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

The network of enzymes that contribute to the signal transduction of extracellular factors in pancreatic cancer is ever increasing. The classical Raf-MEK-ERK signaling cascade plays a crucial role in the regulation of apoptosis, proliferation, and metastasis of pancreatic cancer. Phosphatidylinositide-3-kinase also contributes to growth and prevents apoptosis in pancreatic cancer cells, acting in part via its downstream targets, PKB/AKT and the FRAP/p70s6k signaling complex. Recently, members of the PKC family of serine threonine kinases have emerged as novel modulators of transformation and cell cycle progression of pancreatic cancers. The novel PKD family of serine threonine kinases has just been detected in pancreatic cancer and awaits its functional characterization in these tumors.
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PMID:Novel protein kinases in pancreatic cell growth and cancer. 1262 11

We investigated the effects of the farnesyl transferase inhibitor (FTI) manumycin and the MEK inhibitor PD98059 on growth of human pancreatic cancer, with mutant (SUIT2) or wild-type (BxPC-3) K-ras, xenografted into nude mice. Tumor growth was not reduced by either of the agents at a dose of 3 mg/kg without irradiation. Growth of SUIT2 irradiated at 15 Gy or 30 Gy was reduced by manumycin and PD98059: at 15 Gy, tumor volume doubling time (TVDT) increased from 18.6+/-3.8 to 36.3+/-14.2 days with PD98059 (p<0.05); at 30 Gy, TVDT increased from 32.8+/-6.8 to 70.5+/-10.5 days and 70.7+/-1.5 days, respectively. Manumycin tended to reduce growth of BxPC-3, but the difference in TVDT was not statistically significant. PD98059 significantly increased the TVDT of BxPC-3 at 30 Gy from 34.4+/-18 to 62.6+/-9.8 at 30 Gy. The present results suggest that Ras signaling pathways are potential targets for manipulation of radiosensitivity, and that induction of an alternative pathway may enhance radiosensitivity of pancreatic cancer.
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PMID:Modified radiosensitivity of pancreatic cancer xenografts by farnesyl protein transferase inhibitor and MEK inhibitor. 1288 35

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

Increased expression of the hepatocyte growth factor (HGF) receptor (c-met) and urokinase type plasminogen (uPA) correlated with the development and metastasis of cancers. To investigate the role of HGF/c-met signaling on metastasis in cancer cells stimulated with HGF, we examined the effects of a specific MEK1 inhibitor (PD98059) and a p38 MAP kinase inhibitor (SB203580) on HGF-induced uPA expression in pancreatic cancer cell lines, L3.6PL and IMIM-PC2. Pretreatment of PD98059 decreased HGF-mediated phosphorylation of extracellular receptor kinase (ERK), uPA secretion and expression of matrix metalloproteinases (MMP-2 and MMP-9) in a dose-dependent manner. In contrast, SB203580 pretreatment increased HGF-stimulated ERK phosphorylation, uPA secretion and expression of MMPs. SB203580 also reversed the inhibition of HGF-mediated ERK activation and uPA secretion in the PD98059-pretreated cells. These results suggest that ERK activation by HGF might play important roles in the metastasis of pancreatic cancer and the p38 MAPK pathway also involved in the HGF-mediated uPA secretion and metastasis by regulation of ERK pathway.
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PMID:Growth factor-dependent activation of the MAPK pathway in human pancreatic cancer: MEK/ERK and p38 MAP kinase interaction in uPA synthesis. 1459 83

Several key growth factors, cytokines, and proto-oncogenes transduce their growth- and differentiation-promoting signals through the mitogen-activated protein kinase or extracellular signal-regulated protein kinase (ERK) cascade. Overexpression or constitutive activation of this pathway has been shown to play an important role in the pathogenesis and progression of breast and other cancers, making the components of this signaling cascade potentially important as therapeutic targets. CI-1040 (PD184352) is an orally active, highly specific, small-molecule inhibitor of one of the key components of this pathway (MEK1/MEK2), and thereby effectively blocks the phosphorylation of ERK and continued signal transduction through this pathway. Antitumor activity has been seen in preclinical models with this compound, particularly for pancreas, colon, and breast cancers, which has been shown to correlate with its inhibition of pERK. Clinically, CI-1040 has been shown to be well tolerated in phase I studies, with safety and pharmacokinetic profiles that permit continuous daily dosing. Biomarker studies have shown target inhibition in patients, and antitumor activity has also been observed with a partial response in one patient with pancreatic cancer and stable disease in approximately 25% of phase I patients. Given the central role of the ERK/mitogen-activated protein kinase pathway in mediating growth-promoting signals for a diverse group of upstream stimuli, inhibitors of MEK, as a key central mediator, could have significant clinical benefit in the treatment of breast and other cancers.
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PMID:CI-1040 (PD184352), a targeted signal transduction inhibitor of MEK (MAPKK). 1461 31

In our previous investigation, mitogen-activated protein kinase kinase 2 (MEK2) was detected as a factor which was correlated to the potential of invasion-metastasis. In this study, the immunocytochemical, immunohistochemical and mRNA expressions of MEK2 were examined in pancreatic cancer cell lines and tissue samples, respectively. Constitutive expressions of MEK2 and phosphorylated MEK (p-MEK) were observed in PC-1.0 and ASPC-1 cells, which exhibited a growth pattern of single cells, whereas the relevant expressions were quite faint in PC-1 cells and CAPAN-2 cells, which exhibited a growth pattern of island-like clonies. Simultaneous inductions of MEK2 expressions and cell dissociation were observed after the treatment with a conditioned medium (CM) of PC-1.0 cells. The expression of MEK2 and p-MEK were reduced and the cell aggregation was found in PC-1.0 and ASPC-1 cells after U0126 (a MEK inhibitor) treatment. In vivo, both the MEK2 and p-MEK overexpressed in human pancreatic cancer tissues and p-MEK was found to be more strongly expressed in the invasive front than that in the center of tumor (P<0.05). MEK2 is closely related to pancreatic cancer cell dissociation. MEK2 activation is probably involved in the first step of the cascade in the invasion-metastasis of pancreatic cancer.
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PMID:Involvement of the mitogen-activated protein kinase kinase 2 in the induction of cell dissociation in pancreatic cancer. 1465 42

Pancreatic carcinoma is characterized by poor prognosis and lack of response to conventional therapy. The reasons for this are not fully understood. We have reported that inhibition of 5-lipoxygenase abolished proliferation and induced apoptosis in pancreatic cancer cells while the 5-lipoxygenase metabolite, 5(S)-hydroxyeicosatetraenoic acid [5(S)-HETE] stimulated pancreatic cancer cell proliferation. The current study was designed to investigate the underlying mechanisms for 5(S)-HETE-stimulated proliferation of pancreatic cells. Two human pancreatic cancer cell lines, PANC-1 and HPAF, were used. Cell proliferation was monitored by thymidine incorporation and cell counting. Phosphorylation of P42/44(MAPK) (mitogen activated protein kinase, ERK), MEK (MAPK/ERK kinase), P38 kinase, JNK/SAPK (c-Jun N-terminal kinase/ stress-activated protein kinase), AKT and tyrosine residues of intracellular proteins was measured by Western blot using their corresponding phospho-specific antibodies. The results showed that (1) 5(S)-HETE markedly stimulated pancreatic cancer cell proliferation in a time- and concentration-dependent manner; (2) 5(S)-HETE induced tyrosine phosphorylation of multiple intracellular proteins while the tyrosine kinase inhibitor, genestein, blocked 5(S)-HETE-stimulated cell proliferation; (3) 5(S)-HETE significantly stimulated both MEK and P42/44(MAPK) phosphorylation and the MEK inhibitors, PD098059 and U0126, inhibited 5(S)-HETE-stimulated proliferation in these two cell lines; (4) 5(S)-HETE also stimulated P38 kinase phosphorylation but the P38 inhibitor, SB203580, did not effect 5(S)-HETE-stimulated cell proliferation; (5) 5(S)-HETE markedly stimulated AKT phosphorylation while the phosphatidylinositide-3 (PI3)-kinase inhibitor, wortmannin, blocked 5(S)-HETE-stimulated cell proliferation; (6) phosphorylation of JNK/SAPK was not induced by 5(S)-HETE, and (7) the general protein kinase C (PKC) inhibitor, GF109203X, did not affect 5(S)-HETE-stimulated cancer cell proliferation. These findings suggest that intracellular tyrosine kinases, MEK/ERK and PI3 kinase/AKT pathways are involved in 5(S)-HETE-stimulated pancreatic cancer cell proliferation but P38 kinase, JNK/SAPK and PKC are not involved in this mitogenic effect.
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PMID:Multiple signal pathways are involved in the mitogenic effect of 5(S)-HETE in human pancreatic cancer. 1470 47

Mitogen-activated protein kinase kinase 2 (MEK2), the upstream kinase of extracellular signal-regulated kinase 1/2 (ERK1/2) was previously isolated as cancer cell dissociation related factor. In this study, to further clarify the regulatory mechanism of cancer cell dissociation, two hamster (PC-1.0 and PC-1) and human (Capan-2 and AsPC-1) pancreatic cancer cell lines were analyzed immunocytochemically with anti-ERK1, anti-ERK2 and anti-phosphorylated ERK1/2 (p-ERK1/2) antibodies. U0126 (a MEK1/2 inhibitor) significantly suppressed ERK2 and p-ERK1/2 expressions in PC-1.0 and AsPC-1 cells (P<0.05). Cancer cell dissociation factor (DF) markedly induced ERK2 and p-ERK1/2 expressions in PC-1 and Capan-2 cells (P<0.05), and the induced ERK2 and p-ERK1/2 expressions were inhibited by subsequent U0126-treatment (P<0.05). Simultaneously, light microscopic images showed that DF clearly induced cell dissociation in PC-1 and Capan-2 cells, while U0126-treatment induced cell aggregation in these pancreatic cancer cells. ERK2 activation is closely involved in cell dissociation of pancreatic cancer cells.
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PMID:Relationship between the expression of extracellular signal-regulated kinase 1/2 and the dissociation of pancreatic cancer cells: Involvement of ERK1/2 in the dissociation status of cancer cells. 1501 Aug 17

Mitogen-activated protein kinase kinase 2 (MEK2) was detected as an invasion-metastasis related factor between highly invasive (PC-1.0) and weakly invasive (PC-1) pancreatic cancer cell lines in our previous study. On the other hand, tight junction (TJ) was found to be correlated with carcino-genesis and tumor development. In this study, the expressions and correlation of TJ transmembrane protein occludin and MEK/extracellular signal-regulated kinase (ERK) signaling pathway were analyzed to clarify the regulatory mechanism of cell dissociation in pancreatic cancer cells. Two hamster (PC-1.0 and PC-1) and human (AsPC-1 and CAPAN-2) pancreatic cancer cell lines were analyzed immunocytochemically with anti-occludin, phosphorylated MEK1/2 (p-MEK1/2), phosphorylated ERK1/2 (p-ERK1/2) antibodies. MEK1/2 inhibitor U0126 significantly induced the expression of occludin at the cell-cell junction and substantially suppressed the p-MEK1/2 and p-ERK1/2 expressions in PC-1.0 and AsPC-1 cells. In contrast, dissociation factor (DF) treatment obviously disrupted the occludin expressions at the sites of cell-cell junction and markedly induced the p-MEK1/2 and p-ERK1/2 expressions in PC-1 and CAPAN-2 cells. In addition, occludin expressions at cell-cell junction were restored and p-MEK1/2 and p-ERK1/2 expressions were suppressed by subsequent U0126-treatment in DF treated PC-1 and CAPAN-2 cells. Correspondingly, light microscopic images showed that DF induced the dissociation of cell island-like colonies in PC-1 and CAPAN-2 cells, and U0126-treatment induced cell aggregation in these pancreatic cancer cells. Occludin is involved in the cell dissociation in pancreatic cancer cells. Moreover, MEK/ERK signaling pathway probably regulates the cell dissociation status of pancreatic cancer through influencing the intracellular localization and expression of occludin.
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PMID:Analysis of invasion-metastasis mechanism in pancreatic cancer: involvement of tight junction transmembrane protein occludin and MEK/ERK signal transduction pathway in cancer cell dissociation. 1506 37

Kinase Suppressor of Ras1 (KSR1) functions as a positive modulator of Ras-dependent signaling either upstream of or parallel to Raf-1, and pharmacologic inactivation of KSR1 may serve as a treatment for Rasdriven malignancies such as pancreatic cancer (Xing, H. R., Cordon-Cardo, C., Deng, X., Tong, W., Campodonico, L., Fuks, Z., and Kolesnick, R. (2003) Nat. Med. 9, 1266-1268). Although some studies demonstrated a requirement for KSR1 kinase activity for its action, others suggested KSR1 acts primarily as a scaffold facilitating assembly of the c-Raf-1/MEK module. We recently established a two-stage in vitro reconstitution assay to measure KSR1 kinase activity (Xing, H. R., Lozano, J., and Kolesnick, R. (2000) J. Biol. Chem. 275, 17276-17280). In this assay, KSR1, immunopurified to apparent homogeneity, never comes in contact with recombinant kinases other than c-Raf-1. In the first assay stage, activated KSR1 is incubated with recombinant c-Raf-1 and ATP. In the second stage, activated c-Raf-1 is separated from KSR1, and incubated with unactivated MEK1, unactivated MAPK, Elk-1, and ATP. Elk-1 phosphorylation serves as a specific readout for MAPK activation. However, because KSR1 constitutively associates with MEK1 and this interaction appears critical for KSR1 scaffolding function, it has been argued that the kinase activity detected is an artifact of KSR1-bound MEK1. To address these concerns, we depleted as much as 90% of KSR1-bound MEK1 by high salt washing without altering KSR1 kinase activity. Further, a complete inactivation of KSR1-bound MEK1 by pretreating with the MEK inhibitor PD 98059 prior to the first assay stage did not alter KSR1 kinase activity. In addition, the omission of exogenous recombinant GST-MEK1 from the reaction mixture during the second assay stage abolished Elk-1 phosphorylation confirming KSR1-bound MEK1 does not support MAPK activation in our in vitro assay. Moreover, a kinase-inactive mutant, FLAG-Ki-KSR1(D683A/D700A), which efficiently interacts with endogenous MEK1, lacks kinase activity. These results collectively support our contention that the kinase activity of KSR1 is an intrinsic property of this protein independent of KSR1-bound endogenous MEK.
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PMID:The kinase activity of kinase suppressor of Ras1 (KSR1) is independent of bound MEK. 2427 36


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