Talk:Integumentary System - Mammary Gland Development

Redefining the expression and function of the inhibitor of differentiation 1 in mammary gland development

PLoS One. 2010 Aug 3;5(8):e11947.

Nair R, Junankar S, O'Toole S, Shah J, Borowsky AD, Bishop JM, Swarbrick A.

Cancer Research Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia. Abstract The accumulation of poorly differentiated cells is a hallmark of breast neoplasia and progression. Thus an understanding of the factors controlling mammary differentiation is critical to a proper understanding of breast tumourigenesis. The Inhibitor of Differentiation 1 (Id1) protein has well documented roles in the control of mammary epithelial differentiation and proliferation in vitro and breast cancer progression in vivo. However, it has not been determined whether Id1 expression is sufficient for the inhibition of mammary epithelial differentiation or the promotion of neoplastic transformation in vivo. We now show that Id1 is not commonly expressed by the luminal mammary epithelia, as previously reported. Generation and analysis of a transgenic mouse model of Id1 overexpression in the mammary gland reveals that Id1 is insufficient for neoplastic progression in virgin animals or to prevent terminal differentiation of the luminal epithelia during pregnancy and lactation. Together, these data demonstrate that there is no luminal cell-autonomous role for Id1 in mammary epithelial cell fate determination, ductal morphogenesis and terminal differentiation.

PMID: 20689821 http://www.ncbi.nlm.nih.gov/pubmed/20689821

Molecular mechanisms guiding embryonic mammary gland development

Cold Spring Harb Perspect Biol. 2010 Jun 1;2(6):a003251. Epub 2010 May 19.

Cowin P, Wysolmerski J.

Departments of Cell Biology and Dermatology, New York University School of Medicine, New York, NY 10016, USA. Abstract The mammary gland is an epidermal appendage that begins to form during embryogenesis, but whose development is only completed during pregnancy. Each mammary gland begins as a budlike invagination of the surface ectoderm, which then gives rise to a simple duct system by birth. Subsequent development occurs during sexual maturation and during pregnancy and lactation. In this review, we outline the distinct stages of embryonic mammary development and discuss the molecular pathways involved in the regulation of morphogenesis at each stage. We also discuss the potential relevance of embryonic breast development to the pathophysiology of breast cancer and highlight questions for future research.

PMID: 20484386 http://www.ncbi.nlm.nih.gov/pubmed/20484386

Editorial: The mammary stroma in normal development and function

J Mammary Gland Biol Neoplasia. 2010 Sep;15(3):275-7. Epub 2010 Sep 9.

Schedin P, Hovey RC.

Abstract The mammary gland can no longer be simply viewed as an organ composed of epithelial cells within a passive stromal microenvironment. Many lines of evidence have evolved to reinforce the notion that mammary epithelial cell growth, differentiation, lactation and progression to cancer involves bidirectional interactions between the epithelial population and its surrounding stroma. Within this stroma are numerous systems that are all capable of modulating epithelial function. In this context, the mammary stroma is not simply a depot of adipose tissue in which mammary epithelial cells undertake a unique growth and differentiation process, although adipocytes can impart numerous modulatory signals to epithelial cells, and vice versa. Rather, the stromal environment constitutes and supports a critical vasculature that supplies nutrients and endocrine cues, a lymphatic system that not only removes metabolites but also provides an intimate interface with the immune system, and an extracellular matrix scaffold in which epithelial cells grow, differentiate and regress. Ultimately all of these components play a critical role in directing the epithelial phenotype during normal mammary gland growth and function. An increasing appreciation for these different systems demands a view of mammary epithelial cells in a much different light, and further necessitates the development of model systems that incorporate and integrate increasing complexity.

PMID: 20824491 http://www.ncbi.nlm.nih.gov/pubmed/20824491