Nv. Gorbunov et al., Activation of the nitric oxide synthase 2 pathway in the response of bone marrow stromal cells to high doses of ionizing radiation, RADIAT RES, 154(1), 2000, pp. 73-86
Reverse transcription-polymerase chain reaction and immunofluorescence anal
ysis of D2XRII murine bone marrow stromal cells showed that gamma irradiati
on with doses of 2-50 Gy from Cs-137 stimulated expression of nitric oxide
synthase 2 (Nos2, also known as iNos), The activation of Nos2 was accompani
ed by an increase in the fluorescence of 4,5-diaminofluorescein diacetate,
a nitric oxide trap, and accumulation of 3-nitrotyrosine within cellular pr
oteins in a dose-dependent manner. These effects were inhibited by actinomy
cin D and by N-[3-(aminomethyl)benzyl]acetamidine dihydrochloride, a specif
ic inhibitor of Nos2, The induction of Nos2 expression and Nos2-dependent r
elease of nitric oxide in D2XRII cells was observed within 24 h after irrad
iation and was similar in magnitude to that observed in cultures incubated
with II1b and Tnf, We conducted (1) confocal fluorescence imaging of 3-nitr
otyrosine in bone marrow cells of irradiated C57BL/6J mice and (2) 3-nitrot
yrosine fluorescence imaging of FDC-P1JL26 hematopoietic cells that were co
cultured with previously irradiated D2XRII bone marrow stromal cells. Expos
ure to ionizing radiation increased the production of 3-nitro-tyrosine in i
rradiated bone marrow cells in vivo and in nonirradiated FDC-P1JL26 cells c
ocultured with irradiated D2XRII cells for 1 or 4 h, We suggest that nitrat
ive/oxidative stress to the transplanted multilineage hematopoietic cells d
ue to exposure to nitric oxide released by host bone marrow stromal cells m
ay contribute to the genotoxic events associated with malignant alterations
in bone marrow tissue of transplant recipients who are prepared for engraf
tment by total-body irradiation. (C) 2000 by Radiation Research Society.