Effects of BRCA1 transgene expression on murine mammary gland development and mutagen-induced mammary neoplasia

Arichika Hoshino, Cindy J. Yee, Mel Campbell, Randall L. Woltjer, Rebecca L. Townsend, Riet Van Der Meer, Yu Shyr, Jeffrey T. Holt, Harold L. Moses, Roy A. Jensen

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

To characterize the role of BRCA1 in mammary gland development and tumor suppression, a transgenic mouse model of BRCA1 overexpression was developed. Using the mouse mammary tumor virus (MMTV) promoter/enhancer, transgenic mice expressing human BRCA1 or select mutant controls were generated. Transgenic animals examined during adolescence were shown to express the human transgene in their mammary glands. The mammary glands of 13-week-old virgin homozygous MMTV-BRCA1 mice presented the morphology of moderately increased lobulo-alveolar development. The mammary ductal trees of both hemizygous and homozygous MMTV-BRCA1t340 were similar to those of control non-transgenic littermates. Interestingly, both hemi- and homozygous mice expressing a splice variant of BRCA1 lacking the N-terminal RING finger domain (MMTV-BRCA1sv) exhibited marked mammary lobulo-alveolar development, particularly terminal end bud proliferation. Morphometric analyses of mammary gland whole mount preparations were used to measure epithelial staining indices of ∼35% for homozygous MMTV-BRCA1 mice and ∼60% for both hemizygous and homozygous MMTV-BRCA1sv mice versus ∼25% for non-transgenic mice. Homozygous MMTV-BRCA1 mice showed delayed development of tumors when challenged with 7,12 dimethylbenzanthracene (DMBA), relative to non-transgenic and homozygous BRCA1t340 expressing mice. In contrast, homozygous MMTV-BRCA1sv transgenic animals were sensitized to DMBA treatment and exhibited a very rapid onset of mammary tumor development and accelerated mortality. MMTV-BRCA1 effects on mortality were restricted to DMBA-induced tumors of the mammary gland. These results demonstrate in vivo roles for BRCA1 in both mammary gland development and in tumor suppression against mutagen-induced mammary gland neoplasia.

Original languageEnglish (US)
Pages (from-to)281-291
Number of pages11
JournalInternational Journal of Biological Sciences
Volume3
Issue number5
DOIs
StatePublished - Apr 25 2007

Keywords

  • BRCA1 gene
  • Mammary gland development
  • Transgenic mice

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Applied Microbiology and Biotechnology
  • Molecular Biology
  • Developmental Biology
  • Cell Biology

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