Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.12.2 (MEK)
18,161 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mitogen-activated protein kinases MEK/ERK pathway regulates fundamental processes in malignant cells and represents an attractive target in the development of new cancer treatments especially for human hepatocarcinoma highly resistant to chemotherapy. Although gene extinction experiments have suggested distinct roles for these proteins, the MEK/ERK cascade remains widely considered as exhibiting an overlap of functions. To investigate the functionality of each kinase in tumorigenesis, we have generated stably knock-down clones for MEK1/2 and ERK1/2 isoforms in the human hepatocellular carcinoma line HuH7. Our results have shown that RNAi strategy allows a specific disruption of the targeted kinases and argued for the critical function of MEK1 in liver tumor growth. Transient and stable extinction experiments demonstrated that MEK1 isoform acts as a major element in the signal transduction by phosphorylating ERK1 and ERK2 after growth factors stimulation, whereas oncogenic level of ERK1/2 phosphorylation appears to be MEK1 and MEK2 dependent in basal condition. In addition, silencing of MEK1 or ERK2 abolished cell proliferation and DNA replication in vitro as well as tumor growth in vivo after injection in rodent. In contrast, targeting MEK2 or ERK1 had no effect on hepatocarcinoma progression. These results strongly corroborate the relevance of targeting the MEK cascade as attested by pharmacologic drugs and support the potential application of RNAi in future development of more effective cancer therapies. Our study emphasizes the importance of the MEK/ERK pathway in human hepatocarcinoma cell growth and argues for a crucial role of MEK1 and ERK2 in this regulation.
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PMID:RNAi-mediated MEK1 knock-down prevents ERK1/2 activation and abolishes human hepatocarcinoma growth in vitro and in vivo. 1981 36

Recent studies have suggested that sulforaphane, a compound found largely in cruciferous vegetables, could inhibit tumor growth through regulation of angiogenesis. However, the molecular mechanism by which it inhibits angiogenesis has not been reported. In this study, we examined the molecular mechanisms by which sulforaphane (SNF) inhibits angiogenesis through regulation of FOXO transcription factor in human umbilical vein endothelial cells (HUVECs). Inhibition of MEK/ERK and PI3K/AKT pathways synergistically inhibited cell migration and capillary tube formation by HUVECs and further enhanced the anti-angiogenic effects of sulforaphane. Inhibitors of MEK and AKT kinases synergistically enhanced nuclear translocation of FOXO3a. Inhibition of the MEK/ERK and PI3K/AKT pathways synergistically induced FOXO transcriptional activity and inhibited cell migration and capillary tube formation; these events were further enhanced in the presence of sulforaphane. Phosphorylation deficient mutants of FOXO enhanced antiangiogenic effects of sulforaphane by activating the FOXO transcription factor. In conclusion, activation of FOXO transcription factor by sulforaphane could be an important physiological process to inhibit angiogenesis which may ultimately control tumor growth. These novel antiangiogenic activities of sulforaphane are likely to contribute to its cancer chemopreventive and therapeutic potential.
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PMID:Sulforaphane inhibits angiogenesis through activation of FOXO transcription factors. 1988 1

In previous studies, rhein, one of the major bioactive constituents in the rhizome of rhubarb, inhibited the proliferation of various human cancer cells. However, because of its water insolubility, the anti-tumor efficacy of rhein was limited in vivo. In this study, we observed the anti-tumor activity of rhein lysinate (the salt of rhein and lysine easily dissolves in water) in vivo and investigated its mechanism. Inhibition of ovarian cancer SKOV-3 cell proliferation was determined by MTT assay and the mechanism of action of rhein lysinate was investigated by Western blot analysis. The therapeutic efficacy of rhein lysinate was evaluated by intragastric and intraperitoneal administrations in H22 hepatocellular carcinoma mice. Rhein lysinate inhibited the proliferation of SKOV-3 cells and the IC50 value was 80 microM. Rhein lysinate inhibited the phosphorylation of MEK and ERK and increased the anti-tumor activity of Taxol in vitro. It inhibited tumor growth by both intragastric and intraperitoneal administrations and improved the therapeutic effect of Taxol in H22 hepatocellular carcinoma mice. In conclusion, rhein lysinate offers an anti-tumor activity in vivo and is hopeful to be a chemotherapeutic drug.
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PMID:Rhein lysinate suppresses the growth of tumor cells and increases the anti-tumor activity of Taxol in mice. 1988 52

CUDC-305 is a heat shock protein 90 (HSP90) inhibitor of the novel imidazopyridine class. Here, we report its activities in non-small cell lung cancer (NSCLC) cell lines with gene deregulations conferring primary or secondary resistance to epidermal growth factor receptor (EGFR) inhibitors. We show that CUDC-305 binds strongly to HSP90 extracted from erlotinib-resistant NSCLC cells (IC50 70 nmol/L). This result correlates well with the potent antiproliferative activity in erlotinib-resistant NSCLC cell lines (IC50 120-700 nmol/L) reported previously. Furthermore, it exhibits durable inhibition of multiple oncoproteins and induction of apoptosis in erlotinib-resistant NSCLC cells. CUDC-305 potently inhibits tumor growth in subcutaneous xenograft models of H1975 and A549, which harbor EGFR T790M mutation or K-ras mutations conferring acquired and primary erlotinib resistance, respectively. In addition, CUDC-305 significantly prolongs animal survival in orthotopic lung tumor models of H1975 and A549, which may be partially attributed to its preferential exposure in lung tissue. Furthermore, CUDC-305 is able to extend animal survival in a brain metastatic model of H1975, further confirming its ability to cross the blood-brain barrier. Correlating with its effects in various tumor models, CUDC-305 induces degradation of receptor tyrosine kinases and downstream signaling molecules of the PI3K/AKT and RAF/MEK/ERK pathways simultaneously, with concurrent induction of apoptosis in vivo. In a combination study, CUDC-305 enhanced the antitumor activity of a standard-of-care agent in the H1975 tumor model. These results suggest that CUDC-305 holds promise for the treatment of NSCLC with primary or acquired resistance to EGFR inhibitor therapy.
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PMID:Targeting heat shock protein 90 with CUDC-305 overcomes erlotinib resistance in non-small cell lung cancer. 1995 21

The serine/threonine Pim kinases are up-regulated in specific hematologic neoplasms, and play an important role in key signal transduction pathways, including those regulated by MYC, MYCN, FLT3-ITD, BCR-ABL, HOXA9, and EWS fusions. We demonstrate that SMI-4a, a novel benzylidene-thiazolidine-2, 4-dione small molecule inhibitor of the Pim kinases, kills a wide range of both myeloid and lymphoid cell lines with precursor T-cell lymphoblastic leukemia/lymphoma (pre-T-LBL/T-ALL) being highly sensitive. Incubation of pre-T-LBL cells with SMI-4a induced G1 phase cell-cycle arrest secondary to a dose-dependent induction of p27(Kip1), apoptosis through the mitochondrial pathway, and inhibition of the mammalian target of rapamycin C1 (mTORC1) pathway based on decreases in phospho-p70 S6K and phospho-4E-BP1, 2 substrates of this enzyme. In addition, treatment of these cells with SMI-4a was found to induce phosphorylation of extracellular signal-related kinase1/2 (ERK1/2), and the combination of SMI-4a and a mitogen-activated protein kinase kinase 1/2 (MEK1/2) inhibitor was highly synergistic in killing pre-T-LBL cells. In immunodeficient mice carrying subcutaneous pre-T-LBL tumors, treatment twice daily with SMI-4a caused a significant delay in the tumor growth without any change in the weight, blood counts, or chemistries. Our data suggest that inhibition of the Pim protein kinases may be developed as a therapeutic strategy for the treatment of pre-T-LBL.
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PMID:A small molecule inhibitor of Pim protein kinases blocks the growth of precursor T-cell lymphoblastic leukemia/lymphoma. 1996 90

Soluble APRIL (sAPRIL), the active form of a proliferation-inducing ligand (APRIL), is implicated in the proliferation of tumor cells. Suppressing APRIL function has been considered as a potential strategy for the therapy of APRIL-associated tumors. In the present study, we generated human sAPRIL and its two mutants, Gln187-D-sAPRIL (Gln187 deleted) and Gly187-sAPRIL (Gln187 replaced by Gly). In vitro experiments showed that the two mutants had similar specific binding capacity to lung carcinoma A549 cells compared to the wild-type sAPRIL, and both, especially Gly187-sAPRIL, exhibited significant antagonistic effect on sAPRIL-induced tumor cell proliferation in a dose-dependent manner, which might be predominantly mediated by blocking sAPRIL-induced MEK and ERK phosphorylation but not p38MAPK or JNK signaling. In vivo experiments with nude mice bearing A549 cell-derived xenograft tumor showed that only the Gly187-sAPRIL mutant could significantly suppress the tumor growth. These results suggest that Gln187 may be a crucial amino acid in APRIL-mediated tumor cell proliferation via the MEK-ERK signaling pathway and that the sAPRIL mutants may serve as novel potential antagonists of APRIL for the therapy of APRIL-associated cancers.
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PMID:Two Gln187 mutants of human soluble APRIL inhibit proliferation of lung carcinoma A549 cells. 1999 50

The ERK and mTOR pathways show multiple interconnections that coordinate growth activation and the regulation of protein translation. Although drugs that target these pathways appear to have limited anti-cancer effects as single agents, we hypothesized that the monotherapy anticancer efficacy of these agents could be enhanced by their combination. The MEK inhibitor AZD6244 (ARRY-142886) and the mTOR inhibitor rapamycin were tested as single agents and in combination, using BxPC-3 and MIA PaCa-2 pancreatic cancer models in vivo. In both models, S6 ribosomal protein was almost completely inhibited with combined treatment, but only partially inhibited with the single agents. In addition, 48 h treatment with the drug combination produced greater apoptosis, revealed by caspase 3 cleavage, and growth inhibition measured using bromodeoxyuridine incorporation, compared to the single agents. AZD6244 but not rapamycin exhibited a significant anti-angiogenic effect, as shown by tumor VEGF ELISA assay and CD31 analysis. Plasma and tumor pharmacokinetic analyses indicated that AZD6244 accumulates in tumor tissue at concentrations that produce target inhibition and cell cycle arrest in vitro. In chronic dosing experiments, the drug combination was well tolerated, and showed greater growth inhibition compared to the single agents. These results are consistent with the hypothesis that ERK and mTOR signaling interact at multiple levels to regulate tumor growth in vivo, and support the testing of MEK plus mTOR inhibitor combinations in pancreatic cancer patients.
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PMID:Effects of combined inhibition of MEK and mTOR on downstream signaling and tumor growth in pancreatic cancer xenograft models. 2000 39

Targeting the Ras/Raf/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway represents a promising anticancer strategy. Recently, we have reported a novel class of potent and selective non-ATP-competitive MEK1/2 inhibitors with a unique structure and mechanism of action. RO5068760 is a representative of this class showing significant efficacy in a broad spectrum of tumors with aberrant mitogen-activated protein kinase pathway activation. To understand the relationship between systemic exposures and target (MEK1/2) inhibition as well as tumor growth inhibition, the current study presents a detailed in vivo characterization of efficacy, pharmacokinetics, and pharmacodynamics of RO5068760 in multiple xenograft tumor models. For inhibition of MEK1/2 as measured by the phosphorylated ERK levels, the estimated EC(50)s in plasma were 1.36 micromol/L (880 ng/mL) and 3.35 micromol/L (2168 ng/mL) in LOX melanoma and HT-29 colorectal cancer models, respectively. A similar EC(50) (1.41 micromol/L or 915 ng/mL) was observed in monkey peripheral blood lymphocytes. To achieve tumor growth inhibition (>or=90%), an average plasma drug concentration of 0.65 or 5.23 micromol/L was required in B-RafV600E or K-Ras mutant tumor models, respectively, which were remarkably similar to the IC(90) values (0.64 or 4.1 micromol/L) determined in vitro for cellular growth inhibition. With equivalent in vivo systemic exposures, RO5068760 showed superior efficacy in tumors harboring B-RafV600E mutation. The plasma concentration time profiles indicate that constant p-ERK suppression (>50%) may not be required for optimal efficacy, especially in highly responsive tumors. This study may facilitate future clinical trial design in using biochemical markers for early proof of mechanism and in selecting the right patients and optimal dose regimen.
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PMID:Preclinical in vivo evaluation of efficacy, pharmacokinetics, and pharmacodynamics of a novel MEK1/2 kinase inhibitor RO5068760 in multiple tumor models. 2005 79

Farnesyltransferase (FTase) inhibitors induce growth arrest and apoptosis in various human cancer cells by inhibiting the post-translational activation of Ras. FTase inhibitors also function to suppress the release of vascular endothelial growth factor (VEGF) from tumor cells by inhibiting Ras activation; however, the effects of FTase inhibitors on VEGF-induced angiogenesis in endothelial cells have not been studied. We have investigated the antiangiogenic effect and molecular mechanism of 4-((1-((1-((4-bromophenyl)methyl)-1H-imidazol-5-yl)methyl)-4-(1-napthalenyl)-1H-pyrrol-3-yl)carbonyl)-(9C1)-morpholine (LB42708), a selective nonpeptidic FTase inhibitor, using in vitro and in vivo assay systems. LB42708 inhibited VEGF-induced Ras activation and subsequently suppressed angiogenesis in vitro and in vivo by blocking the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase/p38 mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/Akt/endothelial nitric-oxide synthase pathways in endothelial cells without altering FAK/Src activation. In addition, this inhibitor suppressed VEGF-induced endothelial cell cycle progression at the G(1) phase by suppressing cyclin D1 expression and retinoblastoma phosphorylation as well as up-regulating the cyclin-dependent kinase inhibitors p21 and p27. Knockdown of Ras by short interfering RNA revealed similar inhibitory effects on VEGF-induced angiogenic signal events compared with LB42708. Moreover, the inhibitory effects of LB42708 were significantly higher than those of 4-(2-(4-(8-chloro-3,10-dibromo-6,11-dihydro-5H-benzo-(5,6)-cyclohepta(1,2-b)-pyridin-11(R)-yl)-1-piperidinyl)-2-oxo-ethyl)-1-piperidinecarboxamide (SCH66336), a well known FTase inhibitor. LB42708 suppressed tumor growth and tumor angiogenesis in both xenograft tumor models of Ras-mutated HCT116 cells and its wild-type Caco-2 cells, indicating its potential application in the treatment of both Ras-mutated and wild type tumors. These data indicate that the antitumor effect of LB42708 can be associated with direct inhibition of VEGF-induced tumor angiogenesis by blocking Ras-dependent MAPK and PI3K/Akt signal pathways in tumor-associated endothelial cells.
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PMID:The farnesyltransferase inhibitor LB42708 suppresses vascular endothelial growth factor-induced angiogenesis by inhibiting ras-dependent mitogen-activated protein kinase and phosphatidylinositol 3-kinase/Akt signal pathways. 2040 54

BRAF is a serine-threonine-specific protein kinase that is mutated in 2% of human cancers. Oncogenic BRAF is a validated therapeutic target that constitutively activates mitogen-activated protein kinase kinase (MEK)-extracellular signal-regulated kinase (ERK) signaling, driving tumor cell proliferation and survival. Drugs designed to target BRAF have been developed, but it is difficult to prove that they mediate their antitumor effects by inhibiting BRAF rather than by working through off-target effects. We generated drug-resistant versions of oncogenic BRAF by mutating the gatekeeper residue. Signaling by the mutant proteins was resistant to the small-molecule inhibitor sorafenib, but sorafenib still inhibited the growth of tumors driven by the mutant protein. In contrast, both BRAF signaling and tumor growth were resistant to another RAF drug, PLX4720. These data provide unequivocal evidence that sorafenib mediates its antitumor effects in a manner that is independent of its ability to target oncogenic BRAF, whereas PLX4720 inhibits tumor growth by targeting oncogenic BRAF directly.
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PMID:Gatekeeper mutations mediate resistance to BRAF-targeted therapies. 2053 17


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