UNIPROT:P31749 - FACTA Search

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Query: UNIPROT:P31749 (AKT)
22,954 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pancreatic adenocarcinoma is an aggressive human malignancy and is characterized by resistance to apoptosis. Recently, NADPH oxidase (Nox) 4-mediated generation of intracellular reactive oxygen species (ROS) was proposed to confer antiapoptotic activity and thus a growth advantage to pancreatic cancer cells. The signaling mechanism by which Nox4 transmits cell survival signals remains unclear. Here, we show that both a flavoprotein inhibitor, diphenylene iodonium (DPI), and small interfering RNAs designed to target Nox4 mRNA (siNox4RNAs) inhibited superoxide production in PANC-1 pancreatic cancer cells, and depletion of ROS by DPI or siNox4RNAs induced apoptosis. Parallely, DPI treatment and siNox4RNA transfection blocked activation of the cell survival kinase AKT by attenuating phosphorylation of AKT. Furthermore, AKT phosphorylation of apoptosis signal-regulating kinase 1 (ASK1) on Ser-83 was reduced by DPI and siNox4RNAs. When ASK1Ser83Ala (an AKT phosphorylation-defective ASK1 mutant) was introduced into PANC-1 cells, this mutant alone induced apoptosis. But, addition of DPI or co-transfection of siNox4RNA had no additive effect, indicating that the mutant can substitute for these reagents in apoptosis induction. Taken together, these findings suggest that ROS generated by Nox4, at least in part, transmit cell survival signals through the AKT-ASK1 pathway in pancreatic cancer cells and their depletion leads to apoptosis.
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PMID:Inhibition of NADPH oxidase 4 activates apoptosis via the AKT/apoptosis signal-regulating kinase 1 pathway in pancreatic cancer PANC-1 cells. 1653 36

The epidermal growth factor receptor (EGFR) is considered an important therapeutic target in pancreatic cancer, but it is currently impossible to identify those patients who are most likely to benefit from EGFR-directed therapy. We examined the biological effects of the EGFR tyrosine kinase inhibitor gefitinib (ZD1839, Iressa) in a panel of nine human pancreatic cancer cell lines. The drug strongly inhibited DNA synthesis and induced low levels of apoptosis at clinically relevant concentrations in a subset of three of the lines (L3.6pl, BxPC3, and Cfpac1). Sensitivity to gefitinib correlated directly with ligand [transforming growth factor-alpha (TGF-alpha)] expression (r(2) = 0.71, P = 0.004) but not with surface EGFR expression. The gefitinib-sensitive cells displayed constitutive baseline EGFR phosphorylation, whereas the gefitinib-resistant cells did not. Exposure to gefitinib or a small interfering RNA construct specific for TGF-alpha reversed the constitutive EGFR phosphorylation and downstream target [extracellular signal-regulated kinases (ERK), AKT] phosphorylation in the gefitinib-sensitive cells but had no effects on ERK or AKT phosphorylation in gefitinib-resistant cells. Baseline EGFR phosphorylation was lower in a subclone of L3.6pl selected for low TGF-alpha expression, and these cells were also resistant to gefitinib-mediated growth inhibition. Gefitinib blocked the growth of tumor xenografts derived from L3.6pl cells but had no effect on the growth of tumors derived from EGFR-independent MiaPaCa-2 cells. Together, our data show that TGF-alpha expression identifies a subset of human pancreatic cancer cells that is dependent on EGFR signaling in vitro and in vivo. Quantification of TGF-alpha expression may therefore represent an effective means of identifying EGFR-responsive primary tumors.
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PMID:Transforming growth factor alpha expression drives constitutive epidermal growth factor receptor pathway activation and sensitivity to gefitinib (Iressa) in human pancreatic cancer cell lines. 1658 7

SHP-2 is a tyrosine phosphatase which functions as a positive regulator downstream of RTKs, activating growth-stimulatory signalling pathways. To date, very few G protein-coupled receptors (GPCRs) have been shown to be connected to SHP-2 and very little is known about the positive role of SHP-2 in GPCR signalling. The CCK2 receptor (CCK2R), a GPCR, is now recognized to mediate mitogenic effects of gastrin on gastrointestinal cells. In the present study, we demonstrate the role of SHP-2 in the activation of the AKT pathway by the CCK2R in COS-7 cells transfected with the CCK2R and in a pancreatic cancer cell line expressing the endogenous receptor. Using surface plasmon resonance analysis, we identified a highly conserved ITIM motif, containing the tyrosine residue 438, located in the C-terminal intracellular tail of the CCK2R which directly interacts with the SHP-2 SH2 domains. The interaction was confirmed by pull down assays and co-immunoprecipitation of the receptor with SHP-2. This interaction was transiently increased following gastrin stimulation of the CCK2R and correlated with the tyrosine phosphorylation of SHP-2. Mutational analysis of the key ITIM residue 438 confirmed that the CCK2R ITIM sequence is required for interaction with SHP-2 and the activation of the AKT pathway.
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PMID:An ITIM-like motif within the CCK2 receptor sequence required for interaction with SHP-2 and the activation of the AKT pathway. 1696 36

RON is a member of the c-MET receptor tyrosine kinase family. Like c-MET, RON is expressed by a variety of epithelial-derived tumors and cancer cell lines and it is thought to play a functional role in tumorigenesis. To date, antagonists of RON activity have not been tested in vivo to validate RON as a potential cancer target. In this report, we used an antibody phage display library to generate IMC-41A10, a human immunoglobulin G1 (IgG1) antibody that binds with high affinity (ED50 = 0.15 nmol/L) to RON and effectively blocks interaction with its ligand, macrophage-stimulating protein (MSP; IC50 = 2 nmol/L). We found IMC-41A10 to be a potent inhibitor of receptor and downstream signaling, cell migration, and tumorigenesis. It antagonized MSP-induced phosphorylation of RON, mitogen-activated protein kinase (MAPK), and AKT in several cancer cell lines. In HT-29 colon, NCI-H292 lung, and BXPC-3 pancreatic cancer xenograft tumor models, IMC-41A10 inhibited tumor growth by 50% to 60% as a single agent, and in BXPC-3 xenografts, it led to tumor regressions when combined with Erbitux. Western blot analyses of HT-29 and NCI-H292 xenograft tumors treated with IMC-41A10 revealed a decrease in MAPK phosphorylation compared with control IgG-treated tumors, suggesting that inhibition of MAPK activity may be required for the antitumor activity of IMC-41A10. To our knowledge, this is the first demonstration that a RON antagonist and specifically an inhibitory antibody of RON negatively affects tumorigenesis. Another major contribution of this report is an extensive analysis of RON expression in approximately 100 cancer cell lines and approximately 300 patient tumor samples representing 10 major cancer types. Taken together, our results highlight the potential therapeutic usefulness of RON activity inhibition in human cancers.
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PMID:Therapeutic implications of a human neutralizing antibody to the macrophage-stimulating protein receptor tyrosine kinase (RON), a c-MET family member. 1698 59

Pancreatic ductal adenocarcinoma is a devastating disease, characterized by a rapid progression and poor treatment response. Using gene expression profiling of pancreatic cancer tissues, we previously identified periostin as a potential diagnostic and therapeutic target. In this study, we report the overexpression of periostin in a larger set of pancreatic cancer tissues and show that although the periostin transcript is exclusively expressed in tumour cells, the protein product is only detected in the extracellular matrix adjacent to cancer cells. Using an enzyme-linked immunosorbent assay (ELISA) assay, we show significantly increased levels of periostin in the sera of pancreatic cancer patients compared to non-cancer controls. We demonstrate that periostin promotes the invasiveness of tumour cells by increasing the motility of cells without inducing expression of proteases, and enhances the survival of tumour cells exposed to hypoxic conditions. At the molecular level, we provide evidence that the alpha(6)beta(4) integrin complex acts as the cell receptor of periostin in pancreatic cancer cells and that interaction promotes phosphorylation of focal adhesion kinase (FAK) and protein kinase B (AKT) though activation of the PI3 kinase pathway, but not the RAS/MEK/ERK pathway. These findings suggest an important role of periostin in pancreatic cancer and provide a rationale to study periostin for diagnostic and therapeutic applications.
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PMID:Periostin promotes invasiveness and resistance of pancreatic cancer cells to hypoxia-induced cell death: role of the beta4 integrin and the PI3k pathway. 1704 57

[6]-Gingerol, a major phenolic compound derived from ginger, has anti-bacterial, anti-inflammatory and anti-tumor activities. While several molecular mechanisms have been described to underlie its effects on cells in vitro and in vivo, the underlying mechanisms by which [6]-gingerol exerts anti-tumorigenic effects are largely unknown. The purpose of this study was to investigate the action of [6]-gingerol on two human pancreatic cancer cell lines, HPAC expressing wild- type (wt) p53 and BxPC-3 expressing mutated p53. We found that [6]-gingerol inhibited the cell growth through cell cycle arrest at G1 phase in both cell lines. Western blot analyses indicated that [6]-gingerol decreased both Cyclin A and Cyclin-dependent kinase (Cdk) expression. These events led to reduction in Rb phosphorylation followed by blocking of S phase entry. p53 expression was decreased by [6]-gingerol treatment in both cell lines suggesting that the induction of Cyclin-dependent kinase inhibitor, p21cip1, was p53-independent. [6]-Gingerol induced mostly apoptotic death in the mutant p53-expressing cells, while no signs of early apoptosis were detected in wild type p53-expressing cells and this was related to the increased phosphorylation of AKT. These results suggest that [6]-gingerol can circumvent the resistance of mutant p53- expressing cells towards chemotherapy by inducing apoptotic cell death while it exerts cytostatic effect on wild type p53- expressing cells by inducing temporal growth arrest.
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PMID:[6]-Gingerol induces cell cycle arrest and cell death of mutant p53-expressing pancreatic cancer cells. 1706 13

ZD6474 is a novel, orally available inhibitor of vascular endothelial growth factor receptor kinase insert domain receptor/flk-1 tyrosine kinase activity with additional activity against the epidermal growth factor receptor-1 tyrosine kinase. The aim of this study was to evaluate ZD6474, alone and in combination with gemcitabine, in an orthotopic model of metastatic pancreatic cancer. Nude mice (nine to 10/group) were injected orthotopically with 1x10(6) L3.6pl human pancreatic cancer cells. Eight days later, treatment was initiated with vehicle only, gemcitabine (100 mg/kg intraperitoneal twice weekly), ZD6474 (50 mg/kg oral once daily) or a combination of the two treatments. Animals were killed on day 24 posttreatment initiation. The phosphorylation status level of vascular endothelial growth factor receptor-2 and epidermal growth factor receptor as well as the phosphorylation level of AKT and extracellular signal-regulated kinase-1/2 in different human pancreatic carcinoma cells and in human umbilical vein endothelial cells was analyzed by Western blotting. Compared with controls (1231 mg), the mean weight of treated tumors was reduced to 836, 541 and 308 mg in the gemcitabine, ZD6474 and combination groups, respectively. Lymph node metastasis was significantly reduced in both the ZD6474 alone and combined treatment groups, with 3/10 and 1/5 animals developing metastases, compared with 10/10 and 9/9 in the control and gemcitabine groups (P<0.003 and <0.0003, respectively). Microvessel density and cell proliferation were significantly reduced in the ZD6474 and combined treatment groups (P<0.02). Immunohistochemistry of tumor samples following treatment with ZD6474 resulted in a reduction of the activated and phosphorylated epidermal growth factor receptor, whereas total epidermal growth factor receptor levels were comparable with control tumors. On the basis of Western blot analysis, ZD6474 provides inhibition of tumor angiogenesis through an anti-vascular endothelial growth factor receptor-2 mechanism and inhibition of cancer cell growth through an anti-epidermal growth factor receptor mechanism. ZD6474 decreased primary pancreatic tumor growth and reduced lymph node and liver metastases compared with controls or gemcitabine alone. Tumor growth was inhibited further in animals receiving ZD6474 and gemcitabine in combination.
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PMID:Antiangiogenic and antitumor activity of a novel vascular endothelial growth factor receptor-2 tyrosine kinase inhibitor ZD6474 in a metastatic human pancreatic tumor model. 1741 26

The steroid receptor coactivator amplified in breast cancer 1 (AIB1) as well as epidermal growth factor receptor (EGFR) family members are frequently overexpressed in epithelial tumors, and their expression is associated with poor prognosis. However, a direct role of AIB1 in EGF signaling has not been determined. To address this, we reduced endogenous AIB1 levels using RNA interference in lung, breast, and pancreatic cancer cell lines. We found that a knockdown of AIB1 levels resulted in a loss of the growth response of these cell lines to EGF. Further analysis revealed that the depletion of AIB1 reduced tyrosine phosphorylation of EGFR at multiple residues both at autophosphorylation and Src kinase phosphorylation sites. AIB1 knockdown did not affect tyrosine phosphorylation of the receptor tyrosine kinases, platelet-derived growth factor receptor and HER3, or overall tyrosine phosphorylation of cellular proteins. However, EGF-dependent phosphorylation of HER2 was decreased. EGFR levels and membrane trafficking were not changed by AIB1 depletion, but there was less recruitment of Src homology 2 domain-containing proteins to the EGFR. This led to a substantial reduction in EGF-induced phosphorylation of signal transducers and activators of transcription 5 and c-Jun NH(2)-terminal kinase but no significant change in the activation of AKT. Vanadate treatment of cells revealed that the reduction in EGFR tyrosine phosphorylation is dependent in part on changes in cellular phosphatase activity. We propose that a portion of the oncogenic effect of AIB1 could be through control of EGFR and HER2 activity and subsequent modulation of cellular signaling pathways.
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PMID:Epidermal growth factor receptor tyrosine phosphorylation and signaling controlled by a nuclear receptor coactivator, amplified in breast cancer 1. 1767 Nov 94

Neuropilin-1 (Np-1) is a coreceptor for vascular endothelial growth factor-A (VEGF-A), and both are expressed at high levels in pancreatic ductal adenocarcinomas (PDACs). While VEGF-A has been implicated in tumor angiogenesis, the role of Np-1 in PDAC is less clearly defined. Accordingly, PANC-1 pancreatic cancer cells, which express relatively high levels of Np-1, were transfected with the Np-1 antisense cDNA. By comparison with sham transfected cells, Np-1 antisense expressing clones (Np-1AS) exhibited decreased anchorage independent growth, adhesion and invasiveness, and prolonged doubling times. Np-1AS were also more sensitive to the pro-apoptotic actions of ActD, as evidenced by PARP cleavage, caspase 9 activation and annexin V staining. ActD decreased Bcl-xL and STAT5 levels in the antisense expressing cells, but not in sham-transfected cells, and did not alter STAT3, Bcl-2, phospho-AKT, AKT, Bad, Bax or Bak levels. Immunoprecipitation followed by immunoblotting revealed that Np-1 associated with integrin beta1 and integrin beta1 blockade attenuated adhesion. However, Np-AS expressing clones exhibited enhanced tyrosine phosphorylated focal adhesion kinase. Thus, Np-1 confers a growth and survival advantage to PANC-1 cells, and interacts with integrin beta1 to coordinate signaling events that promote cell adherence and invasiveness.
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PMID:Neuropilin-1 interacts with integrin beta1 and modulates pancreatic cancer cell growth, survival and invasion. 1772 69

BCL-2 is the prototypic anti-apoptotic protein involved in the regulation of apoptosis. Overexpression of BCL-2 is common in pancreatic cancer and confers resistance to the apoptotic effect of chemo- and radiotherapy. Although these cellular effects of BCL-2 are traditionally related to pathways involving the mitochondrial membrane, we sought to investigate whether BCL-2 is involved in other signaling pathways regulating cell survival and focused on AKT. We examined the effect of overexpression of BCL-2 in the MIA-PaCa-2 human pancreatic cancer cell line on the function and subcellular location of AKT. We observed that the stable subclones of MIA-PaCa-2 overexpressing BCL-2 demonstrated increased activity of AKT as well as IKK (a downstream target of AKT), increasing the transcriptional activity of NF-kappaB. Using immunoprecipitation techniques, we observed co-immunoprecipitation of AKT and BCL-2. Immunocytochemistry demonstrated co-localization of BCL-2 and AKT, which was abrogated by treatment with HA14-1, a small molecule inhibitor of BH-3-mediated protein interaction by BCL-2. Furthermore, treatment with HA14-1 decreased phosphorylation of AKT and increased sensitivity to the apoptotic effect of the chemotherapeutic agent, paclitaxel. These results demonstrate an additional mechanism of regulation of cell survival mediated by BCL-2, namely through AKT activation, in the MIA-PaCa-2 pancreatic cancer cell line. Therefore, directed inhibition of BCL-2 may alter diverse pathways controlling cell survival and overcome the apoptotic resistance that is the hallmark of pancreatic cancer.
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PMID:BCL-2 functions as an activator of the AKT signaling pathway in pancreatic cancer. 1796 May 83

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