Ionizing Radiation Upregulates Glutamine Metabolism and Induces Cell Death via Accumulation of Reactive Oxygen Species.

Glutamine metabolism provides energy to tumor cells and also produces reactive oxygen species (ROS). Excessive accumulation of ROS can damage mitochondria and eventually lead to cell death. xCT (SLC7A11) is responsible for the synthesis of glutathione in order to neutralize ROS. In addition, mitophagy can remove damaged mitochondria to keep the cell alive. Ionizing radiation kills tumor cells by causing the accumulation of ROS, which subsequently induces nuclear DNA damage. With this in mind, we explored the mechanism of intracellular ROS accumulation induced by ionizing radiation and hypothesized new methods to enhance the effect of radiotherapy. We used MCF-7 breast cancer cells and HCT116 colorectal cancer cells in our study. The above-mentioned cells were irradiated with different doses of X-rays or carbon ions. Clone formation assays were used to detect cell proliferation, enzyme-linked immunosorbent assay (ELISA) detected ATP, and glutathione (GSH) production, while the expression of proteins was detected by Western blot and quantitative real-time PCR analysis. The production of ROS was detected by flow cytometry, and immunofluorescence was used to track mitophagy-related processes. Finally, BALB/C tumor-bearing nude mice were irradiated with X-rays in order to further explore the protein expression found in tumors with the use of immunohistochemistry. Ionizing radiation increased the protein expressions of ASCT2, GLS, and GLUD in order to upregulate the glutamine metabolic flux in tumor cells. This caused an increase in ATP secretion. Meanwhile, ionizing radiation inhibited the expression of the xCT (SLC7A11) protein and reduced the generation of glutathione, leading to excessive accumulation of intracellular ROS. The mitophagy inhibitor, or knockdown Parkin gene, is able to enhance the ionizing radiation-induced ROS production and increase nucleus DNA damage. This combined treatment can significantly improve the killing effect of radiation on tumor cells. We concluded that ionizing radiation could upregulate the glutamine metabolic flux and enhance ROS accumulation in mitochondria. Ionizing radiation also decreased the SLC7A11 expression, resulting in reduced GSH generation. Therefore, inhibition of mitophagy can increase ionizing radiation-induced cell death.

Sucrose breakdown within guard cells provides substrates for glycolysis and glutamine biosynthesis during light-induced stomatal opening.

Sucrose has long been thought to play an osmolytic role in stomatal opening. However, recent evidence supports the idea that the role of sucrose in this process is primarily energetic. Here we used a combination of stomatal aperture assays and kinetic [U-13 C]-sucrose isotope labelling experiments to confirm that sucrose is degraded during light-induced stomatal opening and to define the fate of the C released from sucrose breakdown. We additionally show that addition of sucrose to the medium did not enhance light-induced stomatal opening. The isotope experiment showed a consistent 13 C enrichment in fructose and glucose, indicating that during light-induced stomatal opening sucrose is indeed degraded. We also observed a clear 13 C enrichment in glutamate and glutamine (Gln), suggesting a concerted activation of sucrose degradation, glycolysis and the tricarboxylic acid cycle. This is in contrast to the situation for Gln biosynthesis in leaves under light, which has been demonstrated to rely on previously stored C. Our results thus collectively allow us to redraw current models concerning the influence of sucrose during light-induced stomatal opening, in which, instead of being accumulated, sucrose is degraded providing C skeletons for Gln biosynthesis.

Glutamina na prevenção e tratamento da mucosite em pacientes adultos oncológicos: uma revisão sistemática da literatura / Glutamine in the prevention and treatment of mucositis in adult cancer patients: a systematic review of literature / La glutamina en la prevención y tratamiento de la mucositis en pacientes adultos con cáncer: una revisión sistemática de la literatura

Introdução: Atualmente, diversos estudos têm avaliado o impacto do uso da glutamina durante o tratamento antineoplásico, pois sua depleção ao longo do tempo pode estar relacionada ao agravamento da mucosite oral e do trato gastrointestinal. Objetivo: O presente trabalho teve como objetivo realizar uma revisão sistemática sobre os conhecimentos disponíveis acerca da utilização da glutamina na prevenção e tratamento da mucosite em pacientes submetidos à radioterapia e/ou quimioterapia. Método: Trata-se de uma revisão sistemática da literatura baseada na metodologia do Instituto Cochrane. Foram selecionados ensaios clínicos em indivíduos adultos, publicados entre 2004 e 2014, nas bases de dados da Medline e Lilacs por meio do Pubmed, com os seguintes descritores: glutamina e radioterapia, glutamina e câncer e mucosite, glutamina e quimioterapia, glutamina e mucosite. Após análise prévia, seis artigos foram selecionados de acordo com os critérios estabelecidos. Resultados: Com relação à dose, forma química, tempo de administração do aminoácido e classificação da mucosite, os estudos se mostraram heterogêneos. Quatro, dos seis artigos avaliados, encontraram benefícios ao seu uso. Nenhum estudo encontrou efeitos deletérios, mas não houve avaliação quanto à sobrevida e à progressão de doença. Conclusão: A utilização da glutamina no tratamento oncológico pode ser uma opção viável, principalmente com relação à prevenção de graus mais graves de mucosite. Mais ensaios clínicos em humanos são necessários, para que seja estabelecida uma dosagem segura de utilização, bem como estudos que avaliem o impacto na resposta ao tratamento e na sobrevida dos indivíduos.

Introduction: Currently, several studies have evaluated the impact of the use of glutamine during anti-cancer treatment because its depletion over time may be related to the aggravation of oral mucositis and of the gastrointestinal tract. Objective: This study aimed to perform a systematic review on the knowledge available in the literature about the use of glutamine in the prevention and treatment of mucositis in patients undergoing radiotherapy and chemoterapy. Method: Human clinical trials published between 2004 and 2014 were selected in the databases indexed in PubMed / Medline and Lilacs, with the following keywords: glutamine and radiotherapy, glutamine and cancer and mucositis, glutamine and chemotherapy, glutamine and mucositis. After preliminary analysis, six articles were selected according to the established eligibility criteria. Results: Regarding the dose, chemical form, amino acid administration time and classification of mucositis, studies have been heterogeneous. Four of the six reviewed articles found benefits to its use. No study found deleterious effects, but there was no evaluation as to the survival and progression of the disease. Conclusion: The use of glutamine in cancer treatment may be a viable option, especially with respect to the prevention of more serious degrees of mucositis. More clinical trials in humans are needed for a safe dosage if use is established, as well as studies to assess the impact on treatment response and survival of individuals.

Introducción: En la actualidad, varios estudios han evaluado el impacto de la utilización de glutamina durante el tratamiento contra el cáncer debido a su disminución a lo largo del tiempo puede estar relacionada con el empeoramiento de la mucositis oral y del tracto gastrointestinal. Objetivo: Este estudio tuvo como objetivo realizar una revisión sistemática de los conocimientos disponibles en la literatura sobre el uso de la glutamina en la prevención y tratamiento de la mucositis en pacientes sometidos a radioterapia y/o quimioterapia. Método: Se trata de una revisión sistemática de la literatura basada en la metodología del Instituto de Cochrane. Se seleccionaron los ensayos clínicos en adultos publicados entre 2004 y 2014 en las bases de datos indexadas en PubMed / Medline y Lilacs, con las siguientes palabras clave: glutamina y la radiación, la glutamina y el cáncer y mucositis, glutamina y quimioterapia, glutamina y mucositis. Después de un análisis preliminar, se seleccionaron seis artículos, de acuerdo con los criterios de elegibilidad establecidos. Resultados: En cuanto a la dosis, la forma química, amino ácido y tiempo de administración clasificación de la mucositis, los estudios se muestran heterogéneos, cuatro de los seis artículos revisados encontraron beneficios de su uso. Ningún estudio encontró efectos deletéreos, pero no había ninguna evaluación en cuanto a la progresión de la supervivencia y la enfermedad. Conclusión: El uso de la glutamina en el tratamiento del cáncer puede ser una opción viable, especialmente con respecto a la prevención de grados más graves de la mucositis. Se necesitan más ensayos clínicos en humanos para que se establezca una dosis segura de uso, así como los estudios para evaluar el impacto en la respuesta al tratamiento y la supervivencia de los individuos.

Effect of gamma-irradiation on agaritine, gamma-glutaminyl-4-hydroxybenzene (GHB), antioxidant capacity, and total phenolic content of mushrooms ( Agaricus bisporus ).

Fresh mushrooms ( Agaricus bisporus ) were irradiated at doses of 1, 3, and 5 kGy to assess the effect of gamma-irradiation on the major aromatic compounds agaritine (beta-N-(gamma-L-(+)-glutamyl)-4-(hydroxymethyl)phenylhydrazine) and GHB (gamma-glutaminyl-4-hydroxybenzene) as well as on the total phenolic content and antioxidant capacity. Up to 3 kGy, agaritine was not affected. At 5 kGy, a significant reduction (p = 0.05) from 1.54 (0 kGy) to 1.35 g/kg dry weight (DW) was observed. gamma-Glutaminyl-4-hydroxybenzene decreased by 22% at 1 kGy and by 31% at 5 kGy. Additionally, agaritine standard solutions at concentrations of 10(-4) and 5 x 10(-5) mol/L were irradiated to compare the effect on agaritine content in aqueous solutions and in the sample matrix. A rapid decay was observed, 50% at 750 Gy (10(-4) mol/L) and 400 Gy (5 x 10(-5) mol/L). The total phenolic content and antioxidant capacity were not significantly (p = 0.05) influenced by irradiation.

Molecular models predict light-induced glutamine tautomerization in BLUF photoreceptors.

The recently discovered photoreceptor proteins containing BLUF (sensor of blue light using FAD) domains mediate physiological responses to blue light in bacteria and euglena. In BLUF domains, blue light activates the flavin chromophore yielding a signaling state characterized by a approximately 10 nm red-shifted absorption. We developed molecular models for the dark and light states of the BLUF domain of the Rhodobacter sphaeroides AppA protein, which are based on the crystal structures and quantum-mechanical simulations. According to these models, photon absorption by the flavin results in a tautomerization and 180 degree rotation of the Gln side chain that interacts with the flavin cofactor. This chemical modification of the Gln residue induces alterations in the hydrogen bond network in the core of the photoreceptor domain, which were observed in numerous spectroscopic experiments. The calculated electronic transition energies and vibrational frequencies of the proposed dark and light states are consistent with the optical and IR spectral changes observed during the photocycle. Light-induced isomerization of an amino acid residue instead of a chromophore represents a feature that has not been described previously in photoreceptors.

1H MR spectroscopy of mesial temporal lobe epilepsies treated with Gamma knife.

Proton MR spectroscopy was used to observe long-term post-irradiation metabolic changes in epileptogenic tissue and in the contralateral parts of the brain which are not available with conventional imaging methods. We studied these changes in the temporal lobe in six patients, following radiosurgery on the amygdala and hippocampus. (1)H MR spectroscopy at 1.5 T with short and long echo times (TE=10 and 135 ms) were used together with standard MR imaging sequences (T1-, T2-weighted). The treatment was performed by Leksell Gamma Knife with a dose of 50 Gy to the center and a 50% isodose to the margin of the target, represented by the mean volume of approximately 7.5 ml. Magnetic resonance imaging and MR spectroscopy examinations were performed at least once per year for 3 years. The most significant changes in spectra were observed approximately 1 year after the irradiation when edema in irradiated area was observed and strong signal of lipids was identified. Later, edema and lipid signals disappeared and follow-up was characterized by a decrease of NAA, Cr, and Cho concentrations in the ipsilateral region of the brain to the irradiation (LCModel calculation from voxel of interest 3.8-4.5 ml positioned into the centrum of target volume). The concentration of NAA, Cr, and Cho after radiosurgery was significantly different from control values ( p<0.05) and also from concentrations in the contralateral part of the brain ( p<0.05). In the contralateral part, the concentration of NAA was significantly increased ( p<0.05) (NAA: before treatment 8.81, after treatment 11.33 mM). No radiotoxic changes were observed in the contralateral part of the brain or behind the area of target volume. The MR spectroscopy findings precluded MRI observation and MRS results completed data about the development of radiotoxic changes in the target volume.

Mutation induction and mutation frequency decline in halogen light-irradiated Escherichia coli K-12 AB1157 strains.

The effects of halogen light irradiation on reversion of argE3-->Arg+ in E. coli K12 strain AB1157 and its mfd- mutant, and on mutation frequency decline (MFD) after transiently incubating irradiated bacteria under non-growing conditions were studied. The induction of mutations, the mutational specificity, and the MFD effect had the same characteristic features as those seen in E. coli B strains after irradiation with 254 nm UV light. MFD which is due to repair of premutagenic lesion in the transcribed strand of glnU gene and prevents mutations leading to supB formation, was not observed in halogen light-induced mutations in the mfd-1 strain. Overproduction of UmuD'C proteins led to a large increase in mutation frequency, which was much greater in mfd- than in mfd+ strains. In bacteria irradiated with halogen light and incubated immediately in a rich medium to express mutations, the formation of supB predominated strongly over that of supE(ochre) in mfd- cells but was at a similar level in mfd+ cells. Introduction of zcf117::Tn10 to AB1157 strain makes cells more sensitive to halogen light irradiation, whereas introduction of mfd-1 does not.

Lyoluminescence dosimetry part II. State-of-the-art.

This is the second part of a review dealing with the development and current state-of-the-art of lyoluminescence dosimetry. Readout equipment described in the review covers a range of devices from simple manually-operated apparatus to semi-automatic machines suitable for loose powders and for encapsulated dosimeters. The survey of dosimetric properties of mannose and glutamine includes response to X- and gamma-rays, electrons, heavy charged particles and to neutrons. Current applications of lyoluminescence dosimetry include radiotherapy, radiation processing of foods and sterilization of medical products, as well as the use of lyoluminescent phosphors for gamma-ray dose intercomparisons in the high-dose range.