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Normal Human Cells (normal + human_cell)
Selected AbstractsNa+/Mg2+ exchange is functionally coupled to the insulin receptor,JOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2004Ana Ferreira Regulation of cellular Mg2+ levels by insulin has been shown in various tissues. However, the mechanisms for hormonal regulation of cellular Mg2+ have not been well described. We studied the effect of insulin on Na+/Mg2+ exchange in normal human cells, measuring Na+/Mg2+ exchange activity as net total Mg2+ efflux driven by an inward Na+ gradient in Mg2+ -loaded red blood cells (RBCs). Na+/Mg2+ exchange was increased significantly by the addition of 2.4 nmol/L of insulin to the flux medium (from 0.60,±,0.06 mmol/L cell,×,h to 0.75,±,0.08 mmol/L cell,×,h [P,=,0.0098, n,=,44]). A dose-response curve for the effects of insulin on the exchanger activity gave an estimated EC50 for insulin of 0.95,±,0.31 nmol/L and a Vmax of 0.86,±,0.12 mmol/L cell,×,h (n,=,7). Kinetics of the Na+/Mg2+ exchange were characterized by measuring its activity as a function of Mg2+ and Na+ concentrations. The K0.5 for cellular Mg2+ was not affected by incubation with insulin. However, the K0.5 for extracellular Na+ decreased from 69.9,±,6.3 to 40.3,±,8.4 mol/L (n,=,5, P,=,0.03) in the presence of insulin. We also studied the effect of wortmannin (WT), a PI 3-kinase inhibitor, on activity of the exchanger. WT significantly blocked the insulin-stimulated Na+/Mg2+ activity (n,=,6, P,=,0.048), with an IC50 of 0.5 nmol/L. LY294002, another PI 3-kinase inhibitor, likewise blocked the insulin-stimulated activity of the exchanger. Therefore, insulin regulates cellular Mg2+ metabolism in part via an increase in the affinity for Na+ of the Na+/Mg2+ exchange and PI 3-kinase activation, suggesting another role for the PI 3-kinase pathway in insulin-mediated cellular events. © 2003 Wiley-Liss, Inc. [source] Antitumour activity and specificity as a function of substitutions in the lipophilic sector of helical lactoferrin-derived peptideJOURNAL OF PEPTIDE SCIENCE, Issue 5 2003Nannan Yang Abstract A peptide L5 (PAWRKAFRWAWRMLKKAA), derived from the N -terminal ,-helical region of bovine lactoferrin (LFB 14,31), that is highly active against several tumour cell lines was reported earlier. In this study, a number of L5 analogues were designed in order to investigate how subsequent replacements of the aromatic amino acids in L5 with three amino acids representing different structural parameters influenced antitumour activity and tumour cell specificity relative to normal human cells. The Trp residues were substituted by Lys, Ile or Ala, while the Phe residue was substituted with Ala. The resulting peptides were investigated for their activity against prokaryotic cells, four tumour cell lines, human lung fibroblasts and human erythrocytes. Most of the peptides were highly active against both E. coli and S. aureus. The peptides were more active against the tumour cell lines than against normal eukaryotic cells but the activity against normal fibroblasts varied more among the peptides than did their antitumour activities. The results revealed that aromatic residues located opposite the cationic sector in L5 were more critical for antitumour activity than were aromatic residues located adjacent to the cationic sector. The biological responses for the peptides against tumour cell lines, fibroblasts, S. aureus (but not E. coli), were highly correlated with the amino acid descriptors used in our QSAR model. The result obtained from the QSAR study identified specific structural features that were important for lytic activity and membrane specificity. Certain structural properties in positions 3, 9 and 11 were shown to be important for antitumour activity, while additional structural properties in position 7 were found to be important with respect to tumour cell specificity. This information may offer a possibility for de novo design of an antitumour peptide with an improved therapeutic index. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd. [source] Review: On TRAIL for malignant glioma therapy?NEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 3 2010J. M. A. Kuijlen J. M. A. Kuijlen, E. Bremer, J. J. A. Mooij, W. F. A. den Dunnen and W. Helfrich (2010) Neuropathology and Applied Neurobiology36, 168,182 On TRAIL for malignant glioma therapy? Glioblastoma (GBM) is a devastating cancer with a median survival of around 15 months. Significant advances in treatment have not been achieved yet, even with a host of new therapeutics under investigation. Therefore, the quest for a cure for GBM remains as intense as ever. Of particular interest for GBM therapy is the selective induction of apoptosis using the pro-apoptotic tumour necrosis factor-related apoptosis-inducing ligand (TRAIL). TRAIL signals apoptosis via its two agonistic receptors TRAIL-R1 and TRAIL-R2. TRAIL is normally present as homotrimeric transmembrane protein, but can also be processed into a soluble trimeric form (sTRAIL). Recombinant sTRAIL has strong tumouricidal activity towards GBM cells, with no or minimal toxicity towards normal human cells. Unfortunately, GBM is a very heterogeneous tumour, with multiple genetically aberrant clones within one tumour. Consequently, any single agent therapy is likely to be not effective enough. However, the anti-GBM activity of TRAIL can be synergistically enhanced by a variety of conventional and novel targeted therapies, making TRAIL an ideal candidate for combinatorial strategies. Here we will, after briefly detailing the biology of TRAIL/TRAIL receptor signalling, focus on the promises and pitfalls of recombinant TRAIL as a therapeutic agent alone and in combinatorial therapeutic approaches for GBM. [source] Molecular Responses to Stress Induced in Normal Human Caucasian Melanocytes in Culture by Exposure to Simulated Solar UV,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2005Laurent Marrot ABSTRACT Melanocytes play a central role in the response of skin to sunlight exposure. They are directly involved in UV-induced pigmentation as a defense mechanism. However, their alteration can lead to melanoma, a process where the role of sun overexposure is highly probable. The transformation process whereby UV damage may result in melanoma initiation is poorly understood, especially in terms of UV-induced genotoxicity in pigmented cells, where melanin can act either as a sunscreen or as a photosensitizer. The aim of this study was to analyze the behavior of melanocytes from fair skin under irradiation mimicking environmental sunlight in terms of spectral power distribution. To do this, normal human Caucasian melanocytes in culture were exposed to simulated solar UV (SSUV, 300,400 nm). Even at relatively high doses (until 20 min exposure, corresponding to 12 kJ/m2 UV-B and 110 kJ/m2 UV-A), cell death was limited, as shown by cell viability and low occurrence of apoptosis (caspase-3 activation). Moreover, p53 accumulation was three times lower in melanocytes than in unpigmented cells such as fibroblasts after SSUV exposure. However, an important fraction of melanocyte population was arrested in G2-M phase, and this correlated well with a high induction level of the gene GADD45, 4 h after exposure. Among the genes involved in DNA repair, gene XPC was the most inducible because its expression increased more than two-fold 15 h after a 20 min exposure, whereas expression of P48 was only slightly increased. In addition, an early induction of Heme Oxygenase 1 (HO1) gene, a typical response to oxidative stress, was also observed for the first time in melanocytes. Interestingly, this induction remained significant when melanocytes were exposed to UV-A radiation only (320,400 nm), and stimulation of melanogenesis before irradiation further increased HO1 induction. These results were obtained with normal human cells after exposure to SSUV radiation, which mimicked natural sunlight. They provide new data related to gene expression and suggest that melanin in light skin could contribute to sunlight-induced genotoxicity and maybe to melanocyte transformation. [source] Casearin X, Its Degradation Product and Other Clerodane Diterpenes from Leaves of Casearia sylvestris: Evaluation of Cytotoxicity against Normal and Tumor Human CellsCHEMISTRY & BIODIVERSITY, Issue 1 2010André Gonzaga, Santos Abstract An EtOH extract of the leaves of Casearia sylvestris afforded new clerodane diterpene, casearin X, together with the known compounds casearins B, D, L, and O, and caseargrewiin F. Casearin X degraded to the corresponding dialdehyde when stored in CDCl3. The diterpenes isolated were cytotoxic to human cancer cell lines, with caseargrewiin F being the most active and the new clerodane, casearin X, the second active compound with IC50 values comparable to the positive control doxorubicin. All isolated diterpenes showed lower activities against normal human cells than against cancer cell lines, which might indicate a possible selective action on cancer cells. Casearin X dialdehyde was not cytotoxic to cancer cells indicating that the occurrence of these CO groups at C(18) and C(19) is incompatible with the cytotoxic activity. [source] | |||||||||||||