Imp2 controls oxidative phosphorylation and is crucial for preserving glioblastoma cancer stem cells.

Growth of numerous cancer types is believed to be driven by a subpopulation of poorly differentiated cells, often referred to as cancer stem cells (CSCs), that have the capacity for self-renewal, tumor initiation, and generation of nontumorigenic progeny. Despite their potentially key role in tumor establishment and maintenance, the energy requirements of these cells and the mechanisms that regulate their energy production are unknown. Here, we show that the oncofetal insulin-like growth factor 2 mRNA-binding protein 2 (IMP2, IGF2BP2) regulates oxidative phosphorylation (OXPHOS) in primary glioblastoma (GBM) sphere cultures (gliomaspheres), an established in vitro model for CSC expansion. We demonstrate that IMP2 binds several mRNAs that encode mitochondrial respiratory chain complex subunits and that it interacts with complex I (NADH:ubiquinone oxidoreductase) proteins. Depletion of IMP2 in gliomaspheres decreases their oxygen consumption rate and both complex I and complex IV activity that results in impaired clonogenicity in vitro and tumorigenicity in vivo. Importantly, inhibition of OXPHOS but not of glycolysis abolishes GBM cell clonogenicity. Our observations suggest that gliomaspheres depend on OXPHOS for their energy production and survival and that IMP2 expression provides a key mechanism to ensure OXPHOS maintenance by delivering respiratory chain subunit-encoding mRNAs to mitochondria and contributing to complex I and complex IV assembly.

Mitochondrial uncoupling as a regulator of life-history trajectories in birds: an experimental study in the zebra finch.

Mitochondria have a fundamental role in the transduction of energy from food into ATP. The coupling between food oxidation and ATP production is never perfect, but may nevertheless be of evolutionary significance. The 'uncoupling to survive' hypothesis suggests that 'mild' mitochondrial uncoupling evolved as a protective mechanism against the excessive production of damaging reactive oxygen species (ROS). Because resource allocation and ROS production are thought to shape animal life histories, alternative life-history trajectories might be driven by individual variation in the degree of mitochondrial uncoupling. We tested this hypothesis in a small bird species, the zebra finch (Taeniopygia guttata), by treating adults with the artificial mitochondrial uncoupler 2,4-dinitrophenol (DNP) over a 32-month period. In agreement with our expectations, the uncoupling treatment increased metabolic rate. However, we found no evidence that treated birds enjoyed lower oxidative stress levels or greater survival rates, in contrast to previous results in other taxa. In vitro experiments revealed lower sensitivity of ROS production to DNP in mitochondria isolated from skeletal muscles of zebra finch than mouse. In addition, we found significant reductions in the number of eggs laid and in the inflammatory immune response in treated birds. Altogether, our data suggest that the 'uncoupling to survive' hypothesis may not be applicable for zebra finches, presumably because of lower effects of mitochondrial uncoupling on mitochondrial ROS production in birds than in mammals. Nevertheless, mitochondrial uncoupling appeared to be a potential life-history regulator of traits such as fecundity and immunity at adulthood, even with food supplied ad libitum.

RNOP-09: pegylated liposomal doxorubicine and prolonged temozolomide in addition to radiotherapy in newly diagnosed glioblastoma--a phase II study.

BACKGROUND: Although Temozolomide is effective against glioblastoma, the prognosis remains dismal and new regimens with synergistic activity are sought for. METHODS: In this phase-I/II trial, pegylated liposomal doxorubicin (Caelyx, PEG-Dox) and prolonged administration of Temozolomide in addition to radiotherapy was investigated in 63 patients with newly diagnosed glioblastoma. In phase-I, PEG-Dox was administered in a 3-by-3 dose-escalation regimen. In phase-II, 20 mg/m2 PEG-Dox was given once prior to radiotherapy and on days 1 and 15 of each 28-day cycle starting 4 weeks after radiotherapy. Temozolomide was given in a dose of 75 mg/m2 daily during radiotherapy (60 Gy) and 150-200 mg/m2 on days 1-5 of each 28-day cycle for 12 cycles or until disease progression. RESULTS: The toxicity of the combination of PEG-Dox, prolonged administration of Temozolomide, and radiotherapy was tolerable. The progression free survival after 12 months (PFS-12) was 30.2%, the median overall survival was 17.6 months in all patients including the ones from Phase-I. None of the endpoints differed significantly from the EORTC26981/NCIC-CE.3 data in a post-hoc statistical comparison. CONCLUSION: Together, the investigated combination is tolerable and feasible. Neither the addition of PEG-Dox nor the prolonged administration of Temozolomide resulted in a meaningful improvement of the patient's outcome as compared to the EORTC26981/NCIC-CE.3 data.

Cannabidiol attenuates cardiac dysfunction, oxidative stress, fibrosis, and inflammatory and cell death signaling pathways in diabetic cardiomyopathy.

Objectives In this study, we have investigated the effects of cannabidiol (CBD) on myocardial dysfunction, inflammation, oxidative/nitrative stress, cell death, and interrelated signaling pathways, using a mouse model of type I diabetic cardiomyopathy and primary human cardiomyocytes exposed to high glucose. Background Cannabidiol, the most abundant nonpsychoactive constituent of Cannabis sativa (marijuana) plant, exerts anti-inflammatory effects in various disease models and alleviates pain and spasticity associated with multiple sclerosis in humans. Methods Left ventricular function was measured by the pressure-volume system. Oxidative stress, cell death, and fibrosis markers were evaluated by molecular biology/biochemical techniques, electron spin resonance spectroscopy, and flow cytometry. Results Diabetic cardiomyopathy was characterized by declined diastolic and systolic myocardial performance associated with increased oxidative-nitrative stress, nuclear factor-kappa B and mitogen-activated protein kinase (c-Jun N-terminal kinase, p-38, p38 alpha) activation, enhanced expression of adhesion molecules (intercellular adhesion molecule-1, vascular cell adhesion molecule-1), tumor necrosis factor-alpha, markers of fibrosis (transforming growth factor-beta, connective tissue growth factor, fibronectin, collagen-1, matrix metalloproteinase-2 and -9), enhanced cell death (caspase 3/7 and poly[adenosine diphosphate-ribose] polymerase activity, chromatin fragmentation, and terminal deoxynucleotidyl transferase dUTP nick end labeling), and diminished Akt phosphorylation. Remarkably, CBD attenuated myocardial dysfunction, cardiac fibrosis, oxidative/nitrative stress, inflammation, cell death, and interrelated signaling pathways. Furthermore, CBD also attenuated the high glucose-induced increased reactive oxygen species generation, nuclear factor-kappa B activation, and cell death in primary human cardiomyocytes. Conclusions Collectively, these results coupled with the excellent safety and tolerability profile of CBD in humans, strongly suggest that it may have great therapeutic potential in the treatment of diabetic complications, and perhaps other cardiovascular disorders, by attenuating oxidative/nitrative stress, inflammation, cell death and fibrosis. (J Am Coll Cardiol 2010;56:2115-25) (C) 2010 by the American College of Cardiology Foundation.

High-level molecular diversity of copper-zinc superoxide dismutase genes among and within species of arbuscular Mycorrhizal fungi.

In the ecologically important arbuscular mycorrhizal fungi (AMF), Sod1 encodes a functional polypeptide that confers increased tolerance to oxidative stress and that is upregulated inside the roots during early steps of the symbiosis with host plants. It is still unclear whether its expression is directed at scavenging reactive oxygen species (ROS) produced by the host, if it plays a role in the fungus-host dialogue, or if it is a consequence of oxidative stress from the surrounding environment. All these possibilities are equally likely, and molecular variation at the Sod1 locus can possibly have adaptive implications for one or all of the three mentioned functions. In this paper, we analyzed the diversity of the Sod1 gene in six AMF species, as well as 14 Glomus intraradices isolates from a single natural population. By sequencing this locus, we identified a large amount of nucleotide and amino acid molecular diversity both among AMF species and individuals, suggesting a rapid divergence of its codons. The Sod1 gene was monomorphic within each isolate we analyzed, and quantitative PCR strongly suggest this locus is present as a single copy in G. intraradices. Maximum-likelihood analyses performed using a variety of models for codon evolution indicated that a number of amino acid sites most likely evolved under the regime of positive selection among AMF species. In addition, we found that some isolates of G. intraradices from a natural population harbor very divergent orthologous Sod1 sequences, and our analysis suggested that diversifying selection, rather than recombination, was responsible for the persistence of this molecular diversity within the AMF population.

Constraint and cost of oxidative stress on reproduction: correlative evidence in laboratory mice and review of the literature.

ABSTRACT: BACKGROUND: One central concept in evolutionary ecology is that current and residual reproductive values are negatively linked by the so-called cost of reproduction. Previous studies examining the nature of this cost suggested a possible involvement of oxidative stress resulting from the imbalance between pro- and anti-oxidant processes. Still, data remain conflictory probably because, although oxidative damage increases during reproduction, high systemic levels of oxidative stress might also constrain parental investment in reproduction. Here, we investigated variation in oxidative balance (i.e. oxidative damage and antioxidant defences) over the course of reproduction by comparing female laboratory mice rearing or not pups. RESULTS: A significant increase in oxidative damage over time was only observed in females caring for offspring, whereas antioxidant defences increased over time regardless of reproductive status. Interestingly, oxidative damage measured prior to reproduction was negatively associated with litter size at birth (constraint), whereas damage measured after reproduction was positively related to litter size at weaning (cost). CONCLUSIONS: Globally, our correlative results and the review of literature describing the links between reproduction and oxidative stress underline the importance of timing/dynamics when studying and interpreting oxidative balance in relation to reproduction. Our study highlights the duality (constraint and cost) of oxidative stress in life-history trade-offs, thus supporting the theory that oxidative stress plays a key role in life-history evolution.

No use for waist-for-height ratio in addition to body mass index to identify children with elevated blood pressure.

Abstract Background. In children, waist-for-height ratio (WHtR) has been proposed to identify subjects at higher risk of cardiovascular diseases. The utility of WHtR to identify children with elevated blood pressure (BP) is unclear. Design. Cross-sectional population-based study of schoolchildren. Methods. Weight, height, waist circumference and BP were measured in all sixth-grade schoolchildren of the canton de Vaud (Switzerland) in 2005/06. WHtR was computed as waist [cm]/height [cm]. Elevated BP was defined according to sex-, age- and height-specific US reference data. The area under the receiver operating characteristic curve (AUC) statistic was computed to compare the ability of body mass index (BMI) z-score and WHtR, alone or in combination, to identify children with elevated BP. Results. 5207 children participated (76% response) [2621 boys, 2586 girls; mean (± SD) age, 12.3 ± 0.5 years; range: 10.1-14.9]. The prevalence of elevated BP was 11%. Mean WHtR was 0.44 ± 0.05 (range: 0.29- 0.77) and 11% had high WHtR (> 0.5). BMI z-score and WHtR were strongly correlated (Spearman correlation coefficient r = 0.76). Both indices were positively associated with elevated BP. AUCs for elevated BP was relatively low for BMI z-score (0.62) or for WHtR (0.62), and was not substantially improved when both indices were considered together (0.63). Conclusions. The ability of BMI z-score or WHtR to identify children aged 10-14 with elevated BP was weak. Adding WHtR did not confer additional discriminative power to BMI alone. These findings do not support the measurement of WHtR in addition to BMI to identify children with elevated BP.

Oxidative phosphorylation flexibility in the liver of mice resistant to high-fat diet-induced hepatic steatosis.

OBJECTIVE To identify metabolic pathways that may underlie susceptibility or resistance to high-fat diet-induced hepatic steatosis. RESEARCH DESIGN AND METHODS We performed comparative transcriptomic analysis of the livers of A/J and C57Bl/6 mice, which are, respectively, resistant and susceptible to high-fat diet-induced hepatosteatosis and obesity. Mice from both strains were fed a normal chow or a high-fat diet for 2, 10, and 30 days, and transcriptomic data were analyzed by time-dependent gene set enrichment analysis. Biochemical analysis of mitochondrial respiration was performed to confirm the transcriptomic analysis. RESULTS Time-dependent gene set enrichment analysis revealed a rapid, transient, and coordinate upregulation of 13 oxidative phosphorylation genes after initiation of high-fat diet feeding in the A/J, but not in the C57Bl/6, mouse livers. Biochemical analysis using liver mitochondria from both strains of mice confirmed a rapid increase by high-fat diet feeding of the respiration rate in A/J but not C57Bl/6 mice. Importantly, ATP production was the same in both types of mitochondria, indicating increased uncoupling of the A/J mitochondria. CONCLUSIONS Together with previous data showing increased expression of mitochondrial β-oxidation genes in C57Bl/6 but not A/J mouse livers, our present study suggests that an important aspect of the adaptation of livers to high-fat diet feeding is to increase the activity of the oxidative phosphorylation chain and its uncoupling to dissipate the excess of incoming metabolic energy and to reduce the production of reactive oxygen species. The flexibility in oxidative phosphorylation activity may thus participate in the protection of A/J mouse livers against the initial damages induced by high-fat diet feeding that may lead to hepatosteatosis.

Re-thinking cell cycle regulators: the cross-talk with metabolism.

Analysis of genetically engineered mice deficient in cell cycle regulators, including E2F1, cdk4, and pRB, showed that the major phenotypes are metabolic perturbations. These key cell cycle regulators contribute to lipid synthesis, glucose production, insulin secretion, and glycolytic metabolism. It has been shown that deregulation of these pathways can lead to metabolic perturbations and related metabolic diseases, such as obesity and type II diabetes. The cyclin-cdk-Rb-E2F1 pathway regulates adipogenesis in addition to its well-described roles in cell cycle regulation and cancer. It was also shown that E2F1 directly participates in the regulation of pancreatic growth and function. Similarly, cyclin D3, cdk4, and cdk9 are also adipogenic factors with strong effects on whole organism metabolism. These examples support the emerging notion that cell cycle regulatory proteins also modulate metabolic processes. These cell cycle regulators are activated by insulin and glucose, even in non-proliferating cells. Most importantly, these cell cycle regulators trigger the adaptive metabolic switch that normal and cancer cells require in order to proliferate. These changes include increased lipid synthesis, decreased oxidative metabolism, and increased glycolytic metabolism. In summary, these factors are essential regulators of anabolic biosynthetic processes, blocking at the same time oxidative and catabolic pathways, which is reminiscent of cancer cell metabolism.

Carboxyl terminus structural requirements for glycosyl-phosphatidylinositol anchor addition to cell surface proteins.

Glycosyl phosphatidylinositol (GPI)-anchored proteins contain in their COOH-terminal region a peptide segment that is thought to direct glycolipid addition. This signal has been shown to require a pair of small amino acids positioned 10-12 residues upstream of an hydrophobic C-terminal domain. We analysed the contribution of the region separating the anchor acceptor site and the C-terminal hydrophobic segment by introducing amino acid deletions and substitutions in the spacer element of the GPI-anchored Thy-1 glycoprotein. Deletions of 7 amino acids in this region, as well as the introduction of 2 charged residues, prevented the glycolipid addition to Thy-1, suggesting that the length and the primary sequence of the spacer domain are important determinants in the signal directing GPI anchor transfer onto a newly synthesized polypeptide. Furthermore, we tested these rules by creating a truncated form of the normally transmembranous Herpes simplex virus I glycoprotein D (gDI) and demonstrating that when its C-terminal region displays all the features of a GPI-anchored protein, it is able to direct glycolipid addition onto another cell surface molecule.

Targeting intratumoral B cells with rituximab in addition to CHOP in angioimmunoblastic T-cell lymphoma. A clinicobiological study of the GELA.

Background In angioimmunoblastic T-cell lymphoma, symptoms linked to B-lymphocyte activation are common, and variable numbers of CD20(+) large B-blasts, often infected by Epstein-Barr virus, are found in tumor tissues. We postulated that the disruption of putative B-T interactions and/or depletion of the Epstein-Barr virus reservoir by an anti-CD20 monoclonal antibody (rituximab) could improve the clinical outcome produced by conventional chemotherapy. DESIGN AND METHODS: Twenty-five newly diagnosed patients were treated, in a phase II study, with eight cycles of rituximab + chemotherapy (R-CHOP21). Tumor infiltration, B-blasts and Epstein-Barr virus status in tumor tissue and peripheral blood were fully characterized at diagnosis and were correlated with clinical outcome. RESULTS: A complete response rate of 44% (95% CI, 24% to 65%) was observed. With a median follow-up of 24 months, the 2-year progression-free survival rate was 42% (95% CI, 22% to 61%) and overall survival rate was 62% (95% CI, 40% to 78%). The presence of Epstein-Barr virus DNA in peripheral blood mononuclear cells (14/21 patients) correlated with Epstein-Barr virus score in lymph nodes (P<0.004) and the detection of circulating tumor cells (P=0.0019). Despite peripheral Epstein-Barr virus clearance after treatment, the viral load at diagnosis (>100 copy/μg DNA) was associated with shorter progression-free survival (P=0.06). Conclusions We report here the results of the first clinical trial targeting both the neoplastic T cells and the microenvironment-associated CD20(+) B lymphocytes in angioimmunoblastic T-cell lymphoma, showing no clear benefit of adding rituximab to conventional chemotherapy. A strong relationship, not previously described, between circulating Epstein-Barr virus and circulating tumor cells is highlighted.