Steroid sulfatase activity and expression in mammary myoepithelial cells

Joanne K. Tobacman*, Marilyn Hinkhouse, Zhila Khalkhali-Ellis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Purpose: This investigation examined mRNA expression and enzymatic activity of steroid sulfatase (STS) in human mammary myoepithelial cells (MMECs) and MCF-7 cells and assessed the effects of 17-β estradiol on the activity of STS. Methods: The mRNA level of STS in MMECs was determined by RT-PCR analysis using specific primers for STS. STS enzymatic activity prior to and after treatment with 17-β estradiol was determined by measuring 3H-metabolites formed after exposure to [3H]estrone 3-sulfate (E1S) and [3H]dehydroepiandrosterone-sulfate (DHEA-S). Results: Our data demonstrate the presence of STS in the MMECs. Based on RT-PCR analysis, MMECs had slightly lower levels of STS compared to MCF-7 cells. However, sulfatase activity was about 120 times greater in the MMECs than the MCF-7 cells (E1S Vmax=2640nmol/(mg DNAh) compared to 20.9nmol/(mg DNAh)). Exposure to 17-β estradiol was associated with 70% reduction in E1S sulfatase activity in the MCF-7 cells and 9% increase in the MMECs after 6 days. Discussion: Our studies indicate for the first time the presence of STS in MMECs. This is suggestive of a previously undetermined role for MMECs in converting precursor hormones into active steroid hormones within mammary tissue. In addition, differential response of the MMECs and the MCF-7 cells to estrogen demonstrates differences in hormone metabolism between these two cell types, perhaps related to the absence of estrogen receptors in the MMECs and their presence in the MCF-7 cells. The MMECs may have an important role in hormonal regulation within mammary tissue.

Original languageEnglish (US)
Pages (from-to)65-68
Number of pages4
JournalJournal of Steroid Biochemistry and Molecular Biology
Issue number1
StatePublished - 2002


  • Dehydroepiandrosterone-sulfate
  • Estradiol
  • Estrone sulfate
  • Mammary
  • Myoepithelial cells
  • Steroid sulfatase

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Molecular Medicine
  • Molecular Biology
  • Endocrinology
  • Clinical Biochemistry
  • Cell Biology


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