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

Recurrent disease following high-dose chemotherapy is a major problem in patients with acute myeloid leukemia (AML). To identify its characteristics, we performed expression profiling in blasts from untreated AML and relapse, using a specific cDNA microarray comprising 4128 genes generated by cDNA subtraction supplemented with cancer-associated genes. Expression analysis of 18 AML bone marrow specimens showed that recurrent AML is commonly associated with the mRNA expression changes in a set of 58 genes. Increased cellular proliferation was indicated by the overexpression of the transferrin receptor, proliferating cell nuclear antigen, and G1 cyclins. An immunohistochemical study for Ki-67-positive blasts in 18 paired bone marrow biopsy samples confirmed a highly significant (P<0.0001) increase in the proliferation fraction at relapse. In addition, we found enhanced activation of the RAF/MEK/ERK cascade as mRNAs of MKP-1, c-jun, c-fos, and egr-1 were significantly increased at relapse. Immunohistochemistry and immunoblotting analyses for biphosphorylated ERK1/2 protein provide additional evidence for enhanced activation of the RAF/MEK/ERK pathway. The degree of increase is significantly correlated with the increased proliferation. Furthermore, the genes identified provide a rationale for further studies on predictive diagnosis and therapeutic intervention.
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PMID:Common alterations in gene expression and increased proliferation in recurrent acute myeloid leukemia. 1474 62

Cyclooxygenase (COX) and its prostanoid metabolites have been implicated in the control of cell survival; however, their role as mitogens remains undefined. To better understand the role of prostanoids on cell growth, we used mouse colon adenocarcinoma (CT26) cells to investigate the role of prostaglandin E(2) (PGE(2)) in cell proliferation. CT26 cells express both COX1 and COX2 and metabolize arachidonic acid to PGE(2.) Treatment with indomethacin, or COX-selective inhibitors, prevents PGE(2) biosynthesis and CT26 cell proliferation. The anti-proliferative effects of COX inhibition are rescued specifically by treatment with PGE(2) or the EP4 receptor-selective agonist PGE(1)-OH via phosphatidylinositol 3-kinase/extracellular signal-regulated kinase (ERK) activation, thus providing a functional link between PGE(2)-induced cell proliferation and EP4-mediated ERK signaling. Indomethacin or COX2 inhibitors, but not COX1 inhibitors, reduced the size and number of CT26-derived tumors in vivo. These inhibitory effects are paralleled by marked declines in the levels of tumor PGE(2), suggesting that their anti-tumor effects are directly associated with the inhibition of COX2 enzymatic activity. The described anti-tumor effects of indomethacin are evident whether it is administered at the time of, or 7 days after, tumor cell injection, suggesting that it has tumor preventive and therapeutic actions. Furthermore, the observation that indomethacin increases the survival rates of tumor-bearing mice, even after withdrawal of the drug, indicates that its effects are long lasting and that it may be potentially useful for the prevention and the clinical management of human cancers.
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PMID:Colon carcinoma cell growth is associated with prostaglandin E2/EP4 receptor-evoked ERK activation. 1512 63

The environmental context in which psychostimulant drugs are experienced influences their ability to induce immediate early genes (IEGs) in the striatum. When given in the home cage amphetamine induces IEGs predominately in striatonigral neurons, but when given in a novel test environment amphetamine also induces IEGs in striatopallidal neurons. The source of the striatopetal projections that regulate the ability of amphetamine to differentially engage these two striatofugal circuits has never been described. We report that transection of corticostriatal afferents selectively blocks, whereas enhancement of cortical activity with an ampakine selectively augments, the number of amphetamine-evoked c-fos-positive striatopallidal (but not striatonigral) neurons. In addition, blockade of the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) signaling cascade preferentially inhibits the number of amphetamine-evoked c-fos-positive striatopallidal neurons. These results suggest that glutamate released from corticostriatal afferents modulates the ability of amphetamine to engage striatopallidal neurons through an ERK/MAPK signaling-dependent mechanism. We speculate that this may be one mechanism by which environmental context facilitates some forms of drug experience-dependent plasticity, such as psychomotor sensitization.
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PMID:Amphetamine-evoked gene expression in striatopallidal neurons: regulation by corticostriatal afferents and the ERK/MAPK signaling cascade. 1544 67

The hyperactivation of fatty acid synthase (FAS)-catalyzed de novo biosynthesis of fatty acids is a molecular marker linked to tumor virulence in population studies of human malignancies. This activation appears to be linked to neoplastic transformation, since high levels of FAS have also been identified in pre-malignant lesions. This dependence of cancer upon accelerated lipogenesis differs from normal human tissues, in which FAS is suppressed by the presence of small amounts of fatty acids in the diet. The molecular mechanisms by which cancer cells constitutively exhibit FAS overexpression and hyperactivity have begun to emerge. The active involvement of the mitogen-activated protein kinase (MAPK) extracellular signal-regulated kinase (MAPK ERK1/2) and phosphatidylinositol-3'-kinase (PI-3'K)/protein kinase B (AKT) transduction cascades in the overexpression of FAS has been recently demonstrated in several cancer cell models. Strikingly, insulin-regulated stimulation of FAS expression in adipose cells is also mediated by the PI-3'K pathway with AKT being involved as a downstream effector. Moreover, FAS overexpression in tumor cells has been demonstrated to occur through a modification of the transcription factor sterol regulatory element-binding protein-1c (SREBP-1c), the major regulatory factor of FAS in liver and adipose tissues, which, in turn, is known to be regulated by MAPK ERK1/2 and PI-3'K/AKT pathways. Therefore, the signal transduction pathways regulating FAS expression in normal and cancer cells seem to share several downstream elements. However, the upstream mechanisms controlling FAS expression in cancer cells must be different from those in normal tissues, since tumor-associated FAS expression seems to be insensitive to nutritional signals. In pre-neoplastic lesions, we hypothesize that the early activation of FAS in pre-malignant cells represents a survival strategy which occurs to compensate for an insufficiency of both oxygen and dietary fatty acids due to, e.g., lack of angiogenesis. Thus, FAS activation reflects an epigenetic dysregulation of the lipogenic pathway in response to the microenvironment of tumors containing regions of poor oxygenation. Upon this unusual metabolic situation, FAS up-regulation also represent a metabolic strategy to maintain high proliferation rates of surviving cells in the absence of exogenous dietary fatty acids. Concomitantly, a variety of oncogenic changes (H-ras, erb B-2, etc.) may result in the constitutive activation of MAPK and PI-3'K/AKT signaling cascades, which, in turn, can activate SREBP-1c and, subsequently, tumor-associated FAS-catalyzed endogenous lipogenesis. Thereafter, high levels of FAS are maintained in coordination with increased demand for fatty acid metabolism and/or membrane synthesis in response to cancer-related overexpression of growth factors (e.g., EGF, heregulin) and/or growth factor receptors (e.g., EGFR, Her-2/neu). The aberrant MAPK and PI-3'K/AKT cascades driven by these oncogenic changes subvert the downregulatory effects of physiological concentrations of dietary fatty acids, resulting in a cancer-associated FAS insensitivity to nutritional signals. This model does not exclude that fundamental differences in the ability of FAS gene to respond to normal fatty acid's downregulatory actions may also synergistically interact with oncogenic signals to constitutively maintain an elevated FAS-dependent de novo endogenous fatty acid biogenesis in cancer cells in spite of high levels of circulating dietary fatty acids.
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PMID:Why does tumor-associated fatty acid synthase (oncogenic antigen-519) ignore dietary fatty acids? 1560 69

Her-2/neu (erbB-2) oncogene overexpression is associated with increased tumor progression and metastasis. Fatty acid synthase (FAS), the key lipogenic enzyme responsible for the endogenous synthesis of fatty acids, has been shown to be one of the genes regulated by Her-2/neu at the level of transcription, translation, and biosynthetic activity. Interestingly, we recently established that both pharmacological inhibition of FAS activity and silencing of FAS gene expression specifically suppress Her-2/neu oncoprotein expression and tyrosine-kinase activity in breast and ovarian Her-2/neu overexpressors. Unraveling the functional organization of this novel bi-directional molecular connection between Her-2/neu and FAS-dependent neoplastic lipogenesis is a major challenge that the field is only beginning to take on. Considering that Her-2/neu overexpression correlates with increased expression of the hypoxia inducible factor-1alpha (HIF-1alpha), which, in a mitogen-activated protein kinase (MAPK)-dependent manner, plays a key role in the expression of several genes including cytokines such as vascular endothelial growth factor (VEGF), we hypothesized that FAS blockade should result in a concomitant down-regulation of VEGF. Unexpectedly, the specific inhibition of the de novo fatty acid synthesis with the small-molecule inhibitor of FAS activity C75 resulted in a dramatic dose-dependent enhancement (up to 500% increase) of VEGF secretion in Her-2/neu-overexpressing SK-Br3, BT-474, and SKOV3 cancer cells. Concurrently, FAS blockade drastically activated MAPK and promoted further a prominent accumulation of HIF-1alpha in Her-2/neu overexpressors. Moreover, U0126-induced inhibition of MAPK activity completely abolished C75-induced up-regulation of HIF-1alpha expression and VEGF secretion, whereas it did not modulate C75-induced down-regulation of Her-2/neu oncogene. Importantly, RNA interference (RNAi)-mediated silencing of the FAS gene recapitulated C75's effects by up-regulating VEGF secretion, MAPK activation and HIF-1alpha expression. Therefore, it appears that perturbation of cancer-associated endogenous fatty metabolism triggers a "hypoxia-like" (oxygen-independent) condition that actively rescues Her-2/neu-dependent MAPK --> HIP-1alpha --> VEGF cascade. It is tempting to suggest that an intact FAS-catalyzed endogenous fatty acid metabolism is a necessary metabolic adaptation to support the enhanced ability of Her-2/neu-overexpressing cancer cells to survive cellular hypoxia in a HIF-alpha-dependent manner.
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PMID:Does endogenous fatty acid metabolism allow cancer cells to sense hypoxia and mediate hypoxic vasodilatation? Characterization of a novel molecular connection between fatty acid synthase (FAS) and hypoxia-inducible factor-1alpha (HIF-1alpha)-related expression of vascular endothelial growth factor (VEGF) in cancer cells overexpressing her-2/neu oncogene. 1566 79

Paradoxically, reactive oxygen species (ROS) can promote normal cellular proliferation and carcinogenesis, and can also induce apoptosis of tumor cells. In this report, we study the contribution of ROS to various cellular signals depending on the nature and the level of ROS produced. In nontransformed NIH 3T3 cells, ROS are at low levels and originate from NADPH oxidase. Hydrogen peroxide (H(2)O(2)), controlled by the glutathione system, is pivotal for the modulation of normal cell proliferation. In CT26 (colon) and Hepa 1-6 (liver) tumor cells, high levels of ROS, close to the threshold of cytotoxicity, are produced by mitochondria and H(2)O(2) is controlled by catalase. N-acetylcysteine, which decreases H(2)O(2) levels, inhibits mitogen-activated protein kinase and normal cell proliferation but increases tumor cell proliferation as H(2)O(2) concentration drops from the toxicity threshold. In contrast, antioxidant molecules, such as mimics of superoxide dismutase (SOD), increase H(2)O(2) levels through superoxide anion dismutation, as well as in vitro proliferation of normal cells, but kill tumor cells. CT26 tumors were implanted in mice and treated by oxaliplatin in association with one of the three SOD mimics manganese(III)tetrakis(4-benzoic acid) porphyrin, copper(II)(3,5-diisopropylsalicylate)2, or manganese dipyridoxyl diphosphate. After 1 month, the volumes of tumors were respectively 35%, 31%, and 63% smaller than with oxaliplatin alone (P < 0.001). Similar data were gained with Hepa 1-6 tumors. In conclusion, antioxidant molecules may have opposite effects on tumor growth. SOD mimics can act in synergy with cytotoxic drugs to treat colon and liver cancers.
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PMID:Controlling tumor growth by modulating endogenous production of reactive oxygen species. 1639 77

The extracellular signal-regulated kinase1/2 (ERK1/2) pathway has a key role in cell survival and brain plasticity, processes that are impaired following exposure to stressful situations. We have recently validated two repeated intermittent stress procedures in male NMRI mice, social threat and repeated exposure to a novel cage, which result in clear behavioral effects following 4 weeks of application. The present results demonstrate that both repeated intermittent stress procedures alter the activity of the ERK1/2 pathway in the brain, as shown by changes in phosphorylated ERK1/2 (phospho-ERK1/2) protein expression and in the expression of downstream proteins: phosphorylated cAMP response element binding protein (CREB) and brain-derived neurotrophic factor (BDNF), in the hippocampus, the frontal cortex and the hypothalamus. The hippocampus showed greater responsiveness to stress as the two stressors increased phospho-ERK1/2 and BDNF expression under acute condition. Following repeated stress, hyperphosphorylation of ERK1/2 was associated with up-regulation of hippocampal BDNF expression in the social threat group but not in mice exposed to novel cage. This lack of a pro-survival effect of ERK1/2 with repeated novel cage exposure may constitute an early event in stress-mediated brain pathology. The sustained BDNF up-regulation in the hippocampi of mice subjected to repeated social threat could be related to rewarding aspects of aggressive interactions, suggested by our previous studies.
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PMID:Social threat and novel cage stress-induced sustained extracellular-regulated kinase1/2 (ERK1/2) phosphorylation but differential modulation of brain-derived neurotrophic factor (BDNF) expression in the hippocampus of NMRI mice. 1583 18

The Ras-Raf-MAPK cascade is a key growth-signaling pathway and its uncontrolled activation results in cell transformation. Although the general features of the signal transmission along the cascade are reasonably defined, the mechanisms underlying Raf activation remain incompletely understood. Here, we show that Raf-1 dephosphorylation, primarily at epidermal growth factor (EGF)-induced sites, abolishes Raf-1 kinase activity. Using mass spectrometry, we identified five novel in vivo Raf-1 phosphorylation sites, one of which, S471, is located in subdomain VIB of Raf-1 kinase domain. Mutational analyses demonstrated that Raf-1 S471 is critical for Raf-1 kinase activity and for its interaction with mitogen-activated protein kinase kinase (MEK). Similarly, mutation of the corresponding B-Raf site, S578, resulted in an inactive kinase, suggesting that the same Raf-1 and B-Raf phosphorylation is needed for Raf kinase activation. Importantly, the naturally occurring, cancer-associated B-Raf activating mutation V599E suppressed the S578A mutation, suggesting that introducing a charged residue at this region eliminates the need for an activating phosphorylation. Our results demonstrate an essential role of specific EGF-induced Raf-1 phosphorylation sites in Raf-1 activation, identify Raf-1 S471 as a novel phosphorylation site critical for Raf-1 and B-Raf kinase activities, and point to the possibility that the V599E mutation activates B-Raf by mimicking a phosphorylation at the S578 site.
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PMID:Identification of Raf-1 S471 as a novel phosphorylation site critical for Raf-1 and B-Raf kinase activities and for MEK binding. 1609 54

There is an urgent need to identify and develop a new generation of therapeutic agents and systemic therapies targeting the estradiol (E2)/estrogen receptor (ER) signaling in breast cancer. In this regard, new information on the mechanisms of E2/ER function and/or cross talk with other prosurvival cascades should provide the basis for the development of other ideal anti-E2 therapies with the intent to enhance clinical efficacy, reduce side effects or both. Our very recent assessment of the mechanisms by which cancer-associated increased lipogenesis and its inhibition alters the E2/ER signaling discovered that fatty acid synthase (FASN), the enzyme catalyzing the terminal steps in the de novo biosynthesis of long-chain fatty acids, differentially modulates the state of sensitivity of breast and endometrial cancer cells to E2-stimulated ER transcriptional activation and E2-dependent cell growth and survival: 1) pharmacological inhibition of FASN activity induced a dramatic augmentation of E2-stimulated ER-driven gene transcription, whereas interference (RNAi)-mediated silencing of FAS gene expression drastically lowered E2 requirements for optimal activation of ER transcriptional activation in breast cancer cells; conversely, pharmacological and RNAi-induced inhibition of FASN worked as an antagonist of E2- and tamoxifen-dependent ER transcriptional activity in endometrial adenocarcinoma cells; 2) pharmacological and RNAi-induced inhibition of FASN synergistically enhanced E2-mediated down-regulation of ER protein and mRNA expression in breast cancer cells, whereas specific FASN blockade resulted in a marked down-regulation of E2-stimulated ER expression in endometrial cancer cells; and 3) FASN inhibition decreased cell proliferation and cell viability by promoting apoptosis in hormone-dependent breast and endometrial cancer cells. In this review we propose that, through a complex mechanism involving the regulation of MAPK/ER cross talk as well as critical E2-related proteins including the Her-2/neu (erbB-2) oncogene and the cyclin-dependent kinase inhibitors p21(WAF1/CIP1) and p27(Kip1), a previously unrevealed connection exists between FASN and the genomic and nongenomic ER activities in breast and endometrial cancer cells. From a clinical perspective, we suggest that if chemically stable FASN inhibitors or cell-selective systems able to deliver RNAi targeting FASN gene demonstrate systemic anticancer effects of FASN inhibition in vivo, additional preclinical studies to characterize their anti-breast cancer actions should be of great interest as the specific blockade of FASN activity may also provide a protective means against endometrial carcinoma associated with tamoxifen-based breast cancer therapy.
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PMID:Targeting fatty acid synthase in breast and endometrial cancer: An alternative to selective estrogen receptor modulators? 1680 39

We previously identified a novel cancer/testis antigen gene CAGE by screening cDNA expression libraries of human testis and gastric cancer cell lines with sera of gastric cancer patients. CAGE is expressed in many cancers and cancer cell lines, but not in normal tissues apart from the testis. In the present study, we investigated its role in the motility of cells of two human cancer cell lines: HeLa and the human hepatic cancer cell line, SNU387. Induction of CAGE by tetracycline or transient transfection enhanced the migration and invasiveness of HeLa cells, but not the adhesiveness of either cell line. Overexpression of CAGE led to activation of ERK and p38 MAPK but not Akt, and inhibition of ERK by PD98059 or p38 MAPK by SB203580 counteracted the CAGE-promoted increase in motility in both cell lines. Overexpression of CAGE also resulted in a reduction of ROS and an increase of ROS scavenging, associated with induction of catalase activity. Inhibition of ERK and p38 MAPK increased ROS levels in cells transfected with CAGE, suggesting that ROS reduce the motility of both cell lines. Inhibition of ERK and p38 MAPK reduced the induction of catalase activity resulting from overexpression of CAGE, and inhibition of catalase reduced CAGE-promoted motility. We conclude that CAGE enhances the motility of cancer cells by activating ERK and p38 MAPK, inducing catalase activity, and reducing ROS levels.
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PMID:CAGE, a novel cancer/testis antigen gene, promotes cell motility by activation ERK and p38 MAPK and downregulating ROS. 1681 99


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