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:2.7.10.2 (focal adhesion kinase)
44,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Inhibiting the mitogenic response of vascular endothelial cells may in part mediate the antiangiogenic and anticancer activity of supranutritional selenium supplements. Our previous work had shown that methylseleninic acid (MSeA), a precursor of the critical anticancer methylselenol metabolite pool, was a potent inhibitor of the growth and survival of human umbilical vein endothelial cells (HUVECs). Here we investigated the effects of MSeA on selected protein kinase signaling transduction pathways to characterize their role in methylselenium induction of HUVEC cell cycle arrest and apoptosis. Exposure of asynchronous HUVECs for 30 h to 3-5 microM MSeA led to a profound G(1) arrest, and exposure to higher levels of MSeA not only led to G(1) arrest but also to DNA fragmentation and caspase-mediated cleavage of poly(ADP-ribose)polymerase, both biochemical hallmarks of apoptosis. Immunoblot analyses indicated that G(1) arrest induced by the sublethal doses of MSeA was associated with dose-dependent reductions of the levels of phospho-protein kinase B (also known as AKT or PKB), phospho-extracellular signal regulated kinase (ERK) 1/2, and phospho-Jun NH(2)-terminal kinases 1/2 in the absence of any change in p38 mitogen-activated protein kinase (MAPK) phosphorylation. Apoptosis induced by MSeA was associated with an increased phosphorylation of p38 MAPK in addition to the dephosphorylation of the above kinases. In HUVECs deprived of endothelial cell growth supplement (ECGS) for 48 h, resumption of ECGS stimulation resulted in an approximately 10-fold increase in mitogenic response, as indicated by [(3)H]thymidine incorporation into DNA. The ECGS-stimulated mitogenic response was inhibited in a dose-dependent manner by MSeA exposure with a IC(50) approximately 1 microM and a complete blockage at 3 microM. Wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3K) upstream of AKT, potently inhibited the ECGS-stimulated DNA synthesis (IC(50), approximately 40 nM). Combining MSeA with Wortmannin showed an additive antimitogenic effect. An inhibitor of MAPK/ERK kinase 1, PD98059, also inhibited ECGS-stimulated DNA synthesis (IC(50), approximately 55 microM), but combining PD98059 with MSeA had an effect similar to that when PD98059 was used alone. A time-course experiment indicated that PI3K (AKT and ribosomal protein S6 kinase) activation occurred between 6 and 12 h of ECGS stimulation, and 3 microM MSeA exposure decreased AKT phosphorylation after 12 h of exposure, whereas no inhibitory effect was observed for ERK1/2 phosphorylation throughout the 30-h exposure duration. Additional experiments indicated that MSeA, Wortmannin, or a more specific PI3K inhibitor, LY294002, seemed to target, in the mid- to late-G(1) phase, a common mechanism(s) controlling G(1) progression to S while having no inhibitory effect on DNA synthesis once S-phase had initiated. Taken together, the results support a potent inhibitory activity at achievable serum levels of MSeA on ECGS-stimulated mitogenesis in the mid- to late-G(1) phase, and the target(s) of this inhibitory activity seems to be PI3K or components of this signal pathway. At pharmacological levels of exposure, modulation of ERK1/2 and other protein kinases may be relevant for the proapoptotic action of MSeA.
...
PMID:Antimitogenic and proapoptotic activities of methylseleninic acid in vascular endothelial cells and associated effects on PI3K-AKT, ERK, JNK and p38 MAPK signaling. 1158 51

Pancreatic cancer is resistant to almost all classes of cytotoxic agents. Gemcitabine seems to be the current drug of choice. We have recently reported that inhibition of the phosphatidylinositide 3-kinase-protein kinase B (PKB/Akt) cell survival pathway by wortmannin enhances gemcitabine-induced apoptosis in cultured human pancreatic cancer cells (1). The present study investigated the effects of wortmannin on orthotopic human pancreatic cancer xenografts implanted in severe combined immunodeficient mice. Animals were given single i.v. bolus injections of 0.175, 0.35, or 0.7 mg/kg of wortmannin and killed at 0.5, 1, 2, or 4 h after treatment. Phosphorylated PKB/Akt levels in tumor tissues were measured by fluorescence image analysis. Wortmannin was found to inhibit PKB/Akt phosphorylation in a time- and dose-dependent manner, reaching a plateau at 4 h and at 0.7 mg/kg. The levels of phosphorylated PKB/Akt were maximally decreased by approximately 50% relative to the vehicle control. Subsequently, the extent of apoptosis in tumors treated with gemcitabine or wortmannin alone or in combination was determined using terminal deoxynucleotidyl transferase-mediated nick end labeling assay and computerized image analysis. Orthotopic tumors exposed to 80 mg/kg gemcitabine for 48 h and then 0.7 mg/kg wortmannin for 4 h showed a 5-fold increase (P = 0.002) in apoptosis compared with those treated with each agent alone and with the vehicle control. The combination treatment also significantly (P < 0.001) inhibited tumor growth. Taken together, our findings support the potential of phosphatidylinositide 3-kinase inhibitors as adjuncts to conventional chemotherapy in the treatment of pancreatic cancer.
...
PMID:Wortmannin inhibits pkb/akt phosphorylation and promotes gemcitabine antitumor activity in orthotopic human pancreatic cancer xenografts in immunodeficient mice. 1159 24

P210BCR-ABL counteracted against the complementary effect of XPB on DNA repair when ultraviolet (UV)-sensitive 27-1 cells were treated with UV or cisplatin but not with hydrogen peroxide. Wortmannin, an inhibitor of PI3 kinase did not affect its anti-repair effect. Enhanced recruitment of p44 with TFIIH after cisplatin treatment is inhibited by the expression of P210BCR-ABL in a kinase activity-dependent manner. Although purified TFIIH from P210BCR-ABL expressor and non-expressor showed almost no difference in molar ratio of each component, the in vitro activity of TFIIH was decreased by 5-10% in repair assay but was increased by more than two-fold in transcription assay.
...
PMID:TFIIH functions are altered by the P210BCR-ABL oncoprotein produced on the Philadelphia chromosome. 1160 Jan 36

Insulin regulates the expression of several hepatic genes. Although the general definition of insulin signaling has progressed dramatically, the elucidation of the complete signaling pathway from insulin receptor to transcription factors involved in the regulation of a specific gene remains to be established. In fact, recent works suggest that multiple divergent insulin signaling pathways regulate the expression of distinct genes. 5-Aminolevulinate synthase (ALAS) is a mitochondrial matrix enzyme that catalyzes the first and rate-limiting step of heme biosynthesis. It has been reported that insulin caused the rapid inhibition of housekeeping ALAS transcription, but the mechanism involved in this repression has not been explored. The present study investigates the role of phosphatidylinositol 3-kinase (PI3-kinase) and mitogen-activated protein kinase pathways in insulin signaling relevant to ALAS inhibition. To explore this, we combined the transient overexpression of regulatory proteins involved in these pathways and the use of small cell permeant inhibitors in rat hepatocytes and HepG2 cells. Wortmannin and LY294002, PI3-kinase inhibitors, as well as lovastatin and PD152440, Ras farnesylation inhibitors, and MEK inhibitor PD98059 abolished the insulin repression of ALAS transcription. The inhibitor of mTOR/p70(S6K) rapamycin had no effect whatsoever upon hormone action. The overexpression of vectors encoding constitutively active Ras, MEK, or p90(RSK) mimicked the inhibitory action of insulin. Conversely, negative mutants of PKB, Ras, or MEK impaired insulin inhibition of ALAS promoter activity. Furthermore, inhibition of one of the pathways blocks the inhibitory effect produced by the activation of the other. Our findings suggest that factors involved in two signaling pathways that are often considered to be functionally separate during insulin action, the Ras/ERK/p90(RSK) pathway and the PI3K/PKB pathway, are jointly required for insulin-mediated inhibition of ALAS gene expression in rat hepatocytes and human hepatoma cells.
...
PMID:Phosphatidylinositol 3-kinase and Ras/mitogen-activated protein kinase signaling pathways are required for the regulation of 5-aminolevulinate synthase gene expression by insulin. 1171 32

Tumor invasion marks a critical point in cancer progression; it is a harbinger of morbidity and mortality. Thus, the cellular events that enable the invasive phenotype are under intense investigation. Epstein-Barr virus (EBV) is associated with a number of cancers, including Burkitt lymphoma (BL) and nasopharyngeal carcinoma (NPC) and is suspected to contribute to their tumorigenesis. On average, 8% of gastric carcinomas have been shown to carry this virus. To explore whether the presence of EBV in gastric carcinoma contributes to tumor progression in this predominantly invasive carcinoma, we examined a panel of 2 in vitro EBV-infected human gastric cancer cell line sublines and their mock-infected AGS parental control line. We found EBV infection caused a marked increase in transmigration of a Matrigel barrier (415% and 303%, p < 0.05, for the 2 infected lines). This correlated with increased motility of these sublines (233% and 140%, p < 0.05). As this pattern of increased motility leading to a more pronounced enhancement of invasion has been noted in other tumor cells, we explored the roles of autocrine signaling pathways previously implicated in carcinoma motility and invasion. Inhibitors to the epidermal growth factor receptor (EGFR) (PD153035), phospholipase C (PLC) (U73122), extracellular-signal regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) (PD089035) and PI-3 kinase (Wortmannin) were not informative. These data suggest that EBV increases migration of AGS cells by a mechanism independent of these autocrine growth factor-induced pathways. Instead, we found that the EBV-infected cells presented increased focal adhesion kinase (FAK) phosphorylation. These findings suggest a role for integrin-mediated signaling in promoting EBV-associated invasiveness.
...
PMID:EBV-expressing AGS gastric carcinoma cell sublines present increased motility and invasiveness. 1211 96

GLP-1, incretin with insulin-independent antidiabetic properties, is insulinomimetic upon glucose metabolism in extrapancreatic tissues, acting through specific receptors not associated to adenylate cyclase activation. We investigated the role of enzymes mediating insulin actions, in the GLP-1-induced glycogen synthase a activation in rat hepatocytes. GLP-1, like insulin, activates PI3K/PKB, p70s6k, p44 and p42 MAP-kinase. Wortmannin (PI3K/PKB inhibitor) blocked the stimulatory action of insulin on glycogen synthase a and reduced that of GLP-1; rapamycin (p70s6k inhibitor) was ineffective and PD98059 (MEK/MAPK inhibitor) decreased only the insulin effect; okadaic acid (PP-2A inhibitor) was ineffective, while TNFalpha (PP-1 inhibitor) blocked the action of insulin and reduced that of GLP-1; H-7 or Ro 31-8220 (PKC inhibitors) decreased the GLP-1 effect, while only H-7 reduced that of insulin. The activation of PI3K/PKB, PKC and PP-1, but not PP-2A, seems to mediate the GLP-1 stimulatory action on glycogen synthase a in rat hepatocytes, while MAPKs and p70s6k could participate in other GLP-1 effects.
...
PMID:Cell signalling of the GLP-1 action in rat liver. 1285 Feb 80

This paper summarizes data from different studies all aimed at elucidating regulation of protein kinase B in the diabetic heart. Two rat models of type 2 diabetes mellitus ((i) elicited via neonatal streptozotocin injection (Stz) and (ii) Zucker fa/fa rats), were used as well as different experimental models viz isolated, Langendorff perfused hearts as well as adult ventricular myocytes. Glucose uptake was elicited by a variety of stimuli and the activation of PKB measured in tandem. Basal glucose uptake was impaired in both diabetes models while basal phosphorylation of PKB differed, showing lower levels in the Stz model but higher levels in the Zucker rats. Neither 100 nM insulin nor 10(-8) M isoproterenol could stimulate PKB phosphorylation to the same extent in the diabetic myocardium as in controls, regardless of the method used, but a combination of these stimuli resulted in an additive response. Concurrent glucose uptake however, was not additive. Wortmannin abolished both insulin and isoproterenol stimulation of glucose uptake as well as PKB phosphorylation. In contrast to the above-mentioned results, the protein tyrosine phosphatase inhibitor vanadate, alone or in combination with insulin, elicited PKB phosphorylation to the same extent in diabetic cardiomyocytes as in controls. Despite this, glucose uptake stimulated by vanadate or insulin in combination with vanadate was attenuated. The combination of insulin and vanadate may however be beneficial to the diabetic heart as it resulted in improved glucose transport. Results from the different studies can be summarized as follows: (i) dysregulation of PKB is evident in the diabetic myocardium, (ii) PKB activation is not always directly correlated with glucose uptake and (iii) insulin resistance is associated with multiple alterations in signal transduction, both above and below PKB activation.
...
PMID:Protein kinase B in the diabetic heart. 1295 95

Insulin-like growth factor-1 (IGF-1) has been described as an important factor in proliferation, cell survival and migration of multiple myeloma (MM) cells. Angiogenesis correlates with development and prognosis of the MM disease. Vascular endothelial growth factor (VEGF) is one of the prominent factors involved in this process. The different functions of IGF-1 were investigated in the 5TMM mouse model with emphasis on proliferation, migration and VEGF secretion, and the signalling pathways involved. Western Blot analysis revealed that ERK1/2 and Akt (PKB) were activated after IGF-1 stimulation. The activation of ERK1/2 was reduced by the PI3K inhibitor Wortmannin, implying that the PI3K pathway is involved in its activation. Insulin-like growth factor-1 induced an increase in DNA synthesis in MM cells, which was mediated by a PI3K/Akt-MEK/ERK pathway. Insulin-like growth factor-1 enhanced F-actin assembly and this process was only PI3K mediated. Stimulation by IGF-1 of VEGF production was reduced by PD98059, indicating that only the MEK-ERK pathway is involved in IGF-1-stimulated VEGF production. In conclusion, IGF-1 mediates its multiple effects on MM cells through different signal transduction pathways. In the future, we can study the potential in vivo effects of IGF-1 inhibition on tumour growth and angiogenesis in MM.
...
PMID:Specific roles for the PI3K and the MEK-ERK pathway in IGF-1-stimulated chemotaxis, VEGF secretion and proliferation of multiple myeloma cells: study in the 5T33MM model. 1499 10

The beta(1) integrin, functioning as a mechanoreceptor, senses a mechanical stimulus generated during collagen matrix contraction and down-regulates the phosphatidylinositol 3-kinase (PI3K)/Akt survival signal triggering apoptosis. The identities of integrin-associated signal molecules in the focal adhesion complex that are responsible for propagating beta(1) integrin viability signals in response to collagen matrix contraction are not known. Here we show that in response to collagen contraction focal adhesion kinase (FAK) is dephosphorylated. In contrast, enforced activation of beta(1) integrin by anti-beta(1) integrin antibody, which protects fibroblasts from apoptosis, preserves FAK phosphorylation. We demonstrate that ligation of beta(1) integrin by type I collagen or by enforced activation of beta(1) integrin by antibody promotes phosphorylation of FAK, p85 subunit of PI3K, and serine 473 of Akt. Wortmannin inhibited Akt but not FAK phosphorylation in response to enforced activation of beta(1) integrin by antibody. Blocking FAK by pharmacologic inhibition or by dominant negative FAK attenuated phosphorylation of p85 subunit of PI3K and Akt. Dominant negative FAK augmented fibroblast apoptosis during collagen contraction, and this was associated with diminished Akt activity. Constitutively active FAK augmented levels of p85 subunit of PI3K and Akt phosphorylation, and fibroblasts were protected from apoptosis. Our data identify a novel role for FAK, functioning upstream of PI3K/Akt, in transducing a beta(1) integrin viability signal in collagen matrices.
...
PMID:Focal adhesion kinase is upstream of phosphatidylinositol 3-kinase/Akt in regulating fibroblast survival in response to contraction of type I collagen matrices via a beta 1 integrin viability signaling pathway. 1516 38

Hepatocyte growth factor (HGF) promotes the proliferation of adult myoblasts and inhibits their differentiation, whereas insulin-like growth factor I (IGF-I) enhances both processes. Recent studies indicate that activation of the phosphoinositide 3'-kinase (PI3K) pathway promotes myoblast differentiation, whereas activation of the mitogen-activated protein kinase/extracellular signal-regulated protein kinase (MAPK/ERK) promotes proliferation and inhibits their differentiation. This simple model is confounded by the fact that both HGF and IGF-I have been shown to activate both pathways. In this study, we have compared the ability of HGF and IGF-I to activate PI3K and MAPK/ERK in i28 myogenic cells. We find that, although the two stimuli result in comparable recruitment of the p85alpha subunit of PI3K into complexes with tyrosine-phosphorylated proteins, the p85beta regulatory subunit and p110alpha catalytic subunit of PI3K are preferentially recruited into these complexes in response to IGF-I. In agreement with this observation, IGF-I is much more potent than HGF in stimulating phosphorylation of Akt/PKB, a protein kinase downstream of PI3K. In contrast, MAPK/ERK phosphorylation was higher in response to HGF and lasted longer, relative to IGF-I. Moreover, the specific PI3K inhibitor, Wortmannin, abolished MAPK/ERK and Elk-1 phosphorylation in HGF-treated cells, suggesting the requirement of PI3K in mediating the HGF-induced MAPK pathway. UO126, a specific MAPK pathway inhibitor, had no effect on PI3K activity or Akt phosphorylation, implying that at least in muscle cells, the MAPK/ERK pathway is not required for HGF-induced PI3K activation. These results provide a biochemical rationale for the previous observations that HGF and IGF-I have opposite effects on myogenic cells, consistent with studies linking PI3K activation to differentiation and MAPK/ERK activation to proliferation in these cells. Moreover, the finding that PI3K activity is required for HGF-induced MAPK activation suggests its additional role in proliferation, rather than exclusively in the differentiation of adult myoblasts.
...
PMID:Differential regulation of the phosphoinositide 3-kinase and MAP kinase pathways by hepatocyte growth factor vs. insulin-like growth factor-I in myogenic cells. 1519 38


<< Previous 1 2 3 4 5 6 7 Next >>

---