oxidants and antioxidants in biology - Oxygen Club of California

Doxorubicin activates nuclear factor-kappaB in
primary cultures of rat hepatocytes
ROSAURA NAVARRO, ROSA MARTÍNEZ, Mª LUISA HERNÁNDEZ,
IGOR AURREKOETXEA, MERCEDES LACORT,
JOSÉ IGNACIO RUIZ-SANZ AND Mª BEGOÑA RUIZ-LARREA
Dpt. Physiology, Medicine School, University of the Basque Country. Bilbao,
Spain
The anthracycline antibiotic doxorubicin is one of the most
potent anticancer drugs in clinical use. However, its clinical utility
is limited by severe, cumulative and dose-dependent cardiotoxicity.
The cytotoxic actions are associated with the generation of free
radicals, the induction of membrane alterations through lipid peroxidation
and the impairment of DNA and RNA synthesis. Oxidative
stress can induce different biological processes, including cell
growth, apoptosis and cell adhesion, presumably by stimulating
signal transduction and the generation of lipid second messengers,
such phosphatidic acid and diacylglycerol (DAG). Previous data
have shown that doxorubicin induces the accumulation of [ 3 H]-
DAG from [ 3 H]-labeled hepatocytes. In the present work the possible
activation of the nuclear factor-kappaB (NF-κB) has been examined
in hepatocyte cultures exposed to doxorubicin. NF-κB is
composed of transcriptionally active p50/p65 heterodimers. The
transcription factor is activated through the proteolytic degradation
of IκBα, translocation of NF-κB to the nucleus, and binding to
DNA. Western blot analysis with anti-IκBα and anti-p65 antibodies
was used. Doxorubicin (10, 20 and 50 µM) induced the cytosolic
degradation of IκBα at 3 and 6 h, and concomitantly the NF-κB
translocation into the nucleus. This effect was dose-dependent. The
possible involvement of free radical in the NF-κB response is also
discussed.
This work was supported by Scientific Research Grants from Gobierno Vasco.
R.N. was awarded a Predoctoral Training Grant from Gobierno Vasco.
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