Mitogenic signaling mediated by oxidants in Ras-transformed fibroblasts.
NIH 3T3 fibroblasts stably transformed with a constitutively active isoform of p21(Ras), H-RasV12 (v-H-Ras or EJ-Ras), produced large amounts of the reactive oxygen species superoxide (.O2-). .O2- production was suppressed by the expression of dominant negative isoforms of Ras or Rac1, as well as by treatment with a farnesyltransferase inhibitor or with diphenylene iodonium, a flavoprotein inhibitor. The mitogenic activity of cells expressing H-RasV12 was inhibited by treatment with the chemical antioxidant N-acetyl-L-cysteine. Mitogen-activated protein kinase (MAPK) activity was decreased and c-Jun N-terminal kinase (JNK) was not activated in H-RasV12-transformed cells. Thus, H-RasV12-induced transformation can lead to the production of .O2- through one or more pathways involving a flavoprotein and Rac1. The implication of a reactive oxygen species, probably .O2-, as a mediator of Ras-induced cell cycle progression independent of MAPK and JNK suggests a possible mechanism for the effects of antioxidants against Ras-induced cellular transformation.
Irani
K
K
Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Xia
Y
Y
Zweier
J L
JL
Sollott
S J
SJ
Der
C J
CJ
Fearon
E R
ER
Sundaresan
M
M
Finkel
T
T
Goldschmidt-Clermont
P J
PJ
D016475:3T3 Cells; D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002453:Cell Cycle; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic; D004247:DNA / Q000096:biosynthesis; D004578:Electron Spin Resonance Spectroscopy; D019204:GTP-Binding Proteins / Q000378:metabolism; D011905:Genes, ras; D048031:JNK Mitogen-Activated Protein Kinases; D051379:Mice; D020928:Mitogen-Activated Protein Kinases; D010084:Oxidation-Reduction; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction; D013481:Superoxides / Q000378:metabolism*; D014162:Transfection; D020744:rac GTP-Binding Proteins
D000975:Antioxidants; D017382:Reactive Oxygen Species; D013481:Superoxides; D004247:DNA; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D019204:GTP-Binding Proteins; D016283:Proto-Oncogene Proteins p21(ras); D020744:rac GTP-Binding Proteins; D000111:Acetylcysteine