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

---

Query: EC:2.7.11.24 (mitogen-activated protein kinase)
95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have investigated the influence of Ki-ras oncogene on Met/hepatocyte growth factor (HGF) receptor signaling in human carcinoma cells. The model system used in these studies included the DLD-1 colon cancer cell line with a mutated Ki-ras allele, and the DKO-4 cell line generated from DLD-1, with its mutant Ki-ras allele inactivated by targeted disruption. These cell lines were transduced with cDNAs of either active Met receptor or dominant negative Met receptor. As compared to the DLD-1 cells, constitutive overexpression of Met receptor in this cell line (DLD-1-Met) resulted in increased tumorigenicity in SCID mice. In contrast, overexpression of Met in DKO-4 cells (DKO-4-Met) that have lost oncogenic Ras activity demonstrated suppressed tumorigenicity with respect to the parent DKO-4 cell line. Tumors formed by the DLD-1-Met cells showed increased levels of mitogen-activated protein kinase (MAPK) and lower levels of apoptosis compared to the DKO-4-Met tumors. Overexpression of the dominant negative Met receptor cDNA decreased the Met phosphorylation levels in both DLD-1 and DKO-4 cells, but only suppressed tumorigenicity in the DKO-4 cell line. In vitro, HGF stimulation of DLD-1 cells resulted in a prolonged duration of MAPK activation, while DKO-4 cells exhibited a rapid attenuation of MAPK phosphorylation. The results suggest that Ki-ras mutations and HGF signaling cooperate to enhance tumor growth by increased duration of MAPK activation and decreased apoptosis in human carcinoma cells.
...
PMID:Met receptor overexpression and oncogenic Ki-ras mutation cooperate to enhance tumorigenicity of colon cancer cells in vivo. 1265 12

Dual specificity phosphatases (DSP) play an important role in control of the cell cycle and signal transduction. We have synthesized a new class of DSP inhibitors. Cpd 5 or [2-(2-mercaptoethanol)-3-methyl-1,4-naphthoquinone] is one of the most potent of these. It inhibits DSPs of cells in culture and induces tyrosine phosphorylation of various DSP substrates, including the Cdc25 target Cdks and it potently inhibits cell growth. In this study, we have evaluated Cpd 5 in vivo for its antitumor and growth inhibitory activity on carcinogen-altered foci. Cpd 5 inhibited growth of the transplantable rat hepatoma cell line JM-1 in vitro, with concomitant phosphorylation of the mitogen-activated protein kinase ERK1/2 but not JNK1/2 or p38. This ERK phosphorylation was associated with growth inhibition, as the ERK phosphorylation inhibitor PD098059 antagonized both ERK phosphorylation and growth inhibition. JM-1 cell lysates were found to contain ERK1/2-specific phosphatase(s) that could be inhibited by Cpd 5 and which are thought to be its major targets. Cpd 5 caused significant inhibition of both intrahepatic and subcutaneous (s.c.) growth of transplanted JM-1 cells in male Fischer F344 rats. The treatment was equally effective whether Cpd 5 was administered either as a single, acute dose or chronically as several lower doses. However, toxicity was much lower with chronic treatment. As in JM-1 cells in vitro, ERK1/2 was phosphorylated when rats in vivo were treated with Cpd 5 and tumor growth inhibition in vivo also was antagonized by treating rats with the ERK1/2 phosphorylation inhibitor PD098059. A single dose of Cpd 5 also inhibited the formation of glutathione S-transferase-pi enzyme-altered cells induced by the hepatocarcinogen N-nitrosodiethylamine. This is the first report of the in vivo activity and growth inhibitory mechanism of a novel class of K vitamin growth inhibitors that have potent tyrosine phosphatase activity.
...
PMID:Antitumor and anticarcinogenic actions of Cpd 5: a new class of protein phosphatase inhibitor. 1266 99

After dissemination from a primary tumor, cancer cells may resume growth, leading to overt metastasis, or enter a state of protracted dormancy. However, mechanisms that determine their fate, or markers that predict it, are mostly unavailable. We previously showed that in HEp3 human head and neck carcinoma, the extracellular signal-regulated kinase (ERK)(MAPK)/p38(SAPK) activity ratio predicts whether the cells will proliferate or enter a state of dormancy in vivo. The proliferative balance of high ERK/p38 ratio was induced by high urokinase (uPA) receptor (uPAR) expression, which activated alpha5beta1-integrin and epidermal growth factor receptor. This signaling pathway was additionally enhanced by uPA binding to uPAR and fibronectin binding to alpha5beta1-integrin. We tested whether the ERK/p38 balance is predictive of in vivo behavior in other cancer cell types and whether altering the balance will shift their phenotype between proliferation and dormancy. ERK and p38 activities were determined using either phospho-specific monoclonal antibodies or a trans-reporting system where GAL4-Elk and GAL4-CHOP trans-activation of luciferase gene served as reporters for ERK and p38 activities, respectively. We show that in breast, prostate, melanoma, and fibrosarcoma cell lines, the level of active phospho-ERK and the ERK/p38 activity ratio predict for the in vivo behavior in approximately 90% of the cell lines tested. Modulation of ERK/p38 activity ratio by multiple pharmacological and genetic interventions confirms that high ERK/p38 ratio favors tumor growth, whereas high p38/ERK ratio induces tumor growth arrest (dormancy) in vivo and that ERK is negatively regulated by p38. A melanoma cell line appeared to have developed an escape mechanism to avoid the growth inhibitory effect of high p38 activity. Mechanistic analysis implicated high uPAR expression and its interaction with and activation of alpha5beta1-integrin as determinants of the in vivo growth promoting high ERK/p38 ratio in several cell lines. The small GTPase, Cdc42, was implicated in activation of p38 and growth arrest. These results suggest that even cells that originate in advanced cancers retain a degree of dependence on surface receptors and matrix for their proliferative signals in vivo and provide a therapeutic opportunity to change their phenotype from tumorigenic to dormant.
...
PMID:ERK(MAPK) activity as a determinant of tumor growth and dormancy; regulation by p38(SAPK). 1267 Sep 23

We previously established two lung cancer cell lines, OKa-C-1 and MI-4, which constitutively produce abundant granulocyte-colony stimulating factor (G-CSF) and granulocyte macrophage-colony stimulating factor (GM-CSF). Inflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-1beta stimulated the expression of G-CSF, GM-CSF, and cyclooxygenase (COX)-2 in the two cell lines. It is known that increased COX-2 activity promotes tumor growth and induces G-CSF and GM-CSF expression in non-malignant cells, and that selective COX-2 inhibitors inhibit the growth of some types of malignant cells. Therefore, we hypothesized that inhibition of COX-2 activity might suppress constitutive production of G-CSF or GM-CSF in addition to reducing the growth of malignant cells. We confirmed that the selective COX-2 inhibitor, NS-398 suppressed the constitutive production of G-CSF and GM-CSF, and the cell growth in both OKa-C-1 and MI-4 cell lines. Prostaglandin E2 (PGE2) reversed the inhibitions of G-CSF and GM-CSF expression, as well as cell growth, by NS-398. This result confirms that the effects of NS-398 are based on the inhibition of COX activity. Some studies have indicated that nuclear factor kappa B (NF-kappaB) or MAPK (mitogen-activated protein kinase) activation is related to upregulation of G-CSF, GM-CSF or COX-2 expression in some types of cells. Therefore, we examined if the actions of NS-398 might be mediated by the MAP kinase pathway or NF-kappaB activity in OKa-C-1 and MI-4 cells. We found that NS-398 inhibits G-CSF and GM-CSF production and cell growth through an extracellular signal-regulated kinase kinase (MEK) signaling pathway in these cell lines. The prognosis of non-small cell lung cancer showing G-CSF gene expression is significantly worse. G-CSF overproduction by tumor cells is observed at an advanced clinical stage. Our findings imply that a COX-2 inhibitor might improve the prognosis of patients with lung cancer through the reduction of G-CSF or GM-CSF.
...
PMID:Cyclooxygenase-2 inhibitor NS-398 suppresses cell growth and constitutive production of granulocyte-colony stimulating factor and granulocyte macrophage-colony stimulating factor in lung cancer cells. 1270 93

Multidrug resistance in cancer cells is often due to ATP-dependent efflux pumps, but is also linked to alterations in cell survival and apoptotic signaling pathways. We have found previously that perturbation of hyaluronan-tumor cell interaction by treatment with hyaluronan oligosaccharides suppresses the phosphoinositide 3-kinase/Akt cell survival signaling pathway in cancer cells and reduces tumor growth in vivo. Here we find that these oligomers suppress both the MAP kinase and phosphoinositide 3-kinase pathways in multidrug resistant tumor cells and sensitize these cells to a variety of chemotherapeutic drugs. On the other hand, increased hyaluronan production induces resistance in drug-sensitive tumor cells. Likewise, increased expression of emmprin, which is a glycoprotein that is present on the surface of most malignant cancer cells and that stimulates hyaluronan production, also induces increased resistance. Thus, perturbation of hyaluronan signaling may provide a dual therapeutic role, since it has intrinsic suppressive effects on tumor growth as well as sensitizing cancer cells to chemotherapeutic agents.
...
PMID:Regulation of multidrug resistance in cancer cells by hyaluronan. 1273 83

The unselective cyclooxygenase (COX) inhibitor S-flurbiprofen and its-in terms of COX-inhibition-"inactive" enantiomer R-flurbiprofen have been previously found to inhibit tumor development and growth in various animal models. The underlying mechanisms are unknown. Here, we show that both R- and S-flurbiprofen reduce survival of three colon cancer cell lines, which differ in the expression of COX-2 (HCT-15, no COX-2; Caco-2, inducible COX-2; and HT-29, constitutive COX-2). The IC50 for S- and R-flurbiprofen ranged from 250 to 450 microM. Both flurbiprofen enantiomers induced apoptosis in all three cell lines as indicated by DNA- and PARP-cleavage. In addition, R- and S-flurbiprofen caused a G1-cell cycle block. The latter was associated with an activation of c-Jun N-terminal kinase (JNK), an increase of the DNA binding activity of the transcription factor AP-1 and down-regulation of cyclin D1 expression. Western blot analysis, as well as supershift experiments, revealed that the AP-1 activation was associated with a change of AP-1 composition toward an increase of JunB. The JNK inhibitor SP600125 antagonized R- and S-flurbiprofen-induced AP-1 DNA binding, suppression of cyclin D1 expression, and the G1-cell cycle block. However, JNK inhibition had no effect on flurbiprofen-induced apoptosis. Hence, the cell cycle arrest is obviously mediated, at least in part, through JNK-activation, whereas R- and S-flurbiprofen-induced apoptosis is largely independent of JNK. Although in vitro effects of R- and S-flurbiprofen were indistinguishable, only R-flurbiprofen inhibited HCT-15 tumor growth in nude mice, suggesting the involvement of additional in vivo targets, which are differently affected by R- and S-flurbiprofen.
...
PMID:Activation of c-Jun-N-terminal-kinase is crucial for the induction of a cell cycle arrest in human colon carcinoma cells caused by flurbiprofen enantiomers. 1275 38

Previous molecular analyses of human astrocytomas have identified many genetic changes associated with astrocytoma formation and progression. In an effort to identify novel gene expression changes associated with astrocytoma formation, which might reveal new potential targets for glioma therapeutic drug design, we used the B8-RAS-transgenic mouse astrocytoma model. Using multiplex gene expression profiling, we found that growth-associated protein 43 (GAP43) RNA and protein expression were lost in select human and mouse glioma cell lines. In this study, we demonstrate that re-expression of GAP43 in deficient C6 glioma cells results in growth suppression in clonogenic assays, as well as in multiple independently derived C6 glioma cell lines in vitro. GAP43-expressing C6 cells also exhibit reduced tumor growth as s.c. explants in immunocompromised mice in vivo. In addition, GAP43-expressing C6 clones demonstrate impaired cell motility and increased homophilic aggregation. GAP43 re-expression is also associated with reduced mitogen-activated protein kinase and AKT activation in C6 cells, suggesting that GAP43 functions as a novel glioma growth suppressor by modulating mitogenic signaling pathways.
...
PMID:The 43000 growth-associated protein functions as a negative growth regulator in glioma. 1278

This study characterizes 3 cases of mesenchymal chondrosarcoma (MC) utilizing a proteomic approach that allows for the detection, visual quantification, cellular compartmentalization, and assessment of the functional state of certain proteins that may promote tumor growth and/or oppose apoptosis. Immunohistochemical procedures were performed to detect the following protein antigens: CD99, interleukin (IL)-1alpha, IL-6, transforming growth factor (TGF)-alpha, conventional (c) protein kinase C (cPKC)-alpha, cPKC-betaII, phosphorylated (p)-PKC-alpha/betaII, c-kit (CD117), platelet-derived growth factor receptor (PDGFR)-alpha, PDGFR-beta, epidermal growth factor receptor (EGFR), human epidermal growth factor receptor (HER)-2/neu, cathepsin D, angiotensin-converting enzyme (ACE), angiotensin II type 1 (AT1) receptor, p21ras, the alpha subunit of farnesyl and geranylgeranyl transferase (FTalpha/GGTalpha), phospho (p)-c-Jun N-terminal kinase (p-JNK), p-p38 mitogen-activated protein kinase (MAPK), cyclin D1, c-Jun, Ki-67, bcl-2, TGF-beta1 latency-associated peptide (LAP), TGF-betaRII, and cyclooxygenase (COX)-2. Immunoreactivities were scored from 0 to 3+ positivity using bright-field microscopy. The results showed that malignant mesenchymal chondroblasts exhibit stronger expressions of CD99, IL-1alpha, cPKC-alpha, p-PKC-alpha/betaII, PDGFR-alpha, p-JNK, Ki-67, and bcl-2 antigens than their more mature-appearing chondrocytic counterparts in MC. In conclusion, molecular profiling of mesenchymal chondrosarcoma using a proteomic approach characterized the mesenchymal chondroblasts as possessing pathways that incorporate PKC-alpha and PDGFR-alpha signaling and anti-apoptotic bcl-2 expression. Specific therapies to target the mesenchymal chondroblasts in mesenchymal chondrosarcoma might include interferon-alpha, rapamycin, ciprofloxacin, and STI571.
...
PMID:Mesenchymal chondrosarcoma: molecular characterization by a proteomic approach, with morphogenic and therapeutic implications. 1281 16

The mechanisms of retinoid activity in tumors remain largely unknown. Here we establish that retinoids cause extensive apoptosis of medulloblastoma cells. In a xenograft model, retinoids largely abrogated tumor growth. Using receptor-specific retinoid agonists, we defined a subset of mRNAs that were induced by all active retinoids in retinoid-sensitive cell lines. We also identified bone morphogenetic protein-2 (BMP-2) as a candidate mediator of retinoid activity. BMP-2 protein induced medulloblastoma cell apoptosis, whereas the BMP-2 antagonist noggin blocked both retinoid and BMP-2-induced apoptosis. BMP-2 also induced p38 mitogen-activated protein kinase (MAPK), which is necessary for BMP-2- and retinoid-induced apoptosis. Retinoid-resistant medulloblastoma cells underwent apoptosis when treated with BMP-2 or when cultured with retinoid-sensitive medulloblastoma cells. Retinoid-induced expression of BMP-2 is thus necessary and sufficient for apoptosis of retinoid-responsive cells, and expression of BMP-2 by retinoid-sensitive cells is sufficient to induce apoptosis in surrounding retinoid-resistant cells.
...
PMID:BMP-2 mediates retinoid-induced apoptosis in medulloblastoma cells through a paracrine effect. 1287 64

Several signaling pathways have been recognized in normal c-kit-mediated signal transduction following stem cell factor (SCF) stimulation including Janus kinase (JAK)/signal transducer and activator of transcription (STAT), mitogen-activated protein kinase (MAPK) and phosphoinositol 3-kinase (PI-3 K) pathways. In gastrointestinal stromal tumor (GIST), c-kit activation is considered to play a central role in its tumorigenesis. However, the signal transduction cascades specific for the SCF-independent c-kit activation in GIST remains to be elucidated. In this study, we examined for the expression of the activated form of STAT3 [phospho-STAT3 (tyr 705)] in eleven cases of GIST by immunohistochemistry. All GISTs had strong nuclear and variable cytoplasmic expression of phospho-STAT3 (tyr 705). Survival and proliferation of two established primary GIST cell lines with c-kit exon-11 mutations were then assessed for their response to inhibitors of c-kit (STI-571), JAK 2 (Tyrphostin AG490), MAPK kinase (PD98059) and PI-3 K(LY294002). GIST cells showed significant inhibition of proliferation and apoptosis when treated with STI571 or AG490 but not in cells treated with PD98059 or LY294002. Bcl-2 was expressed in all of the GIST cases (11 out of 11) and was down-regulated in the primary GIST cells following treatment with AG490. This study demonstrates that STAT3 is constitutively activated in GIST and JAK2 blockade leads to tumor growth inhibition and apoptosis indicating the involvement of the JAK/STAT signaling pathway in GIST cellular survival.
...
PMID:Analysis of signal transducer and activator of transcription 3 (STAT3) in gastrointestinal stromal tumors. 1289


<< Previous 1 2 3 4 5 6 7 8 9 10

---