Manganese superoxide dismutase is not protective in bovine pulmonary artery endothelial cells at systemic oxygen levels.
Bovine pulmonary artery endothelial cells (BPAEC) are extremely sensitive to oxygen, mediated by superoxide production. Ionizing radiation is known to generate superoxide in oxygenated aqueous media; however, at systemic oxygen levels (3%), no oxygen enhancement is observed after irradiation. A number of markers (cell growth, alamarBlue, mitochondrial membrane polarization) for metabolic activity indicate that BPAEC maintained under 20% oxygen grow and metabolize more slowly than cells maintained under 3% oxygen. BPAEC cultured in 20% oxygen grow better when they are transiently transfected with either manganese superoxide dismutase (MnSOD) or copper zinc superoxide dismutase (CuZnSOD) and exhibit improved survival after irradiation (0.5-10 Gy). Furthermore, X irradiation of BPAEC grown in 20% oxygen results in very diffuse colony formation, which is completely ameliorated by either growth in 3% oxygen or overexpression of MnSOD. However, MnSOD overexpression in BPAEC grown in 3% oxygen provides no further radioprotection, as judged by clonogenic survival curves. Radiation does not increase apoptosis in BPAEC but inhibits cell growth and up-regulates p53 and p21 at either 3% or 20% oxygen.
Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania 15219-3138, USA.
Molly S
MS
Stitt-Fischer
Rachel K
RK
Ungerman
Daniel S
DS
Wilen
Karla
K
Wasserloos
Lara M
LM
Renz
Shannon E
SE
Raub
Jim
J
Peterson
Linda L
LL
Pearce
D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D002118:Calcium / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000473:pathology / Q000528:radiation effects*; D005609:Free Radicals; D053078:Membrane Potential, Mitochondrial / Q000528:radiation effects; D008928:Mitochondria / Q000528:radiation effects; D009569:Nitric Oxide / Q000096:biosynthesis; D010100:Oxygen / Q000633:toxicity*; D011651:Pulmonary Artery / Q000473:pathology / Q000528:radiation effects*; D011835:Radiation Protection; D013482:Superoxide Dismutase / Q000502:physiology*
D005609:Free Radicals; D009569:Nitric Oxide; D013482:Superoxide Dismutase; D010100:Oxygen; D002118:Calcium