Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Serine proteases are now considered as crucial contributors to the development of human colon cancer. We have shown recently that thrombin is a potent growth factor for colon cancer cells through activation of the aberrantly expressed protease-activated receptor 1 (PAR1). Here, we analyzed the signaling pathways downstream of PAR1 activation, which lead to colon cancer cell proliferation in HT-29 cells. Our data are consistent with the following cascade of events on activation of PAR1 by thrombin or specific activating peptide: (a) a matrix metalloproteinase-dependent release of transforming growth factor-alpha (TGF-alpha) as shown with TGF-alpha blocking antibodies and measurement of TGF-alpha in culture medium; (b) TGF-alpha-mediated activation of epidermal growth factor receptor (EGFR) and subsequent EGFR phosphorylation; and (c) activation of extracellular signal-regulated protein kinase 1/2 (ERK1/2) and subsequent cell proliferation. The links between these events are shown by the fact that stimulation of cell proliferation and ERK1/2 on activation of PAR1 is reversed by the MMP inhibitor batimastat, TGF-alpha neutralizing antibodies, EGFR ligand binding domain blocking antibodies, and the EGFR tyrosine kinase inhibitors AG1478 and PD168393. Therefore, transactivation of EGFR seems to be a major mechanism whereby activation of PAR1 results in colon cancer cell growth. Finally, PAR1 activation induces Src phosphorylation, which is reversed by using the Src tyrosine kinase inhibitor PP2, suggesting that Src activation plays a permissive role for PAR1-mediated ERK1/2 activation and cell proliferation probably acting downstream of the EGFR. These data explain how thrombin exerts robust trophic action on colon cancer cells and underline the critical role of EGFR transactivation.
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PMID:Activation of proteinase-activated receptor 1 promotes human colon cancer cell proliferation through epidermal growth factor receptor transactivation. 1538 30

Inappropriate activation of the Wnt/APC/beta-catenin signaling pathways plays a critical role at early stages in a variety of human cancers. However, their respective implication in tumor cell invasion is still hypothetical. Here, we show that two activators of the canonical Wnt/beta-catenin transcription pathway, namely Dvl-2, the Axin 501-560 fragment binding glycogen synthase kinase -3beta (GSK-3beta), and the negative Wnt regulator wt-Axin did not alter cell invasion into type I collagen. In addition, both Dvl-2 and Axin 501-560 exerted a permissive action on the proinvasive activity of HGF and intestinal trefoil factor. Upstream activation of Wnt signaling by the Wnt-2 and Wnt-3a ligands, stable overexpression of Wnt-2, as well as GSK-3beta inhibition by lithium, SB216763, and GSK-3beta dominant negative forms (K85R and R96E) conferred the invasive phenotype through several proinvasive pathways. Induction of the matrix metalloprotease MMP-7 (matrilysin) gene and protein by Wnt-2 was abolished by inactivation of the AP-1 binding site in the promoter. Accordingly, invasion induced by Wnt-2 was prevented by soluble FRP-3 and FRP-1, sequestration of Gbetagamma subunits, depletion of the GSK-3beta protein by RNA interference, the c-Jun dominant negative mutant TAM67 and was not reversed by wt-Axin. Thus, the proinvasive activity of Wnt-2 is mediated by a noncanonical Wnt pathway using GSK-3beta and the AP-1 oncogene. Our data provide a potential clue for our understanding of the action and crosstalk between Wnt activators and other proinvasive pathways, in relation with matrix substrates and proteases in human cancers.
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PMID:The proinvasive activity of Wnt-2 is mediated through a noncanonical Wnt pathway coupled to GSK-3beta and c-Jun/AP-1 signaling. 1550 71

Various proteases are involved in cancer progression and metastasis. In particular, gelatinases, matrix metalloproteinase-2 (MMP-2) and MMP-9, have been implicated to play a role in colon cancer progression and metastasis in animal models and patients. In the present review, the clinical relevance and the prognostic value of messenger ribonucleic acid (mRNA) and protein expression and proenzyme activation of MMP-2 and MMP-9 are evaluated in relation to colorectal cancer. Expression of tissue inhibitors of MMPs (TIMPs) in relation with MMP expression in cancer tissues and the relevance of detection of plasma or serum levels of MMP-2 and/or MMP-9 and TIMPs for prognosis are also discussed. Furthermore, involvement of MMP-2 and MMP-9 in experimental models of colorectal cancer is reviewed. In vitro studies have suggested that gelatinase is expressed in cancer cells but animal models indicated that gelatinase expression in non-cancer cells in tumors contributes to cancer progression. In fact, interactions between cancer cells and host tissues have been shown to modulate gelatinase expression in host cells. Inhibition of gelatinases by synthetic MMP inhibitors has been considered to be an attractive approach to block cancer progression. However, despite promising results in animal models, clinical trials with MMP inhibitors have been disappointing so far. To obtain more insight in the (patho)physiological functions of gelatinases, regulation of MMP-2 and MMP-9 expression is discussed. Mitogen activated protein kinase (MAPK) signalling has been shown to be involved in regulation of gelatinase expression in both cancer cells and non-cancer cells. Expression can be triggered by a variety of stimuli including growth factors, cytokines and extracellular matrix (ECM) components. On the other hand, MMP-2 and MMP-9 activity regulates bioavailability and activity of growth factors and cytokines, affects the immune response and is involved in angiogenesis. Because of the multifunctionality of gelatinases, it is unpredictable at what stage of cancer development and in which processes gelatinase activity is involved. Therefore, it is concluded that the use of MMP inhibitors to treat cancer should be considered carefully.
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PMID:The role of gelatinases in colorectal cancer progression and metastasis. 1558 63

Matrix metalloproteinase (MMP)-7 (matrilysin-1) plays significant roles in the growth, invasion, and metastasis of colorectal tumors, while (-)-epigallocatechin-3-gallate (EGCG), a green tea polyphenol with chemopreventive properties, has been shown to be an inhibitor of MMP-2 and MMP-9. In the present study, HT-29 human colorectal cancer cells were treated with EGCG to examine its effects on pro-MMP-7 induction and production using RT-PCR and western blot analyses. Surprisingly, EGCG (10-100 microM) treatment increased both intracellular and extracellular pro-MMP-7 protein levels (2.6-8.4-fold and 1.9-6.4-fold, respectively) in dose- and time-dependent manner, with a significant upregulation of its mRNA expression. EGCG also activated extracellular signal-regulated protein kinase (ERK)1/2, c-JUN NH2-terminal kinase (JNK)1/2 and p38 mitogen-activated protein kinase (MAPK), as previously reported. In addition, the polyphenol triggered the phosphorylation of c-JUN (Ser63 and Ser73) and induced c-JUN/c-FOS, thereby increasing the DNA binding activity of activator protein-1 (AP-1), as shown by an AP-1 luciferase reporter assay. Pharmacological blockade of MAPK activities suggested that pro-MMP-7 expression was induced via JNK1/2 activation, but not in the case of ERK1/2 or p38 MAPK. N-Acetyl-L-cysteine, superoxide (O2-) dismutase and catalase attenuated the EGCG-induced pro-MMP-7 production, suggesting an involvement of oxidative stress in these events. Conversely, EGCG spontaneously generated O2- in a cell-free system that utilized a cytochrome C reduction method. Further, (-)-epicatechin-3-gallate (25 and 100 microM) and green tea polyphenols (33 and 132 microg/ml) induced pro-MMP-7 expression, whereas (-)-epicatechin and (-)-epigallocatechin (100 microM each) did not. Induction of pro-MMP-7 expression by EGCG was also shown in another human colorectal adenocarcinoma cell line, Caco-2. Our results suggest that some green tea catechins induce pro-MMP-7 production via O2- production and the activation of JNK1/2, c-JUN, c-FOS and AP-1 in HT-29 cells.
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PMID:(-)-Epigallocatechin-3-gallate promotes pro-matrix metalloproteinase-7 production via activation of the JNK1/2 pathway in HT-29 human colorectal cancer cells. 1586 May 7

Despite evidence that gonadotropins may facilitate peritoneal metastasis of ovarian cancer by increasing cell adhesion, the action and molecular mechanism of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in ovarian cancer invasion is not well characterized. In the present study, we investigated the effects of FSH and LH on the invasive activity and the expression of metastasis-related proteinases in human epithelial ovarian cancer by Western blot, zymography, reverse transcription-PCR (RT-PCR), ELISA, and Boyden chamber assay. Treatment with FSH or LH (10, 100, or 1,000 ng/mL) significantly increased the invasion of ovarian cancer cell lines, including BG-1, CaOV-3, and SKOV-3 cells but not OVCAR-3 cells. In addition, treatment of SKOV-3 cells with FSH or LH (100 or 1,000 ng/mL) enhanced the expression and activation of matrix metalloproteinases (MMP-2 and MMP-9) as shown by RT-PCR, gelatin zymography, and ELISA. Pretreatment with [(2R)-2-(hydroxamido-carbonylmethyl)-4-methylpentanoyl]-l-tryptophan methylamide (10 micromol/L), a total MMP inhibitor, and 3-(4-phenoxyphenylsulfonyl)-propylthiirane (20 micromol/L), a specific gelatinase inhibitor, neutralized the proinvasive effect of gonadotropins in SKOV-3 cells. In addition, the secretion of tissue inhibitor of metalloproteinases (TIMP-1 and TIMP-2) and plasminogen activator inhibitor-1 was significantly decreased by FSH and LH (100 or 1,000 ng/mL). We further showed that gonadotropins induced an increase in SKOV-3 invasiveness via the activation of protein kinase A (PKA) and phosphatidylinositol 3-kinase (PI3K) signaling pathways. Taken together, these results suggest that gonadotropins may contribute to ovarian cancer metastasis via activation of proteolysis and increase in invasion through the PKA and PI3K pathways.
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PMID:Gonadotropins activate proteolysis and increase invasion through protein kinase A and phosphatidylinositol 3-kinase pathways in human epithelial ovarian cancer cells. 1658 20

The airway epithelium provides a protective barrier against inhaled environmental toxins and microorganisms, and epithelial injury initiates a number of processes to restore its barrier integrity, including activation of matrix metalloproteinases such as MMP-9 (92-kD gelatinase B). Airway epithelial cells continuously produce nitric oxide (NO), which has been linked to cell migration and MMP-9 regulation in several cell types, but the importance of epithelial NO in mediating airway epithelial repair or MMP-9 activation is unknown. Using primary or immortalized human bronchial epithelial cells, we demonstrate that low concentrations of NO promote epithelial cell migration and wound repair in an in vitro wound assay, which was associated with increased localized expression and activation of MMP-9. In addition, in HBE1 cells that were stably transfected with inducible NOS (NOS2), to mimic constitutive epithelial NOS2 expression in vivo, NOS inhibition decreased epithelial wound repair and MMP-9 expression. The stimulatory effects of NO on epithelial wound repair and MMP-9 expression were dependent on cGMP-mediated pathways and were inhibited by 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ), an inhibitor of soluble guanylyl cyclase. Inhibition of cGMP-dependent protein kinase (PKG) attenuated NO-mediated epithelial wound closure, but did not affect MMP-9 expression. However, pharmacologic MMP inhibition and siRNA knockdown of MMP-9 expression demonstrated the contribution of MMP-9 to NO-mediated wound closure. Overall, our results demonstrate that NOS2-derived NO contributes to airway epithelial repair by both PKG-dependent and -independent mechanisms, and involves NO-dependent expression and activation of MMP-9.
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PMID:Nitric oxide promotes airway epithelial wound repair through enhanced activation of MMP-9. 1698 May 54

Bovine fetuin-A is a member of a glycoprotein family with a wide spectrum of functions. Until now the bovine protein has been thought to be a single-chain protein. Recently we have shown that native bovine plasma fetuin-A partially exists as a disulfide-bridged two-chain protein with a heavy N-terminal and a lighter C-terminal chain similar to the structure of human fetuin-A homologue (alpha2HS glycoprotein), and also is partially phosphorylated at residues Ser120, Ser302, Ser305 and Ser306 (Wind et al., Anal. Biochem. 317 (2003) 26-33). Both fetuin-A modifications, the phosphorylation at the four sites as well as the proteolysis which causes longer or shorter light chains (termed lc-1 and lc-2, respectively), are probably brought about by targeted enzymatic activities which still need to be defined. In this study we show that authentic bovine fetuin-A disulfide-bridged two-chain forms, which include the original C-terminus, were liberated from the single-chain precursor by metalloproteinases MMP-3 (stromelysin-1) and MMP-7 (matrilysin), but not by elastase, cathepsin E and cathepsin G. Peptide sequencing suggested cleavage sites chiefly at the Pro277-Ser278 or Arg294-His295 peptide bonds. Fetuin-A radioactive phosphorylation in vitro by protein kinase CK2 caused (32)P incorporation into the fetuin-A light chain lc-1 but not lc-2 or the fetuin-A heavy chain, as revealed by MMP assisted proteolysis. Analysis by nanoESI-MS pinpointed phosphorylation at the native phospho-residues Ser302, Ser305 and Ser306 by increased relative abundance following in vitro phosphorylation. Moreover, CK2 phosphorylation of synthetic C-terminal fetuin-A peptides, used as effective controls to the native protein, strongly implies that CK2 is involved in the in vivo phosphorylation of fetuin-A. The phosphorylation of N-terminally truncated peptide homologs seemed highly dependent on the sequence context N-terminal of the phosphorylation sites, thus providing a likely explanation for the non-phosphorylation of the light chain lc-2 in native fetuin-A.
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PMID:Proteolytic processing by matrix metalloproteinases and phosphorylation by protein kinase CK2 of fetuin-A, the major globulin of fetal calf serum. 1711 14

The mycotoxin CTN (citrinin), a natural contaminant in foodstuffs and animal feeds, has cytotoxic and genotoxic effects on various mammalian cells. CTN is known to cause cell injury, including apoptosis, but the precise regulatory mechanisms of CTN action, particularly in stem cells and embryos, are currently unclear. In the present paper, I report that CTN has cytotoxic effects on mouse embryonic stem cells and blastocysts, and is associated with defects in their subsequent development, both in vitro and in vivo. Experiments in embryonic stem cells (ESC-B5) showed that CTN induces apoptosis via ROS (reactive oxygen species) generation, increased Bax/Bcl-2 ratio, loss of MMP (mitochondrial membrane potential), induction of cytochrome c release, and activation of caspase 3. In this model, CTN triggers cell death via inactivation of the HSP90 [a 90 kDa isoform of the HSP (heat-shock protein) family proteins]/multichaperone complex and subsequent degradation of Ras and Raf-1, further inhibiting anti-apoptotic processes, such as the Ras-->ERK (extracellular-signal-regulated kinase) signal transduction pathway. In addition, CTN causes early developmental injury in mouse ESCs and blastocysts in vitro. Lastly, using an in vivo mouse model, I show that consumption of drinking water containing 10 muM CTN results in blastocyst apoptosis and early embryonic developmental injury. Collectively, these findings show for the first time that CTN induces ROS and mitochondria-dependent apoptotic processes, inhibits Ras-->ERK survival signalling via inactivation of the HSP90/multichaperone complex, and causes developmental injury in vivo.
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PMID:Citrinin induces apoptosis via a mitochondria-dependent pathway and inhibition of survival signals in embryonic stem cells, and causes developmental injury in blastocysts. 1733 Oct 71

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.
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PMID:MMP2 role in breast cancer brain metastasis development and its regulation by TIMP2 and ERK1/2. 1750 12

Membrane type 1-matrix metalloproteinase (MT1-MMP) plays a key role in extracellular matrix remodeling, endothelial cell (EC) migration, and angiogenesis. Whereas cyclic strain (CS) increases MT1-MMP expression, shear stress (SS) decreases MT1-MMP expression. The aim of this study was to determine if changes in levels of Sp1 phosphorylation induced by protein kinase Czeta (PKCzeta) in ECs exposed to SS but not CS are important for MT1-MMP expression. The results showed that SS increased Sp1 phosphorylation, which could be inhibited by pretreatment with PKCzeta inhibitors. In the presence of PKCzeta inhibitors, the SS-mediated decrease in MT1-MMP protein expression was also abolished. These data demonstrate that increased affinity of Sp1 for MT1-MMP's promoter site occurs as a consequence of PKCzeta-induced phosphorylation of Sp1 in response to SS, increasing Sp1 binding affinity for the promoter site, preventing Egr-1 binding, and consequently decreasing MT1-MMP expression.
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PMID:Differential effects of shear stress and cyclic strain on Sp1 phosphorylation by protein kinase Czeta modulates membrane type 1-matrix metalloproteinase in endothelial cells. 1856 43


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