Estrogen exerts a spatial and temporal influence on reactive oxygen species generation that precedes calcium uptake in high-capacity mitochondria: implications for rapid nongenomic signaling of cell growth

Biochemistry. 2006 Mar 7;45(9):2872-81. doi: 10.1021/bi051855x.


Novel findings that emerged from this study underscore the fact that the dynamic nature of mitochondria leads to functional heterogeneity of [Ca(2+)](mito) with respect to estrogen actions in MCF7 cells. We show that estrogen exposure to cells increased [Ca(2+)](mito) in a high-calcium capacity mitochondrial population but not in low-calcium capacity mitochondria. Physiological concentrations of 17beta-estradiol (E2) modulated Ca(2+)(mito) uptake within 90 s. Interestingly, this calcium response lagged behind the induction of mitochondrial reactive oxygen species (mtROS). The rapid induction of Ca(2+)(mito) in response to E2 and its inhibition by mitochondrial blockers suggest that mitochondria are early nongenomic targets of E2. This suggests that a subpopulation of mitochondria is recruited to respond to new metabolic requirements required by estrogen triggers or, as in this case, E2-induced Ca(2+)(mito) and/or mtROS promotes oxidative signaling without involving nuclear estrogen receptor signaling. Although the early E2-induced Ca(2+) did not alter the expression of genes involved in calcium signaling pathways, an intracellular calcium chelator BAPTA-AM and the Ca(2+)(mito) uniporter blocker ruthenium red prevented E2-induced cell growth. We have shown recently that E2-mediated ROS production controls the promoter activity of cyclin D1 by post-translational modification of calcium sensitive transcription factor CREB. The findings of this study offer a new paradigm that rapid E2-induced changes in mtROS and Ca(2+)(mito) are involved in cell cycle progression presumably through the control of early cell cycle genes. Targeting mitochondria to disrupt communication between mitochondria and ROS/Ca(2+) signaling pathways may provide the basis for a novel anticancer strategy for the treatment of estrogen-dependent breast cancer.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Breast Neoplasms / metabolism
  • Calcium / metabolism*
  • Cell Proliferation
  • Enzyme Inhibitors / metabolism
  • Enzyme Inhibitors / pharmacology
  • Estrogens / metabolism
  • Estrogens / pharmacology*
  • Female
  • Humans
  • Microscopy, Confocal
  • Mitochondria / drug effects
  • Mitochondria / metabolism*
  • Reactive Oxygen Species / metabolism*
  • Signal Transduction*
  • Time Factors
  • Tumor Cells, Cultured


  • Enzyme Inhibitors
  • Estrogens
  • Reactive Oxygen Species
  • Calcium