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Published on: January 19, 2024

Doxorubicin-induced MAPK activation in hepatocyte cultures is independent of oxidant damage

Rosaura Navarro1, Rosa Martínez, Idoia Busnadiego

  • 1Department of Physiology, Faculty of Medicine and Dentistry, University of the Basque Country, 48080-Bilbao, Spain.

Annals of the New York Academy of Sciences
|March 27, 2007
PubMed

Insights

Doxorubicin (DOX) triggers mitogen-activated protein kinase (MAPK) cascades, including extracellular signal-regulated kinases (ERK), c-Jun N-terminal kinases (JNK), and p38, in rat hepatocytes. This activation occurs independently of oxidative stress, suggesting a novel mechanism of DOX action.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Pharmacology

Background:

  • Doxorubicin (DOX) is a vital anticancer drug, but its clinical application is restricted by significant toxicity.
  • DOX-induced toxicity is often linked to reactive oxygen species (ROS) generation, which impacts cell signaling pathways crucial for survival and apoptosis.
  • Mitogen-activated protein kinase (MAPK) cascades are known to be activated by oxidative stress.

Purpose of the Study:

  • To investigate the effects of DOX on cytotoxicity, oxidative stress markers, and MAPK pathway phosphorylation in primary rat hepatocytes.
  • To determine if DOX-induced MAPK activation is mediated by oxidative damage.

Main Methods:

  • Primary rat hepatocytes were treated with varying concentrations of DOX (1-50 microM).
  • Cytotoxicity was assessed by measuring lactate dehydrogenase (LDH) release.
  • Oxidative stress indicators, malondialdehyde (MDA) and glutathione (GSH), were quantified using high-performance liquid chromatography (HPLC).
  • Mitochondrial GSH levels were analyzed after Percoll gradient extraction.
  • Protein phosphorylation of ERK, JNK, and p38 kinases was evaluated using Western blot analysis.

Main Results:

  • DOX did not significantly alter LDH release, MDA levels, or intracellular GSH concentrations up to 6 hours of incubation.
  • Mitochondrial GSH levels remained unaffected, ruling out depletion or impaired uptake.
  • DOX dose- and time-dependently increased the phosphorylation of p38 kinases and JNK1/JNK2.
  • Phosphorylation of ERK2 was also elevated by DOX at later time points.

Conclusions:

  • DOX activates ERK, JNK, and p38 kinase pathways in rat hepatocytes.
  • This activation occurs independently of measurable oxidative damage, suggesting a non-ROS-dependent mechanism.
  • These findings provide new insights into the molecular mechanisms underlying DOX's action and toxicity.

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