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Prenatal exposure to bisphenol A, genistein and indole-3-carbinol on early mammary gland development and carcinogenesis in female Sprague-Dawley offspring

ABSTRACT: Rodent studies have indicated that gestational and perinatal bisphenol A (BPA) exposure increase the risk of developing breast cancer during adulthood. In contrast, some dietary compounds such as genistein (GEN) and indole 3-carbinol (I3C) present potential protective effects against inducing hormone-dependent cancers, including that of the mammary gland. Thus, we aimed to evaluate the role of these dietary compounds on early mammary gland development and carcinogenesis in female Sprague-Dawley offspring. Pregnant Sprague-Dawley (SD) rats were treated with BPA at 25 or 250µg/kg b.w./day by gavage from gestational day (GD) 10 to 21 with or without dietary GEN (250 mg/kg chow, ~5.5 mg/kg b.w./day) or I3C (2000 mg/kg chow, ~45.0 mg/kg b.w./day). At post-natal day (PND) 21, some female offspring from different litters were euthanized for mammary gland development and gene expression analyses while other female offspring received a single dose of N-methyl-N-nitrosourea (MNU) for mammary carcinogenesis initiation. The findings this study indicated the prenatal exposure to BPA, GEN and I3C did not significantly alter ductal elongation, number of terminal end buds (TEB) or cell proliferation, and estrogen receptor alpha (ER-α) immunostaining expression in epithelial mammary cells at PND 21. BPA treatment modulated the expression of several genes, but these changes were not associated with a dose dependent response. Dietary GEN and I3C treatment causally and consistent with the mammary gland structures outcomes. Besides, maternal BPA exposure associated with dietary GEN and I3C did not alter the susceptibility to the mammary cancer development in adulthood when the carcinogen was administered in a window of immature mammary gland development.

ORGANISM(S): Rattus norvegicus

PROVIDER: GSE68973 | GEO | 2016/06/03

SECONDARY ACCESSION(S): PRJNA284241

REPOSITORIES: GEO

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Project description:The role of diet in the prevention of breast cancer is widely accepted, yet little is known on how early dietary effects mitigate adult cancer risk. Soy consumption is associated with reduced breast cancer risk in women, an effect largely attributed to the soy isoflavone genistein (GEN). We previously showed lower chemically-induced mammary tumor incidence in young adult rats with lifetime dietary intake of soy protein isolate (SPI), a highly refined soy product in infant formula, than in those fed the control diet Casein (CAS). To gain insight into signaling pathways underlying dietary tumor protection, we performed genome-wide expression profiling of mammary epithelial cells from young adult rats lifetime fed CAS, SPI, or supplemental GEN-based diets. We identified mammary epithelial genes regulated by SPI (79 total) and GEN (99 total) using Affymetrix rat 230A GeneChip arrays and found minimal overlap in gene expression patterns. We showed that the regulated transcripts functionally cluster in biochemical pathways involving metabolism, immune response, signal transduction, and ion transport. We confirmed the differential expression of Wnt (Wnt5a, Sfrp2) and Notch (Notch2, Hes1) signaling components by SPI and/or GEN using QPCR. Wnt pathway inhibition by GEN was supported by lower Cyclin D1 immunoreactivity in mammary ductal epithelium of GEN relative to CAS and SPI, despite their comparable levels of membrane-localized E-cadherin and Î²-catenin. Identification of distinct GEN and SPI responsive genes in mammary epithelial cells may define early events contributing to tumor protection by diet relevant to the prevention of breast and other types of cancer. Experiment Overall Design: Female Sprague-Dawley rats, fed one of the three purified diets, were studied at postnatal day50. Total RNA( each RNA samples were extracted from #4 mammary gland from two animals under the same diet group) purified from non-tumor tissue within the proximal half of each colon, was used to prepare biotinylated probes, which were hybridized to Affymetrix RAE230 rat microarrays.

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Prenatal exposure to bisphenol A, genistein and indole-3-carbinol on early mammary gland development and carcinogenesis in female Sprague-Dawley offspring

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