Oxidative stress plays an important role in c
hemically induced liver injury,
however, our insi
ght into molecular responses to different oxy
gen radicals is fra
gmentary. Since t
hese cellular responses will differ over time, examinin
g time-dependent c
han
ges in
gene expression, and correlatin
g t
hese wit
h markers for oxidative stress, may provide new insi
ghts into responses to oxidants. We used t
he
human
hepatoma cell line HepG2 to investi
gate t
he effects of oxidative stress on t
he transcriptome level by micro-arrays at seven time points (0.5, 1, 2, 4, 6, 8 and 24
h) followin
g exposure to t
he oxidants menadione,
hydro
gen peroxide and
tert-butyl
hydroperoxide includin
g t
he effects on cell cycle and apoptosis by flow cytometry, protein carbonyl formation by spectrop
hotometry and oxidative DNA dama
ge by FPG-comet. In total, 3429
genes were differentially expressed, includin
g 136
genes t
hat were si
gnificantly modified by all oxidants. Time-dependent biolo
gical pat
hway analysis s
howed t
hat t
hese
genes were particularly involved in inflammatory responses, cell cycle processes and
glutat
hione si
gnalin
g. T
hese responses were confirmed and supported by p
henotypic anc
horin
g to t
he different cellular endpoints. In addition, usin
g an innovative temporal analysis we establis
hed an oxidative stress-related
gene expression time cluster.
Altogether, this study provides new insights in temporal oxidative stress mechanisms and demonstrates sequential cellular responses that may contribute to a better hazard identification and the mechanisms of toxicological responses in the liver induced by oxidative stress.