Transfection of a manganese-containing superoxide dismutase gene into hamster tracheal epithelial cells ameliorates asbestos-mediated cytotoxicity.
To determine if overexpression of manganese-containing SOD (MnSOD) alters cell sensitivity to asbestos, an expression cassette containing murine MnSOD cDNA was cotransfected with pSV2neo, a plasmid conferring resistance to the antibiotic G418, into a diploid cell line of hamster tracheal epithelial (HTE) cells. Pools of G418-resistant transfectants were characterized by Southern and Northern blot analyses and enzyme activity assays. Although increases in MnSOD gene copies in individual cell pools ranged from approximately 7- to 86-fold in comparison to cells transfected with pSV2neo alone, steady-state levels of MnSOD mRNA were increased only by 1.4-to 2.3-fold. Despite modest increases in MnSOD mRNA, significant elevations in MnSOD enzyme activity were observed in pools of G418-resistant cells. MnSOD-transfected cell lines were more resistant to the cytotoxic effects of crocidolite asbestos using a sensitive colony-forming efficiency (CFE) assay. These data show that MnSOD has a direct role in cell defense against asbestos-induced cytotoxicity, an oxidant-dependent process.
Mossman
B T
BT
Department of Pathology, University of Vermont College of Medicine, Burlington 05405, USA.
Surinrut
P
P
Brinton
B T
BT
Marsh
J P
JP
Heintz
N H
NH
Lindau-Shepard
B
B
Shaffer
J B
JB
D000818:Animals; D001194:Asbestos / Q000633:toxicity*; D015139:Blotting, Southern; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D006224:Cricetinae; D004847:Epithelial Cells; D004848:Epithelium / Q000201:enzymology; D008345:Manganese; D008647:Mesocricetus; D012333:RNA, Messenger / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics* / Q000378:metabolism; D014132:Trachea / Q000166:cytology / Q000201:enzymology*; D014162:Transfection
D012333:RNA, Messenger; D001194:Asbestos; D008345:Manganese; D013482:Superoxide Dismutase