Carbon sources and pathways for citrate secreted by human prostate cancer cells determined by NMR tracing and metabolic modeling.

Prostate epithelial cells have the unique capacity to secrete large amounts of citrate, but the carbon sources and metabolic pathways that maintain this production are not well known. We mapped potential pathways for citrate carbons in the human prostate cancer metastasis cell lines LNCaP and VCaP, for which we first established that they secrete citrate (For LNCaP 5.6 ± 0.

Dynamic Nuclear Polarization of Silicon Carbide Micro- and Nanoparticles.

Two dominant crystalline phases of silicon carbide (SiC): α-SiC and β-SiC, differing in size and chemical composition, were investigated regarding their potential for dynamic nuclear polarization (DNP). Si nuclei in α-SiC micro- and nanoparticles with sizes ranging from 650 nm to 2.2 μm and minimal oxidation were successfully hyperpolarized without the use of free radicals, while β-SiC samples did not display appreciable degrees of polarization under the same polarization conditions.

Pyruvate-lactate exchange and glucose uptake in human prostate cancer cell models. A study in xenografts and suspensions by hyperpolarized [1- C]pyruvate MRS and [ F]FDG-PET.

Reprogramming of energy metabolism in the development of prostate cancer can be exploited for a better diagnosis and treatment of the disease. The goal of this study was to determine whether differences in glucose and pyruvate metabolism of human prostate cancer cells with dissimilar aggressivenesses can be detected using hyperpolarized [1- C]pyruvate MRS and [ F]FDG-PET imaging, and to evaluate whether these measures correlate. For this purpose, we compared murine xenografts of human prostate cancer LNCaP cells with those of more aggressive PC3 cells.

-mutated cancers are sensitive to the green tea polyphenol epigallocatechin-3-gallate.

Background: Mutations in isocitrate dehydrogenase 1 () occur in various types of cancer and induce metabolic alterations resulting from the neomorphic activity that causes production of -2-hydroxyglutarate (2-HG) at the expense of α-ketoglutarate (α-KG) and NADPH. To overcome metabolic stress induced by these alterations, -mutated ( ) cancers utilize rescue mechanisms comprising pathways in which glutaminase and glutamate dehydrogenase (GLUD) are involved. We hypothesized that inhibition of glutamate processing with the pleiotropic GLUD-inhibitor epigallocatechin-3-gallate (EGCG) would not only hamper 2-HG production, but also decrease NAD(P)H and α-KG synthesis in cancers, resulting in increased metabolic stress and increased sensitivity to radiotherapy.

Imaging Hyperpolarized Pyruvate and Lactate after Blood-Brain Barrier Disruption with Focused Ultrasound.

Imaging of hyperpolarized C-labeled substrates has emerged as an important magnetic resonance (MR) technique to study metabolic pathways in real time in vivo. Even though this technique has found its way to clinical trials, in vivo dynamic nuclear polarization is still mostly applied in preclinical models. Its tremendous increase in signal-to-noise ratio (SNR) overcomes the intrinsically low MR sensitivity of the C nucleus and allows real-time metabolic imaging in small structures like the mouse brain.

Oxidative capacity varies along the length of healthy human tibialis anterior.

Key Points: During exercise skeletal muscles use the energy buffer phosphocreatine. The post-exercise recovery of phosphocreatine is a measure of the oxidative capacity of muscles and is traditionally assessed by P magnetic resonance spectroscopy of a large tissue region, assuming homogeneous energy metabolism. To test this assumption, we collected spatially resolved spectra along the length of human tibialis anterior using a home-built array of P detection coils, and observed a striking gradient in the recovery rate of phosphocreatine, decreasing along the proximo-distal axis of the muscle.

Direct dynamic measurement of intracellular and extracellular lactate in small-volume cell suspensions with (13)C hyperpolarised NMR.

Hyperpolarised (HP) (13)C NMR allows enzymatic activity to be probed in real time in live biological systems. The use of in vitro models gives excellent control of the cellular environment, crucial in the understanding of enzyme kinetics. The increased conversion of pyruvate to lactate in cancer cells has been well studied with HP (13)C NMR.

Structural and dynamic aspects of Ca2+ and Mg2+ binding of the regulatory domains of the Na+/Ca2+ exchanger.

Intracellular Ca2+ regulates the activity of the NCX (Na+/Ca2+ exchanger) through binding to the cytosolic CBD (Ca2+-binding domain) 1 and CBD2. In vitro studies of the structure and dynamics of CBD1 and CBD2, as well as studies of their kinetics and thermodynamics of Ca2+ binding, greatly enhanced our understanding of NCX regulation. We describe the fold of the CBDs in relation to other known structures and review Ca2+ binding of the different CBD variants from a structural perspective.

The second Ca(2+)-binding domain of NCX1 binds Mg2+ with high affinity.

We report the effects of binding of Mg(2+) to the second Ca(2+)-binding domain (CBD2) of the sodium-calcium exchanger. CBD2 is known to bind two Ca(2+) ions using its Ca(2+)-binding sites I and II. Here, we show by nuclear magnetic resonance (NMR), circular dichroism, isothermal titration calorimetry, and mutagenesis that CBD2 also binds Mg(2+) at both sites, but with significantly different affinities.

Overview on the use of NMR to examine protein structure.

Any protein structure determination process contains several steps, starting from obtaining a suitable sample, then moving on to acquiring data and spectral assignment, and lastly to the final steps of structure determination and validation. This unit describes all of these steps, starting with the basic physical principles behind NMR and some of the most commonly measured and observed phenomena such as chemical shift, scalar and residual coupling, and the nuclear Overhauser effect. Then, in somewhat more detail, the process of spectral assignment and structure elucidation is explained.

Binding of calcium is sensed structurally and dynamically throughout the second calcium-binding domain of the sodium/calcium exchanger.

We report the effects of Ca(2+) binding on the backbone relaxation rates and chemical shifts of the AD and BD splice variants of the second Ca(2+)-binding domain (CBD2) of the sodium-calcium exchanger. Analysis of the Ca(2+)-induced chemical shifts perturbations yields similar K(D) values of 16-24 microM for the two CBD2-AD Ca(2+)-binding sites, and significant effects are observed up to 20 A away. To quantify the Ca(2+)-induced chemical shift changes, we performed a comparative analysis of eight Ca(2+)-binding proteins that revealed large differences between different protein folds.

Calcium channel kinetics of melanotrope cells in Xenopus laevis depend on environmental stimulation.

We have tested the hypothesis that the type and kinetics of voltage-activated Ca(2+) channels in a neuroendocrine cell depend on the cell's long-term external input. For this purpose, the presence and kinetics of both low (LVA) and high-voltage-activated (HVA) L-type Ca(2+) channels have been assessed in melanotrope pituitary cells of the amphibian Xenopus laevis. The secretory activity of this cell type can readily be manipulated in vivo by changing the animal's environmental light condition, from a black to a white background.