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Alterations in mammary gland development following neonatal exposure to estradiol, transforming growth factor α, and estrogen receptor antagonist ICI 182,780
Author(s) -
HilakiviClarke Leena,
Cho Elizabeth,
Raygada Margarita,
Kenney Nicholas
Publication year - 1997
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/(sici)1097-4652(199703)170:3<279::aid-jcp9>3.0.co;2-l
Subject(s) - endocrinology , medicine , mammary gland , estrogen , estrogen receptor , biology , transforming growth factor , estrogen receptor alpha , transforming growth factor beta , breast cancer , cancer
High fetal/early postnatal levels of estrogen increase breast cancer risk, but the mechanisms remain unknown. Growth factors, such as transforming growth factor α (TGFα), may participate as secondary modifiers in this process. We characterized a modulatory role of early postnatal exposure to 17β‐estradiol (E 2 ) on the developing mammary gland morphology by treating intact female CD‐1 mice with physiological doses of E 2 (2–4 μg), human recombinant TGFα (4 μg), or an estrogen receptor (ER) antagonist ICI 182,780 (20 μg) during postnatal days 1–3. Early postnatal exposure of E 2 stimulated mammary ductal growth by days 25 and 35, but by day 50 this was inhibited. The level of differentiation from terminal end buds (TEBs) to the lobulo‐alveolar units (LAUs) also was reduced by day 50. The number of TEBs was increased throughout most of the development in the female mice exposed to E 2 during early life. An exposure to TGFα or ICI 182,780 between postnatal days 1 and 3 stimulated ductal growth, formation of TEBs, and the differentiation of mammary epithelial structures. ICI 182,80 treatment also caused hyperplastic lobular‐like structures in 54‐day‐old females. Thus, neonatal exposure to TGFα and ICI 182,780 induced both similar (increase in TEBs) and different (increase/decrease in lobulo‐alveolar differentiation) developmental changes in the mouse mammary gland, when compared with an exposure to E 2 . A unique feature of the postnatal E 2 treatment was that it inhibited ductal migration by days 50–54. Our data suggest than an exposure to E 2 on postnatal days 1–3, possibly combined with secondary epigenetic alterations, leads to various changes within the developing mammary tree. These changes may be potential prerequisites for mammary tumorigenesis. J. Cell. Physiol. 170:279–289, 1997. © 1997 Wiley‐Liss, Inc.