The role that each of the Notch receptors play in controlling alveolar development and cell fate determination in the mouse mammary gland has remained unclear. By utilizing a cre-conditional constitutively active intracellular Notch1 knock-in I define, in vivo, that ectopic Notch1 activation is sufficient to inhibit ductal outgrowth, cause the formation of alveolar-like cell accumulations, and promote Elf5+/ER- cell fate, at the expense of ER+ cell fate, in the mammary gland of pubescent mice. Furthermore, ectopic Notch1 in the pregnant mammary gland is sufficient to promote the formation of pregnancy/lactation-dependent lactating adenomas. These lactating adenomas consist of differentiated secretory cells and normally regress during involution but progress into non-regressing tumours after multiple pregnancies. These lactating adenomas exhibit decapitation secretions characteristic of apocrine differentiation. Together these results suggest that Notch1 may function to promote Elf5+/ER- cell fate and may be misregulated in pregnancy-associated masses and apocrine-carcinoma of the breast in humans.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/18800 |
| Date | 14 February 2010 |
| Creators | Kucharczuk, Aaron |
| Contributors | Egan, Sean |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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