The effect of prepubertal exposure to Bispenol A on rat mammary gland morphology and gene expression.

Zachary Rotter*; Julia S. Pereira; Ricardo Lopez; Fathima Sheriff; Kara Snider and Jose Russo.
Breast Cancer Research Laboratory, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA.

Bisphenol A (BPA), formerly called 4,4’- dihydroxy- 2,2-diphenylpropane, is a commonly used chemical found in re-microwaveable baby bottles and the polycarbonate lining of plastic bottles. BPA is found in normal levels in the environment, mostly as a byproduct of industrial processes. Studies have shown that the levels of BPA found in the environment are non-hazardous to human health. However, research also suggests that BPA could lead to breast cancer since BPA is an endocrine disruptor, meaning it can mimic the hormones that have a functional role in the body. Due to these properties it was of interest to determine if BPA could alter the terminal end buds (TEBs) structures of the mammary gland, which are the target of carcinogenesis.. For this purpose we have analyzed the effects of prepubertal exposure to BPA on the 50 days old rat’s mammary gland. Nursing rats received, through gavage, 250 µg/kg body weight of BPA, during 21 days from the delivery to weaning. The female offspring were sacrificed when they reached 50 days of age. Their abdominal mammary glands were extracted and used for whole mount preparation for TEB counting, or gene expression analysis through cDNA-microarrays. The results indicated a slight decrease in the number of TEBs in mammary glands of the treated rats when compared to the control group. However, the gene expression analysis revealed changes in expression of numerous genes reported in breast cancers, such as Vav2, Nfkb1, Tnsrf11a, and Mycn. We have concluded that although prepubertal exposure to BPA does not affect significantly the rat mammary gland morphology of 50 day old rats when compared to the control group, the compound has an effect on the rat’s gene expression. BPA altered the expression of some genes that have been reported in primary breast cancer as well as in the inflammatory type.. (Zachary Rotter was supported by Huntington Breast Cancer Action Coalition fellowship, Huntington, NY, and this work was supported by NCI and NIEHS Grant UO1 ES012

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