title: Differential response to acute low dose radiation in primary and immortalized endothelial cells.
abstract: OBJECTIVE
  The low dose radiation response of primary human umbilical vein endothelial cells (HUVEC) and its immortalized derivative, the EA.hy926 cell line, was evaluated and compared.
  
  
  METHODS
  DNA damage and repair, cell cycle progression, apoptosis and cellular morphology in HUVEC and EA.hy926 were evaluated after exposure to low (0.05-0.5 Gy) and high doses (2 and 5 Gy) of acute X-rays.
  
  
  RESULTS
  Subtle, but significant increases in DNA double-strand breaks (DSB) were observed in HUVEC and EA.hy926 30 min after low dose irradiation (0.05 Gy). Compared to high dose irradiation (2 Gy), relatively more DSB/Gy were formed after low dose irradiation. Also, we observed a dose-dependent increase in apoptotic cells, down to 0.5 Gy in HUVEC and 0.1 Gy in EA.hy926 cells. Furthermore, radiation induced significantly more apoptosis in EA.hy926 compared to HUVEC.
  
  
  CONCLUSIONS
  We demonstrated for the first time that acute low doses of X-rays induce DNA damage and apoptosis in endothelial cells. Our results point to a non-linear dose-response relationship for DSB formation in endothelial cells. Furthermore, the observed difference in radiation-induced apoptosis points to a higher radiosensitivity of EA.hy926 compared to HUVEC, which should be taken into account when using these cells as models for studying the endothelium radiation response.
authors.affiliation: Radiobiology Unit, Belgian Nuclear Research Centre (SCK•CEN) , Mol , Belgium.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Rombouts
authors.forename: An
authors.initials: A
authors.lastname: Aerts
authors.forename: Michael
authors.initials: M
authors.lastname: Beck
authors.forename: Winnok H
authors.initials: WH
authors.lastname: De Vos
authors.forename: Patrick
authors.initials: P
authors.lastname: Van Oostveldt
authors.forename: Mohammed Abderrafi
authors.initials: MA
authors.lastname: Benotmane
authors.forename: Sarah
authors.initials: S
authors.lastname: Baatout
mesh_terms: D017209:Apoptosis / Q000528:radiation effects; D059447:Cell Cycle Checkpoints / Q000528:radiation effects; D002460:Cell Line; D002478:Cells, Cultured; D004249:DNA Damage; D004307:Dose-Response Relationship, Radiation; D023381:Endpoint Determination; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D006801:Humans; D014965:X-Rays