Nogo receptor 1 regulates formation of lasting memories.

Formation of lasting memories is believed to rely on structural alterations at the synaptic level. We had found that increased neuronal activity down-regulates Nogo receptor-1 (NgR1) in brain regions linked to memory formation and storage, and postulated this to be required for formation of lasting memories. We now show that mice with inducible overexpression of NgR1 in forebrain neurons have normal long-term potentiation and normal 24-h memory, but severely impaired month-long memory in both passive avoidance and swim maze tests. Blocking transgene expression normalizes these memory impairments. Nogo, Lingo-1, Troy, endogenous NgR1, and BDNF mRNA expression levels were not altered by transgene expression, suggesting that the impaired ability to form lasting memories is directly coupled to inability to down-regulate NgR1. Regulation of NgR1 may therefore serve as a key regulator of memory consolidation. Understanding the molecular underpinnings of synaptic rearrangements that carry lasting memories may facilitate development of treatments for memory dysfunction.

Reduced fear memory and anxiety-like behavior in mice lacking formylpeptide receptor 1.

N-formylpeptide receptor 1 (FPR1) is a G protein-coupled receptor that mediates pro-inflammatory chemotactic responses by phagocytic leukocytes to N-formylpeptides produced by bacteria or mitochondria. Mice lacking Fpr1 (Fpr1 (-/-) mice) have increased susceptibility to challenge with certain bacteria. FPR1 is also a receptor for annexin-1, which mediates the anti-inflammatory effects of glucocorticoids as well as negative feedback by glucocorticoids of the hypothalamic-pituitary-adrenocortical axis. However, homeostatic functions of FPR1 in the neuroendocrine system have not previously been defined. Here we show that in systematic behavioral testing Fpr1 (-/-) mice exhibited increased exploratory activity, reduced anxiety-like behavior, and impaired fear memory, but normal spatial memory and learning capacity. Consistent with this, the homeostatic serum level of corticosterone in Fpr1 (-/-) mice was significantly lower compared with wild-type mice. The data implicate Fpr1 in modulation of anxiety-like behavior and fear memory by regulating glucocorticoid production.

MTH1 Inhibitor TH1579 Induces Oxidative DNA Damage and Mitotic Arrest in Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) is an aggressive hematologic malignancy, exhibiting high levels of reactive oxygen species (ROS). ROS levels have been suggested to drive leukemogenesis and is thus a potential novel target for treating AML. MTH1 prevents incorporation of oxidized nucleotides into the DNA to maintain genome integrity and is upregulated in many cancers. Here we demonstrate that hematologic cancers are highly sensitive to MTH1 inhibitor TH1579 (karonudib). A functional precision medicine ex vivo screen in primary AML bone marrow samples demonstrated a broad response profile of TH1579, independent of the genomic alteration of AML, resembling the response profile of the standard-of-care treatments cytarabine and doxorubicin. Furthermore, TH1579 killed primary human AML blast cells (CD45+) as well as chemotherapy resistance leukemic stem cells (CD45+Lin-CD34+CD38-), which are often responsible for AML progression. TH1579 killed AML cells by causing mitotic arrest, elevating intracellular ROS levels, and enhancing oxidative DNA damage. TH1579 showed a significant therapeutic window, was well tolerated in animals, and could be combined with standard-of-care treatments to further improve efficacy. TH1579 significantly improved survival in two different AML disease models in vivo. In conclusion, the preclinical data presented here support that TH1579 is a promising novel anticancer agent for AML, providing a rationale to investigate the clinical usefulness of TH1579 in AML in an ongoing clinical phase I trial. SIGNIFICANCE: The MTH1 inhibitor TH1579 is a potential novel AML treatment, targeting both blasts and the pivotal leukemic stem cells while sparing normal bone marrow cells.

Cognitive impairment in the Tg6590 transgenic rat model of Alzheimer's disease.

Recently, interest in the rat as an animal model of Alzheimer's disease (AD) has been growing. We have previously described the Tg6590 transgenic rat line expressing the amyloid precursor protein containing the Swedish AD mutation (K670M/N671L) that shows early stages of Abeta deposition, predominantly in cerebrovascular blood vessels, after 15 months of age. Here we show that by the age of 9 months, that is long before the appearance of Abeta deposits, the Tg6590 rats exhibit deficits in the Morris water maze spatial navigation task and altered spontaneous behaviour in the open-field test. The levels of soluble Abeta were elevated both in the hippocampus and cortex of transgenic animals. Magnetic resonance imaging showed no major changes in the brains of transgenic animals, although they tended to have enlarged lateral ventricles when compared to control animals. The Tg6590 transgenic rat line should prove a suitable model of early AD for advanced studies including serial cerebrospinal fluid sampling, electrophysiology, neuroimaging or complex behavioural testing.

TH1579, MTH1 inhibitor, delays tumour growth and inhibits metastases development in osteosarcoma model.

BACKGROUND: Osteosarcoma (OS) is the most common primary malignant bone tumour. Unfortunately, no new treatments are approved and over the last 30 years the survival rate remains only 30% at 5 years for poor responders justifying an urgent need of new therapies. The Mutt homolog 1 (MTH1) enzyme prevents incorporation of oxidized nucleotides into DNA and recently developed MTH1 inhibitors may offer therapeutic potential as MTH1 is overexpressed in various cancers. METHODS: The aim of this study was to evaluate the therapeutic benefits of targeting MTH1 with two chemical inhibitors, TH588 and TH1579 on human osteosarcoma cells. Preclinical efficacy of TH1579 was assessed in human osteosarcoma xenograft model on tumour growth and development of pulmonary metastases. FINDINGS: MTH1 is overexpressed in OS patients and tumour cell lines, compared to mesenchymal stem cells. In vitro, chemical inhibition of MTH1 by TH588 and TH1579 decreases OS cells viability, impairs their cell cycle and increases apoptosis in OS cells. TH1579 was confirmed to bind MTH1 by CETSA in OS model. Moreover, 90 mg/kg of TH1579 reduces in vivo tumour growth by 80.5% compared to non-treated group at day 48. This result was associated with the increase in 8-oxo-dG integration into tumour cells DNA and the increase of apoptosis. Additionally, TH1579 also reduces the number of pulmonary metastases. INTERPRETATION: All these results strongly provide a pre-clinical proof-of-principle that TH1579 could be a therapeutic option for patients with osteosarcoma. FUNDING: This study was supported by La Ligue Contre le Cancer, la SFCE and Enfants Cancers Santé.

Ex vivo culture of cells derived from circulating tumour cell xenograft to support small cell lung cancer research and experimental therapeutics.

BACKGROUND AND PURPOSE: Small cell lung cancer (SCLC) is an aggressive disease with median survival of <2 years. Tumour biopsies for research are scarce, especially from extensive-stage patients, with repeat sampling at disease progression rarely performed. We overcame this limitation for relevant preclinical models by developing SCLC circulating tumour cell derived explants (CDX), which mimic the donor tumour pathology and chemotherapy response. To facilitate compound screening and identification of clinically relevant biomarkers, we developed short-term ex vivo cultures of CDX tumour cells. EXPERIMENTAL APPROACH: CDX tumours were disaggregated, and the human tumour cells derived were cultured for a maximum of 5 weeks. Phenotypic, transcriptomic and pharmacological characterization of these cells was performed. KEY RESULTS: CDX cultures maintained a neuroendocrine phenotype, and most changes in the expression of protein-coding genes observed in cultures, for up to 4 weeks, were reversible when the cells were re-implanted in vivo. Moreover, the CDX cultures exhibited a similar sensitivity to chemotherapy compared to the corresponding CDX tumour in vivo and were able to predict in vivo responses to therapeutic candidates. CONCLUSIONS AND IMPLICATIONS: Short-term cultures of CDX provide a tractable platform to screen new treatments, identify predictive and pharmacodynamic biomarkers and investigate mechanisms of resistance to better understand the progression of this recalcitrant tumour.

Neurotrophin levels and behaviour in BALB/c mice: impact of intermittent exposure to individual housing and wheel running.

This study assessed the effects of intermittent individual housing on behaviour and brain neurotrophins, and whether physical exercise could influence alternate individual-housing-induced effects. Five-week-old BALB/c mice were either housed in enhanced social (E) or standard social (S) housing conditions for 2 weeks. Thereafter they were divided into six groups and for 6 weeks remained in the following experimental conditions: Control groups remained in their respective housing conditions (E-control, S-control); enhanced individual (E-individual) and standard individual (S-individual) groups were exposed every other day to individual cages without running-wheels; enhanced running-wheel (E-wheel) and standard running-wheel (S-wheel) groups were put on alternate days in individual running-wheel cages. Animals were assessed for activity in an automated individual cage system (LABORAS) and brain neurotrophins analysed. Intermittent individual housing increased behavioural activity and reduced nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) levels in frontal cortex; while it increased BDNF level in the amygdala and BDNF protein and mRNA in hippocampus. Besides normalizing motor activity and regulating BDNF and NGF levels in hippocampus, amygdala and cerebellum, physical exercise did not attenuate reduction of cortical NGF and BDNF induced by intermittent individual housing. This study demonstrates that alternate individual housing has significant impact on behaviour and brain neurotrophin levels in mice, which can be partially altered by voluntary physical exercise. Our results also suggest that some changes in neurotrophin levels induced by intermittent individual housing are not similar to those caused by continuous individual housing.

Intermittent individual housing increases survival of newly proliferated cells.

In this study, we analyzed how intermittent individual housing with or without a running wheel influenced corticosterone levels and survival of newly proliferated cells in the dentate gyrus of the hippocampus. Female Balb/c mice, in standard or enhanced housing, were divided into groups that were individually housed with or without running wheels on every second day. Intermittent individual housing without, but not with, running wheels increased survival of proliferated cells in the dentate gyrus as compared with continuous group housing in standard or enhanced conditions. Thus, changes in housing conditions on every second day can, under certain circumstances, have an impact on the survival of newly proliferated cells in the dentate gyrus.

Behavioral assessment of intermittent wheel running and individual housing in mice in the laboratory.

Physical cage enrichment--exercise devices for rodents in the laboratory--often includes running wheels. This study compared responses of mice in enriched physical and social conditions and in standard social conditions to wheel running, individual housing, and open-field test. The study divided into 6 groups, 48 female BALB/c mice group housed in enriched and standard conditions. On alternate days, the study exposed 2 groups to individual running wheel cages. It intermittently separated from their cage mates and housed individually 2 groups with no running wheels; 2 control groups remained in enriched or standard condition cages. There were no significant differences between enriched and standard group housed mice in alternate days' wheel running. Over time, enriched, group housed mice ran less. Both groups responded similarly to individual housing. In open-field test, mice exposed to individual housing without running wheel moved more and faster than wheel running and home cage control mice. They have lower body weights than group housed and wheel running mice. Intermittent withdrawal of individual housing affects the animals more than other commodities. Wheel running normalizes some effects of intermittent separation from the enriched, social home cage.

Environmental influences on brain neurotrophins in rats.

Environmental factors can have profound influences on the brain. Enriching environments with physical, social and sensory stimuli are now established to be beneficial to brain development and ageing. A multitude of responses from cellular and molecular mechanisms to macroscopic changes in neural morphology and neurogenesis have been considered in the context for evidences that environmental inputs can regulate brain plasticity in the rat at all stages of life. Data from our laboratory have revealed that enriched environment increased nerve growth factor (NGF) gene expression and protein levels in the hippocampus, and this may contribute to events underlying environmentally induced neural plasticity. Because neurotrophic factors are essential for neural development and survival, they are likely to be involved in the cerebral consequences modified by enriched experiences.

Transgenic overexpression of interleukin-1 receptor antagonist in the CNS influences behaviour, serum corticosterone and brain monoamines.

The effects of brain-directed overexpression of human soluble interleukin-1 receptor antagonist (hsIL-1ra) on behaviour, serum corticosterone (CST) levels and concentrations of dopamine (DA), 5-hydroxytryptamine (5-HT) and their metabolites in different brain regions, were investigated in six months old homozygotic transgenic male mice (Tg hsIL-1ra(+/+)). The transgenic and age-matched wild type (WT) mice were subjected to a battery of behavioural tests for analysis of open field (OF) behaviours, anxiety in elevated plus maze (EPM), and motor performance in rotarod. One week after the last behavioural test, half of the mice from each genotype were subjected to a mild stress, while the remaining mice served as controls for the determination of serum CST levels and monoamine concentrations in different brain regions. Tg hsIL-1ra(+/+) mice had higher locomotor scores and showed less habituation in the OF test, spent more time in the open arms of the EPM and had similar motor performance as compared to WT mice. The serum CST levels were comparable, both in basal conditions and upon stress, in the two genotypes. Tg hsIL-1ra(+/+) mice had lower concentrations of DA, 5-HT and their metabolites in several brain regions, with different effects on monoamine turnover upon stress. In conclusion, brain-directed overexpression of hsIL-1ra resulted in increased locomotion and decreased habituation, an anxiolytic effect, but did not influence motor performance. Finally, the activation of hypothalamo-pituitary-adrenal (HPA)-axis was comparable in the two genotypes, however Tg hsIL-1ra(+/+) mice had a modified metabolism of brain monoamines as compared to WT mice.

Selective nicotinic receptor consequences in APP(SWE) transgenic mice.

The nicotinic (nAChRs) and muscarinic (mAChRs) acetylcholine receptors and acetylcholinesterase (AChE) activity were studied in the brains of APP(SWE) transgenic mice (Tg+) and age-matched nontransgenic controls (Tg-) that were between 4 and 19 months of age. A significant increase in the binding of 125I-labeled alpha-bungarotoxin (alpha7 nAChRs) was observed in most brain regions analyzed in 4-month-old Tg+ mice, preceding learning and memory impairments and amyloid-beta (Abeta) pathology. The enhanced alpha7 receptor binding was still detectable at 17-19 months of age. Increase in [3H]cytisine binding (alpha4beta2 nAChRs) was measured at 17-19 months of age in Tg+ mice, at the same age when the animals showed heavy Abeta pathology. No significant changes in [3H]pirenzepine (M1 mAChRs) or [3H]AFDX 384 (M2 mAChRs) binding sites were found at any age studied. The upregulation of the nAChRs probably reflects compensatory mechanisms in response to Abeta burden in the brains of Tg+ mice.