Pregnancy and stem cell behavior

Kay Uwe Wagner, Gilbert H. Smith

Research output: Contribution to journalReview articlepeer-review

48 Scopus citations


The identification of cancer-initiating epithelial subtypes (i.e. cancer stem cells) is important for gaining a more comprehensive understanding of the process of neoplastic transformation and tumorigenesis. Since reproductive history has a major impact on breast tumorigenesis, it is reasonable to assume that pregnancy and lactation have enduring effects on the cancer susceptibility of multipotent progenitors. Using the Cre-lox technology as a tool to genetically label pregnancy-hormone-responsive cells, we identified a mammary epithelial subtype that is abundant in parous females. These pregnancy-induced mammary epithelial cells (PI-MECs) originate from differentiating cells during the first pregnancy and lactation cycle. They do not undergo apoptosis during postlactational remodeling, and they persist throughout the remainder of a female's life. In this review, we discuss the biological relevance of PI-MECs in multiparous females and their important stem cell-like features, such as self renewal, as well as their ability to produce progeny with diverse cellular fates. Using appropriate animal models, we further demonstrate that PI-MECs are cellular targets for pregnancy-enhanced mammary tumorigenesis.

Original languageEnglish (US)
Pages (from-to)25-36
Number of pages12
JournalJournal of mammary gland biology and neoplasia
Issue number1
StatePublished - Jan 2005


  • Cre recombinase
  • Differentiation
  • ErbB2
  • MMTV
  • Mammary gland
  • Parity-induced mammary epithelial cells
  • Stem cells
  • Tumorigenesis

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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