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:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human hepatocarcinoma cells (SK-HEP-1) were induced to die through apoptosis by treatment with delta 12-prostaglandin (PG)J2, as characterized by the appearance of a typical DNA ladder. The induction of apoptosis by delta 12-PGJ2 was specifically blocked by cycloheximide (CHX). Western analysis using anti-p53 or anti-WAF1 monoclonal antibodies demonstrated that these two protein levels were increased 3 h after delta 12-PGJ2 treatment, and accumulated for up to 12 h. The induction of p53 protein seemed to be dependent on the increase of p53 mRNA level, which was inhibited by CHX treatment. However, delayed addition of CHX after delta 12-PGJ2 treatment failed to affect both p53 mRNA levels and DNA fragmentation following delta 12-PGJ2 treatment, indicating that the inhibition of p53 synthesis may contribute to the protective effect of CHX against delta 12-PGJ2-mediated cytotoxicity. Therefore, our results suggest that the initial events caused by delta 12-PGJ2, leading ultimately to SK-HEP-1 cell death, involve a certain process required for p53 induction. However, the finding that delta 12-PGJ2 is also active against Hep 3B cells which are devoid of a functional p53 indicates that p53 may not be the critical requirement for inducing apoptosis by delta 12-PGJ2.
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PMID:Induction of p53 and apoptosis by delta 12-PGJ2 in human hepatocarcinoma SK-HEP-1 cells. 762 35

Previously we reported that neu differentiation factor (NDF)/heregulin (HRG) elevates tyrosine phosphorylation of its receptors erbB-3, erbB-4, and erbB-2 (through heterodimer formation). We also showed that both NDF/HRG and antibodies to erbB-2 can arrest growth and induce differentiation in breast cancer cells. In this study, we report on the mechanism of NDF/HRG-induced cellular effects. We show that NDF/HRG and antibodies to erbB-2 receptors up-regulate expression of p53 by stabilizing the protein. This is accompanied by up-regulation of the p53 inducible gene, p21CIP1/WAF1, in a variety of cell lines: MCF7 and their derivatives (MCF7/HER2, MN1 and MCF-7-puro), ZR75T and LnCap cells. The induction of p21 is further enhanced when cells are treated with both NDF/HRG and DNA-damaging chemotherapeutic agents (i.e. doxorubicin). The NDF/HRG mediated induction of p21 is dependent on wildtype p53, as it fails to occur in cells expressing dominant negative p53 (MDD2). Furthermore, p21 induction is capable of inactivating cdk2 complexes as measured by Histone H1 phosphorylation assays. Finally, we show that in primary cultures of breast and other cancers, p21 is significantly induced in response to NDF/HRG treatment. Collectively, these observations suggest that the mechanism of breast cancer cell growth inhibition and differentiation via erbB receptors activation is through a p53-mediated pathway.
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PMID:Neu differentiation factor (Heregulin) activates a p53-dependent pathway in cancer cells. 870 May 12

The effect of the CSF-1 receptor, cFMS, on the phosphorylation of the retinoblastoma (RB) tumor suppressor protein and on the cell cycle and cell differentiation was analyzed in a cultured promyelocytic leukemia cell capable of induced myelomonocytic differentiation. A series of cFMS-transfected HL-60 sublines with progressively higher cell surface FMS expression was derived by flow cytometric cell sorting. Overexpression of FMS increased the duration of the cell cycle, prolonging all cell cycle phases especially S phase, which doubled. The increased cell cycle generation times occurred without any detectable changes in RB expression level or phosphorylation. For retinoic acid (RA)-induced myeloid differentiation, progressive overexpression of FMS caused a greater fraction of cells to differentiate and G1/0 arrest compared to wild-type cells after the same number of cell cycle generation times. FMS overexpression also progressively increased the relative amount of dephosphorylated RB protein induced, while reducing the total amount of RB protein. The inducer-originated and FMS-driven changes in RB hypophosphorylation were not effected through changes in p21/WAF1/CIP1 in this p53-negative cell. Similar effects on differentiation and G0 arrest occurred with 1,25-dihydroxy vitamin D3 (D3)-induced monocytic differentiation. FMS did not significantly affect myeloid differentiation induced by DMSO, which does not target steroid-thyroid hormone receptors like RA and D3. While differentiation is typically associated with hypophosphorylated RB in all these cases, the kinetics indicate that the FMS-induced changes in cell cycle and cell differentiation do not depend in a direct causal fashion on the interconversion between hyperphosphorylated and hypophosphorylated RB.
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PMID:FMS (CSF-1 receptor) prolongs cell cycle and promotes retinoic acid-induced hypophosphorylation of retinoblastoma protein, G1 arrest, and cell differentiation. 894 Feb 55

The mitogen-activated protein kinase (MAPK) cascade plays a crucial role in the transduction of extracellular signals into responses governing growth and differentiation. The effects of a specific inhibitor of the MAPK kinase (MEK)/MAPK pathway (PD98059) on nerve growth factor (NGF)-induced growth arrest and inhibition of cell cycle-dependent kinases (CDKs) have been examined. Treatment of NIH 3T3 cells expressing TRKA with PD98059 dramatically reversed the complete inhibition of growth of these cells caused by NGF. PD98059 also blocked the ability of NGF to inhibit the activities of CDK4 and CDK2, while partially preventing NGF induction of p21Cip1/WAF1. To independently evaluate the involvement of the MEK/MAPK pathway in growth arrest, an inducible activated form of the Raf-1 protooncogene (delta RAF-1:ER) was expressed in these cells. Activation of delta RAF-1:ER resulted in a prolonged increase in MAPK activity and growth arrest of these cells, with concomitant induction of p21Cip1/WAF1 and inhibition of CDK2 activity. These effects of delta RAF-1:ER activation were all reversed by treatment of cells with PD98059. These data indicate that in addition to functioning as a positive effector of growth, stimulation of the MEK/MAPK pathway can result in an inhibition of CDK activity and cell cycle arrest.
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PMID:Cell cycle arrest mediated by the MEK/mitogen-activated protein kinase pathway. 901 3

The achondroplasia class of chondrodysplasias comprises the most common genetic forms of dwarfism in humans and includes achondroplasia, hypochondroplasia and thanatophoric dysplasia types I and II (TDI and TDII), which are caused by different mutations in a fibroblast growth-factor receptor FGFR3 (ref. 1). The molecular mechanism and the mediators of these FGFR3-related growth abnormalities are not known. Here we show that mutant TDII FGFR3 has a constitutive tyrosine kinase activity which can specifically activate the transcription factor Stat1 (for signal transducer and activator of transcription). Furthermore, expression of TDII FGFR3 induced nuclear translocation of Stat1, expression of the cell-cycle inhibitor p21(WAF1/CIP1), and growth arrest of the cell. Thus, TDII FGFR3 may use Stat1 as a mediator of growth retardation in bone development. Consistent with this, Stat1 activation and increased p21(WAF1/CIP1) expression was found in the cartilage cells from the TDII fetus, but not in those from the normal fetus. Thus, abnormal STAT activation and p21(WAF1/CIP1) expression by the TDII mutant receptor may be responsible for this FGFR3-related bone disease.
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PMID:Activation of Stat1 by mutant fibroblast growth-factor receptor in thanatophoric dysplasia type II dwarfism. 906 88

In the present study, we report that ginsenoside-Rg5 (G-Rg5), a newly discovered diol-containing ginsenoside, blocks the cell cycle of human hepatoma SK-HEP-1 cells via the down-regulation of cyclin E-dependent kinase activity. The results from flow cytometric analyses show that G-Rg5 arrests the cell cycle of SK-HEP-1 cells at the Gl/S transition phase. The cyclin E-dependent kinase activity that has been immunoprecipitated with cyclin E-specific antibody is down-regulated in response to G-Rg5. The results from immunoblottings show that the down-regulation of cyclin E-dependent kinase activity is related to increased protein levels of p21Cip/WAF1 and to decreased protein levels of cyclin E, CDK2, and CDC25A. Collectively, these data suggest that G-Rg5 blocks cell cycle of SK-HEP-1 cells at the Gl/S transition phase by down-regulating cyclin E-dependent kinase activity and that the down-regulation of cyclin E-dependent kinase activity is caused mainly by induced CDK2 inhibitor, p21Cip/WAF1 and decreased levels of cyclin E.
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PMID:Ginsenoside-Rg5 suppresses cyclin E-dependent protein kinase activity via up-regulating p21Cip/WAF1 and down-regulating cyclin E in SK-HEP-1 cells. 913 50

Members of the epidermal growth factor (EGF) family of tyrosine kinase receptors are involved in the regulation of cell growth and differentiation, and are found to be expressed in many types of cancers. Activation of these receptors can be elicited by multiple ligands, resulting in the formation of a spectrum of heterodimer complexes and a number of biological outcomes. A clear demonstration of biological activation by a single complex has been difficult to address because of the endogenous expression of HERs (human EGF-like receptors) in many cell lines. We have generated a collection of cell lines expressing all HERs alone or in all pairwise combinations in a clone of NIH 3T3 cells (3T3-7d) devoid of detectable EGF receptor family members. Transformation, as measured by growth in soft agar, only occurred in cells expressing two different HER family members. Transformation with activated Neu and the rate of in vivo tumour formation were also correlated with the expression of multiple HERs in the same cell. To further our understanding of the role of heterodimer signalling, we demonstrated that, within a breast carcinoma cell line, activation of HER-3 results in cellular differentiation, prolonged activation of extracellular-signal-related kinase 1 (ERK1) activity and an increase in p21CIP1/WAF1 nuclear staining. In contrast, activation of HER-4 is mitogenic, induces transient activation of ERK1 activity and decreases the nuclear staining of p21CIP1/WAF1. These differences in biochemical and biological responses are correlated with the contrasting abilities of HER-3 and HER-4 to be down-regulated from the cell surface. The cell-surface localization of HER-3 does not change in response to ligand, whereas activation of HER-4 results in a loss of cell-surface staining followed by accumulation into a perinuclear compartment.
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PMID:Role of epidermal growth factor receptor family members in growth and differentiation of breast carcinoma. 951 24

During late stages of breast cancer progression, tumors frequently acquire steroid hormone resistance with concurrent amplification of growth factor receptors; this alteration predicts a poor prognosis. We show here that following treatment with the progestin, R5020, breast cancer cells undergo a "biochemical shift" in the regulation of epidermal growth factor (EGF)-stimulated signaling pathways: R5020 potentiates the effects of EGF by up-regulating EGFR, c-ErbB2 and c-ErbB3 receptors, and by enhancing EGF-stimulated tyrosine phosphorylation of signaling molecules known to associate with activated type I receptors. Independently of EGF, R5020 increases Stat5 protein levels, association of Stat5 with phosphotyrosine-containing proteins, and tyrosine phosphorylation of JAK2 and Shc. Furthermore, progestins "prime" breast cancer cells for growth signals by potentiating EGF-stimulated p42/p44 mitogen-activated protein kinase (MAPK), p38 MAP kinase, and JNK activities. Although the levels of cyclin D1, cyclin E, and p21(WAF1), are up-regulated by R5020 alone, they are synergistically up-regulated by EGF in the presence of R5020. Up-regulation of cell cycle proteins by EGF is blocked by inhibition of p42/p44 MAPK only in the presence of R5020, supporting a shift in the regulation of these cell cycle mediators from MAPK-independent to MAPK-dependent pathways. In summary, progesterone selectively increases the sensitivity of key kinase cascades to growth factors, thereby priming cells for stimulation by latent growth signals. These data support a model in which breast cancer cell growth switches from steroid hormone to growth factor dependence.
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PMID:Convergence of progesterone and epidermal growth factor signaling in breast cancer. Potentiation of mitogen-activated protein kinase pathways. 981 39

Hormones and growth factors regulate cell growth via the mitogen-activated protein (MAP) kinase cascade. Here we examine the actions of the hormone somatostatin on the MAP kinase cascade through one of its two major receptor subtypes, the somatostatin receptor 1 (SSTR1) stably expressed in CHO-K1 cells. Somatostatin antagonizes the proliferative effects of fibroblast growth factor in CHO-SSTR1 cells via the SSTR1 receptor. However, in these cells, somatostatin robustly activates MAP kinase (also called extracellular signal regulated kinase; ERK) and augments fibroblast growth factor-stimulated ERK activity. We show that the activation of ERK via SSTR1 is pertussis toxin sensitive and requires the small G protein Ras, phosphatidylinositol 3-kinase, the serine/threonine kinase Raf-1, and the protein tyrosine phosphatase SHP-2. The activation of ERK by SSTR1 increased the expression of the cyclin-dependent protein kinase inhibitor p21(cip1/WAF1). Previous studies have suggested that somatostatin-stimulated protein tyrosine phosphatase activity mediates the growth effects of somatostatin. Our data suggest that SHP-2 stimulation by SSTR1 may mediate some of these effects through the activation of the MAP kinase cascade and the expression of p21(cip1/WAF1).
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PMID:Somatostatin activation of mitogen-activated protein kinase via somatostatin receptor 1 (SSTR1). 989 10

Phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) and all-trans-retinoic acid (trans-RA) are potent regulators of growth of cancer cells. In this study, we investigated the effect of TPA and trans-RA alone or their combination on proliferation of human breast cancer ZR75-1 and T47D and lung cancer H460 and H292 cell lines. trans-RA caused various degrees of growth inhibition of these cell lines. However, TPA showed inhibition of proliferation of H460 and H292 cells and induction of ZR75-1 cell growth. Although trans-RA did not significantly regulate the growth inhibitory effect of TPA, it completely prevented its growth stimulating function. The divergent effects of TPA were associated with specific disruption of cell cycle events, an induction of G(0)/G(1) arrest in H460 and H292 cells and inhibition of G(0)/G(1) arrest with increase of S phase in ZR75-1 cells. Induction of G(0)/G(1) arrest was accompanied by induction of p21(WAF1) and ERK activity, whereas inhibition of G(0)/G(1) arrest was associated with enhanced activity of JNK and AP-1 but not ERK. trans-RA did not affect TPA-induced p21(WAF1) expression. However, it inhibited TPA-induced AP-1 activity in ZR75-1 cells and the constitutive AP-1 activity in H460 and H292 cells. Thus, trans-RA modulates TPA activity through its interaction through TPA-induced JNK/AP-1 pathway but not TPA-induced ERK/p21(WAF1) pathway.
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PMID:Differential effect of retinoic acid on growth regulation by phorbol ester in human cancer cell lines. 1051 54


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