Language：English   Publishing type：Research paper (scientific journal)  

Oncogenic forms of the kinase FLT3 are important therapeutic targets in acute myeloid leukemia (AML); however, clinical responses to small-molecule kinase inhibitors are short-lived as a result of the rapid emergence of resistance due to point mutations or compensatory increases in FLT3 expression. We sought to develop a complementary pharmacological approach whereby proteasome-mediated FLT3 degradation could be promoted by inhibitors of the deubiquitinating enzymes (DUBs) responsible for cleaving ubiquitin from FLT3. Because the relevant DUBs for FLT3 are not known, we assembled a focused library of most reported small-molecule DUB inhibitors and carried out a cellular phenotypic screen to identify compounds that could induce the degradation of oncogenic FLT3. Subsequent target deconvolution efforts allowed us to identify USP10 as the critical DUB required to stabilize FLT3. Targeting of USP10 showed efficacy in preclinical models of mutant-FLT3 AML, including cell lines, primary patient specimens and mouse models of oncogenic-FLT3-driven leukemia.

DOI： 10.1038/nchembio.2486

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Targeted polypharmacology provides an efficient method of treating diseases such as cancer with complex, multigenic causes provided that compounds with advantageous activity profiles can be discovered. Novel covalent TAK1 inhibitors were validated in cellular contexts for their ability to inhibit the TAK1 kinase and for their polypharmacology. Several inhibitors phenocopied reported TAK1 inhibitor 5Z-7-oxozaenol with comparable efficacy and complementary kinase selectivity profiles. Compound 5 exhibited the greatest potency in RAS-mutated and wild-type RAS cell lines from various cancer types. A biotinylated derivative of 5, 27, was used to verify TAK1 binding in cells. The newly described inhibitors constitute useful tools for further development of multi-targeting TAK1-centered inhibitors for cancer and other diseases.

DOI： 10.1016/j.bmc.2016.11.034

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/leu.2015.175

Language：English   Publishing type：Research paper (scientific journal)  

Bruton's tyrosine kinase (BTK) kinase is a member of the TEC kinase family and is a key regulator of the B-cell receptor (BCR)-mediated signaling pathway. It is important for B-cell maturation, proliferation, survival and metastasis. Pharmacological inhibition of BTK is clinically effective against a variety of B-cell malignances, such as mantle cell lymphoma, chronic lymphocytic leukemia (CLL), acute myeloid leukemia (AML) and activated B-cell-diffuse large B-cell lymphoma. MNK kinase is one of the key downstream regulators in the RAF-MEK-ERK signaling pathway and controls protein synthesis via regulating the activity of eIF4E. Inhibition of MNK activity has been observed to moderately inhibit the proliferation of AML cells. Through a structure-based drug-design approach, we have discovered a selective and potent BTK/MNK dual kinase inhibitor (QL-X-138), which exhibits covalent binding to BTK and noncovalent binding to MNK. Compared with the BTK kinase inhibitor (PCI-32765) and the MNK kinase inhibitor (cercosporamide), QL-X-138 enhanced the antiproliferative efficacies in vitro against a variety of B-cell cancer cell lines, as well as AML and CLL primary patient cells, which respond moderately to BTK inhibitor in vitro. The agent can effectively arrest the growth of lymphoma and leukemia cells at the G₀-G₁ stage and can induce strong apoptotic cell death. These primary results demonstrate that simultaneous inhibition of BTK and MNK kinase activity might be a new therapeutic strategy for B-cell malignances.

DOI： 10.1038/leu.2015.180

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

The tumor suppressor p53 is a key regulator of apoptosis and functions upstream in the apoptotic cascade by both indirectly and directly regulating Bcl-2 family proteins. In cells expressing wild-type (WT) p53, the HDM2 protein binds to p53 and blocks its activity. Inhibition of HDM2:p53 interaction activates p53 and causes apoptosis or cell-cycle arrest. Here, we investigated the ability of the novel HDM2 inhibitor CGM097 to potently and selectively kill WT p53-expressing AML cells. The antileukemic effects of CGM097 were studied using cellbased proliferation assays (human AML cell lines, primary AML patient cells, and normal bone marrow samples), apoptosis, and cell-cycle assays, ELISA, immunoblotting, and an AML patient-derived in vivo mouse model. CGM097 potently and selectively inhibited the proliferation of human AML cell lines and the majority of primary AML cells expressing WT p53, but not mutant p53, in a target-specific manner. Several patient samples that harbored mutant p53 were comparatively unresponsive to CGM097. Synergy was observed when CGM097 was combined with FLT3 inhibition against oncogenic FLT3-expressing cells cultured both in the absence as well as the presence of cytoprotective stromal-secreted cytokines, as well as when combined with MEK inhibition in cells with activated MAPK signaling. Finally, CGM097 was effective in reducing leukemia burden in vivo. These data suggest that CGM097 is a promising treatment for AML characterized as harboring WT p53 as a single agent, as well as in combination with other therapies targeting oncogene-activated pathways that drive AML.

DOI： 10.1158/1535-7163.MCT-15-0429

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

The rapid proliferation of myeloid leukemia cells is highly dependent on increased glucose metabolism. Through an unbiased metabolomics analysis of leukemia cells, we found that the glycogenic precursor UDP-D-glucose is pervasively upregulated, despite low glycogen levels. Targeting the rate-limiting glycogen synthase 1 (GYS1) not only decreased glycolytic flux but also increased activation of the glycogen-responsive AMP kinase (AMPK), leading to significant growth suppression. Further, genetic and pharmacological hyper-activation of AMPK was sufficient to induce the changes observed with GYS1 targeting. Cancer genomics data also indicate that elevated levels of the glycogenic enzymes GYS1/2 or GBE1 (glycogen branching enzyme 1) are associated with poor survival in AML. These results suggest a novel mechanism whereby leukemic cells sustain aberrant proliferation by suppressing excess AMPK activity through elevated glycogenic flux and provide a therapeutic entry point for targeting leukemia cell metabolism.

DOI： 10.1038/leu.2015.46

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Current treatment options as well as clinical efficacy are limited for chronic myelogenous leukemia (CML), Ph+ acute lymphoblastic leukemia (ALL), and acute myeloid leukemia (AML). In response to the pressing need for more efficacious treatment approaches and strategies to override drug resistance in advanced stage CML, Ph+ ALL, and AML, we investigated the effects of inhibition of ILK as a potentially novel and effective approach to treatment of these challenging malignancies. Using the small molecule ILK inhibitor, Cpd22, and ILK knockdown, we investigated the importance of ILK in the growth and viability of leukemia. Our results suggest that the ILK inhibition may be an effective treatment for CML, Ph+ ALL, and AML as a single therapy, with ILK expression levels positively correlating with the efficacy of ILK inhibition. The identification of ILK as a novel target for leukemia therapy warrants further investigation as a therapeutic approach that could be of potential clinical benefit in both acute and chronic myeloid leukemias.

DOI： 10.1016/j.leukres.2015.09.005

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Oncogenic forms of NRAS are frequently associated with hematologic malignancies and other cancers, making them important therapeutic targets. Inhibition of individual downstream effector molecules (eg, RAF kinase) have been complicated by the rapid development of resistance or activation of bypass pathways. For the purpose of identifying novel targets in NRAS-transformed cells, we performed a chemical screen using mutant NRAS transformed Ba/F3 cells to identify compounds with selective cytotoxicity. One of the compounds identified, GNF-7, potently and selectively inhibited NRAS-dependent cells in preclinical models of acute myelogenous leukemia and acute lymphoblastic leukemia. Mechanistic analysis revealed that its effects were mediated in part through combined inhibition of ACK1/AKT and of mitogen-activated protein kinase kinase kinase kinase 2 (germinal center kinase). Similar to genetic synthetic lethal approaches, these results suggest that small molecule screens can be used to identity novel therapeutic targets in cells addicted to RAS oncogenes.

DOI： 10.1182/blood-2014-12-615906

Language：English   Publishing type：Research paper (scientific journal)  

Direct targeting of rat sarcoma (RAS), which is frequently mutated, has proven to be challenging, and inhibition of individual downstream RAS mediators has resulted in limited clinical efficacy. We designed a chemical screen to identify compounds capable of potentiating mammalian target of rapamycin (mTOR) inhibition in mutant RAS-positive leukemia, and identified a Wee1 inhibitor. Synergy was observed in both mutant neuroblastoma RAS viral oncogene homolog (NRAS)-and mutant kirsten RAS viral oncogene homolog (KRAS)-positive acute myelogenous leukemia (AML) cell lines and primary patient samples. The observed synergy enhanced dephosphorylation of AKT, 4E-binding protein 1 and s6 kinase, and correlated with increased apoptosis. The specificity of Wee1 as the target of MK-1775 was validated by Wee1 knockdown, as well as partial reversal of drug combination-induced apoptosis by a cyclin-dependent kinase 1 (CDK1) inhibitor. Importantly, we also extended our findings to other mutant RAS-expressing malignancies, including mutant NRAS-positive melanoma, and mutant KRAS-positive colorectal cancer, pancreatic cancer and lung cancer. We observed favorable responses with combined Wee1/mTOR inhibition in human cancer cell lines from multiple malignancies, and inhibition of tumor growth in in vivo models of mutant KRAS lung cancer and leukemia. The present study introduces for the first time Wee1 inhibition combined with mTOR inhibition as a novel therapeutic strategy for the selective treatment of mutant RAS-positive leukemia and other mutant RAS-expressing malignancies.

DOI： 10.1038/leu.2014.149

Language：English   Publishing type：Research paper (scientific journal)  

Purpose: Activating mutations in the RAS oncogene occur frequently in human leukemias. Direct targeting of RAS has proven to be challenging, although targeting of downstream RAS mediators, such as MEK, is currently being tested clinically. Given the complexity of RAS signaling, it is likely that combinations of targeted agents will be more effective than single agents. Experimental Design: A chemical screen using RAS-dependent leukemia cells was developed to identify compounds with unanticipated activity in the presence of an MEK inhibitor and led to identification of inhibitors of IGF1R. Results were validated using cell-based proliferation, apoptosis, cell-cycle, and gene knockdown assays; immunoprecipitation and immunoblotting; and a noninvasive in vivo bioluminescence model of acute myeloid leukemia (AML). Results: Mechanistically, IGF1R protein expression/activity was substantially increased in mutant RASexpressing cells, and suppression of RAS led to decreases in IGF1R. Synergy between MEK and IGF1R inhibitors correlated with induction of apoptosis, inhibition of cell-cycle progression, and decreased phospho-S6 and phospho-4E-BP1. In vivo, NSG mice tail veins injected with OCI-AML3-luc+ cells showed significantly lower tumor burden following 1 week of daily oral administration of 50 mg/kg NVP-AEW541 (IGF1R inhibitor) combined with 25 mg/kg AZD6244 (MEK inhibitor), as compared with mice treated with either agent alone. Drug combination effects observed in cell-based assays were generalized to additional mutant RAS-positive neoplasms. Conclusions: The finding that downstream inhibitors of RAS signaling and IGF1R inhibitors have synergistic activity warrants further clinical investigation of IGF1R and RAS signaling inhibition as a potential treatment strategy for RAS-driven malignancies.

DOI： 10.1158/1078-0432.CCR-14-0902

Language：English   Publishing type：Research paper (scientific journal)  

Chromosomal rearrangements involving the H3K4 methyltransferase mixed-lineage leukemia (MLL) trigger aberrant gene expression in hematopoietic progenitors and give rise to an aggressive subtype of acute myeloid leukemia (AML). Insights into MLL fusionmediated leukemogenesis have not yet translated into better therapies because MLL is difficult to target directly, and the identity of the genes downstream of MLL whose altered transcription mediates leukemic transformation are poorly annotated.We used a functional genetic approach to uncover that AML cells driven by MLL-AF9 are exceptionally reliant on the cell-cycle regulator CDK6, but not its functional homolog CDK4, and that the preferential growth inhibition induced by CDK6 depletion is mediated through enhanced myeloid differentiation. CDK6 essentiality is also evident in AML cells harboring alternate MLL fusions and a mouse model of MLL-AF9-driven leukemia and can be ascribed to transcriptional activation of CDK6 by mutant MLL. Importantly, the context-dependent effectsof loweringCDK6expressionarecloselyphenocopiedbya small-moleculeCDK6inhibitor currently in clinicaldevelopment.These data identify CDK6 as critical effector of MLL fusions in leukemogenesis that might be targeted to overcome the differentiation block associated with MLL-rearranged AML, and underscore that cell-cycle regulators may have distinct, noncanonical, and nonredundant functions in different contexts.

DOI： 10.1182/blood-2014-02-558114

Language：English   Publishing type：Research paper (scientific journal)  

Objectives: Tyrosine kinase inhibitor (TKI)-treated acute myeloid leukemia (AML) patients commonly show rapid and significant peripheral blood blast cell reduction, however a marginal decrease in bone marrow blasts. This suggests a protective environment and highlights the demand for a better understanding of stromal:leukemia cell communication. As a strategy to improve clinical efficacy, we searched for novel agents capable of potentiating the stroma-diminished effects of TKI treatment of mutant FLT3-expressing cells. Methods: We designed a combinatorial high throughput drug screen using well-characterized kinase inhibitor-focused libraries to identify novel kinase inhibitors capable of overriding stromal-mediated resistance to TKIs, such as PKC412 and AC220. Standard liquid culture proliferation assays, cell cycle and apoptosis analysis, and immunoblotting were carried out with cell lines or primary AML to validate putative candidates from the screen and characterize the mechanism(s) underlying observed synergy. Results and Conclusions: Our study led to the observation of synergy between selective Akt inhibitors and FLT3 inhibitors against mutant FLT3-positive AML in either the absence or presence of stroma. Our findings are consistent with evidence that Akt activation is characteristic of mutant FLT3-transformed cells, as well as observed residual Akt activity following FLT3 inhibitor treatment. In conclusion, our study highlights the potential importance of Akt as a signaling factor in leukemia survival, and supports the use of the co-culture chemical screen to identify agents able to potentiate TKI anti-leukemia activity in a cytoprotective microenvironment.

DOI： 10.1371/journal.pone.0056473

Language：English   Publishing type：Research paper (scientific journal)  

Large chromosomal deletions are among the most common molecular abnormalities in cancer, yet the identification of relevant genes has proven difficult. The 5q- syndrome, a subtype of myelodysplastic syndrome (MDS), is a chromosomal deletion syndrome characterized by anemia and thrombocytosis. Although we have previously shown that hemizygous loss of RPS14 recapitulates the failed erythroid differentiation seen in 5q-syndrome, it does not affect thrombocytosis. Here we show that a microRNA located in the common deletion region of 5q- syndrome, miR-145, affects megakaryocyte and erythroid differentiation. We find that miR-145 functions through repression of Fli-1, a megakaryocyte and erythroid regulatory transcription factor. Patients with del(5q) MDS have decreased expression of miR-145 and increased expression of Fli-1. Overexpression of miR-145 or inhibition of Fli-1 decreases the production of megakaryocytic cells relative to erythroid cells, whereas inhibition of miR-145 or overexpression of Fli-1 has a reciprocal effect. Moreover, combined loss of miR-145 and RPS14 cooperates to alter erythroid-megakaryocytic differentiation in a manner similar to the 5q- syndrome. Taken together, these findings demonstrate that coordinate deletion of a miRNAand a protein-coding gene contributes to the phenotype of a human malignancy, the 5q- syndrome.

DOI： 10.1182/blood-2010-12-324715

Language：English   Publishing type：Research paper (scientific journal)  

We describe a case of encephalomyelitis mimicking multiple sclerosis associated with chronic graft-versus-host disease (GVHD) occurring after allogeneic bone marrow transplanation (BMT) for myelodysplastic syndrome. Immunosuppressive therapy, consisting of a therapeutic dose of cyclosporine A and a maintenance dose of methylprednisolone, was effective in treating symptoms. Although central nervous system GVHD is very rare and remains controversial, presentation of neurological symptoms after allogeneic BMT warrants consideration of GVHD in the differential diagnosis.

DOI： 10.2169/internalmedicine.48.2003

Language：English   Publishing type：Research paper (scientific journal)  

We report a case of severe parainfluenza (PIV) 3 pneumonia in a hematopoietic stem cell transplant recipient that was successfully treated with oral ribavirin and methylprednisolone. A 42-year-old woman diagnosed with acute myelogenous leukemia (FAB M5a) in first complete remission underwent allogeneic bone marrow transplantation from an HLA-matched unrelated donor in May 2006. In July 2007, she developed PIV3 pneumonia. Her respiratory status progressively worsened and she required O₂ inhalation at 6 L/min. After an informed consent was obtained, oral ribavirin was initiated (16 mg/kg per day) for 1 week on July 31. By day 3 of treatment, the high-grade fever had disappeared. However, it recurred after ribavirin was discontinued. In addition, the patient's hypoxia continued to worsen, requiring O₂ inhalation at 9 L/min. To suppress the inflammatory reaction in the lung caused by PIV3 pneumonia, intravenous methylprednisolone (1,000 mg once a day for 3 days) was started along with high-dose oral ribavirin (16 mg/kg per day) on August 11. The patient showed dramatic clinical improvement, and oxygen inhalation was discontinued on September 3. Our case suggests that with concomitant effective anti-viral treatment, corticosteroids may suppress host inflammatory or immune reactions that lead to respiratory failure.

DOI： 10.1007/s12185-008-0148-6

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s10067-008-0856-6

Language：English   Publishing type：Research paper (scientific journal)  

Primary plasma cell leukaemia (PCL) is a rare, aggressive neoplasm of plasma cell dyscrasia. Conventional chemotherapy is usually ineffective, with an overall survival of only 8 months. Here, we describe a 42-year-old man with primary PCL, who was successfully treated with haploidentical (2-HLA loci mismatched) haematopoietic stem-cell transplantation (HSCT). To overcome the human leukocyte antigen (HLA) disparity, in vivo T-cell purging by the pre-transplant administration of antithymocyte globulin followed by a conventional prophylactic treatment against graft-versus-host disease (GVHD) resulted in an avoidance of severe GVHD as well as infectious complications. The patient has maintained complete remission for 13 months after haploidentical HSCT, indicating that a graft-versus-PCL effect might be preserved. Haploidentical HSCT can be a potentially curative treatment for patients with primary PCL who do not have an HLA-identical donor.

DOI： 10.1093/jjco/hym130

Language：English   Publishing type：Research paper (scientific journal)  

Toxoplasmosis is a rare but rapidly fatal complication that can occur following hematopoietic stem cell transplantation (HSCT). Over a 17-yr period at our institutions, a definite diagnosis of toxoplasmosis was made in only two of 925 allogeneic HSCT recipients (0.22%) and none of 641 autologous HSCT recipients. These two patients received a conventional conditioning regimen followed by transplantation from an HLA-matched donor; however, they developed severe graft-vs.-host disease, which required intensive immunosuppressive therapy. Despite prophylactic treatment with trimethoprim/sulfamethoxazole, their immunosuppressive state, as indicated by a low CD4⁺ cell count, might have resulted in toxoplasmosis encephalitis. Rapid and non-invasive methods such as a polymerase chain reaction (PCR) test of their cerebrospinal fluid for Toxoplasma gondii and magnetic resonance imaging of the brain were useful for providing a definitive diagnosis and prompt therapy in these patients: one patient stabilized and survived after responding to treatment with pyrimethamine/sulfodiazine whereas the other died of bacterial infection. In addition, retrospective PCR analyses of the frozen stored peripheral blood samples disclosed that detection of T. gondii preceded the onset of disease, indicating routine PCR testing of peripheral blood specimens may be an early diagnostic tool. It should be noted that when patients receiving HSCT have an unexplained fever and/or neurological complications, PCR tests should be considered to avoid cerebral lesions and improve the outcome of the patients.

DOI： 10.1111/j.1600-0609.2007.00919.x

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/sj.bmt.1705764

Language：English   Publishing type：Research paper (scientific journal)  

Perforin gene (PRF1) mutations cause the primary form of hemophagocytic lymphohistiocytosis (HLH). We report a genetic defect of PRF1 in a 62-year-old Japanese man with recurrent episodes of HLH. Sequencing of PRF1 from both peripheral blood mononuclear cells and nail clippings showed compound heterozygous mutation, including deletion of two base pairs at codons 1090 and 1091 (1090-1091delCT) and guanine-to-adenine conversion at nucleotide position 916 (916G→A). Although primary HLH has been detected in infants and children, genetic mutation of PRF1 or other genes should be considered a differential diagnosis of HLH even in the elderly.

DOI： 10.3324/haematol.11233

Language：English   Publishing type：Research paper (scientific journal)  

To investigate effects of the preautografting administration of rituximab on the mobilization and engraftment of peripheral blood stem cells (PBSC), we retrospectively analyzed the outcomes of 43 newly diagnosed diffuse-large B-cell lymphoma patients who received CHOP chemotherapy with or without rituximab as a first-line treatment before autologous PBSC transplantation (PBSCT). There was no difference in the number of CD34⁺ cells among PBSC between the non-rituximab and the rituximab groups. Although B-cells were completely depleted from PBSC in the rituximab group, we found no difference in the expression of CXCR-4, VLA-4 and c-Kit on PBSC, indicating that rituximab did not affect the expression of these adhesion molecules, which might be involved in the mechanism of mobilization. There was no significant difference in the recovery of neutrophils and platelets, transplant-related toxicity and post-transplant complications between the two groups. Despite the short follow-up, there was no significant difference in progression-free survival between the two groups. These results indicated no adverse effect of rituximab on the mobilization and engraftment of PBSC. Larger studies are required to determine the impact of rituximab on the mobilization and function of PBSC as well as whether a survival advantage exists in patients who undergo auto-PBSCT with rituximab.

DOI： 10.1038/sj.bmt.1705649

Language：English   Publishing type：Research paper (scientific journal)  

Primary cardiac lymphoma (PCL) is defined as lymphoma involving only the heart and/or pericardium, or with an intrapericardial location of the main tumor mass. It is an extremely rare type of lymphoma and has a poor prognosis because of diagnostic delay and the disease site. PCL is histologically characterized by a mostly diffuse large B-cell lymphoma. The median survival time has been reported to be 7 months. We present the case of a 55-year-old woman who presented with chest oppression and dyspnea on effort. Following a close examination, PCL with a high International Prognostic Index was diagnosed. She received 6 courses of R-CHOP therapy (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone) and achieved complete remission. The patient then underwent a consolidation therapy consisting of high-dose chemotherapy including rituximab, followed by autologous peripheral blood stem cell transplantation. There were no complications, such as pulmonary embolism, fatal arrhythmia, or acute heart failure, throughout chemotherapy. Our experience indicates that this therapy is safe and effective and can improve the outcome of high-risk PCL.

DOI： 10.1532/IJH97.06197

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2169/internalmedicine.46.0291

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1200/JCO.2006.08.5654

Language：English   Publishing type：Research paper (scientific journal)  

Caveolin-1 (Cav-1) has been suggested to function as a negative regulator of mitogen-stimulated proliferation and the Ras-p42/44 ERK (MAP kinase) pathway in a variety of cell types. However, the molecular basis of this suppression has not been clarified. Spred/Sprouty family proteins are also negative regulators of the ERK pathway by interacting with Raf-1. The Spred/Sprouty family proteins contain a cysteine-rich (CR) domain at the C-terminus, which is thought to be palmitoylated like Cav-1 and necessary for membrane anchoring. In this study, we demonstrated that Spred-1 localized in cholesterol-rich membrane raft/caveola fractions and interacted with Cav-1. To clarify the biological effect of Cav-1/Spred-1 interaction, we used hematopoietic cells that lacked expression of caveolins but expressed Spred-1. Forced expression of Cav-1 suppressed SCF- and IL-3-induced proliferation and ERK activation. Furthermore, forced expression of exogenous Spred-1 in Cav-1-expressing cells further suppressed proliferation and ERK activation. These data suggest that Spred-1 inhibits ERK activation in collaboration with Cav-1.

DOI： 10.1111/j.1365-2443.2005.00886.x

Language：English   Publishing type：Research paper (scientific journal)  

We report here that loss of the Sprouty2 gene (also known as Spry2) in mice resulted in enteric nerve hyperplasia, which led to esophageal achalasia and intestinal pseudo-obstruction. Glial cell line-derived neurotrophic factor (GDNF) induced hyperactivation of ERK and Akt in enteric nerve cells. Anti-GDNF antibody administration corrected nerve hyperplasia in Sprouty2-deficient mice. We show Sprouty2 to be a negative regulator of GDNF for the neonatal development or survival of enteric nerve cells.

DOI： 10.1038/nn1485

Language：English   Publishing type：Research paper (scientific journal)  

T helper 2 cytokines, including interleukin (IL)-4, IL-5, and IL-13, play a critical role in allergic asthma. These cytokines transmit signals through the Janus kinase/signal transducer and activator of transcription (STAT) and the Ras-extracellular signal-regulated kinase (ERK) signaling pathways. Although the suppressor of cytokine signaling (SOCS) family proteins have been shown to regulate the STAT pathway, the mechanism regulating the ERK pathway has not been clarified. The Sprouty-related Ena/VASP homology 1-domain-containing protein (Spred)-1 has recently been identified as a negative regulator of growth factor-mediated, Ras-dependent ERK activation. Here, using Spred-1 -deficient mice, we demonstrated that Spred-1 negatively regulates allergen-induced airway eosinophilia and hyperresponsiveness, without affecting helper T cell differentiation. Biochemical assays indicate that Spred-1 suppresses IL-5-dependent cell proliferation and ERK activation. These data indicate that Spred-1 negatively controls eosinophil numbers and functions by modulating IL-5 signaling in allergic asthma.

DOI： 10.1084/jem.20040616

Language：English   Publishing type：Research paper (scientific journal)  

Sprouty/Spred family proteins have been identified as negative regulators of growth factor-induced ERK/mitogen-activated protein (MAP) kinase activation. However, it has not been clarified whether these proteins regulate cytokine-induced ERK activity. We found that Spred-1 is highly expressed in interleukin-3 (IL-3)-dependent hematopoietic cell lines and bone marrow-derived mast cells. To investigate the roles of Spred-1 in hematopoiesis, we expressed wild-type Spred-1 and a dominant negative form, of Spred-1, ΔC-Spred, in IL-3-and stem cell factor (SCF)-dependent cell lines as well as hematopoietic progenitor cells from mouse bone marrow by retrovirus gene transfer. In IL-3-dependent Ba/F3 cells expressing c-kit, forced expression of Spred-1 resulted in a reduced proliferation rate and ERK activation in response to not only SCF but also IL-3. In contrast, ΔC-Spred augmented IL-3-induced cell proliferation and ERK activation. Wild-type Spred-1 inhibited colony formation of bone marrow cells in the presence of cytokines, whereas AC-Spred-1 expression enhanced colony formation. Augmentation of ERK activation and proliferation in response to IL-3 was also observed in Spred-1-deficient bone marrow-derived mast cells. These data suggest that Spred-1 negatively regulates hematopoiesis by suppressing not only SCF-induced but also IL-3-induced ERK activation.

DOI： 10.1074/jbc.M405189200

Language：English   Publishing type：Research paper (scientific journal)  

We present a case of pulmonary metastasis from pancreatic cancer with biphasic radiological patterns: demarcated nodules, irregularly shaped opacities showing the so-called 'air-space pattern', and both typical and atypical radiological findings. The histology of the demarcated nodules was poorly differentiated adenocarcinoma identical to the pancreatic tumor, while that of the irregularly shaped opacities was well-differentiated adenocarcinoma showing a lepidic growth pattern. Pulmonary metastasis from pancreatic cancer may contain components of various differentiations showing different radiological findings.

DOI： 10.1016/j.compmedimag.2004.09.001

Language：English   Publishing type：Research paper (scientific journal)  

We describe a case of malignant lymphoma which presented in the body cavities without identifiable tumor masses. Malignant lymphoma cells showed strong atypia with prominent nuclei and basophilic cytoplasm containing vacuoles. The chromosomes showed diploidy and complex abnormalities including translocations and deletions. We diagnosed this patient with primary effusion lymphoma (PEL), even though she tested negative for human herpes virus-8 (HHV-8) which has been suggested to be causally related to PEL. Interestingly, the patient also showed complicated protein-losing enteropathy, and PEL occurred after repeated chylous ascites and chylothorax. The possible pathogenesis of this rare disease is discussed here.

DOI： 10.2169/internalmedicine.43.236

Language：English   Publishing type：Research paper (scientific journal)  

The signalling cascade including Raf, mitogen-activated protein kinase (MAPK) kinase and extracellular-signal-regulated kinase (ERK) is important in many facets of cellular regulation^1-3. Raf is activated through both Ras-dependent and Ras-independent mechanisms^4-6, but the regulatory mechanisms of Raf activation remain unclear^7-9. Two families of membrane-bound molecules, Sprouty and Sprouty-related EVH1-domain-containing protein (Spred) have been identified^10-13 and characterized as negative regulators of growth-factor-induced ERK activation^14-25. But the molecular functions of mammalian Sproutys have not been clarified. Here we show that mammalian Sprouty4 suppresses vascular epithelial growth factor (VEGF)-induced, Ras-independent activation of Raf1 but does not affect epidermal growth factor (EGF)-induced, Ras-dependent activation of Raf1. Sprouty4 binds to Raf1 through its carboxy-terminal cysteine-rich domain, and this binding is necessary for the inhibitory activity of Sprouty4. In addition, Sprouty4 mutants of the amino-terminal region containing the conserved tyrosine residue, which is necessary for suppressing fibroblast growth factor signalling^19,25, still inhibit the VEGF-induced ERK pathway. Our results show that receptor tyrosine kinases use distinct pathways for Raf and ERK activation and that Sprouty4 differentially regulates these pathways.

DOI： 10.1038/ncb978

Language：English   Publishing type：Research paper (scientific journal)  

We have reported on Spred-1 and Spred-2, which inhibit MAP kinase activation by interacting with c-kit and ras/raf. Here, we report the cloning of a third member in this family, Spred-3. Spred-3 is expressed exclusively in the brain and its gene locates in chromosome 19q13.13 in human. Like Spred-1 and -2, Spred-3 contains an EVH1 domain in the N-terminus and a Sprouty-related cysteine-rich region (SPR domain) in the C-terminus that is necessary for membrane localization. However, Spred-3 does not possess a functional c-kit binding domain (KBD), since the critical amino acid Arg residue in this region was replaced with Gly in Spred-3. Although Spred-3 suppressed growth factor-induced MAP kinase (Erk) activation, inhibitory activity of Spred-3 was lower than that of Spred-1 or Spred-2. By the analysis of chimeric molecules between Spred-3 and Spred-1, we found that the SPR domain, rather than KBD, is responsible for efficient Erk suppression. The finding of Spred-3 revealed the presence of a novel family of regulators for the Ras/MAP kinase pathway, each member of which may have different specificities for extracellular signals.

DOI： 10.1016/S0006-291X(03)00259-6

Language：English   Publishing type：Research paper (scientific journal)