Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.12.2 (MEK)
 18,161 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

2-Methoxyestradiol (2-ME(2)) is a novel anticancer agent because of its ability to potentiate apoptotic cell death and inhibit cancer cell growth and angiogenesis. The modes of action of this agent, however, have not yet been fully elucidated. In our study, we have investigated whether 2-ME2 is able to modulate beta-catenin signaling in prostate cancer cells, which is one of the major players in cell-cell adhesion, proliferation, apoptosis and carcinogenesis. We found that beta-catenin levels were significantly upregulated by 2-ME(2) in a dose-dependent manner in androgen dependent and independent prostate cancer total cellular extracts. We further show that beta-catenin levels were significantly increased in the membrane fraction, while nuclear fractions of beta-catenin were downregulated in the 2-ME(2)-treated cells. Accumulation of dephospho-beta-catenin (nondegraded form) parallel with Bcl-2 and Cyclin D1 downregulation was also achieved after 2-ME(2) treatment. Moreover, we demonstrate that the beta-catenin production by 2-ME(2) is mediated through the MEK/ERK-2 signaling pathway. Collectively, these results suggest that the cytostatic effect of 2-ME(2) may be mediated through the prevention of the translocation of beta-catenin to the nucleus parallel with an increase in cell-cell adhesion by increasing membrane beta-catenin production, eventually preventing cell migration. Moreover, dephospho-beta-catenin accumulation by 2ME(2) in the cytoplasm may contribute to the induction of apoptosis of these cells. Finally, studies testing the efficacy of 2-ME(2) in human prostate cancer are warranted to determine whether the inhibition of the expected loss of membranous beta-catenin and the upregulation of nuclear beta-catenin can prevent prostate cancer development and progression.
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PMID:2-Methoxyestradiol modulates beta-catenin in prostate cancer cells: a possible mediator of 2-methoxyestradiol-induced inhibition of cell growth. 1793 27

Hepatocellular carcinoma (HCC) is a frequent neoplasia which still misses a therapeutical gold standard. Recently, new acquisitions in cancerogenesis process evidenced the genetic and epigenetic alterations of genes involved in the different metabolic pathways of liver cancer suggesting that antibodies, small molecules, demethylating agents, etc. specifically acting against molecular target can be utilized alone or in combination in clinical practice. The main altered targets are: cell membrane receptors, in particular tyrosine kinase receptors, factors involved in cell signalling, specifically Wnt/beta-catenin, Ras/Raf/MEK/ERK and PI3K/Akt/mTOR pathways, proteins linked to cell cycle regulation pathway (i.e. p53, p16/INK4, cyclin/cdk complex) or in invasiveness (EMT, TGFbeta) and proteins involved in DNA metabolism. Genetic or epigenetic changes in these molecules have been used in preclinical settings and, some of them also in clinical trials of phase II and III. This scenario opens new avenues for the prevention and the treatment of HCC. In the present review the main metabolic pathways and molecular alterations have been described together with recent advances in molecular and gene therapy.
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PMID:Molecular pathways and related target therapies in liver carcinoma. 1804 79

The RNA-binding protein Musashi1 (Msi1) is a positive regulator of Notch-mediated transcription in Drosophila melanogaster and neural progenitor cells and has been identified as a putative human breast stem cell marker. Here we describe a novel functional role for Msi1: its ability to drive progenitor cell expansion along the luminal and myoepithelial lineages. Expression of Msi1 in mammary epithelial cells increases the abundance of CD24(hi) Sca-1(+), CD24(hi) CD29(+), CK19, CK6, and double-positive CK14/CK18 progenitor cells. Proliferation is associated with increased proliferin-1 (PLF1) and reduced Dickkopf-3 (DKK3) secretion into the conditioned medium from Msi-expressing cells, which is associated with increased colony formation and extracellular signal-regulated kinase (ERK) phosphorylation. Treatment with the MEK inhibitor U0126 inhibits ERK activation and decreases Notch and beta-catenin/T-cell factor (TCF) reporter activity resulting from Msi1 expression. Reduction of DKK3 in control cells with a short hairpin RNA (shRNA) increases Notch and beta-catenin/TCF activation, whereas reduction of PLF1 with a shRNA in Msi1-expressing cells inhibits these pathways. These results identify Msi1 as a key determinant of the mammary lineage through its ability to coordinate cell cycle entry and activate the Notch and Wnt pathways by a novel autocrine process involving PLF1 and DKK3.
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PMID:Musashi1 modulates mammary progenitor cell expansion through proliferin-mediated activation of the Wnt and Notch pathways. 1836 62

The molecular mechanisms behind the anti-neoplastic effects of non-steroidal anti-inflammatory drugs (NSAIDs) are not completely understood and cannot be explained by the inhibition of the cyclooxygenase (COX) enzymes COX-1 and COX-2 alone. We previously reported that both the selective COX-1 inhibitor SC-560 and the selective COX-2 inhibitor CAY10404 exhibit anti-tumor effects in human hepatoma cells. NSAID inhibitors have many COX-independent actions and, among others, the mitogen-activated protein kinase (MAPK) pathways are targets for NSAIDs. Here, we examined the role of MEK/ERK1/2 signaling in the anti-neoplastic effects of both selective COX-1 and COX-2 inhibitors in two human hepatoma cell lines. Treatment of hepatoma cells with the selective COX-1 inhibitor SC-560, as well as with the selective COX-2 inhibitor CAY10404, was associated with activation of ERK1/2 in a time- and dose-dependent manner. Treatment with COX-1 and COX-2 inhibitors in the presence of the selective MEK1/2 inhibitor U0126 effectively suppressed ERK1/2 activation and combinations of either SC-560 or CAY10404 with U0126 resulted in synergistic effects on cell growth inhibition and induction of apoptosis. In HuH-6 hepatoma cells the combination-induced apoptosis was associated with caspase-9 and -3 activation, PARP cleavage, release of cytochrome c from the mitochondria into the cytosol and down-regulation of survivin and beta-catenin levels. In conclusion, our study showed that growth inhibitory concentrations of selective COX-1 and COX-2 inhibitors increased ERK1/2 phosphorylation in hepatoma cells, and that inhibition of the MEK/ERK signaling pathway potentiates the antitumor activity of both types of inhibitors. Therefore, our results provide preclinical support for a combined chemotherapeutic approach with selective NSAIDs and MEK inhibitors for the treatment of hepatocellular carcinoma.
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PMID:Potentiation of the antitumor effects of both selective cyclooxygenase-1 and cyclooxygenase-2 inhibitors in human hepatic cancer cells by inhibition of the MEK/ERK pathway. 1842 14

The Wnt family of glycoprotein growth factors controls a number of central cellular processes such as proliferation, differentiation and ageing. All the Wnt proteins analyzed so far either activate or inhibit the canonical beta-catenin signaling pathway that regulates transcription of the target genes. In addition, some of them activate noncanonical signaling pathways that involve components such as the JNK, heterotrimeric G proteins, protein kinase C, and calmodulin-dependent protein kinase II, although the precise signaling mechanisms are only just beginning to be revealed. We demonstrate here that Wnt-11 signaling is sufficient to inhibit not only the canonical beta-catenin mediated Wnt signaling but also JNK/AP-1 and NF-kappaB signaling in the CHO cells, thus serving as a noncanonical Wnt ligand in this system. Inhibition of the JNK/AP-1 pathway is mediated in part by the MAPK kinase MKK4 and Akt. Moreover, protein kinase C is involved in the regulation of JNK/AP-1 by Wnt-11, but not of the NF-kappaB pathway. Consistent with the central role of Akt, JNK and NF-kappaB in cell survival and stress responses, Wnt-11 signaling promotes cell viability. Hence Wnt-11 is involved in coordination of key signaling pathways.
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PMID:Wnt-11 signaling leads to down-regulation of the Wnt/beta-catenin, JNK/AP-1 and NF-kappaB pathways and promotes viability in the CHO-K1 cells. 1857 62

Mitotic serine/threonine kinase Aurora-A (Aur-A) plays a critical role in regulating centrosome segregation and spindle assemble. Aur-A overexpression causes excessive centrosome duplication and abnormal spindle structure, leading to tumor malignant progression. Here, we investigated Aur-A expression in nasopharyngeal carcinoma (NPC) and the association between Aur-A and NPC invasiveness. We showed that overexpression of Aur-A in tumor tissues was correlated with cranial bone invasion and clinical stage in NPC patients. Suppression of Aur-A by either selective Aurora inhibitory VX-680 or small-interfering RNA caused G(2)/M arrest and apoptotic cell death in NPC CNE-2 cells. Significantly, inhibition of Aur-A suppressed CNE-2 cell invasion and restored membrane expression of epithelial markers, E-cadherin and beta-catenin, suggesting a reversed epithelial-mesenchymal transition process in cancer cells. In addition, we found that Aur-A-regulated epithelial-mesenchymal transition and invasion were mediated by mitogen-activated protein kinase (MAPK) phosphorylation. Moreover, suppression of MAP kinase by small-interfering RNA or its upstream MEK1/2-selective inhibitor U0126 abrogated cell invasion enhanced by Aur-A overexpression. On the other hand, forced overexpression of constitutively active form of MEK1/2, MEK2DD, in CNE-2 cancer cells rescued cell invasive ability suppressed by VX-680-imposed Aur-A inhibition. Our results indicated that Aur-A acted through a downstream MAP kinase pathway to promote epithelial-mesenchymal transition and invasiveness in nasopharyngeal tumorigenesis. Small chemical inhibitor VX-680 may offer as a promising molecular targeting agent in human NPC.
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PMID:Inhibition of Aurora-A suppresses epithelial-mesenchymal transition and invasion by downregulating MAPK in nasopharyngeal carcinoma cells. 1866 45

Down-regulation of the KAI1 (CD82) metastasis suppressor is common in advanced human cancer, but underlying mechanism(s) regulating KAI1 expression are only now being elucidated. Recent data provide evidence that low levels of KAI1 mRNA in LNCaP cells are caused by binding of beta-catenin/Reptin complexes to a specific motif in the proximal promoter, which prevents binding of Tip60/Pontin activator complexes to the same motif, thus inhibiting transcription. Here, we explored a pathway by which phorbol 12-myristate 13-acetate (PMA) up-regulates KAI1 transcription in LNCaP prostate cancer cells. Pretreatment with specific inhibitors showed that induction of KAI1 by PMA uses classic isoforms of protein kinase C (cPKC), is independent of Ras and Raf, and requires activation of MEK1/2 and ERK1/2, but does not involve p38MAPK. Induction of KAI1 transcription by PMA was associated with enhanced overall acetylation of histones H3 and H4, but only acetylation of H3 was blocked by a PKC inhibitor. Chromatin immunoprecipitation showed that PMA induces recruitment of Tip60/Pontin activator complexes to NFkappaB-p50 motifs in the proximal promoter, and this was blocked by a PKC inhibitor. These changes were not associated with differences in overall levels of Tip60, Pontin, beta-catenin, or Reptin protein expression but with PMA-induced nuclear translocation of Tip60.
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PMID:Phorbol ester enhances KAI1 transcription by recruiting Tip60/Pontin complexes. 1904 21

Oral cancer is a prevalent type of cancer in Asian countries. Several studies indicated that garlic extracts such as diallyl disulfide (DADS) and diallyl trisulfide (DATS) have anticancer effects. However, the inhibitory effects of water soluble garlic extracts, S-allylcysteine (SAC), on the malignant progression of oral cancer have not been studied well yet. Thus, the purpose of this study was to investigate the inhibitory effects of SAC on the proliferation and progression of human oral squamous cancer CAL-27 cells. In the present study, we demonstrated that SAC dose dependently inhibited the growth of human oral squamous cancer cells. Our results showed that SAC induced the expression of E-cadherin adhesion molecule. Immunocytochemical staining result also revealed that SAC could restore the distribution of E-cadherin molecule on cell membrane. We further demonstrated that SAC stabilized the adherent junction complex of E-cadherin/beta-catenin in oral cancer cells. Treatment with the MAPK/MEK specific inhibitor, PD098059, could up-regulate the expression of E-cadherin molecule. Furthermore, SAC significantly inhibited the activation of MAPK/ERK signaling pathway. These findings were associated with the down-regulation of the SLUG repressor protein. In conclusion, our results indicated that SAC effectively inhibited the proliferation, up-regulated the expression of E-cadherin molecule and stabilized the E-cadherin/beta-catenin adherent junction complex in human oral squamous cancer cells. The mechanism of action was in part through the suppression of MAPK/ERK signaling pathway and down-regulation of the SLUG repressor protein.
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PMID:S-allylcysteine modulates the expression of E-cadherin and inhibits the malignant progression of human oral cancer. 1915 22

Prostaglandin-F(2alpha) (PGF(2alpha)) is a product of the cyclooxygenase pathway and is a local signaling molecule that activates a G-protein coupled prostanoid receptor named FP. FP receptors can stimulate T-cell factor (Tcf) transcriptional activation by stabilization of beta-catenin and can upregulate the expression of mRNA encoding cysteine-rich protein 61 (Cyr61), a secreted extracellular matrix protein that stimulates angiogenesis. We now show in both HEK cells and human microglial cells that the induction of Cyr61 protein expression by the human FP receptor utilizes a novel mechanism involving the activation of Ras and Raf followed by a MEK/ERK independent activation of Tcf signaling. The upregulation of Cyr61 in microglial cells may contribute to glioma tumorigenesis and could be a potential therapeutic target.
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PMID:PGF(2alpha) stimulates FP prostanoid receptor mediated crosstalk between Ras/Raf signaling and Tcf transcriptional activation. 1924 65

Bone morphogenic protein 4 (BMP4), a member of the TGF-beta superfamily, induced neural differentiation of neural stem cells (NSCs) grown in a medium containing basic fibroblast growth factor (bFGF). The Ras protein level and the activities of the downstream ERKs were increased by transfection of BMP4 or treatment with recombinant BMP4. The effects of BMP4, including activation of the Ras-ERK pathway and induction of the neuron marker beta-tubulin type III (Tuj1), were blocked by co-treatment of the BMP4 antagonist, noggin. The roles of the Ras-ERK pathway in neuronal differentiation by BMP4 were revealed by measuring the effect of the ERK pathway inhibition by dominant negative Ras or PD98059, the MEK specific inhibitor. BMP4 is a transcriptional target of Wnt/beta-catenin signaling, and both the mRNA and protein levels of BMP4 were increased by treatment of valproic acid (VPA), a chemical inhibitor of glycogen synthase kinase 3beta (GSK3beta) activating the Wnt/beta-catenin pathway. The BMP4- mimicking effects of VPA, activation of the Ras-ERK pathway and induction of Tuj1, also were blocked by noggin. These results indicate the potential therapeutic usage of VPA as a replacement for BMP4.
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PMID:Bone morphogenetic protein 4 stimulates neuronal differentiation of neuronal stem cells through the ERK pathway. 1928 92


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