Modulation of trophoblast cell death by oxygen and EGF

Mol Med. 2002 Dec;8(12):847-56.

Abstract

Background: Preeclampsia, a maternal hypertensive disease, is characterized by shallow invasion of the maternal spiral arterioles resulting in hypoxia/reperfusion type insult; however, the molecular mechanism is unknown. The aim of this study was to determine the mechanism of altered oxygen tension or inhibition of phosphatidyl-inositol-3-kinase (PI3K) on trophoblast survival and to investigate the effect of epidermal growth factor (EGF) on maintaining cellular integrity.

Materials and method: We have used flow cytometry, immunoblotting, and fluoroimmunocytochemistry to study apoptosis in a characterized, spontaneously transformed first trimester extravillous-like trophoblast cell line that exhibits many characteristics of in vivo trophoblast.

Results: Time-dependent exposure of first trimester extravillous-like trophoblast to all oxygen tensions tested promoted dissipation of the mitochondrial membrane potential (psi(m)) and resulted in a significant increase in celldeath by 48 hr as determined by dual staining flow cytometry. Western blot analysis revealed expression ofcleaved caspase-3 and caspase-9 increased with time with hypoxia and hyperoxia promoting the greatest elevation indicating that longer duration of exposure to a change inoxygen tension causes increased apoptosis via a mitochondrial-mediated pathway. Disruption of the anti-apoptotic PI3K pathway by LY294002 (40 microM), its specific inhibitor, caused further significant dissipation of the psi(m) (p< 0.01) and cleavage of caspase-3. EGF was able to maintain the psi(m) and to prevent cleavage of caspase-3 even in the presence of LY294002, indicating that its survival effects were independent of the PI3K pathway.

Conclusions: These results suggest that inhibition of the PI3K/Akt pathway can sensitize first-trimester trophoblast-like cells into oxygen-induced cell death and that EGF exerts its anti-apoptotic effect independently of PI3K/Akt.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Caspases / metabolism
  • Cell Death / drug effects
  • Cell Death / physiology*
  • Cell Line
  • Culture Media
  • Epidermal Growth Factor / metabolism*
  • Epidermal Growth Factor / pharmacology
  • Flow Cytometry
  • Humans
  • Oxygen / metabolism*
  • Oxygen / pharmacology
  • Phosphoinositide-3 Kinase Inhibitors
  • Trophoblasts / metabolism*

Substances

  • Culture Media
  • Phosphoinositide-3 Kinase Inhibitors
  • Epidermal Growth Factor
  • Caspases
  • Oxygen