Elevated superoxide production by active H-ras enhances human lung WI-38VA-13 cell proliferation, migration and resistance to TNF-alpha

Accumulating evidence has suggested that cellular production of superoxide acts as an intracellular messenger to regulate gene expression and modulate cellular activities, In this report, we set out to investigate the role of active H-ras-mediated superoxide production on tumor cell malignancy in a SV-40 transformed human lung WI-38 VA-13 cell line, Stable transfection and expression of constitutively active mutant V12-H-ras (V12-H-ras) dramatica lly increased intracellular production of superoxide, The expression of V12 -H-ras significantly enhanced cell proliferation, migration and resistance to TNF-alpha treatment compared to that of parental and vector control cell s, while expression of wild type H-ras (WT-H-ras) only had modest effects. Upon scavenging by superoxide dismutase and other molecules that decrease t he intracellular level of active H-ras mediated superoxide production, cell proliferation, migration and resistance to TNF-alpha were significantly re duced. Furthermore, we demonstrated that the activation of membrane NADPH o xidase activity by expression of active I-P-ras contributed to the intracel lular superoxide production. The causal relationship between membrane super oxide production and increased cell proliferation, migration, and resistanc e to TNF-alpha by the expression of active H-ras, has provided direct evide nce to demonstrate that superoxide acts as an intracellular messenger to ca scade res oncogenic signal relay and to modulate turner malignant activity.