Authors: Reed JL, Nugent AC, Furey ML, Szczepanik JE, Evans JW, Zarate CA Jr
Journal: Neuroimage Clin. 2018 Jul 5;20:92-101. doi: 10.1016/j.nicl.2018.07.006. eCollection 2018.
BACKGROUND: An urgent need exists for faster-acting pharmacological treatments in major depressive disorder (MDD). The glutamatergic modulator ketamine has been shown to have rapid antidepressant effects, but much remains unknown about its mechanism of action. Functional MRI (fMRI) can be used to investigate how ketamine impacts brain activity during cognitive and emotional processing.
METHODS: This double-blind, placebo-controlled, crossover study of 33 unmedicated participants with MDD and 26 healthy controls (HCs) examined how ketamine affected fMRI activation during an attentional bias dot probe task with emotional face stimuli across multiple time points. A whole brain analysis was conducted to find regions with differential activation associated with group, drug session, or dot probe task-specific factors (emotional valence and congruency of stimuli).
RESULTS: A drug session by group interaction was observed in several brain regions, such that ketamine had opposite effects on brain activation in MDD versus HC participants. Additionally, there was a similar finding related to emotional valence (a drug session by group by emotion interaction) in a large cluster in the anterior cingulate and medial frontal cortex.
CONCLUSIONS: The findings show a pattern of brain activity in MDD participants following ketamine infusion that is similar to activity observed in HCs after placebo. This suggests that ketamine may act as an antidepressant by normalizing brain function during emotionally valenced attentional processing.
Authors: Little MP, Wakeford R, Borrego D, French B, Zablotska LB, Adams MJ, Allodji R, de Vathaire F, Lee C, Brenner AV, Miller JS, Campbell D, Pearce MS, Doody MM, Holmberg E, Lundell M, Sadetzki S, Linet MS, Berrington de González A
Journal: The Lancet. 2018 Jul 16. doi: https://doi.org/10.1016/S2352-3026(18)30092-9.
Background: Substantial evidence links exposure to moderate or high doses of ionising radiation, particularly in childhood, with increased risk of leukaemia. The association of leukaemia with exposure to low-dose (<100 mSv) radiation is less certain, although this is the dose range most relevant to the general population. We aimed to estimate the risk of leukaemia associated with low-dose radiation exposure in childhood (age <21 years).
Methods: In this analysis of historical cohort studies, we pooled eligible cohorts reported up to June 30, 2014. We evaluated leukaemia and myeloid malignancy outcomes in these cohorts with the relevant International Classification of Diseases and International Classification of Diseases for Oncology definitions. The cohorts included had not been treated for malignant disease, had reported at least five cases of the relevant haematopoietic neoplasms, and estimated individual active bone marrow (ABM) doses. We restricted analysis to individuals who were younger than 21 years at first irradiation who had mean cumulative ABM doses of less than 100 mSv. Dose-response models were fitted by use of Poisson regression. The data were received in fully anonymised form by the statistical analyst.
Findings: We identified nine eligible cohorts from Canada, France, Japan, Sweden, the UK, and the USA, including 262,573 people who had been exposed to less than 100 mSv enrolled between June 4, 1915, and Dec 31, 2004. Mean follow-up was 19.63 years (SD 17.75) and mean cumulative ABM dose was 19.6 mSv (SD 22.7). 154 myeloid malignancies were identified (which included 79 acute myeloid leukaemias, eight myelodysplastic syndromes, and 36 chronic myeloid leukaemias, in addition to other unspecified myeloid malignancies) and 40 acute lymphoblastic leukaemias, with 221 leukaemias (including otherwise unclassified leukaemias but excluding chronic lymphocytic leukaemia) identified overall. The fitted relative risks at 100 mSv were 3.09 (95% CI 1.41–5.92; ptrend=0·008) for acute myeloid leukaemia and myelodysplastic syndromes combined, 2.56 (1.09–5.06; ptrend=0.033) for acute myeloid leukaemia, and 5.66 (1.35–19.71; ptrend=0.023) for acute lymphoblastic leukaemia. There was no clear dose-response for chronic myeloid leukaemia, which had a relative risk at 100 mSv of 0.36 (0.00–2·36; ptrend=0.394). There were few indications of between-cohort heterogeneity or departure from linearity. For acute myeloid leukaemia and myelodysplastic syndromes combined and for acute lymphoblastic leukaemia, the dose-responses remained significant for doses of less than 50 mSv. Excess absolute risks at 100 mSv were in the range of 0.1–0.4 cases or deaths per 10,000 person-years.
Interpretation: The risks of acute myeloid leukaemia and acute lymphoblastic leukaemia were significantly increased after cumulative doses of ionising radiation of less than 100 mSv in childhood or adolescence, with an excess risk also apparent for cumulative radiation doses of less than 50 mSv for some endpoints. These findings support an increased risk of leukaemia associated with low-dose exposure to radiation and imply that the current system of radiological protection is prudent and not overly protective.
Authors: Yohe ME, Gryder BE, Shern JF, Song YK, Chou HC, Sindiri S, Mendoza A, Patidar R, Zhang X, Guha R, Butcher D, Isanogle KA, Robinson CM, Luo X, Chen JQ, Walton A, Awasthi P, Edmondson EF, Difilippantonio S, Wei JS, Zhao K, Ferrer M, Thomas CJ, Khan J
Journal: Sci Transl Med. 2018 Jul 4;10(448). pii: eaan4470. doi: 10.1126/scitranslmed.aan4470.
The RAS isoforms are frequently mutated in many types of human cancers, including PAX3/PAX7 fusion-negative rhabdomyosarcoma. Pediatric RMS arises from skeletal muscle progenitor cells that have failed to differentiate normally. The role of mutant RAS in this differentiation blockade is incompletely understood. We demonstrate that oncogenic RAS, acting through the RAF-MEK [mitogen-activated protein kinase (MAPK) kinase]-ERK (extracellular signal-regulated kinase) MAPK effector pathway, inhibits myogenic differentiation in rhabdomyosarcoma by repressing the expression of the prodifferentiation myogenic transcription factor, MYOG. This repression is mediated by ERK2-dependent promoter-proximal stalling of RNA polymerase II at the MYOG locus. Small-molecule screening with a library of mechanistically defined inhibitors showed that RAS-driven RMS is vulnerable to MEK inhibition. MEK inhibition with trametinib leads to the loss of ERK2 at the MYOG promoter and releases the transcriptional stalling of MYOG expression. MYOG subsequently opens chromatin and establishes super-enhancers at genes required for late myogenic differentiation. Furthermore, trametinib, in combination with an inhibitor of IGF1R, potently decreases rhabdomyosarcoma cell viability and slows tumor growth in xenograft models. Therefore, this combination represents a potential therapeutic for RAS-mutated rhabdomyosarcoma.
Authors: Wyss AB, Sofer T, Lee MK, Terzikhan N, Nguyen JN, Lahousse L, Latourelle JC, Smith AV, Bartz TM, Feitosa MF, Gao W, Ahluwalia TS, Tang W, Oldmeadow C, Duan Q, de Jong K, Wojczynski MK, Wang XQ, Noordam R, Hartwig FP, Jackson VE, Wang T, Obeidat M, Hobbs BD, Huan T, Gui H, Parker MM, Hu D, Mogil LS, Kichaev G, Jin J, Graff M, Harris TB, Kalhan R, Heckbert SR, Paternoster L, Burkart KM, Liu Y, Holliday EG, Wilson JG, Vonk JM, Sanders JL, Barr RG, de Mutsert R, Menezes AMB, Adams HHH, van den Berge M, Joehanes R, Levin AM, Liberto J, Launer LJ, Morrison AC, Sitlani CM, Celedón JC, Kritchevsky SB, Scott RJ, Christensen K, Rotter JI, Bonten TN, Wehrmeister FC, Bossé Y, Xiao S, Oh S, Franceschini N, Brody JA, Kaplan RC, Lohman K, McEvoy M, Province MA, Rosendaal FR, Taylor KD, Nickle DC, Williams LK, Burchard EG, Wheeler HE, Sin DD, Gudnason V, North KE, Fornage M, Psaty BM,, Myers RH, O'Connor G, Hansen T, Laurie CC, Cassano PA, Sung J, Kim WJ, Attia JR, Lange L, Boezen HM, Thyagarajan B, Rich SS, Mook-Kanamori DO, Horta BL, Uitterlinden AG, Im HK, Cho MH, Brusselle GG, Gharib SA, Dupuis J, Manichaikul A, London SJ
Journal: Nat Commun. 2018 Jul 30;9(1):2976. doi: 10.1038/s41467-018-05369-0.
Nearly 100 loci have been identified for pulmonary function, almost exclusively in studies of European ancestry populations. We extend previous research by meta-analyzing genome-wide association studies of 1000 Genomes imputed variants in relation to pulmonary function in a multiethnic population of 90,715 individuals of European (N = 60,552), African (N = 8,429), Asian (N = 9,959), and Hispanic/Latino (N = 11,775) ethnicities. We identify over 50 additional loci at genome-wide significance in ancestry-specific or multiethnic meta-analyses. Using recent fine-mapping methods incorporating functional annotation, gene expression, and differences in linkage disequilibrium between ethnicities, we further shed light on potential causal variants and genes at known and newly identified loci. Several of the novel genes encode proteins with predicted or established drug targets, including KCNK2 and CDK12. Our study highlights the utility of multiethnic and integrative genomics approaches to extend existing knowledge of the genetics of lung function and clinical relevance of implicated loci.
Authors: Burton JH, Mazcko CN, LeBlanc AK, Covey JM, Ji JJ, Kinders RJ, Parchment RE, Khanna C, Paoloni M, Lana SE, Weishaar K, London CA, Kisseberth WC, Krick E, Vail DM, Childress MO, Bryan JN, Barber LG, Ehrhart EJ, Kent MS, Fan TM, Kow KY, Northup N, Wilson-Robles H, Tomaszewski JE, Holleran JL, Muzzio M, Eiseman J, Beumer JH, Doroshow JH, Pommier Y
Journal: Clin Cancer Res. 2018 Jul 30. pii: clincanres.1498.2018. doi: 10.1158/1078-0432.CCR-18-1498. [Epub ahead of print]
PURPOSE: Only one chemical class of topoisomerase I (TOP1) inhibitors is FDA approved, the camptothecins with irinotecan and topotecan widely used. Because of their limitations (chemical instability, drug efflux-mediated resistance, and diarrhea), novel TOP1 inhibitors are warranted. Indenoisoquinoline non-camptothecin topoisomerase I (TOP1) inhibitors overcome chemical instability and drug resistance that limit camptothecin use. Three indenoisoquinolines, LMP400 (Indotecan), LMP776 (Indimitecan) and LMP744, were examined in a phase I study for lymphoma-bearing dogs to evaluate differential efficacy, pharmacodynamics, toxicology and pharmacokinetics.
EXPERIMENTAL DESIGN: Eighty-four client-owned dogs with lymphomas were enrolled in dose-escalation cohorts for each indenoisoquinoline, with an expansion phase for LMP744. Efficacy, tolerability, pharmacokinetics and target engagement were determined.
RESULTS: The maximally tolerated doses (MTDs) were 17.5 mg/m2 for LMP 776 and 100 mg/m2 for LMP744; bone marrow toxicity was dose-limiting; up to 65 mg/m2 LMP400 was well-tolerated and MTD was not reached. None of the drugs induced notable diarrhea. Sustained tumor accumulation was observed for LMP744;gH2AX induction was demonstrated in tumors 2 and 6 hours after treatment; a decrease in TOP1 protein was observed in most lymphoma samples across all compounds and dose levels, which is consistent with the fact that tumor response was also observed at low doses LMP744. Objective responses were documented for all indenoisoquinolines; efficacy (13/19 dogs) was greatest for LMP744.
CONCLUSIONS: These results demonstrate proof-of-mechanism for indenoisoquinoline TOP1 inhibitors supporting their further clinical development. They also highlight the value of the NCI Comparative Oncology Program (https://ccr.cancer.gov/Comparative-Oncology-Program) for evaluating novel therapies in immune-competent pets with cancers.
Authors: Liu W, Aerbajinai W, Li H, Liu Y, Gavrilova O, Jain S, Rodgers GP
Journal: Endocrinology. 2018 Jul 19. doi: 10.1210/en.2018-00451. [Epub ahead of print]
Glucose-stimulated insulin secretion (GSIS) is essential for blood glucose homeostasis and is impaired in type 2 diabetes mellitus. Understanding the regulatory components of GSIS has clinical implications for diabetes treatment. Here we found that olfactomedin 4 (OLFM4) is endogenously expressed in pancreatic islet β cells and further investigated its potential roles in glucose homeostasis and the pathogenesis of type 2 diabetes using mouse models. Olfm4-deficient mice showed significantly improved glucose tolerance and significantly increased insulin levels after glucose challenge compared with wild-type (WT) mice. GSIS, mitochondrial ATP production, and mitochondrial respiration were all significantly increased in islets isolated from Olfm4-deficient mice compared with those isolated from WT mice. In a high fat diet (HFD)-induced diabetes mouse model, the increase in insulin levels after glucose challenge was significantly higher in Olfm4-deficient mice compared with WT mice. The impaired glucose tolerance and insulin resistance in HFD-fed mice were improved by loss of Olfm4. Olfm4 was found to be mainly localized in the mitochondria and interacts with GRIM-19 (gene associated with retinoid-interferon mortality) in Min6 pancreatic β cells. Collectively, these studies suggest that Olfm4 negatively regulates GSIS. OLFM4 may represent a potential therapeutic target for impaired glucose tolerance and type-2 diabetes patients.
Authors: Liu X, Shu S, Korn ED
Journal: Proc Natl Acad Sci U S A. 2018 Jul 11. pii: 201808800. doi: 10.1073/pnas.1808800115. [Epub ahead of print]
The three mammalian nonmuscle myosin 2 (NM2) monomers, like all class 2 myosin monomers, are hexamers of two identical heavy (long) chains and two pairs of light (short) chains bound to the heavy chains. The heavy chains have an N-terminal globular motor domain (head) with actin-activated ATPase activity, a lever arm (neck) to which the two light chains bind, and a coiled-coil helical tail. Monomers polymerize into bipolar filaments, with globular heads at each end separated by a bare zone, by antiparallel association of their coiled-coil tails. NM2 filaments are highly dynamic in situ, frequently disassembling and reassembling at different locations within the cell where they are essential for multiple biological functions. Therefore, it is important to understand the mechanisms of filament polymerization and depolymerization. Monomers can exist in two states: folded and unfolded. It has been thought that unfolded monomers form antiparallel dimers that assemble into bipolar filaments. We now show that polymerization in vitro proceeds from folded monomers to folded antiparallel dimers to folded antiparallel tetramers that unfold forming antiparallel bipolar tetramers. Folded dimers and tetramers then associate with the unfolded tetramer and unfold, forming a mature bipolar filament consisting of multiple unfolded tetramers with an entwined bare zone. We also demonstrate that depolymerization is essentially the reverse of the polymerization process. These results will advance our understanding of NM2 filament dynamics in situ.
Authors: Tabor KM, Smith TS, Brown M, Bergeron SA, Briggman KL, Burgess HA
Journal: Current Biology. 2018 Aug 2. doi: 10.1016/j.cub.2018.06.020.
Filtering mechanisms prevent a continuous stream of sensory information from swamping perception, leading to diminished focal attention and cognitive processing. Mechanisms for sensory gating are commonly studied using prepulse inhibition, a paradigm that measures the regulated transmission of auditory information to the startle circuit; however, the underlying neuronal pathways are unresolved. Using large-scale calcium imaging, optogenetics, and laser ablations, we reveal a cluster of 30 morphologically identified neurons in zebrafish that suppress the transmission of auditory signals during prepulse inhibition. These neurons project to a key sensorimotor interface in the startle circuit—the termination zone of auditory afferents on the dendrite of a startle command neuron. Direct measurement of auditory nerve neurotransmitter release revealed selective presynaptic inhibition of sensory transmission to the startle circuit, sparing signaling to other brain regions. Our results provide the first cellular resolution circuit for prepulse inhibition in a vertebrate, revealing a central role for presynaptic gating of sensory information to a brainstem motor circuit.
Authors: Zhu S, Hu Z, Tian R, Yung BC, Yang Q, Zhao S, Kiesewetter DO, Niu G, Sun H, Antaris AL, Chen X
Journal: Adv Mater. 2018 Jul 9:e1802546. doi: 10.1002/adma.201802546. [Epub ahead of print]
The significantly reduced tissue autofluorescence and scattering in the NIR-II region (1000-1700 nm) opens many exciting avenues for detailed investigation of biological processes in vivo. However, the existing NIR-II fluorescent agents, including many molecular dyes and inorganic nanomaterials, are primarily focused on complicated synthesis routes and unknown immunogenic responses with limited potential for clinical translation. Herein, the >1000 nm tail emission of conventional biocompatible NIR cyanine dyes with emission peaks at 700-900 nm is systematically investigated, and a type of bright dye for NIR-II imaging with high potential for accelerating clinical translation is identified. The asymmetry of the π domain in the S1 state of NIR cyanine dyes is proven to result in a twisted intramolecular charge-transfer process and NIR-II emission, establishing a general rule to guide future NIR-I/II fluorophore synthesis. The screened NIR dyes are identified to possess a bright emission tail in the NIR-II region along with high quantum yield, high molar-extinction coefficient, rapid fecal excretion, and functional groups amenable for bioconjugation. As a result, NIR cyanine dyes can be used for NIR-II imaging to afford superior contrast and real-time imaging of several biological models, facilitating the translation of NIR-II bioimaging to clinical theranostic applications.
Authors: Akkaya M, Traba J, Roesler AS, Miozzo P, Akkaya B, Theall BP, Sohn H, Pena M, Smelkinson M, Kabat J, Dahlstrom E, Dorward DW, Skinner J, Sack MN, Pierce SK
Journal: Nat Immunol. 2018 Jul 9. doi: 10.1038/s41590-018-0156-5. [Epub ahead of print]
B cells are activated by two temporally distinct signals, the first provided by the binding of antigen to the B cell antigen receptor (BCR), and the second provided by helper T cells. Here we found that B cells responded to antigen by rapidly increasing their metabolic activity, including both oxidative phosphorylation and glycolysis. In the absence of a second signal, B cells progressively lost mitochondrial function and glycolytic capacity, which led to apoptosis. Mitochondrial dysfunction was a result of the gradual accumulation of intracellular calcium through calcium response-activated calcium channels that, for approximately 9 h after the binding of B cell antigens, was preventable by either helper T cells or signaling via the receptor TLR9. Thus, BCR signaling seems to activate a metabolic program that imposes a limited time frame during which B cells either receive a second signal and survive or are eliminated.