Article

Cellular Iron Depletion Stimulates the JNK and p38 MAPK Signaling Transduction Pathways, Dissociation of ASK1-Thioredoxin, and Activation of ASK1

Iron Metabolism and Chelation Program, Department of Pathology and Bosch Institute, University of Sydney, Sydney, New South Wales 2006, Australia.
Journal of Biological Chemistry (Impact Factor: 4.57). 03/2011; 286(17):15413-27. DOI: 10.1074/jbc.M111.225946
Source: PubMed

ABSTRACT

The role of signaling pathways in the regulation of cellular iron metabolism is becoming increasingly recognized. Iron chelation is used for the treatment of iron overload but also as a potential strategy for cancer therapy, because iron depletion results in cell cycle arrest and apoptosis. This study examined potential signaling pathways affected by iron depletion induced by desferrioxamine (DFO) or di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone (Dp44mT). Both chelators affected multiple molecules in the mitogen-activated protein kinase (MAPK) pathway, including a number of dual specificity phosphatases that directly de-phosphorylate MAPKs. Examination of the phosphorylation of major MAPKs revealed that DFO and Dp44mT markedly increased phosphorylation of stress-activated protein kinases, JNK and p38, without significantly affecting the extracellular signal-regulated kinase (ERK). Redox-inactive DFO-iron complexes did not affect phosphorylation of JNK or p38, whereas the redox-active Dp44mT-iron complex significantly increased the phosphorylation of these kinases similarly to Dp44mT alone. Iron or N-acetylcysteine supplementation reversed Dp44mT-induced up-regulation of phospho-JNK, but only iron was able to reverse the effect of DFO on JNK. Both iron chelators significantly reduced ASK1-thioredoxin complex formation, resulting in the increased phosphorylation of ASK1, which activates the JNK and p38 pathways. Thus, dissociation of ASK1 could serve as an important signal for the phosphorylation of JNK and p38 activation observed after iron chelation. Phosphorylation of JNK and p38 likely play an important role in mediating the cell cycle arrest and apoptosis induced by iron depletion.

  • Source
    • "Under resting state, thioredoxin (Trx) bonded the N-terminal domains of ASK1 to form Trx-ASK1 compound, thus inhibiting ASK1 activation. Under the external stimulation (such as oxidative stress and inflammatory factors), Trx and ASK1 were separated to cause ASK1 activation, thus inducing the MAP2 phosphorylation and downstream JNK activation[9,16]. Study of Nakagawa et al. showed that ASK1−/− mice effectively protect APAP-induced liver injury through inhibiting JNK activation[9]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: To explore the protective effect and its molecular mechanism of apoptosis signal-regulating kinase1 (ASK1) inhibitor (GS-459679) on acetaminophen-induced liver injury in mice.
    Full-text · Article · Jan 2016 · Asian Pacific Journal of Tropical Medicine
    • "In fact, these agents induce G 1 /S arrest to mediate anti-proliferative activity and apoptosis [30–35,37]. Moreover, thiosemicarbazones can inhibit numerous oncogenic signaling pathways (e.g., the transforming growth factor-[38], c-Jun N-terminal kinase (JNK) and p38 mitogenactivated protein kinase (MAPK) [39], Ras/ERK [38], protein kinase B (AKT)/phosphatidylinositol-3-kinase [37] [38], STAT3 [40], c-Src [41] and ROCK1/pMLC2 pathways [42], etc.; for review see Lui et al. [43]). More recently, thiosemicarbazones have also been demonstrated to induce autophagy [44] [45] and to inhibit the epithelial-to-mesenchymal transition (EMT) [46] [47] that is crucial for metastasis (discussed further below). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Cancer is a disease that is a "moving target", since as the condition progresses, the molecular targets change and evolve. Moreover, due to clonal selection, a specific anti-cancer drug with one molecular target may only be effective for a limited time period before drug resistance results and the agent becomes ineffective. Hence, the concept of an anti-tumor therapeutic exhibiting polypharmacology can be highly advantageous, rather than a therapeutic obstacle. A novel class of agents possessing these desirable properties are the di-2-pyridylketone thiosemicarbazones, which bind iron and copper to affect a variety of critical molecular targets in tumors. In fact, these compounds possess multiple properties that enable them to overcome the "triad of death" in cancer, namely: primary tumor growth, drug resistance and metastasis. In fact, at the molecular level, their potent anti-oncogenic activity includes: up-regulation of the metastasis suppressor, N-myc downstream regulated gene 1; up-regulation of the tumor suppressor, PTEN; down-regulation of the proto-oncogene, cyclin D1; inhibition of the rate-limiting step in DNA synthesis catalyzed by ribonucleotide reductase; and the inhibition of multiple oncogenic signaling pathways, e.g., Ras/MAPK signaling, protein kinase B (AKT)/phosphatidylinositol-3-kinase, ROCK/pMLC2, etc. This Perspective article discusses the advantages of incorporating polypharmacology into anti-cancer drug design using the di-2-pyridylketone thiosemicarbazones as a pertinent example. Copyright © 2015 Elsevier Ltd. All rights reserved.
    No preview · Article · Aug 2015 · Pharmacological Research
  • Source
    • "In good accordance with our results, mRNA expression studies with the thiosemicarbazone Dp44mT (di-2-pyridylketone-4,4,- dimethyl-3-thiosemicarbazone) suggested that iron depletion is responsible for elevated levels of DITT3 (a synonym for the gene encoding CHOP) (Yu and Richardson, 2011). Indeed, investigations regarding the stability of metal complexes of 3-AP and 3-AP-Me with iron, zinc, and copper revealed that terminally dimethylated thiosemicarbazones, such as 3-AP-Me, form metal complexes with higher stability (Enyedy et al., 2010, 2011). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Triapine (3-AP), a ribonucleotide reductase inhibitor, has been extensively evaluated in clinical trials in the last decade. This study addresses the role of ER stress in the anticancer activity of 3-AP and the derivative 3-AP-Me, differing from 3-AP only by dimethylation of the terminal nitrogen. Treatment of colon cancer cells with 3-AP or 3-AP-Me activated all three ER stress pathways (PERK, IRE1a and ATF6) by phosphorylation of eIF2α and upregulation of ATF4 and ATF6 gene expression, and particularly 3-AP-Me lead to an upregulation of the alternatively spliced mRNA variant XBP1s (16-fold). Moreover, 3-AP and 3-AP-Me activated the cellular stress kinases JNK and p38 MAPK, and inhibition of JNK activity antagonized the cytotoxic effect of both compounds. Subsequent to induction of the unfolded protein response (UPR), a significant upregulation of pro-apoptotic proteins was detected, including the transcription factor CHOP and the BH3-only member protein Bim, an essential factor for ER stress-related apoptosis. In correlation with the higher degree of ER stress after 3-AP-Me treatment, also a more potent depolarization of mitochondrial membranes was found. These data suggest that 3-AP and 3-AP-Me induce apoptosis via ER stress. This was further corroborated by showing that inhibition of protein biosynthesis with cycloheximide prior to 3-AP and 3-AP-Me treatment leads to a significant reduction of the anti-proliferative properties of both compounds. Taken together, this study demonstrates that induction of ER stress contributes to the mode of action of 3-AP and that terminal methylation leads to an even more pronounced manifestation of this effect.
    Full-text · Article · Dec 2013 · Molecular pharmacology
Show more