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Exertional heat stroke (EHS) is a potentially lethal condition resulting from high core body temperatures (TC) in combination with a systemic inflammatory response syndrome (SIRS) with varying degrees of severity across victims, and limited understanding of the underlying mechanism(s). We established a mouse model of severe EHS to identify mechanisms of hyperthermia/inflammation that may be responsible for organ damage. Mice were forced to run on a motorized wheel in a 37.5°C chamber until loss of consciousness and were either removed immediately (exertional heat injury or EHI; TCMax = 42.4 ± 0.2°C) or remained in the chamber an additional 20 min (EHS; TCMax = 42.5 ± 0.4°C). Exercise control mice (ExC) experienced identical procedures to EHS at 25°C. At 3 h post-EHS, there was evidence for an immune/inflammatory response as elevated blood chemokine [interferon γ-induced protein 10 (IP-10), keratinocytes-derived chemokine (KC), macrophage inflammatory proteins (MIP-1α), MIP-1β, MIP-2] and cytokine [granulocyte colony-stimulating factor (G-CSF), interleukins (IL-10), IL-6] levels peaked and were highest in EHS mice compared with EHI and ExC mice. Immunoblotting of organs susceptible to EHS damage indicated that several kinases were sensitive to stress associated with heat/inflammation and exercise; specifically, phosphorylation of liver c-Jun NH2-terminal kinase (JNK) at threonine 183/tyrosine 185 immediately (0 h) postheating related to heat illness severity. We have established a mouse EHS model, and JNK [or its downstream target(s)] could underlie EHS symptomatology, allowing the identification of molecular pathways or countermeasure targets to mitigate heat illness severity, enable complete recovery, and decrease overall EHS-related fatalities.

Mice undergoing repeated exertional heat injuries, within 1 wk of an initial heat injury, appear to have some protective adaptations. During the second exertional heat injury, mice were able to run longer and sustain higher body temperatures before collapse. Despite this, the mice undergoing a second exertional heat injury were more resilient to the heat as evidenced by attenuated minimum body temperature, higher HPS70 (serum and liver), lower corticosterone, and lower FABP2.

Key points The pathogenic mechanism and the neuromuscular reflex-related phenotype (e.g. tremors accompanied by clonus) of Amish nemaline myopathy, as well as of other recessively inherited TNNT1 myopathies, remain to be clarified. The truncated slow skeletal muscle isoform of troponin T (ssTnT) encoded by the mutant TNNT1 gene is unable to incorporate into myofilaments and is degraded in muscle cells. By contrast to extrafusal muscle fibres, spindle intrafusal fibres of normal mice contain a significant level of cardiac TnT and a low molecular weight splice form of ssTnT. Intrafusal fibres of ssTnT-knockout mice have significantly increased cardiac TnT. Rotarod and balance beam tests have revealed abnormal neuromuscular co-ordination in ssTnT-knockout mice and a blunted response to a spindle sensitizer, succinylcholine. The loss of ssTnT and a compensatory increase of cardiac TnT in intrafusal nuclear bag fibres may increase myofilament Ca2+ -sensitivity and tension, impairing spindle function, thus identifying a novel mechanism for the development of targeted treatment. Abstract A nonsense mutation at codon Glu180 of TNNT1 gene causes Amish nemaline myopathy (ANM), a recessively inherited disease with infantile lethality. TNNT1 encodes the slow skeletal muscle isoform of troponin T (ssTnT). The truncated ssTnT is unable to incorporate into myofilament and is degraded in muscle cells. The symptoms of ANM include muscle weakness, atrophy, contracture and tremors accompanied by clonus. An ssTnT-knockout (KO) mouse model recapitulates key features of ANM such as atrophy of extrafusal slow muscle fibres and increased fatigability. However, the neuromuscular reflex-related symptoms of ANM have not been explained. By isolating muscle spindles from ssTnT-KO and control mice aiming to examine the composition of myofilament proteins, we found that, in contrast to extrafusal fibres, intrafusal fibres contain a significant level of cardiac TnT and the low molecular weight splice form of ssTnT. Intrafusal fibres from ssTnT-KO mice have significantly increased cardiac TnT. Rotarod and balance beam tests revealed impaired neuromuscular co-ordination in ssTnT-KO mice, indicating abnormality in spindle functions. Unlike the wild-type control, the beam running ability of ssTnT-KO mice had a blunted response to a spindle sensitizer, succinylcholine. Immunohistochemistry detected ssTnT and cardiac TnT in nuclear bag fibres, whereas fast skeletal muscle TnT was detected in nuclear chain fibres, and cardiac α-myosin was present in one of the two nuclear bag fibres. The loss of ssTnT and a compensatory increase of cardiac TnT in nuclear bag fibres would increase myofilament Ca2+ -sensitivity and tension, thus affecting spindle activities. This mechanism provides an explanation for the pathophysiology of ANM, as well as a novel target for treatment.

The active participation of skeletal muscles is a unique characteristic of exertional heat stroke. Nevertheless, the only well-documented link between skeletal muscle activities and exertional heat stroke pathophysiology is the extensive muscle damage (e. g., rhabdomyolysis) and subsequent leakage of intramuscular content into the circulation of exertional heat stroke victims. Here, we will present and discuss rarely explored roles of skeletal muscles in the context of exertional heat stroke pathophysiology and recovery. This includes an overview of heat production that contributes to severe hyperthermia and the synthesis and secretion of bioactive molecules, such as cytokines, chemokines and acute phase proteins. These molecules can alter the overall inflammatory status from pro- to anti-inflammatory, affecting other organ systems and influencing recovery. The activation of innate immunity can determine whether a victim is ready to return to physical activity or experiences a prolonged convalescence. We also provide a brief discussion on whether heat acclimation can shift skeletal muscle secretory phenotype to prevent or aid recovery from exertional heat stroke. We conclude that skeletal muscles should be considered as a key organ system in exertional heat stroke pathophysiology.

5′ AMP-activated protein kinase (AMPK) activation may be part of the exercise-induced process that enhances insulin sensitivity. Independent of exercise, acute prior treatment of skeletal muscles isolated from young rats with a pharmacological AMPK activator, 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR), causes subsequently improved insulin-stimulated glucose uptake (GU). However, efficacy of a single prior AICAR exposure on insulin-stimulated GU in muscles from old animals has not been studied. The purpose of this study was to determine whether brief, prior exposure to AICAR (3.5 h before GU assessment) leads to subsequently increased GU in insulin-stimulated skeletal muscles from old rats. Epitrochlearis muscles from 24-month-old male rats were isolated and initially incubated ±AICAR (60 min), followed by incubation without AICAR (3 h), then incubation ±insulin (50 min). Muscles were assessed for GU (via 3-O-methyl-[3H]-glucose accumulation) and site-specific phosphorylation of key proteins involved in enhanced GU, including AMPK, Akt, and Akt substrate of 160 kDa (AS160), via Western blotting. Prior ex vivo AICAR treatment resulted in greater GU by insulin-stimulated muscles from 24-month-old rats. Prior AICAR treatment also resulted in greater phosphorylation of AMPK (T172) and AS160 (S588, T642, and S704). Glucose transporter type 4 (GLUT4) protein abundance was unaffected by prior AICAR and/or insulin treatment. These findings demonstrate that skeletal muscles from older rats are susceptible to enhanced insulin-stimulated GU after brief activation of AMPK by prior AICAR. Consistent with earlier research using muscles from young rodents, increased phosphorylation of AS160 is implicated in this effect, which was not attributable to altered GLUT4 glucose transporter protein abundance.

Acute myeloid leukemia harboring internal tandem duplication of FMS-like tyrosine kinase 3 (AMLFLT3-ITD) is associated with poor prognosis. We evaluated the results of the AML-05 study, in which all AMLFLT3-ITD patients were assigned to receive hematopoietic stem cell transplantation (HSCT) in the first remission (1CR). We also investigated the effects of additional genetic alterations on FLT3-ITD. The 5-year overall survival (OS) and event-free survival (EFS) rates among the 47 AMLFLT3-ITD patients were 42.2 and 36.8%, respectively. The 5-year disease-free survival rate among 29 patients without induction failure was 58.4%. We defined the allelic ratio (AR) of FLT3-ITD to WT > 0.7 as high. Significant differences were found in OS (AR-high, 20% vs. AR-low, 66%, p 0.7 and expression of the NUP98-NSD1 chimera strongly impacted OS and EFS. Although all the AMLFLT3-ITD patients received HSCT at 1CR, the treatment outcome of AMLFLT3-ITD patients did not improve compared with those in a previous study. Heterogeneity was observed among AMLFLT3-ITD patients.

Muscle is a heterogeneous tissue composed of multiple fiber types. Earlier research revealed fiber type-selective postexercise effects on insulin-stimulated glucose uptake (ISGU) from insulin-resistant rats (increased for type IIA, IIB, IIBX, and IIX, but not type I). In whole muscle from insulin-resistant rats, the exercise increase in ISGU is accompanied by an exercise increase in insulin-stimulated AS160 phosphorylation (pAS160), an ISGU-regulating protein. We hypothesized that, in insulin-resistant muscle, the fiber type-selective exercise effects on ISGU would correspond to the fiber type-selective exercise effects on pAS160. Rats were fed a 2-wk high-fat diet (HFD) and remained sedentary (SED) or exercised before epitrochlearis muscles were dissected either immediately postexercise (IPEX) or at 3 h postexercise (3hPEX) using an exercise protocol that previously revealed fiber type-selective effects on ISGU. 3hPEX muscles and SED controls were incubated ± 100µU/mL insulin. Individual myofibers were isolated and pooled on the basis of myosin heavy chain (MHC) expression, and key phosphoproteins were measured. Myofiber glycogen and MHC expression were evaluated in muscles from other SED, IPEX, and 3hPEX rats. Insulin-stimulated pAktSer473 and pAktThr308 were unaltered by exercise in all fiber types. Insulin-stimulated pAS160 was greater for 3hPEX vs. SED on at least one phosphosite (Ser588, Thr642, and/or Ser704) in type IIA, IIBX, and IIB fibers, but not in type I or IIX fibers. Both IPEX and 3hPEX glycogen were decreased versus SED in all fiber types. These results provided evidence that fiber type-specific pAS160 in insulin-resistant muscle may play a role in the previously reported fiber type-specific elevation in ISGU in some, but not all, fiber types.

Earlier research using muscle tissue demonstrated that postexercise elevation in insulin-stimulated glucose uptake (ISGU) occurs concomitant with greater insulin-stimulated Akt substrate of 160 kDa (AS160) phosphorylation (pAS160) on sites that regulate ISGU. Because skeletal muscle is a heterogeneous tissue, we previously isolated myofibers from rat epitrochlearis to assess fiber type-selective ISGU. Exercise induced greater ISGU in type I, IIA, IIB, and IIBX but not IIX fibers. This study tested if exercise effects on pAS160 correspond with previously published fiber type-selective exercise effects on ISGU. Rats were studied immediately postexercise (IPEX) or 3.5 h postexercise (3.5hPEX) with time-matched sedentary controls. Myofibers dissected from the IPEX experiment were analyzed for fiber type (myosin heavy chain isoform expression) and key phosphoproteins. Isolated muscles from the 3.5hPEX experiment were incubated with or without insulin. Myofibers (3.5hPEX) were analyzed for fiber type, key phosphoproteins, and GLUT4 protein abundance. We hypothesized that insulin-stimulated pAS160 at 3.5hPEX would exceed sedentary controls only in fiber types characterized by greater ISGU postexercise. Values for phosphorylation of AMP-activated kinase substrates (acetyl CoA carboxylaseSer79and AS160Ser704) from IPEX muscles exceeded sedentary values in each fiber type, suggesting exercise recruitment of all fiber types. Values for pAS160Thr642and pAS160Ser704from insulin-stimulated muscles 3.5hPEX exceeded sedentary values for type I, IIA, IIB, and IIBX but not IIX fibers. GLUT4 abundance was unaltered 3.5hPEX in any fiber type. These results advanced understanding of exercise-induced insulin sensitization by providing compelling support for the hypothesis that enhanced insulin-stimulated phosphorylation of AS160 is linked to elevated ISGU postexercise at a fiber type-specific level independent of altered GLUT4 expression.

Background Decreased cortical excitability has been proposed as a potential mechanism underlying task failure during sustained muscular contractions, and cortical excitability may decrease with old age. We tested the hypothesis that transcranial direct current stimulation, which has been reported to raise cortical excitability, would prolong the time to task failure during a sustained muscular contraction in older adults. Methods Thirteen older adults (68.3±2.0 years; eight women and five men) performed isometric, elbow flexions to failure while receiving sham or anodal transcranial direct current stimulation. Order of stimulation was randomized, and the subjects and investigators were blinded to condition. Time to task failure was measured alongside selected psychological indices of perceived exertion and affect. Results Anodal transcranial direct current stimulation prolonged mean time to task failure by approximately 15% (16.9±2.2 vs 14.7±1.8 minutes) and slowed the rate of increase in rating of perceived exertion (0.29±0.03 vs 0.31±0.03) relative to the sham condition. Conclusions These preliminary findings suggest that anodal transcranial direct current stimulation enhances time to task failure of a sustained, submaximal contraction in older adults by potentially increasing cortical excitability and/or influencing the perception of exertion. These results raise the question of whether interventions that acutely increase cortical excitability could enhance physical function and/or exercise-induced adaptations in older adults.

We evaluated effects of calorie restriction (CR: consuming 60–65% of ad libitum [AL] intake) initiated late-in-life with or without acute exercise on insulin-stimulated glucose uptake (ISGU) of skeletal muscle by studying four groups of 26-month-old rats: sedentary-AL, sedentary-CR (8-week duration), 3 hours post-exercise (3hPEX)-AL and 3hPEX-CR. ISGU was determined in isolated epitrochlearis muscles incubated ± insulin. Muscles were assessed for signaling proteins (immunoblotting) and lipids (mass spectrometry). ISGU from sedentary-CR and 3hPEX-AL exceeded sedentary-AL; 3hPEX-CR exceeded all other groups. Akt (Ser473, Thr308) and Akt substrate of 160 kDa (AS160; Ser588, Thr642, Ser704) phosphorylation levels tracked with ISGU. Among the 477 lipids detected, 114 were altered by CR (including reductions in 15 of 25 acylcarnitines), and 27 were altered by exercise (including reductions in 18 of 22 lysophosphatidylcholines) with only six lipids overlapping between CR and exercise. ISGU significantly correlated with 23 lipids, including: acylcarnitine 20:1 (r = .683), lysophosphatidylethanolamine19:0 (r = −.662), acylcarnitine 24:0 (r = .611), and plasmenyl-phosphatidylethanolamine 37:5 (r = −.603). Muscle levels of ceramides (a lipid class previously linked to insulin resistance) were not altered by CR and/or exercise nor significantly correlated with ISGU, implicating other mechanisms (which potentially involve other lipids identified in this study) for greater ISGU and Akt and AS160 phosphorylation with these interventions.

Background and purpose Muscle weakness predisposes older adults to a fourfold increase in functional limitations and has previously been associated with reduced motor cortex excitability in aging adults. The purpose of this study was to determine whether a single session of anodal transcranial direct current stimulation (tDCS) of the motor cortex would increase elbow flexion muscle strength and electromyographic (EMG) amplitude in very old individuals. Methods Eleven very old individuals-85.8 (4.3) years-performed 3 maximal isometric elbow flexion contractions before and after 20 minutes of sham or anodal tDCS on different days. Order of stimulation was randomized, and the study participants and investigators were blinded to condition. In addition, voluntary activation capacity of the elbow flexors was determined by comparing voluntary and electrically evoked forces. Results Anodal tDCS did not alter muscle strength or EMG activity in comparison to sham stimulation. Elbow flexion voluntary activation capacity was very high among the study participants: 99.3% (1.8%). Conclusion Contrary to our hypothesis, we observed no effect of anodal tDCS and no impairment in elbow flexor voluntary activation capacity in the very old. Whether anodal tDCS would exert a positive effect and support our initial hypothesis in another muscle group that does exhibit impairments in voluntary activation in older adults is a question that is still to be addressed.

Introduction Testosterone (T) induces motor dysfunction in transgenic (Tg) mice that overexpress wild-type androgen receptor (AR) in skeletal muscles. Because many genes implicated in motor neuron disease are expressed in skeletal muscle, mutant proteins may act in muscle to cause dysfunction in motor neuron disease. Methods We examined contractile properties of the extensor digitorum longus (EDL) and soleus (SOL) muscles in vitro after 5 and 3 days of T treatment in motor-impaired Tg female mice. Results Both muscles showed deficits in tetanic force after 5 days of T treatment, without losses in muscle mass, protein content, or fiber number. After 3 days of T treatment, only SOL showed a deficit in tetanic force comparable to that of 5 days of treatment. In both treatments, EDL showed slowed twitch kinetics, whereas SOL showed deficits in the twitch/tetanus ratio. Conclusions These results suggest calcium-handling mechanisms in muscle fibers are defective in motor-impaired mice. Muscle Nerve 47: 823–834, 2013

In this paper, we propose a new kind of tripedal locomotion—namely, robotic walking with three legs. We develop a prototype robot, which we call Martian III, having three stretchable legs fixed to each other at the center of the body. Therefore the coxa (the hip joint) is completely fixed in this robot, and the only control we have are the linear actuators to stretch the three legs in the radial directions. The robot is developed as a minimal model to examine our basic idea, to make the robot swing by actuating the legs and then generate locomotion utilizing geometric effect of rigid body rolling on a flat floor. The experiments with robot succeeds in forwarding and rotary locomotion with appropriate choices of oscillatory along each leg. Further analysis of the movement of Martian III indicates that the direction of the swing leg depends on the deformation of each leg. Moreover, due to the result of the measurement experiment and movement analysis of rotation locomotion, we found out two typical type of gaits.

In this perspective article, we review the effects of selected anabolic hormones on the motoric system and speculate on the role these hormones may have on influencing muscle and physical function via their impact on the nervous system. Both muscle strength and anabolic hormone levels decline around middle age into old age over a similar time period, and several animal and human studies indicate that exogenously increasing anabolic hormones (e.g., testosterone and insulin-like growth factor-1 (IGF-1)) in aged subjects is positively associated with improved muscle strength. While most studies in humans have focused on the effects of anabolic hormones on muscle growth, few have considered the impact these hormones have on the motoric system. However, data from animals demonstrate that administering either testosterone or IGF-1 to cells of the central and peripheral motor system can increase cell excitability, attenuate atrophic changes, and improve regenerative capacity of motor neurons. While these studies do not directly indicate that changes in anabolic hormones contribute to reduced human performance in the elderly (e.g., muscle weakness and physical limitations), they do suggest that additional research is warranted along these lines.

Spinal and bulbar muscular atrophy (SBMA) is characterized by progressive muscle weakness linked to a polyglutamine expansion in the androgen receptor (AR). Current evidence indicates that mutant AR causes SBMA by acting in muscle to perturb its function. However, information about how muscle function is impaired is scant. One fundamental question is whether the intrinsic strength of muscles, an attribute of muscle independent of its mass, is affected. In the current study, we assess the contractile properties of hindlimb muscles in vitro from chronically diseased males of three different SBMA mouse models: a transgenic (Tg) model that broadly expresses a full-length human AR with 97 CAGs (97Q), a knock-in (KI) model that expresses a humanized AR containing a CAG expansion in the first exon, and a Tg myogenic model that overexpresses wild-type AR only in skeletal muscle fibers. We found that hindlimb muscles in the two Tg models (97Q and myogenic) showed marked losses in their intrinsic strength and resistance to fatigue, but were minimally affected in KI males. However, diseased muscles of all three models showed symptoms consistent with myotonic dystrophy type 1, namely, reduced resting membrane potential and deficits in chloride channel mRNA. These data indicate that muscle dysfunction is a core feature of SBMA caused by at least some of the same pathogenic mechanisms as myotonic dystrophy. Thus mechanisms controlling muscle function per se independent of mass are prime targets for SBMA therapeutics.

Myelodysplastic syndromes (MDS) and myelodysplastic/myeloproliferative neoplasms (MDS/MPN) are heterogeneous groups of chronic myeloid neoplasms characterized by clonal hematopoiesis, varying degrees of cytopenia or myeloproliferative features with evidence of myelodysplasia and a propensity to acute myeloid leukemia (AML).1 In recent years, a number of novel gene mutations, involving TET2, ASXL1, DNMT3A, EZH2, IDH1/2, and c-CBL, have been identified in adult cases of chronic myeloid neoplasms, which have contributed to our understanding of disease pathogenesis.2, 3, 4, 5, 6, 7 However, these mutations are rare in pediatric cases, with the exception of germline or somatic c-CBL mutations found in 10–15% of chronic myelomonocytic leukemia (CMML) and juvenile myelomonocytic leukemia (JMML),8 highlighting the distinct pathogenesis of adult and pediatric neoplasms.9 Recently, we reported high frequencies of mutations, involving the RNA splicing machinery, that are largely specific to myeloid neoplasms, showing evidence of myeloid dysplasia in adult.10 Affecting a total of eight components of the RNA splicing machinery (U2AF35, U2AF65, SF3A1, SF3B1, SRSF2, ZRSR2, SF1 and PRPF40B) commonly involved in the 3′ splice-site (3′SS) recognition, these pathway mutations are now implicated in the pathogenesis of myelodysplasia.10 To investigate the role of the splicing-pathway mutations in the pathogenesis of pediatric myeloid malignancies, we have examined 165 pediatric cases with AML, MDS, chronic myeloid leukemia (CML) and JMML for mutations in the four major splicing factors, U2AF35, ZRSR2, SRSF2, and SF3B1, commonly mutated in adult cases. Bone marrow or peripheral blood tumor specimens were obtained from 165 pediatric patients with various myeloid malignancies, including de novo AML (n=93), MDS (n=28), CML (n=17) and JMML (n=27), and the genomic DNA (gDNA) was subjected to mutation analysis (Supplementary Table 1). The status of the RAS pathway mutations for the current JMML series has been reported previously (Supplementary Table 2).11, 12 Nineteen leukemia cell lines derived from AML (YNH-1, ML-1, KASUMI-3, KG-1, HL60, inv-3, SN-1, NB4 and HEL), acute monocytic leukemia (THP-1, SCC-3, J-111, CTS, P31/FUJ, MOLM-13, IMS/MI and KOCL-48) and acute megakaryoblastic leukemia (CMS and CMY) were also analyzed for mutations. Peripheral blood gDNA from 60 healthy adult volunteers was used as controls. Informed consent was obtained from the patients and/or their parents and from the healthy volunteers. We previously showed that for U2AF35, SRSF2 and SF3B1, most of the mutations in adult cases were observed in exons 2 and 7, exon 1, and exons 14 and 15, respectively.10 Therefore, we confirmed mutation screening to these ‘hot-spot' exons. In contrast, all the coding exons were examined for ZRSR2, because no mutational hot spots have been detected. Briefly, the relevant exons were amplified using PCR and mutations were examined by Sanger sequencing, as previously described.10 The Fisher's exact test was used to evaluate the statistical significance of frequencies of mutations for U2AF35, SF3B1, ZRSR2 or SRSF2 in adult cases and pediatric cases. This study was approved by the Ethics Committee of the University of Tokyo (Approval number 948-7). No mutations were identified in the 28 cases with pediatric MDS, which included 13 cases with refractory anemia with excess blasts, 5 with refractory cytopenia of childhood, 2 with Down syndrome-related MDS, 2 with Fanconi anemia-related MDS, 2 with secondary MDS and 4 with unclassified MDS. Similarly, no mutations were detected in 93 cases with de novo AML or in 17 with CML, as well as 19 leukemia-derived cell lines. Our previous study in adult patients showed the frequency of mutations in U2AF35, SF3B1, ZRSR2 or SRSF2 to be 60/155 cases with MDS without increased ring sideroblasts and 8/151 de novo AML patients, emphasizing the rarity of these mutations in pediatric MDS (P

T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/LBL) accounts for 10% to 15% of newly diagnosed cases of childhood acute lymphoblastic leukemia (ALL), arising from the malignant transformation of hematopoietic progenitors primed toward T cell development, as result of a multistep oncogenic process. However, since the prognostic significance of these genetic alterations in pediatric T-ALL is not clear, genetic basis which contributes aggressive phenotype or progression of pediatric T-ALL is still to be elucidated. Therefore, to discover driver genetic events, which involved in the aggressive phenotype of pediatric T-ALL and to identify it's novel prognostic markers, we performed integrated genetic analysis in a large cohort of T-ALL case. Our cohorts included samples from Tokyo Children's Cancer Study Group (TCCSG) and Japan Association of Childhood Leukemia Study (JACLS). Whole transcriptome sequencing (WTS) was performed in 123 cases. Representative recurrent fusion genes were as follows, SIL-TAL1 (n=25), MLL-ENL (n=5), PICALM-MLLT10 (n=5), and NUP214-ABL1 (n=2). Intriguingly, novel recurrent in-frame SPI1 fusions (STMN1-SPI1 n=2; TCF7-SPI1 n=5) were detected, and RT-PCR analysis in additional 60 cases revealed other 2 TCF7-SPI1 fusions. Thus, SPI1 fusions accounted for 4% of pediatric T-ALL/LBL. Expression data of WTS revealed cases with SPI1 fusion showed significantly higher expression of SPI1 compared to cases without SPI1 fusion, implicating that aberrant high expression of SPI1 involved in leukemogenesis. To address the functional activities of SPI1 fusions, we performed luciferase assay using the reporter vector contained the CSF1 promoter region with SPI1 binding site. Transient transfection of Hela cells with the SPI1 fusions expression vectors as well as the wild type SPI1 expression vector showed strikingly high levels of transcription of the reporter genes, as compared to transfection with the empty expression vector, indicating that both SPI1 fusions have transcriptional activities. Next, to analyze the leukemogenic potential of SPI1 fusions in vitro, we transduced fusions cDNA into mouse double negative T-cells. Since p16(CDKN2A) is frequently silenced in T-ALL, we also used p16 null double negative T-cells. Both wild-type and p16 null double negative T-cells expressing SPI1 fusions showed increased cell proliferation compared to the MOCK cells. We further evaluated the impact of SPI1 fusions on T cells differentiation. TCF7-SPI1 or MOCK vector was transduced mononuclear cells isolated from mouse bone marrow. These cells were cultured under stimulating factors, such as IL6 and TPO for 3 days, and then transplanted into the irradiated mouse. Subsequently, 6 week after transplantation, FACS analysis was performed. Of interest, significantly high population of cells expressing TCF7-SPI1 was observed in the immature single positive stage, implicating that their differentiation was impaired at the pre-T cell stage. These results indicate that novel SPI1 fusions have a potential leukemogenic effect in pediatric T-ALL. We defined SPI1 overexpression cases as outliers of SPI1 expression, resulting in extremely poor prognosis (log-rank p = 1.9 ×10-6). Of note, significant poor outcome was confirmed by univariate and multivariate analysis in cases with SPI1 overexpression cases (log-rank p = 9.3 ×10-6, and p = 2.0 ×10-6, respectively). In conclusion, SPI1 fusions expressing cells expanded and they remained at an immature stage, implicating a potential leukemogenic activity of these fusions. Not only the cases with SPI1 fusions, but also the cases with high SPI1 expression without fusions showed extremely poor prognosis, suggesting the prognostic value of aberrant SPI1 expression in pediatric T-ALL. Although it remains unclear, why cases with SPI1 fusions/high SPI1 expression have a poor prognosis, our results indicate that these cases are genetically distinct subgroup from other pediatric T-ALL. Disclosures Kataoka: Kyowa Hakko Kirin: Honoraria; Yakult: Honoraria; Boehringer Ingelheim: Honoraria. Ogawa:Kan research institute: Consultancy, Research Funding; Takeda Pharmaceuticals: Consultancy, Research Funding; Sumitomo Dainippon Pharma: Research Funding.

Anaplastic lymphoma kinase (ALK) was originally identified from a rare subtype of non-Hodgkin's lymphomas carrying t(2;5)(p23;q35) translocation, where ALK was constitutively activated as a result of a fusion with nucleophosmin (NPM). Aberrant ALK fusion proteins were also generated in inflammatory fibrosarcoma and a subset of non-small-cell lung cancers, and these proteins are implicated in their pathogenesis. Recently, ALK has been demonstrated to be constitutively activated by gene mutations and/or amplifications in sporadic as well as familial cases of neuroblastoma. Here we describe another mechanism of aberrant ALK activation observed in a neuroblastoma-derived cell line (NB-1), in which a short-form ALK protein (ALK(del2-3)) having a truncated extracellular domain is overexpressed because of amplification of an abnormal ALK gene that lacks exons 2 and 3. ALK(del2-3) was autophosphorylated in NB-1 cells as well as in ALK(del2-3)-transduced cells and exhibited enhanced in vitro kinase activity compared with the wild-type kinase. ALK(del2-3)-transduced NIH3T3 cells exhibited increased colony-forming capacity in soft agar and tumorigenicity in nude mice. RNAi-mediated ALK knockdown resulted in the growth suppression of ALK(del2-3)-expressing cells, arguing for the oncogenic role of this mutant. Our findings provide a novel insight into the mechanism of deregulation of the ALK kinase and its roles in neuroblastoma pathogenesis.

Background Pediatric acute myeloid leukemia (AML) comprises approximately 20% of pediatric leukemia cases. AML is a major therapeutic challenge in pediatric oncology, and the current overall survival rate is In addition, recent studies have reported that the NUP98-NSD1 fusion is an adverse AML prognostic marker and that PRDM16 (also termed MEL1) is a representative gene that is overexpressed in patients who have the NUP98-NSD1 fusion. PRDM16 overexpression occurs in nearly a quarter of pediatric AML patients who are NUP98-NSD1 negative, and this overexpression is increased in specimens with other high-risk lesions (e.g., FLT3-ITD, NUP98-NSD1,and MLL-PTD). Patients and Methods To obtain a complete overview of gene rearrangements and other genetic lesions, we performed RNA sequencing of samples from 47 de novo pediatric AML patients using Illumina HiSeq 2000, including 39 patients with normal karyotypes and 6 patients with Trisomy 8. Among these 47 patients, 35 patients overexpressed PRDM16, which was strongly associated with a poor prognosis in our previous studies. As a control, we selected 12 patients with low PRDM16 expression levels. All patients were enrolled and treated as part of the AML-05 study conducted by the Japan Pediatric Leukemia/Lymphoma Study Group. We determined the known gene mutations present in these patients using the RNA sequencing data. Results Approximately 300 candidate gene rearrangements were identified in 46/47 samples, including 26 in-frame and 78 out-of-frame gene rearrangements. Several recurrent gene rearrangements identified in this study involved previously reported targets in AML, such as FUS-ERG, NUP98-NSD1,and MLL-MLLT3. However, several novel gene rearrangements were identified in the current study, including HOXA10-HOXA-AS3, PRDM16-XXX, CUL1-YYY, and DAZAP1-ZZZ. At present, we are validating these novel gene rearrangements using Sanger sequencing. Known gene alterations, such as FLT3-ITD, MLL-PTD, and mutations of RAS, KIT, CEBPA, WT1, and NPM1 genes, were detected by RNA sequencing. Conclusion In the present study, RNA sequencing was employed to elucidate the complexity of gene rearrangements/mutations in pediatric AML genomes. Our results indicate that a subset of pediatric AML represents a discrete entity that can be discriminated from adult AML in terms of the spectrum of gene rearrangements/mutations. We identified at least one potential gene rearrangement or driver mutation in nearly all AML samples, including various novel fusion genes. Thus, our results suggest that gene rearrangements and mutations play essential roles in pediatric AML. Disclosures No relevant conflicts of interest to declare.

Background Acute myeloid leukemia harboring internal tandem duplication of fms-like tyrosine kinase 3 (AMLFLT3-ITD) is associated with poor prognosis, but the previous studies have reported that the inferior outcome is only confined to those with high allelic ratio (AR) of ITD/wild type (WT). In our previous AML99 study (2000-2002), AMLFLT3-ITD showed a poor outcome compared to the WT cases (5-year OS; 35% vs. 84%, P Patients & Methods AML-05 study, registered at http://www.umin.ac.jp/ctr/ as UMIN000000511, is a Japanese nation-wide multi-institutional study for children (age0.4 as high and AR ≤ 0.4 as low as previously reported (Meshinchi S. Blood2006). Results We found 47 patients (10.6%) with AMLFLT3-ITD in this study (30 males, 17 females, and median age of 11 years at diagnosis). The median WBC count was 65,300/ml (3,690 - 522,050/mL). FAB classification included M1 (n=10), M2 (n=9), M4 (n=9), and M5 (n=11), and AML with normal karyotype was dominant (19/47, 40.4%). Of the 29 patients (61.7%) who achieved CR, twenty-seven received HSCT in 1CR and 19 patients survived (19/27, 70.4%). On the other hand, 14/16 non-CR patients received HSCT, but only 4 survived. The only demographic difference between the 29 CR and 16 non-CR cases was the median WBC count at diagnosis (19,000 vs. 124,000/μL, P AR was analyzed in 44 patients with median ratio of 0.68 (range, 0.11 to 4.47). Median AR was not different between CR vs. non-CR cases (0.53 vs. 0.72). There were no difference in 5-year OS (52.8% vs. 42.5%, P=0.302), DFS (54.5% vs. 64.5%, P=0.524), and EFS (50.0% vs. 34.4%, P=0.283) between patients with low (n=12) and high AR (n=32), however, induction rate was significantly higher in the low AR patients (91.7% vs. 53.1%, P=0.018). It was rather surprising that all FLT3-ITDs were found only in JM domain and not in TKI domain in the current trial. In addition, six of 47 (12.8%) AMLFLT3-ITD patients had NPM1mutation simultaneously, and all received HSCT at 1CR and survived. Discussion and Conclusion We observed a different induction rate between AMLFLT3-ITD patients with low and high AR, but poor final outcomes in both. Regardless of the level of AR, patients with AMLFLT3-ITD, especially who fail to achieve remission, have dismal outcome and effective therapy combined with novel FLT3 inhibitor is urgently needed to overcome the disease. Disclosures: No relevant conflicts of interest to declare.

Recently, mutational and epigenetic profiling of a large acute myeloid leukemia (AML) patient cohort revealed that NADP+dependent isocitrate dehydrogenase (IDH)1/2-mutated AMLs display global DNA hypermethylation and a specific hypermethylation signature, suggesting a shared proleukemogenic effect. To explore the involvements of IDH1/2 in the pathogenesis in pediatric hematological malignancies. We analyzed mutations that involve the activation sites of IDH1/2 using polymerase chain reaction amplification/sequencing in a total of 244 samples of pediatric myeloid malignancies as well as infantile leukemia including 17 AML-derived cell lines, 115 primary cases of AML, 28 primary cases of MDS, 15 primary cases of juvenile myelomonocytic leukaemia (JMML), 6 chronic myeloid leukemia (CML)-derived cell line, 18 primary cases of CML and 45 infantile leukemia(6 AML and 39 acute lymphoblastic leukemia (ALL) patients). Moreover, to assess whetherIDH1/2 mutations overlap with known gene abnormalities, such as FLT3, c-KIT, and NPM1 mutations, mutational analyses of FLT3, c-KIT, and NPM1 were also performed. The common IDH2 R140Q mutation was detected in a single AML case, whereas no IDH1 mutation was detected in samples of myeloid malignancies. Although no IDH2 mutation was detected in infantile leukemias, novel P127S, H133I and I130V of IDH1 mutations were detected in 4 of 45 (8.9%) infantile ALL cases. No IDH1 and IDH2 mutations were detected in the JMML, MDS, or CML samples examined. Six AML samples including one cell line had c-KIT mutations (D816V, N822K, or D419fs), 12 AML cases had FLT3-ITD and 10 infantile leukemia cases had FLT3 mutations (D835E or I836). The NPM1 mutation was detected in 2 of 132 AML samples. The AML case harboring the IDH2 mutation, Case 39 was a 12-year-old boy diagnosed as AML-M2 according to the French-American-British cooperative group classification system having t(8;21)(q22;q22), showed no abnormalities of NPM1, c-KIT, and FLT3. Remarkably, among 4 infantile ALL cases with IDH1 mutations, 3 cases showed mixed lineage leukemia(MLL) rearrangements with t(4;11). The FLT3-D835 mutation was found in 1 of 4 patients with IDH1 mutations. These results suggest that although the involvements of IDH1/2 mutations in the pathogenesis of pediatric myeloid malignancies are extremely rare, closely positioned to near activation site, R132 IDH1, these IDH1 mutations are the candidate second genetic events in a subset of MLL-leukemia. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 71. doi:1538-7445.AM2012-71

Abstract 1475 Background: Acute myeloid leukemia (AML) is a complex disease caused by mutations, deregulated gene expression, and epigenetic modifications of genes leading to increased proliferation and decreased differentiation of hematopoietic progenitor cells. In hematological malignancies with 11p15 translocations, the nucleoporin 98-kDa (NUP98) protein regulates nucleocytoplasmic transport of protein and RNA. More than 20 different chromosomal rearrangements involving NUP98 have been identified. The cryptic translocation t(5;11)(q35;p15.5), which creates a fusion gene between the NSD1 and the NUP98. The NUP98-NSD1 fusion gene has been associated with a deletion of the long arm of chromosome 5, del(5q), in pediatric AML patients. Recently, NUP98-NSD1 was identified in childhood AML by fluorescence in situ hybridization (FISH) with subtelomeric probes. However, the frequency and clinical impact of NUP98-NSD1 in pediatric AML remain uncertain. Methods: To estimate the frequency and clinical impact of the NUP98-NSD1 in pediatric AML, we examined the NUP98-NSD1 fusion transcript in a consecutive series of 157 newly diagnosed AML patients enrolled in the AML99 protocol in Japan clinical trial. Total RNA extracted from the leukemia cells of the patient at diagnosis was reverse transcribed to cDNA. The PCR was performed using the primer sets for detection of NUP98-NSD1. The PCR amplification was performed with a DNA thermal cycler followed by direct sequencing with an ABI PRISM 310 Genetic Analyzer. We also examined somatic mutations of the FLT3, KIT, WT1, NPM1, NRAS, KRAS and MLL genes, which are prevalent in AML, in these AML patients with NUP98-NSD1. Results: In the current study, we identified the NUP98-NSD1 by RT-PCR followed by direct sequencing in 6 (3.8%) out of 157 AML patients, and clustered significantly in the cytogenetically normal AML subgroup (6/33, 18.2%). Significant differences between patients with and without NUP98-NSD1 were observed in 4-year OS (33.3% versus 80.0%), and EFS (33.3% versus 69.2%). NUP98-NSD1 was highly seen in males (5 males and 1 female). The statistical differences between patients with and without NUP98-NSD1 was not significant in age (median: 7 years [range: 2–15 years] versus 6 years [range: 0–15 years]), and the initial WBC count (median: 115.9 × 109/L [range: 9.0–329 × 109/L] versus 51.8 × 109/L [range: 1.0–621 × 109/L]). Interestingly, NUP98-NSD1 was observed in 4 patients with normal karyotype, and was observed in 2 patients with del(9q). NUP98-NSD1 could not be identified by conventional G-banding technique in any cases. Patients with NUP98-NSD1 had any mutation of FLT3 -ITD (66.7%), WT1 (50%), KIT (16.7%) or RAS (33.3%). Furthermore, NUP98-NSD1 was frequently found in M4 or M5 patients according to FAB classification. Conclusions: We identified the NUP98-NSD1 in 6 out of 157 AML patients, and clustered significantly in the cytogenetically normal AML subgroup. Patients with NUP98-NSD1 had any FLT3 -ITD, WT1, KIT or RAS mutations. These results suggest that simultaneous occurrence of FLT3 -ITD, WT1, KIT mutations and RAS aberrations in NUP98 -related leukemia may be associated with poor prognosis. The NUP98-NSD1 was not identified by conventional G-banding technique, confirming that this translocation can exist as the only cytogenetic alteration. Therefore, FISH and RT-PCR analyses for NUP98-NSD1 fusion gene is recommended at the onset of disease in larger series of AML patients presenting an apparently normal karyotype, del(9q) or del(5q) to gain insight into the actual incidence and clinical features of patients with t(5;11)(q35;p15.5). Disclosures: No relevant conflicts of interest to declare.

Abstract 5106 NADP+dependent isocitrate dehydrogenase 1 (IDH1) and 2 (IDH2) catalyzes the oxidative carboxylation of isocitrate to α-ketoglutarate (α-KG) in citric acid cycle. Recently, recurrent somatic missense mutations in IDH1 at codon R132, as well as IDH2 at codon R172 have been identified in low-grade gliomas/secondary glioblastoma by high throughput sequencing. Subsequent studies also revealed that acquired somatic mutations in IDH1 and IDH2 frequently occurred in adult hematological malignancies, such as acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS), and that these mutations were associated with older age, poor prognosis, cytogenetically normal AML, and the genotype of mutated NPM1 without FLT3-internal tandem duplication (ITD). Tumor-derived IDH1 and IDH2 mutations impair the affinity of the enzymes for the substrates and dominantly inhibit wild-type IDH1 and IDH2 activities through the formation of catalytically inactive heterodimers. However, little is known about the incidence and prognostic values of IDH1 and IDH2 mutations in pediatric hematological malignancies. Here, we analyzed mutations that involve the activation sites of IDH1 and IDH2 using polymerase chain reaction amplification/sequencing in a total of 244 samples of pediatric myeloid malignancies as well as infantile leukemia including 17 AML-derived cell lines, 115 primary cases of AML, 28 primary cases of MDS, 15 primary cases of juvenile myelomonocytic leukaemia (JMML), 6 chronic myeloid leukemia (CML)-derived cell line, 18 primary cases of CML and 45 infantile leukemia(6 AML and 39 acute lymphoblastic leukemia (ALL) patients). Moreover, to assess whether IDH1 and IDH2 mutations overlap with known gene abnormalities, such as FLT3, c-KIT, and NPM1 mutations, mutational analyses of FLT3, c-KIT, and NPM1 were also performed. The common IDH2 R140Q mutation was detected in a single AML case, whereas no IDH1 mutation was detected in samples of myeloid malignancies. Although no IDH2 mutation was detected in infantile leukemias, novel P127S, H133I and I130V of IDH1 mutations were detected in 4 of 45 (8.9%) infantile ALL cases. No IDH1 and IDH2 mutations were detected in the JMML, MDS, or CML samples examined. Six AML samples including one cell line had c-KIT mutations (D816V, N822K, or D419fs), 12 AML cases had FLT3-ITD and 10 infantile leukemia cases had FLT3 mutations (D835E or I836). The NPM1 mutation was detected in 2 of 132 AML samples. The AML case harboring the IDH2 mutation, Case 39 was a 12-year-old boy diagnosed as AML-M2 according to the French-American-British cooperative group classification system having t(8;21)(q22;q22), showed no abnormalities of NPM1, c-KIT, and FLT3. Remarkably, among 4 infantile ALL cases with IDH1 mutations, 3 cases showed mixed lineage leukemia(MLL) rearrangements with t(4;11). The FLT3-D835 mutation was found in 1 of 4 patients with IDH1 mutations. These results suggested that IDH1 mutations are one of the second genetic events in infant ALL with MLL rearrangements; however, it was concluded that the involvements of IDH1 and IDH2 mutations in the pathogenesis of pediatric myeloid malignancies are extremely rare. Disclosures: No relevant conflicts of interest to declare.

Cord blood transplantation (CBT) became one of the important alternatives in allogeneic stem cell transplantation for children with hematological malignancies. We have analyzed the clinical outcomes of CBT for children with acute lymphoblastic leukemia (ALL) in Japan and identified risk factors of transplant outcome, when they had no prior transplant. From 1997 to 2006, total 332 children with ALL have undergone CBT from unrelated donor and 270 of them had no prior transplant. They are 0–15 yrs (median 5) and 4 to 60kg of body weight (median 18). Serological disparities of HLA for graft-versus-host disease (GVHD) direction were 0(n=54), 1(n=168) and 2(n=47), and disease status at transplant were 1st complete remission (CR) (n=120), 2nd CR (n=71), and more advanced stages (n=75). The median number of nucleated cells in cord blood unit was 4.93×107/kg (1.35–24.9), and that of CD34+ cells was 1.53×105/kg (0.17–15.0). As preconditioning, total body irradiation (TBI) was given in 194 patients and methotrexate (MTX) was given as GVHD prophylaxis in 159 patients. The neutrophil engraftment was achieved in 88.5% (95%CI: 84.1–91.8%) of patients and platelet engraftment (>50k) was obtained in 72.6% (95%CI: 66.8–77.7). The incidence of grade II–IV and III–IV acute GVHD was 45.6% (95%CI: 39.5–51.4) and 20.4% (95%CI: 15.8–25.4) respectively. Non-relapse mortality was observed in 22.6% (95%CI: 17.7–27.8) and 35.2% (95%CI: 29.2–41.3) of patients relapsed after CBT. The five year event free survival (EFS) of all patients was 38.1% (95%CI: 34.9–41.3); 47.4%(95%CI: 42.4–52.4) in 1st CR, 45.5%(95%CI: 38.9–52.1) in 2nd CR and 15.2%(95%CI: 10.8–38.9) in more advanced stages, respectively. The multivariate analysis revealed that the larger number of CD34+ cells (p

Cord blood transplantation (CBT) from an unrelated donor is recognized as one of the major treatment modalities in allogeneic stem cell transplantation (SCT) for children with hematologic malignancies. We analyzed the clinical outcomes of CBT for children with acute lymphoblastic leukemia (ALL) in Japan and identified the risk factors for the transplant outcomes. From 1997 to 2006, 332 children with ALL underwent CBT from unrelated donors, 270 of which had no prior transplant. Their disease statuses at transplant were first complete remission (CR) (n = 120), second CR (n = 71), and more advanced stages (n = 75). As preconditioning for SCT, total body irradiation (TBI) was given to 194 patients and, for the prophylaxis of graft-versus-host disease (GVHD), methotrexate (MTX) was given to 159 patients. The cumulative incidents of neutrophil and platelet recovery (>20 K) were 88.5% and 78.4%, respectively. The incidents of grade II-IV, III-IV acute GVHD (aGVHD), and chronic GVHD (cGVHD) were 45.6%, 20.4%, and 19.2%, respectively, and treatment-related mortality was 22.6%. The 5-year event-free survival (EFS) and overall survival (OS) at CR1, CR2, and advanced status were 47.4%, 45.5%, 15.0%, and 63.7%, 59.7%, and 20.7%, respectively. Multivariate analysis revealed that MTX with calcineurin inhibitor (CNI) was associated with decreased incidence of grade II-IV GVHD (CNI alone: hazard ratio [HR] = 1.74, 95% confidence interval [CI] = 1.06-2.83, P = .027; CNI + prednisolone (PSL), HR = 1.61, 95% CI = 1.03-2.50, P = .036), III-IV aGVHD (CNI alone: HR = 3.02, 95% CI = 1.55-5.91, P = 0.001; CNI + PSL, HR = 1.89, 95% CI = 0.93-3.83, P = .078), or cGVHD (CNI alone: HR = 1.78, 95% CI = 0.83-3.82, P = .143; CNI + PSL, HR = 2.44, 95% CI = 1.24-4.82, P = .01), compared with CNI alone or CNI + PSL. At an advanced stage of disease, GVHD prophylaxis with MTX + CNI is associated with improved OS compared with CNI alone (CNI alone: HR = 3.20, 95% CI = 1.43-7.15, P = .005; CNI + PSL, HR = 1.47, CI = 0.67-3.20, P = .332). Our retrospective study showed that CBT for children with ALL is feasible and GVHD prophylaxis with MTX + CNI is associated with significant favorable outcomes in prevention of aGVHD and cGVHD as well as survival advantage in advanced cases.