This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sheffield, L. G. Search for Related Content PubMed PubMed Citation Articles by Sheffield, L. G. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Hazardous Substances DB ESTRADIOL HYDROCORTISONE Medline Plus Health Information Hormones

Hormonal Regulation of Epidermal Growth Factor Receptor Content and Signaling in Bovine Mammary Tissue¹

Dairy Science Department, University of Wisconsin, Madison, Wisconsin 53706

Address all correspondence and requests for reprints to: Dr. Lewis G. Sheffield, Dairy Science Department, University of Wisconsin, 1675 Observatory Drive, Madison, Wisconsin 53706.

Mammary tissue from midpregnant heifers was cultured with epidermal growth factor (EGF) or transforming growth factor for 1–3 days. After 1 day, 10 nM EGF or transforming growth factor doubled DNA synthesis, whereas lower concentrations (0.1 or 1 nM) increased DNA synthesis 2- to 3-fold after 2–3 days in culture. In other studies, bovine mammary tissue was transplanted to ovariectomized athymic mice and treated for 10 days with saline, estradiol (1 µg/day), progesterone (1 mg/day), or estradiol + progesterone. Subsequent explant culture of the bovine tissue indicated that estradiol + progesterone augmented the ability of EGF to stimulate DNA synthesis. The increased response to EGF was associated with increased EGF binding and with increased EGF-induced tyrosine kinase that paralleled the increased EGF binding. In other studies, athymic mice bearing xenografted bovine mammary tissue were primed for 10 days with estradiol and progesterone, followed by 2-day treatment with saline (control), hydrocortisone (200 µg/day), PRL (1 mg/day), or hydrocortisone + PRL. Hydrocortisone and PRL alone decreased, and PRL + hydrocortisone eliminated, EGF-induced DNA synthesis. EGF receptor content was unaffected by hydrocortisone but was reduced by PRL or hydrocortisone + PRL. Furthermore, the ability of EGF to induce tyrosine kinase activity was decreased by PRL and by hydrocortisone + PRL. The decreased kinase activity was greater than the decrease in receptor binding, suggesting a specific modulation of EGF receptor kinase activity in response to lactogenic hormones.

This article has been cited by other articles:

				R. M. Akers Major advances associated with hormone and growth factor regulation of mammary growth and lactation in dairy cows. J Dairy Sci, April 1, 2006; 89(4): 1222 - 1234. [Abstract] [Full Text] [PDF]

				V. C.-L. Lin, E. H. Ng, S. E. Aw, M. G.-K. Tan, E. H.-L. Ng, and B. H. Bay Progesterone Induces Focal Adhesion in Breast Cancer Cells MDA-MB-231 Transfected with Progesterone Receptor Complementary DNA Mol. Endocrinol., March 1, 2000; 14(3): 348 - 358. [Abstract] [Full Text]