Superoxide Anions Are Involved in Doxorubicin‐Induced ERK Activation in Hepatocyte Cultures

Abstract

Doxorubicin (DOX), an antineoplastic agent widely used for the treatment of cancer, belongs to the anthracycline family of antitumor antibiotics. DOX may undergo one-electron reduction to the corresponding semiquinone free radical by flavin-containing reductases. Under aerobic conditions, the semiquinone radical reacts rapidly with oxygen to generate superoxide anion, undergoing redox cycling. At moderate concentrations, reactive oxygen species (ROS) play an important role as regulatory mediators in signaling processes. We have shown that DOX increased phosphorylation of enzymes comprising mitogen-activated protein (MAP) kinase cascades in primary hepatocyte cultures, and that this action was independent of oxidant damage. In particular, extracellular signal-regulated kinase (ERK) was phosphorylated by the drug treatment. In this work, we have determined the possible involvement of particular free radicals in DOX-induced ERK phosphorylation in hepatocyte cultures by using specific free radical scavengers. The levels of ERK phosphorylation were measured by Western blot analysis with an anti-Thr202/Tyr204-phosphorylated p44/p42 MAPK antibody. Deferoxamine (DFO; iron chelator), catalase (hydrogen peroxide-removing enzyme), or alpha-tocopherol (peroxyl-radical scavenger) did not affect DOX-increased ERK phosphorylation levels. However, the cell-permeable superoxide dismutase mimetic MnTBAP and the flavin-containing enzyme inhibitor diphenyleneiodonium reverted DOX-induced effects. These results suggest that superoxide anions, probably generated by DOX metabolism, are involved in the effects of the anthracycline on the MAP kinase cascade activation.

Reactive oxygen species mediate thymoquinone-induced apoptosis and activate ERK and JNK signaling

“…Having established that TQ is an oxidative stress-causing agent in colon cancer cells, we then studied its effects on the MAPK. The ERK, JNK, and p38 subfamilies have all been shown to be activated in response to oxidant injury and therefore might contribute to influencing survival [27,28]. The involvement of the MAPK in response to oxidant stress was confirmed in DLD-1 cells in our study: JNK and ERK, but not p38 kinases, were activated significantly in the presence of TQ.…”

“…ROS causing oxidative stress are known to activate members of the MAPK family [27,28]. The latter ones are important mediators of signal transduction, and play a key role in the regulation of many cellular processes, such as cell growth and proliferation, differentiation, and apoptosis.…”

Protection by Panax ginseng C.A. Meyer against the genotoxicity of doxorubicin in somatic cells of Drosophila melanogaster

“…DOX may also be involved in secondary malignancies. The main mechanisms of action proposed for DOX include the inhibition of topoisomerase II, DNA intercalation, free radical formation, reductive bioactivation of the quinine ring to a semiquinone radical, DNA alkylation and cross-linking (Gewirtz, 1999;Ramji et al, 2003;Navarro et al, 2006). These mechanisms can result in the cleavage of DNA which, if not repaired, may lead to mutations and chromosomal aberrations in tumors as well as in healthy cells (Antunes and Takahashi, 1998;Gentile et al, 1998;Islaih et al, 2005;Antunes et al, 2007;Costa and Nepomuceno, 2006;Fragiorge et al, 2007;Valadares et al, 2008).…”

Na+/K+-ATPase α3 mediates sensitivity of hepatocellular carcinoma cells to bufalin

“…First, bufalin combining with Na + /K + -ATPase isoform ·3 will activate Src which can activate the Ras/Raf/MEK/ERK1/2 signal pathway (22)(23)(24). Second, the active ROS itself also mediates the activation of ERK1/2 (31,32). At this point, it is suggested that activated ERK1/2 and Akt team up for bufalin to induce cell death in HCC cell lines.…”