Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The T cell costimulatory receptor 4-1BB enhances cell cycle progression and proliferation of CD8(+) T cells in both an IL-2-dependent and -independent manner. In these studies, 4-1BB costimulation was shown to increase cyclin D2, D3, and E expression, and concomitantly down-regulate the expression of the cyclin-dependent kinase inhibitor p27(kip1). 4-1BB increases cyclin D2 transcription via mitogen-activated/extracellular signal-regulated kinase-1/2 and LY294002-sensitive phosphatidylinositol 3-kinase (PI3K) signaling pathways. In addition, 4-1BB up-regulates cyclin D2 translation via PI3K/Akt/mammalian target of rapamycin (mTOR) pathways, presumably triggered by IL-2/IL-2 receptor ligation. The enhanced cyclin D2 and D3 expression initiates up-regulation of cyclin E expression and down-regulation of p27(kip1). Our results suggest a role for cyclin D2, D3, and E, and p27(kip1) proteins in the 4-1BB-mediated cell cycle progression of CD8(+) T cells in vivo.
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PMID:4-1BB enhances CD8+ T cell expansion by regulating cell cycle progression through changes in expression of cyclins D and E and cyclin-dependent kinase inhibitor p27kip1. 1288 87

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) ligands have been demonstrated to inhibit growth of several cancer cells. Here, we investigated whether one of the PPAR-gamma ligands, 15-deoxy-Delta12,14-prostaglandin J2 (15-deoxy-PGJ2) inhibits cell growth of two human neuroblastoma cells (SK-N-SH and SK-N-MC) in a PPAR-gamma-dependent manner. PPAR-gamma was expressed in these cells, and 15-deoxy-PGJ2 increased expression, DNA binding activity, and transcriptional activity of PPAR-gamma. 15-Deoxy-PGJ2 also inhibited cell growth in time- and dose-dependent manners in both cells. Cells were arrested in G2/M phase after 15-deoxy-PGJ2 treatment with concomitant increase in the expression of G2/M phase regulatory protein cyclin B1 but decrease in the expression of cdk2, cdk4, cyclin A, cyclin D1, cyclin E, and cdc25C. Conversely, related to the growth inhibitory effect, 15-deoxy-PGJ2 increased the induction of apoptosis in a dose-dependent manner. Consistent with the induction of apoptosis, 15-deoxy-PGJ2 increased the expression of proapoptotic proteins caspase 3, caspase 9, and Bax but down-regulated antiapoptotic protein Bcl-2. 15-Deoxy-PGJ2 also activated extracellular signal-regulated kinase (ERK) 2. In addition, mitogen-activated protein kinase kinase (MEK) 1/2 inhibitor PD98059 (2'-amino-3'-methoxyflavone) decreased 15-deoxy-PGJ2-induced ERK2 activation, and expression of PPAR-gamma, capase-3, and cyclin B1. Moreover, MEK1/2 inhibitor PD98059 significantly prevented against the 15-deoxy-PGJ2-induced cell growth inhibition. We also found that PPAR-gamma antagonist GW9662 (2-chloro-5-nitro-N-phenylbenzamide) reversed the 15-deoxy-PGJ2-induced cell growth inhibition, PPAR-gamma expression, and activation of ERK2. These results demonstrate that 15-deoxy-PGJ2 inhibits growth of human neuroblastoma cells via the induction of apoptosis in a PPAR-gamma-dependent manner through activation of ERK pathway and suggest that 15-deoxy-PGJ2 may have promising application as a therapeutic agent for neuroblastoma.
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PMID:Peroxisome proliferator-activated receptor-gamma activator 15-deoxy-Delta12,14-prostaglandin J2 inhibits neuroblastoma cell growth through induction of apoptosis: association with extracellular signal-regulated kinase signal pathway. 1296 53

The Runx2 (CBFA1/AML3/PEBP2alphaA) transcription factor promotes lineage commitment and differentiation by activating bone phenotypic genes in postproliferative osteoblasts. However, the presence of Runx2 in actively dividing osteoprogenitor cells suggests that the protein may also participate in control of osteoblast growth. Here, we show that Runx2 is stringently regulated with respect to cell cycle entry and exit in osteoblasts. We addressed directly the contribution of Runx2 to bone cell proliferation using calvarial osteoblasts from wild-type and Runx2-deficient mice (i.e., Runx2(-/-) and Runx2(DeltaC/DeltaC)). Runx2(DeltaC/DeltaC) mice express a protein lacking the Runx2 COOH terminus, which integrates several cell proliferation-related signaling pathways (e.g., Smad, Yes/Src, mitogen-activated protein kinase, and retinoblastoma protein). Calvarial cells but not embryonic fibroblasts from Runx2(-/-) or Runx2(DeltaC/DeltaC) mutant mice exhibit increased cell growth rates as reflected by elevations of DNA synthesis and G(1)-S phase markers (e.g., cyclin E). Reintroduction of Runx2 into Runx2(-/-) calvarial cells by adenoviral delivery restores stringent cell growth control. Thus, Runx2 regulates normal osteoblast proliferation, and the COOH-terminal region is required for this biological function. We propose that Runx2 promotes osteoblast maturation at a key developmental transition by supporting exit from the cell cycle and activating genes that facilitate bone cell phenotype development.
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PMID:Cell growth regulatory role of Runx2 during proliferative expansion of preosteoblasts. 1450 Mar 68

The recognition of biologically distinct tumor subsets is fundamental to understanding tumorigenesis. This study investigated the mutational status of the serine/threonine kinase BRAF and the cyclin E regulator FBXW7 (CDC4, FBW7, AGO, SEL10) related to two distinct pancreatic carcinoma subsets: the medullary KRAS2-wild-type and the cyclin E overexpressing tumors, respectively. Among KRAS2-wild-type carcinomas, 33% (3 of 9) contained BRAF V599E mutations; one of which was identified in the pancreatic cancer cell line COLO357. Among 74 KRAS2-mutant carcinomas, no BRAF mutations were identified. Among the KRAS2/BRAF wild-type carcinomas, no mutations within pathway members MEK1, MEK2, ERK1, ERK2, RAP1B, or BAD were found. Using pancreatic cancer microarrays and immunohistochemistry, we determined that 6% (4 of 46 and 5 of 100 in two independent panels) of pancreatic adenocarcinomas overexpress cyclin E. We identified two potential mechanisms for this overexpression including the amplification/gain of CCNE1 gene copies in the Panc-1 and Su86.86 cell lines and a novel somatic homozygous mutation (H460R, in one of 11 pancreatic cancer xenografts having allelic loss) in FBXW7, which was accompanied by cyclin E overexpression by immunohistochemistry. Both BRAF and FBXW7 mutations functionally activate kinase effectors important in pancreatic cancer and extend the potential options for therapeutic targeting of kinases in the treatment of phenotypically distinct pancreatic adenocarcinoma subsets.
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PMID:BRAF and FBXW7 (CDC4, FBW7, AGO, SEL10) mutations in distinct subsets of pancreatic cancer: potential therapeutic targets. 1450 35

We tested the hypothesis that Mg(2+) influences growth of vascular smooth muscle cells (VSMCs) by modulating cell cycle activation through mitogen-activated protein (MAP) kinase-dependent pathways. Rat VSMCs were grown in culture medium containing normal Mg(2+) (1.02 mmol/L, control) and increasing concentrations of Mg(2+) (2-4 mmol/L) for 1-8 days. Effects of varying extracellular Mg(2+) concentration ([Mg(2+)](e)) on intracellular free Mg(2+) concentration ([Mg(2+)](i)) were assessed using mag-fura. Growth actions of Mg(2+) were evaluated by measuring cell cycle activation, DNA synthesis, and protein synthesis. Expression of cell cycle promoters, cyclin D1, cyclin E, Cdk2, and Cdk4 was assessed by immunoblotting. Phosphorylation of cell cycle inhibitors p21(cip1) and p27(kip1) and MAP kinases, ERK1/2, p38MAP kinase, and JNK was evaluated using phospho-specific antibodies. [Mg(2+)](i) increased in a dose-dependent manner in response to increasing [Mg(2+)](e). These effects were evident within 2 days and maximal responses were obtained after 6 days. High [Mg(2+)](e) induced cell cycle activation with a lower proportion of cells in G(1) phase (75 +/- 1.0%) and a higher fraction of cells in S phase (12 +/- 0.7%) versus control (G(1), 88.5 +/- 1.4%; S, 6.8 +/- 1.2%; P < 0.05). This was associated with increased protein content of cyclin D1 and Cdk4 and decreased activation of p21(cip1) and p27(kip1). In cells exposed to 2 mmol/L Mg(2+), DNA and protein synthesis was increased approximately threefold. Phosphorylation of MEK1/2 and ERK1/2 was enhanced two to threefold in cells grown in 2 mmol/L Mg(2+). These effects were rapid, occurring within 2 days. Phosphorylation of MEK3/6, p38 MAP kinase, and JNK was unaltered by increasing [Mg2](e). PD98059 (10(-5) mol/L), specific MEK1/2 inhibitor, but not SB202190 (10(-5) mol/L) (specific p38 MAP kinase inhibitor), attenuated Mg(2+)-induced growth actions. These data demonstrate the novel findings that cell cycle activation and growth regulation by Mg(2+) occurs via ERK1/2-dependent, p38 MAP kinase-independent pathways.
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PMID:Modulation of vascular smooth muscle cell growth by magnesium-role of mitogen-activated protein kinases. 1456 62

Cancer is a multistep process involving cooperation between oncogenic or tumor suppressor mutations and interactions between the tumor and surrounding normal tissue. Here we present the first description of cooperative tumorigenesis in Drosophila, by using a system that mimics the development of tumors in mammals. We have used the MARCM system to generate mutant clones of the apical-basal cell polarity tumor suppressor gene, scribble, in the context of normal tissue. We show that scribble mutant clones in the eye disc exhibit ectopic expression of cyclin E and ectopic cell cycles, but do not overgrow due to increased cell death mediated by the JNK pathway and the surrounding wild-type tissue. In contrast, when oncogenic Ras or Notch is expressed within the scribble mutant clones, cell death is prevented and neoplastic tumors develop. This demonstrates, for the first time in Drosophila, that activated alleles of Ras and Notch can act as cooperating oncogenes in the development of epithelial tumors, and highlights the importance of epithelial polarity regulators in restraining oncogenes and preventing tumor formation.
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PMID:scribble mutants cooperate with oncogenic Ras or Notch to cause neoplastic overgrowth in Drosophila. 1459 75

Pyrrolidine dithiocarbamate (PDTC), a metal chelating compound, is known to induce cell death in vascular smooth muscle cells (VSMC). However, the molecular mechanism for PDTC-induced VSMC death is not well understood. Addition of PDTC reduced cell growth and DNA synthesis on VSMC in low density conditions. However, in serum depleted medium, PDTC did not affect the cell viability, suggesting that certain factors in serum may mediate the cytotoxic effect of PDTC. Several metal chelators prevented the cell death induced by PDTC. In a serum-deprived condition, addition of exogenous metals, copper, iron, and zinc, restored the cytotoxic effect of PDTC. These data indicate that metals such as copper, iron, and zinc in serum may mediate the cytotoxic effect of PDTC. At low VSMC density in 10% FBS, treatment of PDTC, which induced a cell-cycle block in G1-phase, induced down-regulation of cyclins and CDKs and up-regulation of the CDK inhibitor p21 expression, whereas up-regulation of p27 or p53 by PDTC was not observed. Finally, we determined PDTC-mediated signaling pathway involved in VSMC death. Among relevant pathways, PDTC induced marked activation of p38MAPK and JNK. Expression of dominant negative p38MAPK and SB203580, a p38MAPK specific inhibitor, blocked PDTC-dependent p38MAPK, growth inhibition, and p21 expression. These data demonstrate that the p38MAPK pathway participates in p21 induction, which consequently leads to decrease of cyclin D1/cdk4 and cyclin E/cdk2 complexes and PDTC-dependent VSMC growth inhibition. In conclusion, an understanding of the molecular mechanisms of PDTC in VSMC provides a theoretical basis for clinical approaches using antioxidant therapies in atherosclerosis.
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PMID:PDTC, metal chelating compound, induces G1 phase cell cycle arrest in vascular smooth muscle cells through inducing p21Cip1 expression: involvement of p38 mitogen activated protein kinase. 1460 33

The receptor activator of NF-kappaB ligand (RANKL), a recently identified member of the tumor necrosis factor (TNF) superfamily, has been shown to induce osteoclastogenesis and dendritic cell survival. Most members of the TNF superfamily suppress cell proliferation and induce apoptosis, but whether RANKL does so is not known. We demonstrate that treatment of monocyte RAW 264.7 cells with RANKL induces dose-dependent growth inhibition (IC50 = 10 ng/ml) as determined by dye uptake and [3H]thymidine incorporation methods. Suppression of RANKL-induced NF-kappaB activation by dominant-negative IkappaBalpha or by the NEMO-peptide had no effect on RANKL-induced cell growth inhibition. Inhibition of RANKL-induced JNK activation, however, abolished the RANKL-induced apoptosis. Suppression of interaction of RANK with TRAF6 by TRAF6-binding peptide abrogated the anti-proliferative effects of RANKL, suggesting the critical role of TRAF6. Flow cytometric analysis of cells treated with RANKL showed accumulation of cells in G0/G1 phase of the cell cycle, and this accumulation correlated with a decline in the levels of cyclin D1, cyclin D3, and cyclin E and an increase in cyclin-dependent kinase inhibitor p27 (Kip). Flow cytometric analysis showed the presence of annexin V-positive cells in cultures treated with RANKL. RANKL-induced apoptosis was further confirmed using calcein AM/ethidium homodimer-1 dye and cleavage of poly(ADP-ribose) polymerase (PARP), procaspase 3, and procaspase 9; benzyloxycarbonyl-VAD, the pancaspase inhibitor, suppressed the PARP cleavage. Thus, overall, our studies indicate that RANKL can inhibit cell proliferation and induce apoptosis through a TRAF-6-dependent but NF-kappaB-independent mechanism.
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PMID:Evidence that receptor activator of nuclear factor (NF)-kappaB ligand can suppress cell proliferation and induce apoptosis through activation of a NF-kappaB-independent and TRAF6-dependent mechanism. 1464 59

In neuroblastoma (NB), expression of the TrkA receptor is correlated with good prognosis while N-myc amplification is correlated with poor prognosis. Decreased N-myc levels are key to controlling growth and inducing differentiation in NB cells. In this report, we detail mechanisms by which nerve growth factor (NGF) decreases N-myc levels in TrkA-transfected NB cells and its effect on NB cell proliferation. NGF induced a decrease in N-myc mRNA within 1 h of treatment that occurred in the presence of cycloheximide. The stability of N-myc mRNA was not affected by NGF, indicating a transcriptional control of N-myc mRNA by NGF. NGF but not brain-derived neurotrophic factor (BDNF) decreased N-myc levels demonstrating that p75 alone was not involved. The NGF-induced decrease in N-myc expression was blocked by the Trk tyrosine kinase (TK) antagonist K252a indicating that signals transduced by Trk TK downstream targets were involved. Pharmacologic inhibitors implicated the mitogen-activated protein kinase (MAPK) path. This was supported by the finding that expression of a constitutively activated component of the MAPK path, MAPK kinase (MEK), decreased N-myc levels. Alterations in the level of N-myc are known to alter NB cell cycle progression by affecting the levels of E2Fs and p27(kip1). Consistent with these findings, NGF decreased NB cell number and decreased cyclin E-dependent kinase activity via an increase in p27(kip1). Thus, our results indicate that the MAP kinase is selectively involved in the NGF-induced N-myc downregulation through a transcriptional mechanism. Furthermore, NGF affects the time required for 15N TrkA cells to complete a replication cycle by decreasing N-myc, E2Fs, cyclin E kinase activity and increasing p27(kip1) binding to cyclin E kinase.
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PMID:NGF activation of TrkA decreases N-myc expression via MAPK path leading to a decrease in neuroblastoma cell number. 1469 55

Epidermal growth factor receptor (EGFR) activation is absolutely required for cervical cell proliferation. This suggests that EGFR-inhibitory agents may be of therapeutic value. In the present study, we investigated the effects of epigallocatechin-3-gallate (EGCG), a bioactive green tea polyphenol, on EGFR signaling in cervical cells. EGCG inhibits epidermal growth factor-dependent activation of EGFR, and EGFR-dependent activation of the mitogen-activated protein kinases ERK1/2. EGCG also inhibits EGFR-dependent AKT activity. The EGCG-dependent reduction in ERK and AKT activity is associated with reduced phosphorylation of downstream substrates, including p90RSK, FKHR, and BAD. These changes are associated with increased p53, p21(WAF-1), and p27(KIP-1) levels, reduced cyclin E level, and reduced CDK2 kinase activity. Consistent with these findings, flow cytometry and TUNEL (terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling) staining revealed EGCG-dependent G(1) arrest. Moreover, sustained EGCG treatment caused apoptotic cell death. In addition to inhibiting EGFR, cell-free studies demonstrated that EGCG directly inhibits ERK1/2 and AKT, suggesting that EGCG acts simultaneously at multiple levels to inhibit EGF-dependent signaling. Importantly, the EGCG inhibition is selective, as EGCG does not effect the EGFR-dependent activation of JNK. These results suggest that EGCG acts to selectively inhibit multiple EGF-dependent kinases to inhibit cell proliferation.
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PMID:Epigallocatechin-3-gallate inhibits epidermal growth factor receptor signaling pathway. Evidence for direct inhibition of ERK1/2 and AKT kinases. 1470 54


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