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

IFNs have been ascribed to mediate antitumor effects. IFN regulatory factor-1 (IRF-1) is a major target gene of IFNs. It inhibits cell proliferation and oncogenic transformation. Here, we show that 60% of all mRNAs deregulated by oncogenic transformation mediated by c-myc and H-ras are reverted to the expression levels of nontransformed cells by IRF-1. These include cell cycle-regulating genes. An indirect target is cyclin D1. Activation of IRF-1 decreased cyclin D1 expression and cyclin-dependent kinase 4 kinase activity concomitant with change in the levels of hyperphosphorylated retinoblastoma protein. These effects are mediated by inhibition of the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase pathway and a transcriptional repression of cyclin D1. As shown by in vitro assays and tumor growth in nude mice, IRF-1-mediated effects on cell cycle progression were found to be overridden by ectopic expression of cyclin D1. Conversely, decrease of cyclin D1 by RNA interference experiments prevents transformation and tumor growth. The data show that cyclin D1 is a key target for IRF-1-mediated tumor-suppressive effects.
...
PMID:Tumor suppression by IFN regulatory factor-1 is mediated by transcriptional down-regulation of cyclin D1. 1740 3

Matrix metalloproteinase 2 (MMP2) is important in breast cancer (BC) invasion and metastasis. We previously reported that BC brain metastases, in a rat syngeneic model developed in our laboratory, have high expression and activity of MMP2. The MMP2 mechanism of action in the brain is still under intense scrutiny. To study the role of MMP2 in the development of BC brain metastasis we transfected ENU1564 rat mammary adenocarcinoma cells with tissue inhibitor of MMP2 (TIMP2). Animals inoculated with ENU1564-TIMP2 cells had decreased orthotopic tumor growth, decreased orthotopic metastatic behavior and did not develop brain metastases. These results were associated with decreased MMP2 activity, demonstrated by gel zymography. Mitogen activated protein kinase (MAPK) pathway components, such as ERK1/2, have been correlated to MMP expression and/or astrocyte activity. We found that BC brain metastases have peripheral astrocyte reactivity and higher expression of glial fibrillary acidic protein (GFAP) and phosphorylated-ERK1/2 (p-ERK1/2). Additionally, rat astrocyte-conditioned media increased in vitro invasion of ENU1564 cancer cells and increased expression of MMP2 and p-ERK1/2. Blockage of ERK1/2 phosphorylation by treatment with MEK inhibitor (PD98059) decreased the expression of MMP2 in cancer cells grown in rat astrocyte-conditioned media. Our results are highly suggestive that MMP2 plays a role in the development of BC metastases, in particular to the brain. Furthermore, our results suggest that astrocyte factors and the ERK1/2 signaling pathway may be associated with BC brain metastasis development; and that ERK1/2 may regulate MMP2 in a way that is modifiable by astrocyte factors.
...
PMID:MMP2 role in breast cancer brain metastasis development and its regulation by TIMP2 and ERK1/2. 1750 12

Activation of the extracellular signal-regulated kinase1/2 (ERK1/2) signaling cascade mediates human multiple myeloma (MM) growth and survival triggered by cytokines and adhesion to bone marrow stromal cells (BMSCs). Here, we examined the effect of AZD6244 (ARRY-142886), a novel and specific MEK1/2 inhibitor, on human MM cell growth in the bone marrow (BM) milieu. AZD6244 blocks constitutive and cytokine-stimulated ERK1/2 phosphorylation and inhibits proliferation and survival of human MM cell lines and patient MM cells, regardless of sensitivity to conventional chemotherapy. Importantly, AZD6244 (200 nM) induces apoptosis in patient MM cells, even in the presence of exogenous interleukin-6 or BMSCs associated with triggering of caspase 3 activity. AZD6244 sensitizes MM cells to both conventional (dexamethasone) and novel (perifosine, lenalidomide, and bortezomib) therapies. AZD6244 down-regulates the expression/secretion of osteoclast (OC)-activating factors from MM cells and inhibits in vitro differentiation of MM patient PBMCs to OCs induced by ligand for receptor activator of NF-kappaB (RANKL) and macrophage-colony stimulating factor (M-CSF). Finally, AZD6244 inhibits tumor growth and prolongs survival in vivo in a human plasmacytoma xenograft model. Taken together, these results show that AZD6244 targets both MM cells and OCs in the BM microenvironment, providing the preclinical framework for clinical trials to improve patient outcome in MM.
...
PMID:Targeting MEK induces myeloma-cell cytotoxicity and inhibits osteoclastogenesis. 1751 Mar 21

Waldenstrom macroglobulinemia (WM) is an incurable low-grade lymphoplasmacytic lymphoma. We demonstrate up-regulated Akt activity in WM, and that Akt down-regulation by Akt knockdown and the inhibitor perifosine leads to significant inhibition of proliferation and induction of apoptosis in WM cells in vitro, but not in normal donor peripheral blood and hematopoietic progenitors. Importantly, down-regulation of Akt induced cytotoxicity of WM cells in the bone marrow microenvironment (BMM) context. Perifosine induced significant reduction in WM tumor growth in vivo in a subcutaneous xenograft model through inhibition of Akt phosphorylation and downstream targets. We also demonstrated that Akt pathway down-regulation inhibited migration and adhesion in vitro and homing of WM tumor cells to the BMM in vivo. Proteomic analysis identified other signaling pathways modulated by perifosine, such as activation of ERK MAPK pathway, which induces survival of tumor cells. Interestingly, MEK inhibitor significantly enhanced perifosine-induced cytotoxicity in WM cells. Using Akt knockdown experiments and specific Akt and PI3K inhibitors, we demonstrated that ERK activation is through a direct effect, rather than feedback activation, of perifosine upstream ERK pathway. These results provide understanding of biological effects of Akt pathway in WM and provide the framework for clinical evaluation of perifosine in WM patients.
...
PMID:The Akt pathway regulates survival and homing in Waldenstrom macroglobulinemia. 1776 32

2-Methoxyestradiol (2ME2) is an endogenous estradiol metabolite that inhibits microtubule polymerization, tumor growth, and angiogenesis. Because prostate cancer is often treated with radiotherapy, and 2ME2 has shown efficacy as a single agent against human prostate carcinoma, we evaluated 2ME2 as a potential radiosensitizer in prostate cancer models. A dose-dependent decrease in mitogen-activated protein kinase phosphorylation was observed in human PC3 prostate cancer cells treated with 2ME2 for 18 h. This decrease correlated with in vitro radiosensitization measured by clonogenic assays, and these effects were blocked by the expression of constitutively active MEK. Male nude mice with subcutaneous PC3 xenografts in the hind leg were treated with 2ME2 (75 mg/kg) p.o. for 5 days, and 2 Gy radiation fractions were delivered each day at 4 h after drug treatment. A statistically significant super-additive effect between radiation and 2ME2 was observed in this subcutaneous model, using analysis of within-animal slopes. A PC-3M orthotopic model was also used, with bioluminescence imaging as an end point. PC-3M cells stably expressing the luciferase gene were surgically implanted into the prostates of male nude mice. Mice were given oral doses of 2ME2 (75 mg/kg), with radiation fractions (3 Gy) delivered 4 h later. Mice were then imaged weekly for 4 to 5 weeks with a Xenogen system. A significant super-additive effect was also observed in the orthotopic model. These data show that 2ME2 is an effective radiosensitizing agent against human prostate cancer xenografts, and that the mechanism may involve a decrease in mitogen-activated protein kinase phosphorylation by 2ME2.
...
PMID:Radiosensitization and modulation of p44/42 mitogen-activated protein kinase by 2-Methoxyestradiol in prostate cancer models. 1780 47

Manumycin-A (Man-A) is a farnesyltransferase inhibitor (FTI), which was originally identified as an effective tumoricide against several cancers, especially ones harboring constitutively active Ras. However, it is becoming apparent that Man-A can stimulate tumor death independently of FTases. Antioxidant treatment blocked Man-A-stimulated DNA damage and reversed Man-A-inhibited tumor growth. However, the precise molecular details of how these reactive oxygen species (ROS) influence cell signaling modules are poorly understood. We examined how ROS may modulate death and survival pathways in a panel of tumor cells. Man-A treatment resulted in a massive induction of superoxide anion (.O(2) (-)) only in Man-A-sensitive tumors. Within 1 hr, Man-A caused the ROS-dependent activation of caspases 9 and 3. In this time-frame, the Ras-Raf target, MEK, and the survival protein Akt were dephosphorylated in ROS-dependent fashions and then cleaved in ROS and caspase-dependent manners. Pretreatment with ROS scavengers blocked the adverse effects of Man-A, including the processing of caspases and the cleavage of MEK and Akt. These events were noted before any losses in Ras activity or changes in its maturation could be detected. Finally, transfection with cDNAs encoding the antioxidant enzymes catalase, superoxide dismutase and thioredoxin reductase inhibited superoxide induction and apoptosis. Together, our data suggest that the elimination of tumors by Man-A can be independent of the inhibiting of Ras. However, one universal feature observed is the generation of death-triggering intracellular oxidants that appear to directly participate in the select targeting of growth and survival proteins that then either augment or ensure tumor cell death.
...
PMID:Reactive oxygen species-dependent destruction of MEK and Akt in Manumycin stimulated death of lymphoid tumor and myeloma cell lines. 1798 47

Calcium/calmodulin-dependent protein kinase II (CaMKII) regulates numerous physiological functions. Inhibition of CaMKII activity, mostly by synthetic reagents, has been proved to suppress cell growth in many cases. So far there are no reports about the physiological functions and underlying mechanisms of endogenous CaMKII inhibitory proteins in cell cycle progression. Here we report the characterization of a novel human endogenous CaMKII inhibitor, human CaMKII inhibitory protein alpha (hCaMKIINalpha), which directly interacts with activated CaMKII and effectively inhibits CaMKII activity. hCaMKIINalpha expression is negatively correlated with the severity of human colon adenocarcinoma. Overexpression of hCaMKIINalpha inhibits colon adenocarcinoma growth in vitro and in vivo by arresting the cell cycle at the S phase through its conserved inhibitory region (27CIR), whereas silencing the hCaMKIINalpha expression accelerates tumor growth and cell cycle progression. We found that the effect of hCaMKIINalpha on cell cycle is correlated with up-regulation of p27 expression, which may be due to the inhibition of proteasome degradation, but not transcriptional regulation, of p27. Moreover, hCaMKIINalpha deactivated MEK/ERK, which is prerequisite to the inhibition of Thr-187 phosphorylation and subsequent proteasomal degradation of p27, causing the inhibition of S-phase progression of cell cycle. The findings underscore a link between hCaMKIINalpha-mediated inhibition of CaMKII activity and p27-dependent pathways in controlling tumor cell growth and cell cycle and imply a potential application of hCaMKIINalpha in the therapeutics of colon cancers.
...
PMID:A novel endogenous human CaMKII inhibitory protein suppresses tumor growth by inducing cell cycle arrest via p27 stabilization. 3259 54

High-grade gliomas release excitotoxic concentrations of glutamate which contributes to their malignant phenotype. To improve our understanding of the mechanisms by which glutamate enhances tumor growth and invasion, we examined alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-mediated signaling in glioma cell lines. shRNA was used to stably knockdown GluR1, the most abundant AMPA receptor subunit in glioma, to evaluate its role in tumor signaling, proliferation and tumorigenicity. In a tissue array, there was a statistically significant increase in GluR1 expression in glioblastoma samples compared to anaplastic astrocytoma and low-grade tumors. In vitro, we observed a time and dose-dependent increase in MAPK phosphorylation following exposure to AMPA, which was blocked with AMPA receptor antagonists and the MEK1 inhibitor PD98059. Retroviral delivery of GluR1 shRNA in U251 and U87 glioma cells reduced GluR1 protein expression, inhibited AMPA-mediated increases in MAPK phosphorylation, and decreased glioma proliferation in vitro. U251 and U87 shGluR1 cells implanted into the flanks of nude mice grew slower than controls, which correlated with a decrease in proliferation measured by Ki-67 staining and an increase in apoptosis. These results suggest that AMPA receptors are abundantly expressed in high-grade gliomas and gene silencing of the GluR1 AMPA receptor subunit results in abrogation of AMPA-mediated signaling and tumor growth.
...
PMID:Knockdown of GluR1 expression by RNA interference inhibits glioma proliferation. 1831 90

The present studies were initiated to determine in greater molecular detail how MEK1/2 inhibitors [PD184352 and AZD6244 (ARRY-142886)] interact with UCN-01 (7-hydroxystaurosporine) to kill mammary carcinoma cells in vitro and radiosensitize mammary tumors in vitro and in vivo and whether farnesyl transferase inhibitors interact with UCN-01 to kill mammary carcinoma cells in vitro and in vivo. Expression of constitutively activated MEK1 EE or molecular suppression of JNK and p38 pathway signaling blocked MEK1/2 inhibitor and UCN-01 lethality, effects dependent on the expression of BAX, BAK, and, to a lesser extent, BIM and BID. In vitro colony formation studies showed that UCN-01 interacted synergistically with the MEK1/2 inhibitors PD184352 or AZD6244 and the farnesyl transferase inhibitors FTI277 and R115,777 to kill human mammary carcinoma cells. Athymic mice carrying approximately 100 mm(3) MDA-MB-231 cell tumors were subjected to a 2-day exposure of either vehicle, R115,777 (100 mg/kg), the MEK1/2 inhibitor PD184352 (25 mg/kg), UCN-01 (0.2 mg/kg), or either of the drugs in combination with UCN-01. Transient exposure of tumors to R115,777, PD184352, or UCN-01 did not significantly alter tumor growth rate or the mean tumor volume in vivo approximately 15 to 30 days after drug administration. In contrast, combined treatment with R115,777 and UCN-01 or with PD184352 and UCN-01 significantly reduced tumor growth. Tumor cells isolated after combined drug exposure exhibited a significantly greater reduction in plating efficiency using ex vivo colony formation assays than tumor cells that were exposed to either drug individually. Irradiation of mammary tumors after drug treatment, but not before or during treatment, significantly enhanced the lethal effects of UCN-01 and MEK1/2 inhibitor treatment. These findings argue that UCN-01 and multiple inhibitors of the RAS-MEK pathway have the potential to suppress mammary tumor growth, and to interact with radiation, in vitro and in vivo.
...
PMID:Transient exposure of carcinoma cells to RAS/MEK inhibitors and UCN-01 causes cell death in vitro and in vivo. 1834 48

Previous study reported that the activation of Ras pathway cooperated with E6/E7-mediated inactivation of p53/pRb to transform immortalized normal human astrocytes (NHA/hTERT) into intracranial tumors strongly resembling human astrocytomas. The mechanism of how H-Ras contributes to astrocytoma formation is unclear. Using genetically modified NHA cells (E6/E7/hTERT and E6/E7/hTERT/Ras cells) as models, we investigated the mechanism of Ras-induced tumorigenesis. The overexpression of constitutively active H-RasV12 in E6/E7/hTERT cells robustly increased the levels of urokinase plasminogen activator (uPA) mRNA, protein, activity and invasive capacity of the E6/E7/hTERT/Ras cells. However, the expressions of MMP-9 and MMP-2 did not significantly change in the E6/E7/hTERT and E6/E7/hTERT/Ras cells. Furthermore, E6/E7/hTERT/Ras cells also displayed higher level of uPA activity and were more invasive than E6/E7/hTERT cells in 3D culture, and formed an intracranial tumor mass in a NOD-SCID mouse model. uPA specific inhibitor (B428) and uPA neutralizing antibody decreased uPA activity and invasion in E6/E7/hTERT/Ras cells. uPA-deficient U-1242 glioblastoma cells were less invasive in vitro and exhibited reduced tumor growth and infiltration into normal brain in xenograft mouse model. Inhibitors of Ras (FTA), Raf (Bay 54-9085) and MEK (UO126), but not of phosphatidylinositol 3-kinase (PI3K) (LY294002) and of protein kinase C (BIM) pathways, inhibited uPA activity and cell invasion. Our results suggest that H-Ras increased uPA expression and activity via the Ras/Raf/MEK signaling pathway leading to enhanced cell invasion and this may contribute to increased invasive growth properties of astrocytomas.
...
PMID:H-Ras increases urokinase expression and cell invasion in genetically modified human astrocytes through Ras/Raf/MEK signaling pathway. 1838 43


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

---