Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.1.1 (hexokinase)
 5,274 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel requires both phosphorylation of its R domain and the presence of nucleoside triphosphates for activation. Our previous work suggested that hydrolysis of nucleoside triphosphates may be required to support channel activity. However, recent studies have suggested that the nonhydrolyzable adenosine triphosphate analogue, 5'-adenylylimidodiphosphate (AMP-PNP), may support some Cl- channel activity in sweat gland duct epithelia in the presence of low ATP concentration and in Cl- channels associated with expression of the P-glycoprotein multidrug resistance transporter. To examine the effect of AMP-PNP, we applied it to the cytosolic surface of phosphorylated CFTR Cl- channels contained in excised, cell-free patches of membrane. We found that preparations of 10 mM AMP-PNP opened phosphorylated CFTR Cl- channels. However, this effect was due to contaminating ATP: high-pressure liquid chromatography analysis of AMP-PNP demonstrated that 10 mM AMP-PNP could contain up to 50 microM ATP, which could account for the observed stimulation of CFTR Cl- channel activity. When contaminating ATP was hydrolyzed with hexokinase, AMP-PNP was unable to support CFTR channel activity. AMP-PNP (10 mM) also failed to attenuate or potentiate the current induced by 0.3 mM ATP. These results suggest that AMP-PNP has no direct effect on CFTR Cl- channels.
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PMID:5'-Adenylylimidodiphosphate does not activate CFTR chloride channels in cell-free patches of membrane. 768 26

Molecular imaging is broadly defined as the characterization and measurement of biological processes in living animals, model systems, and humans at the cellular and molecular level using remote imaging detectors. One underlying premise of molecular imaging is that this emerging field is not defined by the imaging technologies that underpin acquisition of the final image per se, but rather is driven by the underlying biological questions. In practice, the choice of imaging modality and probe is usually reduced to choosing between high spatial resolution and high sensitivity to address a given biological system. Positron emission tomography (PET) and single-photon emission computed tomography (SPECT) inherently use image-enhancing agents (radiopharmaceuticals) that are synthesized at sufficiently high specific activity to enable use of tracer concentrations of the compound (picomolar to nanomolar) for detecting molecular signals while providing the desired levels of image contrast. The tracer technologies strategically provide high sensitivity for imaging small-capacity molecular systems in vivo (receptors, enzymes, transporters) at a cost of lower spatial resolution than other technologies. We review several significant PET and SPECT advances in imaging receptors (somatostatin receptor subtypes, neurotensin receptor subtypes, alpha(v)beta(3) integrin), enzymes (hexokinase, thymidine kinase), transporters (MDR1 P-glycoprotein, sodium-iodide symporter), and permeation peptides (human immunodeficiency virus type 1 (HIV-1) Tat conjugates), as well as innovative reporter gene constructs (herpes simplex virus 1 thymidine kinase, somatostatin receptor subtype 2, cytosine deaminase) for imaging gene promoter activation and repression, signal transduction pathways, and protein-protein interactions in vivo.
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PMID:Molecular imaging of gene expression and protein function in vivo with PET and SPECT. 1235 50

18F-fluorodeoxyglucose (FDG) uptake in hepatocellular carcinoma (HCC) is associated with tumor differentiation and expression of P-glycoprotein (P-gp), a drug efflux pump that plays an important role in chemoresistance. The aim of the study was to clarify the factors that affects FDG uptake in HCC in vivo and in vitro. The standardized uptake value (SUV) and the tumor to non-tumor SUV ratio (TNR) for FDG uptake in HCC in vivo was determined by FDG-PET in 28 patients. Expression levels of glucose transporter-1 (GLUT-1), GLUT-2 and type II hexokinase (HK-II) were examined immunohistochemically in resected specimens. The glucose-6-phosphatase (G-6-Pase) activity was determined in tissue homogenates. In vitro, PLC/PRF/5 cells and doxorubicin-resistant PLC/DOR cells were used to examine the effect of P-gp on FDG uptake. The effects of two P-gp inhibitors, verapamil and cepharanthine, on accumulation of FDG were also examined. in vivo, GLUT-1 expression was low in HCCs, but was significantly higher in poorly differentiated HCCs than in moderately differentiated HCCs (P=0.043) and was positively correlated with SUV (r=0.75, P<0.0001) and TNR (r=0.7, P<0.0001). GLUT-2 and HK-II expression and G-6-Pase activity were not correlated with tumor differentiation, SUV or TNR. P-gp was over-expressed in PLC/DOR cells, and accumulation of FDG was significantly higher in PLC/PRF/5 cells than in PLC/DOR cells (P=0.04). Verapamil and cepharanthine restored FDG uptake in PLC/DOR cells, but not in PLC/PRF/5 cells. Collectively, our results show that FDG uptake in HCC is weakly correlated with GLUT-1 expression, and that FDG could be a substrate of P-gp, which may act as an efflux pump to reduce FDG accumulation.
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PMID:P-glycoprotein expression affects 18F-fluorodeoxyglucose accumulation in hepatocellular carcinoma in vivo and in vitro. 1936 Mar 42

Jasmonates act as signal transduction intermediates when plants are subjected to environmental stresses such as UV radiation, osmotic shock and heat. In the past few years several groups have reported that jasmonates exhibit anti-cancer activity in vitro and in vivo and induce growth inhibition in cancer cells, while leaving the non-transformed cells intact. Recently, jasmonates were also discovered to have cytotoxic effects towards metastatic melanoma both in vitro and in vivo. Three mechanisms of action have been proposed to explain this anti-cancer activity. The bio-energetic mechanism - jasmonates induce severe ATP depletion in cancer cells via mitochondrial perturbation. Furthermore, methyl jasmonate (MJ) has the ability to detach hexokinase from the mitochondria. Second, jasmonates induce re-differentiation in human myeloid leukemia cells via mitogen-activated protein kinase (MAPK) activity and were found to act similar to the cytokinin isopentenyladenine (IPA). Third, jasmonates induce apoptosis in lung carcinoma cells via the generation of hydrogen peroxide, and pro-apoptotic proteins of the Bcl-2 family. Combination of MJ with the glycolysis inhibitor 2-deoxy-d-glucose (2DG) and with four conventional chemotherapeutic drugs resulted in super-additive cytotoxic effects on several types of cancer cells. Finally, jasmonates have the ability to induce death in spite of drug-resistance conferred by either p53 mutation or P-glycoprotein (P-gp) over-expression. In summary, the jasmonates are anti-cancer agents that exhibit selective cytotoxicity towards cancer cells, and thus present hope for the development of cancer therapeutics.
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PMID:Methyl jasmonate: a plant stress hormone as an anti-cancer drug. 1966 Jul 69

Extranodal nasal-type natural killer/T-cell lymphoma (ENKTL) is an Epstein-Barr virus (EBV) associated lymphoma that progresses rapidly and relapses frequently. Advanced ENKTL is multidrug chemoresistant and has a poor prognosis. In this study, we aim to develop a novel hexokinase domain component 1 (HKDC1)-based antitumor target for ENKTL that is involved with the antimetabolic signaling pathway, EBV replication, and P-glycoprotein (P-gp) expression. We showed that HKDC1 is highly upregulated in ENKTL cells and HKDC1 knockdown significantly suppresses ENKTL tumor growth. In addition, HKDC1 is highly identical with four other hexokinase isoforms, with the only difference being in the last eight amino acids (aa) at the C-terminal. Further investigation showed that peptide delivery of the last eight aa of HKDC1 at the C-terminal (HKC8) with D-configuration using transferrin (Tf) receptor internalization sequence (Tf-D-HKC8) inhibits HKDC1 association with vascular endothelial growth factor 1 (VDAC1), resulting in mitochondrial dysfunction and reactive oxygen species (ROS) overgeneration and subsequently suppressing EBV replication and P-gp expression, making it very effective in killing EBV-positive ENKTL cells. Further in vivo experiments showed that local injection of Tf-D-HKC8 peptide significantly suppresses ENKTL tumor growth and EBV replication in ENKTL xenograft mouse models. We conclude that HKDC1 C-terminal-based peptides inhibit ENKTL by modulation of mitochondrial function and EBV suppression.
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PMID:HKDC1 C-terminal based peptides inhibit extranodal natural killer/T-cell lymphoma by modulation of mitochondrial function and EBV suppression. 3220 47