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Mapping of Three Genetic Determinants of Susceptibility to Estrogen-Induced Mammary Cancer within the Emca8 Locus on Rat Chromosome 5

ABSTRACT: We are using the ACI rat model of 17beta-estradiol induced mammary cancer to define the mechanisms through which estrogens contribute to breast cancer development; identify and functionally characterize the genetic variants that determine susceptibility; and define the hormone-gene-environment interactions that influence development of mammary cancer in this physiologically relevant rat model. Female ACI rats are uniquely susceptible to development of mammary cancer when treated continuously with physiologic levels of 17beta-estradiol. Induction of mammary cancer in female ACI rats occurs through a mechanism that is largely dependent upon estrogen receptor-alpha. Interval mapping analyses of progeny generated in intercrosses between susceptible ACI rats and resistant Brown Norway (BN) rats revealed seven quantitative trait loci (QTL), designated Emca3 (Estrogen-induced mammary cancer) through Emca9, each of which harbors one or more genetic determinants of mammary cancer susceptibility. Genes that reside within Emca8 on RNO5 and were differentially expressed between 17beta-estradiol treated ACI and ACI.BN-Emca8 congenic rats were identified as Emca8 candidates.

ORGANISM(S): Rattus norvegicus

PROVIDER: GSE39788 | GEO | 2013/02/08

SECONDARY ACCESSION(S): PRJNA171714

REPOSITORIES: GEO

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Project description:We are using ACI and BN rats, which differ markedly in their susceptibility to 17beta-Estradiol (E2)-induced mammary cancer, to identify genetic variants and environmental factors that determine mammary cancer susceptibility. The objective of this study was to characterize the cellular and molecular responses to E2 in the mammary glands of ACI and BN rats to identify qualitative and quantitative phenotypes that associate with and/or may confer differences in susceptibility to mammary cancer. Female ACI and BN rats were treated with E2 for 1, 3 or 12 weeks and cell proliferation, apoptosis, differentiation and gene expression were evaluated. The luminal epithelium of ACI rats exhibited a rapid and sustained proliferative response to E2. By contrast, the proliferative response exhibited by the mammary epithelium of BN rats was restrained and transitory. Moreover, the epithelium of BN rats appeared to undergo differentiation in response to E2, as evidenced by production of milk proteins as well as luminal ectasia and associated changes in the extracellular matrix (ECM). Marked differences in expression of genes that encode proteins with well-defined roles in mammary gland development (Pgr, Wnt4, Tnfsf11, Prlr, Stat5a, Areg, Gata3), differentiation and milk production (Lcn2, Spp1), regulation of extracellular environment (Mmp7, Mmp9), and cell-cell or cell-ECM interactions (Cd44, Cd24, Cd52) were observed. We propose that these cellular and molecular phenotypes are heritable and may underlie, at least in part, the differences in mammary cancer susceptibility exhibited by ACI and BN rats. Two groups of 17beta-estradiol treated female rats were compared. Five ACI and five BN rats were treated with 17beta-estradiol for 12 weeks. Total RNA was isolated from the mammary glands of these animals, labeled, and hybridized to Affymetrix Rat Genome 230 2.0 Arrays (Affymetrix Inc.). Significantly differentially expressed genes were found between these groups.

Dataset Information

Mapping of Three Genetic Determinants of Susceptibility to Estrogen-Induced Mammary Cancer within the Emca8 Locus on Rat Chromosome 5

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