DNA damage, superoxide, and mutant K-ras in human lung adenocarcinoma cells.
DNA single-strand breaks (quantitative comet assay) were assessed to indicate ongoing genetic instability in a panel of human lung adenocarcinoma cell lines. Of these, 19/20 showed more DNA damage than a nontransformed cell line from human peripheral lung epithelium, HPL1D. DNA damage was significantly greater in those derived from pleural effusates vs those from lymph node metastases. DNA strand breaks correlated positively with superoxide (nitroblue tetrazolium reduction assay), and negatively with amount of OGG1, a repair enzyme for oxidative DNA damage. Levels of CuZn superoxide dismutase varied moderately among the lines and did not correlate with other parameters. A role for mutant K-ras through generation of reactive oxygen species was examined. Cells with mutant K-ras had significantly lower amounts of manganese superoxide dismutase (MnSOD) vs those with wild-type K-ras, but MnSOD protein correlated positively with superoxide levels. In a subset of cell lines with similar levels of MnSOD, comparable to those in HPL1D cells, K-ras activity correlated positively with levels of both superoxide and DNA strand breaks. These results suggest that persistent DNA damage in some lung adenocarcinoma cells may be caused by superoxide resulting from mutant K-ras activity, and that OGG1 is important for prevention of this damage.
Romanowska
Malgorzata
M
Laboratory of Comparative Carcinogenesis, National Cancer Institute at Frederick, Building 538/206, Fort Detrick, Frederick, MD 21702, USA.
Maciag
Anna
A
Smith
Andrew L
AL
Fields
Janet R
JR
Fornwald
Laura W
LW
Kikawa
Keith D
KD
Kasprzak
Kazimierz S
KS
Anderson
Lucy M
LM
D000230:Adenocarcinoma / Q000235:genetics / Q000503:physiopathology*; D045744:Cell Line, Tumor; D004249:DNA Damage; D045647:DNA Glycosylases / Q000378:metabolism; D045643:DNA Repair Enzymes / Q000378:metabolism; D011905:Genes, ras / Q000235:genetics*; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics / Q000503:physiopathology*; D009361:Neoplasm Invasiveness / Q000235:genetics; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D018631:ras Proteins / Q000378:metabolism
D013481:Superoxides; D013482:Superoxide Dismutase; D010744:Phosphoric Monoester Hydrolases; D045647:DNA Glycosylases; C479058:oxoguanine glycosylase 1, human; C078207:8-oxodGTPase; D018631:ras Proteins; D045643:DNA Repair Enzymes