Antiproliferative activity of some novel platinum complexes on C6 glioma and MCF-7 breast cancer cells

The anti-cancer chemotherapeutic potential of novel platinum(II) complexes of salicylate derivatives [Pt(dppe)(SA)2, Pt(dppm)(SA)2] and fumaric acid [Pt(dppe)(FU)2] were determined, using two cancer cell lines, breast cancer (MCF-7) and glioma cells (C6). IC50 values of the three compounds were lower in the cisplatin-resistant cell type C6 cell lines than in MCF-7 cells.Key words: Cisplatin, antiproliferative activity, breast cancer cells (MCF-7), glioma cells (C6), IC50

Molecular cloning and biochemical characterization of a Tau class glutathione S-transferase from Pinus brutia Ten

Key message A new Tau class GST gene was cloned from Pinus brutia Ten. cDNA sequence was analysed for conserved sequences. Substrate specificity, optimum pH, and temperature values of the recombinant PbGST Tau enzyme were determined. Tau class glutathione S-transferases (GSTs) are essential enzymes for detoxification in plants. To date, a lot of the members of this family have been characterized from different plants but the studies on the conifers are very scarce. This study investigates for the first time molecular cloning and biochemical characterization of a Tau class GST gene (PbGST Tau) from Pinus brutia Ten. The full length PbGST Tau ORF was 687 bp having a molecular mass of 27.37 kDa. Catalytic and ligand binding sites of PbGST Tau are well conserved and shared maximum identity with Pinus tabulaeformis GST Tau. Kinetic analysis with respect to 1-chloro-2,4-dinitrobenzene (CDNB) and ethacrynic acid (ECA) as substrates exhibited a K-m of 3.66 mM and 0.3 mM, respectively. PbGST Tau enzyme had an optimum activity at pH 6.0 and 8.0 when CDNB and ECA were used as substrate, respectively. The highest activity was measured at 25 degrees C. Through enzyme assays, phylogenetic analysis and structural modelling, we provide a detailed characterization of the PbGST Tau gene and the enzyme. This study is going to provide new insights into the phylogenetic and biochemical analysis of GST family in conifers

Novel debittering process of green table olives: application of β-glucosidase bound onto superparamagnetic nanoparticles

In this work, the olive β-glucosidase (β-glu) enzyme was immobilized onto superparamagnetic nanoparticles (SPMNs). Moreover, immobilized enzyme was also used for the debittering process for natural edible olives from Edremit, Turkey. Owing to SPMNs, the system can be easily removed by a simple magnet and reused many times for debittering process. The free olive β-glucosidase (E), β-glucosidase bound SPMNs (IE), free commercial β-glucosidase (CE), and commercial β-glucosidase bound SPMNs (ICE) were comparatively studied for oleuropein removal. In 6 h, the treatment of E, IE, and ICE hydrolyzed the 15.8%, 56.4%, and 80.0% of the oleuropein for 1000 g of olives, respectively, and further treatment showed that the IE and ICE reached the 100% after 22 h treatment. The results revealed that the IE and ICE with biocompatible properties of SPMNs have the economical, fast, and reusable properties for the industrial debittering process in the table olive production

Interleukin-6 represses the transcription of the CCAAT/enhancer binding protein-α gene in hepatoma cells by inhibiting its ability to autoactivate the proximal promoter region

The cytokine interleukin-6 (IL-6) plays key roles in the immune and inflammatory responses, acute-phase reaction and hematopoiesis. Such biological actions of IL-6 are characterised by both the activation and the inhibition of gene transcription. Unfortunately, in contrast to gene activation, the mechanism by which IL-6 suppresses transcription remains largely unclear. We have, therefore, investigated this aspect using the Xenopus laevis CCAAT/enhancer binding protein-α (C/EBPα) gene promoter as a model. We show by transient transfection assays of various promoter–luciferase DNA constructs into hepatoma cells that a C/EBP recognition sequence in the proximal promoter region is essential for the IL-6-mediated repression. Electrophoretic mobility shift assays showed that C/EBPα was the major protein that bound to this site and, consistent with its expression pattern, the binding was reduced when the cells were exposed to IL-6. Co-transfection assays revealed for the first time that the ability of C/EBPα, but not C/EBPβ or Sp1, to transactivate the promoter was decreased dramatically when the cells were incubated with IL-6. These studies, therefore, identify a novel mechanism for IL-6-mediated repression of gene transcription that involves a reduction in C/EBPα-mediated activation

Characterisation and developmental regulation of the Xenopus laevis CCAAT-enhancer binding protein β gene

We report here the cloning, characterisation and developmental expression profile of the Xenopus laevis CCAAT-enhancer binding protein β (xC/EBPβ) gene. The protein synthesised from the xC/EBPβ gene interacts specifically with a C/EBP-recognition sequence and acts as a transcriptional activator. Several conserved regions are present in the xC/EBPβ sequence, including the basic region, leucine zipper, activation domains, three in-frame AUG codons, and a consensus site for mitogen activated protein kinase. The corresponding mRNA is present at high levels in the kidney, liver, lung, muscle and adipose tissue, and at low levels in the ovary, brain and heart. Although the xC/EBPβ mRNA and protein are present throughout embryogenesis, there is a biphasic increase in their expression levels during development. Whole-mount in situ hybridisation shows a restricted spatial expression profile of the xC/EBPβ gene during early embryogenesis, with transcripts present around the blastopore lip and in the endodermal cells at the mid-gastrula stage, and, the whole dorsal side at the neurula and early tailbud stage. The expression domain becomes almost ubiquitous during later embryonic development, and includes the brain, spinal cord, somites and regions that give rise to the liver and the heart

Analysis of the Xenopus laevis CCAAT-enhancer binding protein α gene promoter demonstrates species-specific differences in the mechanisms for both auto-activation and regulation by Sp1

Transcription factors belonging to the CCAAT-enhancer binding protein (C/EBP) family have been implicated in the regulation of gene expression during differentiation, development and disease. Autoregulation is relatively common in the modulation of C/EBP gene expression and the murine and human C/EBPα genes have been shown to be auto-activated by different mechanisms. In the light of this finding, it is essential that autoregulation of C/EBPα genes from a wider range of different species be investigated in order to gauge the degree of commonality, or otherwise, that may exist. We report here studies that investigate the regulation of the Xenopus laevis C/EBPα gene (xC/EBPα). The –1131/+41 promoter region was capable of directing high levels of expression in both the human hepatoma Hep3B and the Xenopus kidney epithelial A6 cell lines, and was auto-activated by expression vectors specifying for xC/EBPα or xC/EBPβ. Deletion analysis showed that the –321/+41 sequence was sufficient for both the constitutive promoter activity and auto-activation and electrophoretic mobility shift assays identified the interaction of C/EBPs and Sp1 to this region. Although deletion of either the C/EBP or the Sp1 site drastically reduced the xC/EBPα promoter activity, multimers of only the C/EBP site could confer autoregulation to a heterologous SV40 promoter. These results indicate that, in contrast to the human promoter and in common with the murine gene, the xC/EBPα promoter was subject to direct autoregulation. In addition, we demonstrate a novel species-specific action of Sp1 in the regulation of C/EBPα expression, with the factor able to repress the murine promoter but activate the Xenopus gene

Evaluation of in vitro effects of some analgesic drugs on erythrocyte and recombinant carbonic anhydrase I and II

The in vitro effects of the injectable form of analgesic drugs, dexketoprofen trometamol, dexamethasone sodium phosphate, metamizole sodium, diclofenac sodium, thiocolchicoside, on the activity of purified human carbonic anhydrase I and II were evaluated. The effect of these drugs on erythrocyte hCA I and hCA II was compared to recombinant hCA I and hCA II expressed in Ecoli. IC50 values of the drugs that caused inhibition were determined by means of activity percentage diagrams. The IC50 concentrations of dexketoprofen trometamol and dexamethasone sodium phosphate on hCA I were 683 mu M and 4250 mu M and for hCA II 950 mu M and 6200 mu M respectively. Conversely, the enzyme activity was increased by diflofenac sodium. In addition, thiocolchicoside has not any affect on hCA I and hCA II. The effect of these drugs on erythrocyte hCA I and hCA II were consistent with the inhibition of recombinant enzymes