Ana Soto, M.D.
NIEHS grantees developed a new method, using mouse mammary tissue, to test the direct effects of estrogen and estrogen-like substances on the developing mammary gland. Because the method completely isolates the fetal mammary glands from the mouse embryo, it removes the potential joint effects of maternal estrogen.
In previous studies, it was difficult to determine whether observed effects of bisphenol-A (BPA) were caused by estrogen-like activity or by other effects. This was because the estrogen-like chemicals interfered with maternal estrogens and could interrupt pregnancy. In the absence of maternal estrogen, researchers can isolate the effects of estrogen and estrogen-like chemical exposures on the development of fetal mammary tissue.
The researchers tested BPA, an estrogen-like chemical found in plastics, with the new method. They found that environmental levels of BPA significantly increased the growth of mammary gland tissue in the absence of natural estrogens that were previously linked to increased risk of breast cancer in adulthood. The findings show that BPA at low doses acts directly on the fetal mammary gland and leads to effects previously observed in other animal model studies.
Citation: Speroni L, Voutilainen M, Mikkola ML, Klager SA, Schaeberle CM, Sonnenschein C, Soto AM. 2017. New insights into fetal mammary gland morphogenesis: differential effects of natural and environmental estrogens. Sci Rep 7:40806.