Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P05412 (c-Jun)
 11,453 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Our previous studies showed that docetaxel-induced apoptosis of human melanoma cells was dependent on the activation of the c-jun NH(2)-terminal kinase (JNK) signaling pathway but was inhibited by the extracellular signal-regulated kinase (ERK)-1/2 pathway. However, the mechanisms by which these pathways were modulated by docetaxel were not clear. We report here that docetaxel induces activation of protein kinase C (PKC) signaling differentially through PKCepsilon and PKCdelta isoforms. Activation of PKCepsilon was most marked in docetaxel-resistant cells and paralleled the activation of the ERK1/2 pathway. Inhibition of PKCepsilon by small interfering RNA molecules resulted in down-regulation of phosphorylated ERK1/2 and sensitization of cells to docetaxel-induced apoptosis. Experiments also showed that beta-tubulin class III, a molecular target of docetaxel, coimmunoprecipitated with PKCepsilon and colocalized in confocal microscopic studies. In contrast to PKCepsilon, high levels of activated PKCdelta were associated with activation of the JNK pathway and sensitivity to docetaxel. Activation of PKCdelta seemed to be upstream of JNK because inhibition of PKCdelta by small interfering RNA abrogated activation of the JNK pathway. Although PKCdelta could be activated in resistant cells, downstream activation of JNK and c-Jun did not occur. In summary, these results suggest that the outcome of docetaxel-induced apoptotic events in human melanoma cells depends on their PKC isoform content and signaling responses. PKCepsilon was associated with prosurvival signaling through ERK, whereas PKCdelta was associated with proapoptotic responses through JNK activation.
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PMID:Regulation of docetaxel-induced apoptosis of human melanoma cells by different isoforms of protein kinase C. 1795 7

Melanoma is the most aggressive skin cancer and a serious health problem worldwide because of its increasing incidence and the lack of satisfactory chemotherapy for late stages of the disease. The marine depsipeptide Aplidin (plitidepsin) is an antitumoral agent under phase II clinical development against several neoplasias, including melanoma. We report that plitidepsin has a dual effect on the human SK-MEL-28 and UACC-257 melanoma cell lines; at low concentrations (</=45 nM), it inhibits the cell cycle by inducing G(1) and G(2)/M arrest, whereas at higher concentrations it induces apoptosis as assessed by poly-(ADP-ribose) polymerase cleavage and the appearance of a hypodiploid peak in flow cytometry analyses. Plitidepsin activates Rac1 GTPase and c-Jun NH(2)-terminal kinase (JNK). In addition, it induces AKT and p38 mitogen-activated protein kinase (MAPK) phosphorylation. By using inhibitors, we found that JNK and p38 MAPK activation depends on Rac1 but not on phosphatidylinositol 3-kinase (PI3K), whereas AKT activation is independent of Rac1 but requires PI3K activity. Plitidepsin cytotoxicity diminishes by Rac1 inhibition or by the blockage of JNK and p38 MAPK using 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole (SB203580), but not by PI3K inhibition using wortmannin or 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002). It is remarkable that plitidepsin and dacarbazine, the alkylating agent most active for treating metastatic melanoma, show a synergistic antiproliferative effect that was paralleled at the level of JNK activation. These results indicate that Rac1/JNK activation is critical for cell cycle arrest and apoptosis induction by plitidepsin in melanoma cells. They also support the combined use of plitidepsin and dacarbazine in in vivo studies.
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PMID:Plitidepsin has a dual effect inhibiting cell cycle and inducing apoptosis via Rac1/c-Jun NH2-terminal kinase activation in human melanoma cells. 1808 42

The present studies defined the biological effects of a GST fusion protein of melanoma differentiation-associated gene-7 (mda-7), GST-MDA-7 (1 and 30 nmol/L), on cell survival and cell signaling in primary human glioma cells in vitro. GST-MDA-7, in a dose- and time-dependent fashion killed glioma cells with diverse genetic characteristics; 1 nmol/L caused arrest without death, whereas 30 nmol/L caused arrest and killing after exposure. Combined inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) and AKT function was required to enhance 1 nmol/L GST-MDA-7 lethality in all cell types, whereas combined activation of MEK1 and AKT was required to suppress 30 nmol/L GST-MDA-7 lethality; both effects are mediated in part by modulating c-Jun NH(2)-terminal kinase (JNK) 1-3 activity. The geldanamycin 17AAG inhibited AKT and ERK1/2 in GBM cells and enhanced GST-MDA-7 lethality. JNK1-3 signaling promoted BAX activation and mitochondrial dysfunction. In GBM6 cells, GST-MDA-7 (30 nmol/L) transiently activated p38 mitogen-activated protein kinase, which was modestly protective against JNK1-3-induced toxicity, whereas GST-MDA-7 (300 nmol/L) caused prolonged intense p38 mitogen-activated protein kinase activation, which promoted cell death. In GBM12 cells that express full-length mutant activated ERBB1, inhibition of ERBB1 did not modify GST-MDA-7 lethality; however, in U118 established glioma cells, stable overexpression of wild-type ERBB1 and/or truncated active ERBB1vIII suppressed GST-MDA-7 lethality. Our data argue that combined inhibition of ERK1/2 and AKT function, regardless of genetic background, promotes MDA-7 lethality in human primary human glioma cells via JNK1-3 signaling and is likely to represent a more ubiquitous approach to enhancing MDA-7 toxicity in this cell type than inhibition of ERBB1 function.
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PMID:Regulation of GST-MDA-7 toxicity in human glioblastoma cells by ERBB1, ERK1/2, PI3K, and JNK1-3 pathway signaling. 1828 16

2-acetyl furanonaphthoquinone (FNQ) is a naturally occurring drug with enhanced toxicity versus glucose-starved tumor cells, which frequently show topoisomerase II drug resistance. Since loss of p53 tumor suppressor function or overexpression of the anti-apoptotic bcl-2 gene can decrease susceptibility to some cancer therapies, we now investigated the effect of FNQ against genetically matched C8161 melanoma cell lines transduced to express unequal levels of Bcl-2, or engineered to harbour a functional wt p53 for comparison with dominant-negative mutant p53 R175H. Cells with differing p53 genotype showed susceptibility to FNQ. However, this response was attenuated in those overexpressing mutant p53, although a brief p53 induction was early seen in FNQ-treated wt p53 cells. Cells susceptible to FNQ showed cleavage of anti-apoptotic Mcl-1, sustained activation of the c-Jun N-terminal Kinase (p-JNK), and apoptosis-associated PARP fragmentation, all of which were counteracted in bcl-2 overexpressing cells. Suppression of JNK activation with the specific inhibitor, SP600125 also prevented FNQ-mediated cell death. Our data suggests that Bcl-2, persistent JNK phosphorylation and cleavage of anti-apoptotic Mcl-1 are key events controlling susceptibility to FNQ.
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PMID:Mcl-1 cleavage and sustained phosphorylation of c-Jun-N-terminal kinase mediate melanoma apoptosis induced by 2-acetyl furanonaphthoquinone: roles of Bcl-2 and p53. 1845 32

Type I interferons (IFNs) activate Janus tyrosine kinase-signal transducer and activator of transcription pathway for exerting pleiotropic biological effects, including antiviral, antiproliferative, and immunomodulatory responses. Here, we demonstrate that filamin B functions as a scaffold that links between activated Rac1 and a c-Jun NH(2)-terminal kinase (JNK) cascade module for mediating type I IFN signaling. Filamin B interacted with Rac1, mitogen-activated protein kinase kinase kinase 1, mitogen-activated protein kinase kinase 4, and JNK. Filamin B markedly enhanced IFNalpha-dependent Rac1 activation and the sequential activation of the JNK cascade members. Complementation assays using M2 melanoma cells revealed that filamin B, but not filamin A, is required for IFNalpha-dependent activation of JNK. Furthermore, filamin B promoted IFNalpha-induced apoptosis, whereas short hairpin RNA-mediated knockdown of filamin B prevented it. These results establish a novel function of filamin B as a molecular scaffold in the JNK signaling pathway for type I IFN-induced apoptosis, thus providing the biological basis for antitumor and antiviral functions of type I IFNs.
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PMID:Filamin B serves as a molecular scaffold for type I interferon-induced c-Jun NH2-terminal kinase signaling pathway. 1881 75

The BRAFV600E mutation is common in human melanoma. This mutation enhances IkappaB kinase (IKK)/nuclear factor-kappaB (NF-kappaB) and extracellular signal-regulated kinase/activator protein signaling cascades. In this study, we evaluated the efficacy of targeting either B-Raf or IKKbeta in combination with the DNA alkylating agent temozolomide for treatment of advanced metastatic melanoma. Xenografts of Hs294T human metastatic melanoma cells exhibiting the BRAFV600E mutation were treated with inhibitors of IKKbeta (BMS-345541), B-Raf (BAY 54-9085), and/or temozolomide. Drug response was mechanistically analyzed in vitro and in vivo. In this study, we determined that the antitumor activity of all three drugs depends on inhibition of NF-kappaB. BMS-345541 inhibits IKKbeta-mediated phosphorylation of IkappaBalpha and thus blocks the nuclear localization of NF-kappaB, whereas BAY 54-9085 inhibits activation of NF-kappaB through a mechanism that does not involve stabilization of IkappaBalpha. Moreover, BMS-345541, but not BAY 54-9085, activates the death pathways of p53 and c-Jun-NH2-kinase, contributing to the killing of melanoma cells. Temozolomide inhibits both NF-kappaB and extracellular signal-regulated kinase activity, conferring effective in vivo antitumor activity. Thus, temozolomide, but not BAY 54-9085, has a synergistic in vivo antitumor effect with BMS-345541. We conclude that the efficacy of antimelanoma therapy depends on inhibition of expression of antiapoptotic genes transcriptionally regulated by NF-kappaB. In contrast, drug targeting of the extracellular signal-regulated kinase/mitogen-activated protein kinase pathway alone in melanoma cells is ineffective for melanoma therapy in cases where NF-kappaB is not also targeted.
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PMID:Molecular determinants of melanoma malignancy: selecting targets for improved efficacy of chemotherapy. 1927 65

Constitutive ERK activation, superoxide dismutases (SOD) and p53 mutations are implicated in modulating tumor apoptotic response. We now investigated whether human melanoma survival in response to sodium nitroprusside (SNP) is modulated by: (a) stable introduction of a DN-mutant p53; (b) pharmacologically inhibiting ERK activation with UO126; (c) addition of exogenous SOD. Nitroprusside releases nitric oxide (NO) when intact, or acts in a NO-independent manner via iron and residual cyanide after light exposure (lex-SNP). When tested at 300 microM in 72 h treatments by cytometric live-dead assays, intact SNP caused a 50% lethality versus a 30% lethality induced by lex-SNP. No protection from SNP toxicity was seen when inhibiting the PI3-kinase pathway with LY294002 or c-Jun NH(2) kinase signaling with SP600125. However, pretreatment with UO126 protected from SNP-mediated cell death including counteracting apoptosis-associated Bax expression and PARP cleavage, plus reversing loss of Cu,Zn-SOD. Moreover, addition of exogenous SOD also protected cells from SNP toxicity. In spite of the greater earlier effects of intact SNP, cells treated with single doses of either intact or lex-SNP, revealed about a 90% mortality in longer 120 h treatments, and these were also counteracted by UO126 or exogenous SOD. This report is the first to show that: constitutive ERK activation characteristic of cancer cells, increases a nitroprusside-induced apoptosis modulated by SOD.
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PMID:ERK activation increases nitroprusside induced apoptosis in human melanoma cells irrespective of p53 status: role of superoxide dismutases. 1939 58

Integrins control a variety of signal transduction pathways central to cell survival, proliferation, and differentiation and their functions and expression levels are altered in many types of cancer. Although alpha5beta1 is one of the most studied integrins in cancer, its functions in different aspects of this disease have not been completely elucidated. In particular, controversial data exist on its role in tumor invasion and metastasis. In order to establish mechanisms underlying involvement of alpha5beta1 integrin in invasion, we depleted its expression in MCF-7Dox human breast carcinoma cells via siRNA. We demonstrated that concomitant to alpha5beta1 integrin depletion, was a sharp decrease in MMP-2 collagenase expression and inhibition of the invasiveness of these cells in vitro. Similar reduction of invasion potential was observed upon siRNA-mediated silencing of the MMP-2 gene. Down-regulation of alpha5beta1 integrin was accompanied by a substantial decrease in the amounts of active (phosphorylated) forms of Akt, Erk1/2 kinases and c-Jun oncoprotein. Moreover, in MCF-7Dox cells, blocking the activity of above kinases by specific inhibitors strongly reduced expression of MMP-2 and c-Jun, and suppressed invasion of the cells in vitro. Similar results were observed upon siRNA-mediated silencing of c-Jun expression. Co-immunoprecipitation experiments demonstrated that alpha5beta1 integrin interacts with MMP-2 collagenase on the surface of MCF-7Dox breast carcinoma and SKMel-147 human melanoma cells. Our data suggest that alpha5beta1 integrin controls invasion of the studied cells via regulation of MMP-2 collagenase expression which can occur either through signaling pathways involving PI-3K, Akt, and Erk protein kinases and the c-Jun or via direct recruitment of MMP-2 to the cell surface.
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PMID:Integrin alpha5beta1 controls invasion of human breast carcinoma cells by direct and indirect modulation of MMP-2 collagenase activity. 1961 14

Cytotoxic T lymphocytes (CTL) may undergo massive expansion upon appropriate antigenic stimulation. Homeostasis is maintained by a subsequent "contraction" of these cells. Activation-induced cell death (AICD) and programmed cell death prevent the untoward side effects, arising from excessive numbers and prolonged persistence of activated CTL, that occur upon uncontrolled and/or continued expansion. However, effector cell persistence has been identified as a hallmark of successful T-cell-mediated adoptive immunotherapy. Thus, prevention of AICD may be critical to achieve more successful clinical results. We have previously shown that treatment with the c-Jun NH(2)-terminal kinase (JNK) inhibitor SP600125 protects human melanoma epitope Mart-1(27-35)-reactive CTL from apoptotic death upon their reencounter with cognate antigen. However, inhibition of JNK also interferes with the functional ability of the CTL to secrete IFN-gamma. Here, we show that reactive oxygen species (ROS) inhibitors, such as the superoxide dismutase mimetic Mn (III) tetrakis (5, 10, 15, 20-benzoic acid) porphyrin (MnTBAP), efficiently protected Mart-1(27-35)-reactive primary CTL from AICD without impairing their functional capability. MnTBAP prevented the increase in intracellular ROS, mitochondrial membrane collapse, and DNA fragmentation observed in control-treated cells upon cognate antigen encounter. Furthermore, the mechanism of AICD prevention in primary CTL included blockade of JNK activation. Finally, tumor-reactive in vitro expanded tumor infiltrating lymphocytes, which are used clinically in cancer immunotherapy, also benefit from MnTBAP-mediated antioxidant treatment. Thus, modulation of the redox pathway might improve CTL persistence and lead to better clinical results for T cell-based immunotherapies.
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PMID:Inhibition of superoxide generation upon T-cell receptor engagement rescues Mart-1(27-35)-reactive T cells from activation-induced cell death. 1963 95

Cutaneous melanoma is the most aggressive skin cancer; it is highly metastatic and responds poorly to current therapies. The expression of platelet-derived growth factor receptors (PDGF-Rs) is reported to be reduced in metastatic melanoma compared with benign nevi or normal skin; we then hypothesized that PDGF-Ralpha may control growth of melanoma cells. We show here that melanoma cells overexpressing PDGF-Ralpha respond to serum with a significantly lower proliferation compared with that of controls. Apoptosis, cell cycle arrest, pRb dephosphorylation, and DNA synthesis inhibition were also observed in cells overexpressing PDGF-Ralpha. Proliferation was rescued by PDGF-Ralpha inhibitors, allowing to exclude nonspecific toxic effects and indicating that PDGF-Ralpha mediates autocrine antiproliferation signals in melanoma cells. Accordingly, PDGF-Ralpha was found to mediate staurosporine cytotoxicity. A protein array-based analysis of the mitogen-activated protein kinase pathway revealed that melanoma cells overexpressing PDGF-Ralpha show a strong reduction of c-Jun phosphorylated in serine 63 and of protein phosphatase 2A/Balpha and a marked increase of p38gamma, mitogen-activated protein kinase kinase 3, and signal regulatory protein alpha1 protein expression. In a mouse model of primary melanoma growth, infection with the Ad-vector overexpressing PDGF-Ralpha reached a significant 70% inhibition of primary melanoma growth (P < .001) and a similar inhibition of tumor angiogenesis. All together, these data demonstrate that PDGF-Ralpha strongly impairs melanoma growth likely through autocrine mechanisms and indicate a novel endogenous mechanism involved in melanoma control.
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PMID:Platelet-derived growth factor-receptor alpha strongly inhibits melanoma growth in vitro and in vivo. 1964 3


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