335. Cancer Res. 2000 Jan 15;60(2):321-7.
Radiation-induced apoptosis of endothelial cells in the murine central nervous
system: protection by fibroblast growth factor and sphingomyelinase deficiency.
Peña LA(1), Fuks Z, Kolesnick RN.
Author information:
(1)Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New
York, New York 10021, USA.
Injury to the central nervous system (CNS) by ionizing radiation may be a
consequence of damage to the vascular endothelium. Recent studies showed that
radiation-induced apoptosis of endothelial cells in vitro and in the lung in vivo
is mediated by the lipid second messenger ceramide via activation of acid
sphingomyelinase (ASM). This apoptotic response to radiation can be inhibited by
basic fibroblast growth factor or by genetic mutation of ASM. In the CNS,
single-dose radiation has been shown to result in a 15% loss of endothelial cells
within 24 h, but whether or not this loss is associated with apoptosis remains
unknown. In the present studies, dose- and time-dependent induction of apoptosis
was observed in the C57BL/6 mouse CNS. Apoptosis was quantified by terminal
deoxynucleotidyl transferase-mediated nick end labeling, and specific endothelial
apoptosis was determined by histochemical double labeling with terminal
deoxynucleotidyl transferase-mediated nick end labeling and Lycopersicon
esculentum lectin. Beginning at 4 h after single-dose radiation, apoptosis was
ongoing for 24 h and peaked at 12 h at an incidence of 0.7-1.4% of the total
cells in spinal cord sections. Up to 20% of the apoptotic cells were endothelial.
This effect was also seen in multiple regions of the brain (medulla, pons, and
hippocampus). A significant reduction of radiation-induced apoptosis was observed
after i.v. basic fibroblast growth factor treatment (0.45-4.5 microg/mouse).
Identical results were noted in C3H/HeJ mice. Furthermore, irradiated ASM
knockout mice displayed as much as a 70% reduction in endothelial apoptosis. This
study demonstrates that ionizing radiation induces early endothelial cell
apoptosis throughout the CNS. These data are consistent with recent evidence
linking radiation-induced stress with ceramide and suggest approaches to modify
the apoptotic response in control of radiation toxicity in the CNS.
PMID: 10667583 [PubMed - indexed for MEDLINE]