Visit our Expo - Redox and Inflammation signaling 2012

Session III : Protein kinase cascades as therapeutic targets Poster III, 39
Doxorubicin-induced MAP kinase activation in hepatocyte cultures is independent of
oxidant damage
Rosaura Navarro, Rosa Martínez, Idoia Busnadiego, M. Begoña Ruiz-Larrea and José
Ignacio Ruiz-Sanz
Department of Physiology, Medicine and Dentistry School, University of the Basque
Country, 48080-Bilbao, Spain. E-mail: mbego.ruizlarrea@ehu.es
Doxorubicin (DOX) is a potent anticancer drug, whose clinical use is limited due to its
toxicity. DOX cytotoxic effects have been associated with reactive oxygen species (ROS)
generated during the drug metabolism. ROS induce signaling cascades leading to changes in
the phosphorylation status of target proteins, which are keys for cell survival or apoptosis.
The mitogen-activated protein kinase (MAPK) cascades are routes activated in response to
oxidative stress. In this work the effects of DOX on cytotoxicity, indicators of oxidative stress
(malondialdehyde –MDA- and GSH), and the phosphorylation status of extracellular signalregulated
kinases (ERKs), c-Jun N-terminal kinases (JNKs) and p38 kinases were analyzed in
primary cultures of rat hepatocytes. DOX (1- 50 µM) did not modify LDH release into the
medium during the incubation time up to 6 h. The levels of MDA, determined by HPLC, and
the intracellular GSH were constant during the treatment with the drug. GSH levels from
mitochondria extracted by Percoll gradient from cultured hepatocytes were not modified by
DOX, thus excluding its depletion or any impaired mitochondrial uptake. Characterization of
proteins by Western blot analysis revealed that DOX increased phosphorylation of p38
kinases, JNK1/2 and ERK1/2. In conclusion, DOX triggers activation of ERK, JNK and p38
kinases in primary hepatocyte cultures independently of oxidant damage.
This work was supported by the Basque Government (Research Project and Predoctoral
Training Grant to R.N.) and the University of the Basque Country (UPV00081.327-E-
15294/2003).
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