorigenesis. We investigated age-related changes in the susceptibility of mice (before, during and after puberty) to radiation-induced mammary tumorigenesis using this model. Female Min and wild-type mice having the C57BL/6J background were irradiated with 2 Gy of X-rays at 2, 5, 7 and 10 weeks and sacrificed at 18 weeks of age. Min mice irradiated at 7-10 weeks of age (after puberty) developed mammary tumors with squamous metaplasia, whereas their wild-type littermates did not. Interestingly, irradiation of Min mice at 2-5 weeks (before and during puberty, respectively) did not induce mammary tumors but rather cystic nodules with metaplasia. The mammary tumors exhibited increased nuclear beta-catenin protein and loss of the wild-type Apc allele. Our results show that susceptibility to radiation-induced mammary tumorigenesis increases after puberty in Min mice, suggesting that the tumorigenic effect of ionizing radiation targets the lobular-alveolar progenitor cells, which increase in number with age and are controlled by beta-catenin signaling.
\nReference: Imaoka T et al. (2005) Radiat. Res. 165(2):165-173., The 6th Japan-France Workshop},
 title = {Mammary tumorigenesis in ApcMin/+ mice is enhanced by X-irradiation with a characteristic age dependence},
 year = {2006}
}