Hormone-Sensing Mammary Epithelial Progenitors: Emerging Identity and Hormonal Regulation

Gerard A. Tarulli, Geraldine Laven-Law, Reshma Shakya, Wayne D. Tilley, Theresa E. Hickey

Research output: Contribution to journalReview articlepeer-review

12 Citations (Scopus)


The hormone-sensing mammary epithelial cell (HS-MEC—expressing oestrogen receptor-alpha (ERα) and progesterone receptor (PGR)) is often represented as being terminally differentiated and lacking significant progenitor activity after puberty. Therefore while able to profoundly influence the proliferation and function of other MEC populations, HS-MECs are purported not to respond to sex hormone signals by engaging in significant cell proliferation during adulthood. This is a convenient and practical simplification that overshadows the sublime, and potentially critical, phenotypic plasticity found within the adult HS-MEC population. This concept is exemplified by the large proportion (~80 %) of human breast cancers expressing PGR and/or ERα, demonstrating that HS-MECs clearly proliferate in the context of breast cancer. Understanding how HS-MEC proliferation and differentiation is driven could be key to unraveling the mechanisms behind uncontrolled HS-MEC proliferation associated with ERα- and/or PGR-positive breast cancers. Herein we review evidence for the existence of a HS-MEC progenitor and the emerging plasticity of the HS-MEC population in general. This is followed by an analysis of hormones other than oestrogen and progesterone that are able to influence HS-MEC proliferation and differentiation: androgens, prolactin and transforming growth factor-beta1.

Original languageEnglish
Pages (from-to)75-91
Number of pages17
Issue number1-2
Publication statusPublished - Jun 2015
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported by grants from the National Health and Medical Research Council of Australia (ID 1008349; ID 1084416) and Cancer Australia (ID 627229), the National Breast Cancer Foundation (ID PS-15-041), a Fellowship Award from the US Department of Defense Breast Cancer Research Program (BCRP; W81XWH-11-1-0592) and a Florey Fellowship from the Royal Adelaide Hospital Research Foundation.

Publisher Copyright:
© 2015, Springer Science+Business Media New York.


  • Androgen
  • Endocrine hormones
  • Hormone-sensing cells
  • Luminal progenitors
  • Prolactin


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