Publications by authors named "Young K Song"

39 Publications

BAF complexes drive proliferation and block myogenic differentiation in fusion-positive rhabdomyosarcoma.

Nat Commun 2021 Nov 26;12(1):6924. Epub 2021 Nov 26.

Genetics Branch, NCI, NIH, Bethesda, MD, USA.

Rhabdomyosarcoma (RMS) is a pediatric malignancy of skeletal muscle lineage. The aggressive alveolar subtype is characterized by t(2;13) or t(1;13) translocations encoding for PAX3- or PAX7-FOXO1 chimeric transcription factors, respectively, and are referred to as fusion positive RMS (FP-RMS). The fusion gene alters the myogenic program and maintains the proliferative state while blocking terminal differentiation. Here, we investigated the contributions of chromatin regulatory complexes to FP-RMS tumor maintenance. We define the mSWI/SNF functional repertoire in FP-RMS. We find that SMARCA4 (encoding BRG1) is overexpressed in this malignancy compared to skeletal muscle and is essential for cell proliferation. Proteomic studies suggest proximity between PAX3-FOXO1 and BAF complexes, which is further supported by genome-wide binding profiles revealing enhancer colocalization of BAF with core regulatory transcription factors. Further, mSWI/SNF complexes localize to sites of de novo histone acetylation. Phenotypically, interference with mSWI/SNF complex function induces transcriptional activation of the skeletal muscle differentiation program associated with MYCN enhancer invasion at myogenic target genes, which is recapitulated by BRG1 targeting compounds. We conclude that inhibition of BRG1 overcomes the differentiation blockade of FP-RMS cells and may provide a therapeutic strategy for this lethal childhood tumor.
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http://dx.doi.org/10.1038/s41467-021-27176-wDOI Listing
November 2021

Immuno-transcriptomic profiling of extracranial pediatric solid malignancies.

Cell Rep 2021 Nov;37(8):110047

University of Toronto Musculoskeletal Oncology Unit, Sinai Health System; Department of Surgery, University of Toronto, Toronto, ON, Canada.

We perform an immunogenomics analysis utilizing whole-transcriptome sequencing of 657 pediatric extracranial solid cancer samples representing 14 diagnoses, and additionally utilize transcriptomes of 131 pediatric cancer cell lines and 147 normal tissue samples for comparison. We describe patterns of infiltrating immune cells, T cell receptor (TCR) clonal expansion, and translationally relevant immune checkpoints. We find that tumor-infiltrating lymphocytes and TCR counts vary widely across cancer types and within each diagnosis, and notably are significantly predictive of survival in osteosarcoma patients. We identify potential cancer-specific immunotherapeutic targets for adoptive cell therapies including cell-surface proteins, tumor germline antigens, and lineage-specific transcription factors. Using an orthogonal immunopeptidomics approach, we find several potential immunotherapeutic targets in osteosarcoma and Ewing sarcoma and validated PRAME as a bona fide multi-pediatric cancer target. Importantly, this work provides a critical framework for immune targeting of extracranial solid tumors using parallel immuno-transcriptomic and -peptidomic approaches.
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http://dx.doi.org/10.1016/j.celrep.2021.110047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8642810PMC
November 2021

Genomic Classification and Clinical Outcome in Rhabdomyosarcoma: A Report From an International Consortium.

J Clin Oncol 2021 09 24;39(26):2859-2871. Epub 2021 Jun 24.

Department of Pediatrics, Seattle Children's Hospital, Fred Hutchinson Cancer Research Center, University of Washington, Seattle, WA.

Purpose: Rhabdomyosarcoma is the most common soft tissue sarcoma of childhood. Despite aggressive therapy, the 5-year survival rate for patients with metastatic or recurrent disease remains poor, and beyond fusion status, no genomic markers are available for risk stratification. We present an international consortium study designed to determine the incidence of driver mutations and their association with clinical outcome.

Patients And Methods: Tumor samples collected from patients enrolled on Children's Oncology Group trials (1998-2017) and UK patients enrolled on malignant mesenchymal tumor and RMS2005 (1995-2016) trials were subjected to custom-capture sequencing. Mutations, indels, gene deletions, and amplifications were identified, and survival analysis was performed.

Results: DNA from 641 patients was suitable for analyses. A median of one mutation was found per tumor. In fusion-negative cases, mutation of any RAS pathway member was found in > 50% of cases, and 21% had no putative driver mutation identified. (15%), (15%), and (13%) mutations were found at a higher incidence than previously reported and mutations were associated with worse outcomes in both fusion-negative and fusion-positive cases. Interestingly, mutations in isoforms predominated in infants < 1 year (64% of cases). Mutation of was associated with histologic patterns beyond those previously described, older age, head and neck primary site, and a dismal survival. Finally, we provide a searchable companion database (ClinOmics), containing all genomic variants, and clinical annotation including survival data.

Conclusion: This is the largest genomic characterization of clinically annotated rhabdomyosarcoma tumors to date and provides prognostic genetic features that refine risk stratification and will be incorporated into prospective trials.
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http://dx.doi.org/10.1200/JCO.20.03060DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8425837PMC
September 2021

Case Report: Single-Cell Transcriptomic Analysis of an Anaplastic Oligodendroglioma Post Immunotherapy.

Front Oncol 2020 14;10:601452. Epub 2021 Jan 14.

Neuro-Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States.

Glioma is the most common primary malignant brain tumor with a poor prognosis. Immune checkpoint inhibitors have been of great interest in investigation of glioma treatments. Here, we report single-cell transcriptomic analyses of two tumor areas from an oligodendroglioma taken from a patient who had multiple tumor recurrences, following several chemotherapies and radiation treatments. The patient subsequently received nivolumab and was considered have disease progression based on conventional diagnostic imaging after two cycles of treatment. He underwent a debulking surgical resection and pathological diagnosis was recurrent disease. During the surgery, tumor tissues were also collected from the enhancing and non-enhancing areas for a scRNAseq analysis to investigate the tumor microenvironment of these radiographically divergent areas. The scRNAseq analysis reveals a plethora of immune cells, suggesting that the increased mass observed on MRI may be partially a result of immune cell infiltration. The patient continued to receive immunotherapy after a short course of palliative radiation and remained free of disease progression for at least 12 months after the last surgery, suggesting a sustained response to immunotherapy. The scRNAseq analysis indicated that the radiological progression was in large part due to immune cell infiltrate and continued immunotherapy led to a positive clinical outcome in a patient who would have otherwise been admitted to hospice care with halting of immunotherapy. Our study demonstrates the potential of scRNAseq analyses in understanding the tumor microenvironment, which may assist the clinical decision-making process for challenging glioma cases following immunotherapy.
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http://dx.doi.org/10.3389/fonc.2020.601452DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7841290PMC
January 2021

Outcome-Related Signatures Identified by Whole Transcriptome Sequencing of Resectable Stage III/IV Melanoma Evaluated after Starting Hu14.18-IL2.

Clin Cancer Res 2020 07 9;26(13):3296-3306. Epub 2020 Mar 9.

Department of Human Oncology, University of Wisconsin-Madison, Madison, Wisconsin.

Purpose: We analyzed whole transcriptome sequencing in tumors from 23 patients with stage III or IV melanoma from a pilot trial of the anti-GD2 immunocytokine, hu14.18-IL2, to identify predictive immune and/or tumor biomarkers in patients with melanoma at high risk for recurrence.

Experimental Design: Patients were randomly assigned to receive the first of three monthly courses of hu14.18-IL2 immunotherapy either before (Group A) or after (Group B) complete surgical resection of all known diseases. Tumors were evaluated by histology and whole transcriptome sequencing.

Results: Tumor-infiltrating lymphocyte (TIL) levels directly associated with relapse-free survival (RFS) and overall survival (OS) in resected tumors from Group A, where early responses to the immunotherapy agent could be assessed. TIL levels directly associated with a previously reported immune signature, which associated with RFS and OS, particularly in Group A tumors. In Group A tumors, there were decreased cell-cycling gene RNA transcripts, but increased RNA transcripts for repair and growth genes. We found that outcome (RFS and OS) was directly associated with several immune signatures and immune-related RNA transcripts and inversely associated with several tumor growth-associated transcripts, particularly in Group A tumors. Most of these associations were not seen in Group B tumors.

Conclusions: We interpret these data to signify that both immunologic and tumoral cell processes, as measured by RNA-sequencing analyses detected shortly after initiation of hu14.18-IL2 therapy, are associated with long-term survival and could potentially be used as prognostic biomarkers in tumor resection specimens obtained after initiating neoadjuvant immunotherapy.
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http://dx.doi.org/10.1158/1078-0432.CCR-19-3294DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7334053PMC
July 2020

MEK inhibition induces MYOG and remodels super-enhancers in RAS-driven rhabdomyosarcoma.

Sci Transl Med 2018 07;10(448)

Oncogenomics Section, Genetics Branch, National Cancer Institute, National Institutes of Health (NIH), Bethesda, MD 20892, USA.

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 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 promoter and releases the transcriptional stalling of 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.
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http://dx.doi.org/10.1126/scitranslmed.aan4470DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8054766PMC
July 2018

Clinically Relevant Cytotoxic Immune Cell Signatures and Clonal Expansion of T-Cell Receptors in High-Risk -Not-Amplified Human Neuroblastoma.

Clin Cancer Res 2018 11 21;24(22):5673-5684. Epub 2018 May 21.

Oncogenomics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.

High-risk neuroblastoma is an aggressive disease. DNA sequencing studies have revealed a paucity of actionable genomic alterations and a low mutation burden, posing challenges to develop effective novel therapies. We used RNA sequencing (RNA-seq) to investigate the biology of this disease, including a focus on tumor-infiltrating lymphocytes (TIL). We performed deep RNA-seq on pretreatment diagnostic tumors from 129 high-risk and 21 low- or intermediate-risk patients with neuroblastomas. We used single-sample gene set enrichment analysis to detect gene expression signatures of TILs in tumors and examined their association with clinical and molecular parameters, including patient outcome. The expression profiles of 190 additional pretreatment diagnostic neuroblastomas, a neuroblastoma tissue microarray, and T-cell receptor (TCR) sequencing were used to validate our findings. We found that -not-amplified (-NA) tumors had significantly higher cytotoxic TIL signatures compared with -amplified (-A) tumors. A reported MYCN activation signature was significantly associated with poor outcome for high-risk patients with -NA tumors; however, a subgroup of these patients who had elevated activated natural killer (NK) cells, CD8 T cells, and cytolytic signatures showed improved outcome and expansion of infiltrating TCR clones. Furthermore, we observed upregulation of immune exhaustion marker genes, indicating an immune-suppressive microenvironment in these neuroblastomas. This study provides evidence that RNA signatures of cytotoxic TIL are associated with the presence of activated NK/T cells and improved outcomes in high-risk neuroblastoma patients harboring -NA tumors. Our findings suggest that these high-risk patients with -NA neuroblastoma may benefit from additional immunotherapies incorporated into the current therapeutic strategies. .
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http://dx.doi.org/10.1158/1078-0432.CCR-18-0599DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6504934PMC
November 2018

Frequent inactivating germline mutations in DNA repair genes in patients with Ewing sarcoma.

Genet Med 2017 08 26;19(8):955-958. Epub 2017 Jan 26.

Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA.

Purpose: Ewing sarcoma is a small round blue cell tumor that is highly malignant and predominantly affects the adolescent and young adult population. It has long been suspected that a genetic predisposition exists for this cancer, but the germ-line genetic underpinnings of this disease have not been well established.

Methods: We performed germline variant analysis of whole-genome or whole-exome sequencing of samples from 175 patients affected by Ewing sarcoma.

Results: We discovered pathogenic or likely pathogenic germline mutations in 13.1% of our cohort. Pathogenic mutations were highly enriched for genes involved with DNA damage repair and for genes associated with cancer predisposition syndromes.

Conclusion: Our findings reported here have important clinical implications for patients and families affected by Ewing sarcoma. Genetic counseling should be considered for patients and families affected by this disease to take advantage of existing risk management strategies. Our study also highlights the importance of germline sequencing for patients enrolled in precision-medicine protocols.Genet Med advance online publication 26 January 2017.
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http://dx.doi.org/10.1038/gim.2016.206DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5529247PMC
August 2017

CD19 CAR immune pressure induces B-precursor acute lymphoblastic leukaemia lineage switch exposing inherent leukaemic plasticity.

Nat Commun 2016 07 27;7:12320. Epub 2016 Jul 27.

Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.

Adoptive immunotherapy using chimeric antigen receptor (CAR) expressing T cells targeting the CD19 B lineage receptor has demonstrated marked success in relapsed pre-B-cell acute lymphoblastic leukaemia (ALL). Persisting CAR-T cells generate sustained pressure against CD19 that may drive unique mechanisms of resistance. Pre-B ALL originates from a committed pre-B cell or an earlier progenitor, with potential to reprogram into other hematopoietic lineages. Here we report changes in lineage markers including myeloid conversion in patients following CD19 CAR therapy. Using murine ALL models we study the long-term effects of CD19 CAR-T cells and demonstrate partial or complete lineage switch as a consistent mechanism of CAR resistance depending on the underlying genetic oncogenic driver. Deletion of Pax5 or Ebf1 recapitulates lineage reprogramming occurring during CD19 CAR pressure. Our findings establish lineage switch as a mechanism of CAR resistance exposing inherent plasticity in genetic subtypes of pre-B-cell ALL.
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http://dx.doi.org/10.1038/ncomms12320DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4974466PMC
July 2016

MultiDimensional ClinOmics for Precision Therapy of Children and Adolescent Young Adults with Relapsed and Refractory Cancer: A Report from the Center for Cancer Research.

Clin Cancer Res 2016 08 18;22(15):3810-20. Epub 2016 Mar 18.

Oncogenomics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland.

Purpose: We undertook a multidimensional clinical genomics study of children and adolescent young adults with relapsed and refractory cancers to determine the feasibility of genome-guided precision therapy.

Experimental Design: Patients with non-central nervous system solid tumors underwent a combination of whole exome sequencing (WES), whole transcriptome sequencing (WTS), and high-density single-nucleotide polymorphism array analysis of the tumor, with WES of matched germline DNA. Clinically actionable alterations were identified as a reportable germline mutation, a diagnosis change, or a somatic event (including a single nucleotide variant, an indel, an amplification, a deletion, or a fusion gene), which could be targeted with drugs in existing clinical trials or with FDA-approved drugs.

Results: Fifty-nine patients in 20 diagnostic categories were enrolled from 2010 to 2014. Ages ranged from 7 months to 25 years old. Seventy-three percent of the patients had prior chemotherapy, and the tumors from these patients with relapsed or refractory cancers had a higher mutational burden than that reported in the literature. Thirty patients (51% of total) had clinically actionable mutations, of which 24 (41%) had a mutation that was currently targetable in a clinical trial setting, 4 patients (7%) had a change in diagnosis, and 7 patients (12%) had a reportable germline mutation.

Conclusions: We found a remarkably high number of clinically actionable mutations in 51% of the patients, and 12% with significant germline mutations. We demonstrated the clinical feasibility of next-generation sequencing in a diverse population of relapsed and refractory pediatric solid tumors. Clin Cancer Res; 22(15); 3810-20. ©2016 AACR.
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http://dx.doi.org/10.1158/1078-0432.CCR-15-2717DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4970946PMC
August 2016

MYCN controls an alternative RNA splicing program in high-risk metastatic neuroblastoma.

Cancer Lett 2016 Feb 10;371(2):214-24. Epub 2015 Dec 10.

Oncogenomics Section, Genetics Branch, National Cancer Institute, National Institute of Health, Bethesda, MD 20892, USA. Electronic address:

The molecular mechanisms underlying the aggressive behavior of MYCN driven neuroblastoma (NBL) is under intense investigation; however, little is known about the impact of this family of transcription factors on the splicing program. Here we used high-throughput RNA sequencing to systematically study the expression of RNA isoforms in stage 4 MYCN-amplified NBL, an aggressive subtype of metastatic NBL. We show that MYCN-amplified NBL tumors display a distinct gene splicing pattern affecting multiple cancer hallmark functions. Six splicing factors displayed unique differential expression patterns in MYCN-amplified tumors and cell lines, and the binding motifs for some of these splicing factors are significantly enriched in differentially-spliced genes. Direct binding of MYCN to promoter regions of the splicing factors PTBP1 and HNRNPA1 detected by ChIP-seq demonstrates that MYCN controls the splicing pattern by direct regulation of the expression of these key splicing factors. Furthermore, high expression of PTBP1 and HNRNPA1 was significantly associated with poor overall survival of stage4 NBL patients (p ≤ 0.05). Knocking down PTBP1, HNRNPA1 and their downstream target PKM2, an isoform of pro-tumor-growth, result in repressed growth of NBL cells. Therefore, our study reveals a novel role of MYCN in controlling global splicing program through regulation of splicing factors in addition to its well-known role in the transcription program. These findings suggest a therapeutically potential to target the key splicing factors or gene isoforms in high-risk NBL with MYCN-amplification.
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http://dx.doi.org/10.1016/j.canlet.2015.11.045DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4738031PMC
February 2016

Aurora B kinase is a potent and selective target in MYCN-driven neuroblastoma.

Oncotarget 2015 Nov;6(34):35247-62

Oncogenomics Section, Genetics Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.

Despite advances in multimodal treatment, neuroblastoma (NB) is often fatal for children with high-risk disease and many survivors need to cope with long-term side effects from high-dose chemotherapy and radiation. To identify new therapeutic targets, we performed an siRNA screen of the druggable genome combined with a small molecule screen of 465 compounds targeting 39 different mechanisms of actions in four NB cell lines. We identified 58 genes as targets, including AURKB, in at least one cell line. In the drug screen, aurora kinase inhibitors (nine molecules) and in particular the AURKB-selective compound, barasertib, were the most discriminatory with regard to sensitivity for MYCN-amplified cell lines. In an expanded panel of ten NB cell lines, those with MYCN-amplification and wild-type TP53 were the most sensitive to low nanomolar concentrations of barasertib. Inhibition of the AURKB kinase activity resulted in decreased phosphorylation of the known target, histone H3, and upregulation of TP53 in MYCN-amplified, TP53 wild-type cells. However, both wild-type and TP53 mutant MYCN-amplified cell lines arrested in G2/M phase upon AURKB inhibition. Additionally, barasertib induced endoreduplication and apoptosis. Treatment of MYCN-amplified/TP53 wild-type neuroblastoma xenografts resulted in profound growth inhibition and tumor regression. Therefore, aurora B kinase inhibition is highly effective in aggressive neuroblastoma and warrants further investigation in clinical trials.
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http://dx.doi.org/10.18632/oncotarget.6208DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4742102PMC
November 2015

Clonality and evolutionary history of rhabdomyosarcoma.

PLoS Genet 2015 Mar 13;11(3):e1005075. Epub 2015 Mar 13.

Genetics Branch, Oncogenomics Section, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America; Pediatric Oncology Branch, Center for Cancer Research, National Institutes of Health, Bethesda, Maryland, United States of America.

To infer the subclonality of rhabdomyosarcoma (RMS) and predict the temporal order of genetic events for the tumorigenic process, and to identify novel drivers, we applied a systematic method that takes into account germline and somatic alterations in 44 tumor-normal RMS pairs using deep whole-genome sequencing. Intriguingly, we find that loss of heterozygosity of 11p15.5 and mutations in RAS pathway genes occur early in the evolutionary history of the PAX-fusion-negative-RMS (PFN-RMS) subtype. We discover several early mutations in non-RAS mutated samples and predict them to be drivers in PFN-RMS including recurrent mutation of PKN1. In contrast, we find that PAX-fusion-positive (PFP) subtype tumors have undergone whole-genome duplication in the late stage of cancer evolutionary history and have acquired fewer mutations and subclones than PFN-RMS. Moreover we predict that the PAX3-FOXO1 fusion event occurs earlier than the whole genome duplication. Our findings provide information critical to the understanding of tumorigenesis of RMS.
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http://dx.doi.org/10.1371/journal.pgen.1005075DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4358975PMC
March 2015

The genetics of splicing in neuroblastoma.

Cancer Discov 2015 Apr 30;5(4):380-95. Epub 2015 Jan 30.

Department of Neurology, University of California, San Francisco, San Francisco, California. Department of Neurosurgery, University of California, San Francisco, San Francisco, California. Department of Pediatrics, University of California, San Francisco, San Francisco, California.

Unlabelled: Regulation of mRNA splicing, a critical and tightly regulated cellular function, underlies the majority of proteomic diversity and is frequently disrupted in disease. Using an integrative genomics approach, we combined both genomic data and exon-level transcriptome data in two somatic tissues (cerebella and peripheral ganglia) from a transgenic mouse model of neuroblastoma, a tumor that arises from the peripheral neural crest. Here, we describe splicing quantitative trait loci associated with differential splicing across the genome that we use to identify genes with previously unknown functions within the splicing pathway and to define de novo intronic splicing motifs that influence splicing from hundreds of bases away. Our results show that these splicing motifs represent sites for functional recurrent mutations and highlight novel candidate genes in human cancers, including childhood neuroblastoma.

Significance: Somatic mutations with predictable downstream effects are largely relegated to coding regions, which comprise less than 2% of the human genome. Using an unbiased in vivo analysis of a mouse model of neuroblastoma, we have identified intronic splicing motifs that translate into sites for recurrent somatic mutations in human cancers.
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http://dx.doi.org/10.1158/2159-8290.CD-14-0892DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4390477PMC
April 2015

Expression quantitative trait loci and receptor pharmacology implicate Arg1 and the GABA-A receptor as therapeutic targets in neuroblastoma.

Cell Rep 2014 Nov 23;9(3):1034-46. Epub 2014 Oct 23.

Department of Neurology, University of California, San Francisco, San Francisco, CA 94143, USA; Department of Pediatrics, University of California, San Francisco, San Francisco, CA 94143, USA; Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA 94143, USA. Electronic address:

The development of targeted therapeutics for neuroblastoma, the third most common tumor in children, has been limited by a poor understanding of growth signaling mechanisms unique to the peripheral nerve precursors from which tumors arise. In this study, we combined genetics with gene-expression analysis in the peripheral sympathetic nervous system to implicate arginase 1 and GABA signaling in tumor formation in vivo. In human neuroblastoma cells, either blockade of ARG1 or benzodiazepine-mediated activation of GABA-A receptors induced apoptosis and inhibited mitogenic signaling through AKT and MAPK. These results suggest that ARG1 and GABA influence both neural development and neuroblastoma and that benzodiazepines in clinical use may have potential applications for neuroblastoma therapy.
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http://dx.doi.org/10.1016/j.celrep.2014.09.046DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4251494PMC
November 2014

Absence of STAT1 in donor-derived plasmacytoid dendritic cells results in increased STAT3 and attenuates murine GVHD.

Blood 2014 Sep 25;124(12):1976-86. Epub 2014 Jul 25.

Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, and.

Selective targeting of non-T cells, including antigen-presenting cells (APCs), is a potential strategy to prevent graft-versus-host-disease (GVHD) but to maintain graft-versus-tumor (GVT) effects. Because type I and II interferons signal through signal transducer and activator of transcription-1 (STAT1), and contribute to activation of APCs after allogeneic bone marrow transplant (alloBMT), we examined whether the absence of STAT1 in donor APCs could prevent GVHD while preserving immune competence. Transplantation of STAT1(-/-) bone marrow (BM) prevented GVHD induced by STAT1(+/+) T cells, leading to expansion of B220(+) cells and regulatory T cells. STAT1(-/-) BM also preserved GVT activity and enhanced overall survival of tumor-challenged mice in the setting of GVHD. Furthermore, recipients of allogeneic STAT1(-/-) BM demonstrated increased CD9(-)Siglec H(hi) plasmacytoid dendritic cells (pDCs), and depletion of pDCs after STAT1(-/-) BM transplantation prevented GVHD resistance. STAT1(-/-) pDCs were found to produce decreased free radicals, IFNα, and interleukin (IL)-12, and increased IL-10. Additionally, STAT1(-/-) pDCs that were isolated after alloBMT showed increased gene expression of S100A8 and S100A9, and transplantation of S100A9(-/-) BM reduced GVHD-free survival. Finally, elevated STAT3 was found in STAT1(-/-) pDCs isolated after alloBMT. We conclude that interfering with interferon signaling in APCs such as pDCs provides a novel approach to regulate the GVHD/GVT axis.
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http://dx.doi.org/10.1182/blood-2013-05-500876DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4168352PMC
September 2014

Comprehensive genomic analysis of rhabdomyosarcoma reveals a landscape of alterations affecting a common genetic axis in fusion-positive and fusion-negative tumors.

Cancer Discov 2014 Feb 23;4(2):216-31. Epub 2014 Jan 23.

1Pediatric Oncology Branch, Oncogenomics Section, Center for Cancer Research, NIH; 2Laboratory of Pathology, National Cancer Institute, Bethesda, Maryland; 3Broad Institute of MIT and Harvard, Cambridge; 4Medical Oncology and Center for Cancer Genome Discovery, Dana-Farber Cancer Institute; 5Department of Pathology, Harvard Medical School, Boston, Massachusetts; 6University of Nebraska Medical Center, Omaha, Nebraska; 7Department of Pediatrics, Division of Hematology/Oncology, University of Texas Southwestern Medical Center, Dallas, Texas; and 8Department of Pediatrics, Seattle Children's Hospital, Fred Hutchinson Cancer Research Center, University of Washington, Seattle, Washington; 9The Tumour Bank, The Children's Cancer Research Unit, The Children's Hospital at Westmead, Westmead, New South Wales, Australia; 10Department of Oncology, Hospital Sant Joan de Deu de Barcelona, Barcelona, Spain.

Unlabelled: Despite gains in survival, outcomes for patients with metastatic or recurrent rhabdomyosarcoma remain dismal. In a collaboration between the National Cancer Institute, Children's Oncology Group, and Broad Institute, we performed whole-genome, whole-exome, and transcriptome sequencing to characterize the landscape of somatic alterations in 147 tumor/normal pairs. Two genotypes are evident in rhabdomyosarcoma tumors: those characterized by the PAX3 or PAX7 fusion and those that lack these fusions but harbor mutations in key signaling pathways. The overall burden of somatic mutations in rhabdomyosarcoma is relatively low, especially in tumors that harbor a PAX3/7 gene fusion. In addition to previously reported mutations in NRAS, KRAS, HRAS, FGFR4, PIK3CA, and CTNNB1, we found novel recurrent mutations in FBXW7 and BCOR, providing potential new avenues for therapeutic intervention. Furthermore, alteration of the receptor tyrosine kinase/RAS/PIK3CA axis affects 93% of cases, providing a framework for genomics-directed therapies that might improve outcomes for patients with rhabdomyosarcoma.

Significance: This is the most comprehensive genomic analysis of rhabdomyosarcoma to date. Despite a relatively low mutation rate, multiple genes were recurrently altered, including NRAS, KRAS, HRAS, FGFR4, PIK3CA, CTNNB1, FBXW7, and BCOR. In addition, a majority of rhabdomyosarcoma tumors alter the receptor tyrosine kinase/RAS/PIK3CA axis, providing an opportunity for genomics-guided intervention.
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http://dx.doi.org/10.1158/2159-8290.CD-13-0639DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4462130PMC
February 2014

Massively parallel sequencing reveals an accumulation of de novo mutations and an activating mutation of LPAR1 in a patient with metastatic neuroblastoma.

PLoS One 2013 16;8(10):e77731. Epub 2013 Oct 16.

Oncogenomics Section, Pediatric Oncology Branch, Advanced Technology Center, National Cancer Institute, Bethesda, Maryland, United States of America.

Neuroblastoma is one of the most genomically heterogeneous childhood malignances studied to date, and the molecular events that occur during the course of the disease are not fully understood. Genomic studies in neuroblastoma have showed only a few recurrent mutations and a low somatic mutation burden. However, none of these studies has examined the mutations arising during the course of disease, nor have they systemically examined the expression of mutant genes. Here we performed genomic analyses on tumors taken during a 3.5 years disease course from a neuroblastoma patient (bone marrow biopsy at diagnosis, adrenal primary tumor taken at surgical resection, and a liver metastasis at autopsy). Whole genome sequencing of the index liver metastasis identified 44 non-synonymous somatic mutations in 42 genes (0.85 mutation/MB) and a large hemizygous deletion in the ATRX gene which has been recently reported in neuroblastoma. Of these 45 somatic alterations, 15 were also detected in the primary tumor and bone marrow biopsy, while the other 30 were unique to the index tumor, indicating accumulation of de novo mutations during therapy. Furthermore, transcriptome sequencing on the 3 tumors demonstrated only 3 out of the 15 commonly mutated genes (LPAR1, GATA2, and NUFIP1) had high level of expression of the mutant alleles, suggesting potential oncogenic driver roles of these mutated genes. Among them, the druggable G-protein coupled receptor LPAR1 was highly expressed in all tumors. Cells expressing the LPAR1 R163W mutant demonstrated a significantly increased motility through elevated Rho signaling, but had no effect on growth. Therefore, this study highlights the need for multiple biopsies and sequencing during progression of a cancer and combinatorial DNA and RNA sequencing approach for systematic identification of expressed driver mutations.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0077731PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3797724PMC
June 2014

Targeting wild-type and mutationally activated FGFR4 in rhabdomyosarcoma with the inhibitor ponatinib (AP24534).

PLoS One 2013 4;8(10):e76551. Epub 2013 Oct 4.

Oncogenomics Section, Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America.

Rhabdomyosarcoma (RMS) is the most common childhood soft tissue sarcoma. Despite advances in modern therapy, patients with relapsed or metastatic disease have a very poor clinical prognosis. Fibroblast Growth Factor Receptor 4 (FGFR4) is a cell surface tyrosine kinase receptor that is involved in normal myogenesis and muscle regeneration, but not commonly expressed in differentiated muscle tissues. Amplification and mutational activation of FGFR4 has been reported in RMS and promotes tumor progression. Therefore, FGFR4 is a tractable therapeutic target for patients with RMS. In this study, we used a chimeric Ba/F3 TEL-FGFR4 construct to test five tyrosine kinase inhibitors reported to specifically inhibit FGFRs in the nanomolar range. We found ponatinib (AP24534) to be the most potent FGFR4 inhibitor with an IC50 in the nanomolar range. Ponatinib inhibited the growth of RMS cells expressing wild-type or mutated FGFR4 through increased apoptosis. Phosphorylation of wild-type and mutated FGFR4 as well as its downstream target STAT3 was also suppressed by ponatinib. Finally, ponatinib treatment inhibited tumor growth in a RMS mouse model expressing mutated FGFR4. Therefore, our data suggests that ponatinib is a potentially effective therapeutic agent for RMS tumors that are driven by a dysregulated FGFR4 signaling pathway.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0076551PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3790700PMC
May 2014

Development of peptide nucleic acid probes for detection of the HER2 oncogene.

PLoS One 2013 10;8(4):e58870. Epub 2013 Apr 10.

Pediatric Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America.

Peptide nucleic acids (PNAs) have gained much interest as molecular recognition tools in biology, medicine and chemistry. This is due to high hybridization efficiency to complimentary oligonucleotides and stability of the duplexes with RNA or DNA. We have synthesized 15/16-mer PNA probes to detect the HER2 mRNA. The performance of these probes to detect the HER2 target was evaluated by fluorescence imaging and fluorescence bead assays. The PNA probes have sufficiently discriminated between the wild type HER2 target and the mutant target with single base mismatches. Furthermore, the probes exhibited excellent linear concentration dependence between 0.4 to 400 fmol for the target gene. The results demonstrate potential application of PNAs as diagnostic probes with high specificity for quantitative measurements of amplifications or over-expressions of oncogenes.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0058870PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3622650PMC
October 2013

Synthetic lethal screen identifies NF-κB as a target for combination therapy with topotecan for patients with neuroblastoma.

BMC Cancer 2012 Mar 21;12:101. Epub 2012 Mar 21.

Oncogenomics Section, Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA.

Background: Despite aggressive multimodal treatments the overall survival of patients with high-risk neuroblastoma remains poor. The aim of this study was to identify novel combination chemotherapy to improve survival rate in patients with high-risk neuroblastoma.

Methods: We took a synthetic lethal approach using a siRNA library targeting 418 apoptosis-related genes and identified genes and pathways whose inhibition synergized with topotecan. Microarray analyses of cells treated with topotecan were performed to identify if the same genes or pathways were altered by the drug. An inhibitor of this pathway was used in combination with topotecan to confirm synergism by in vitro and in vivo studies.

Results: We found that there were nine genes whose suppression synergized with topotecan to enhance cell death, and the NF-κB signaling pathway was significantly enriched. Microarray analysis of cells treated with topotecan revealed a significant enrichment of NF-κB target genes among the differentially altered genes, suggesting that NF-κB pathway was activated in the treated cells. Combination of topotecan and known NF-κB inhibitors (NSC 676914 or bortezomib) significantly reduced cell growth and induced caspase 3 activity in vitro. Furthermore, in a neuroblastoma xenograft mouse model, combined treatment of topotecan and bortezomib significantly delayed tumor formation compared to single-drug treatments.

Conclusions: Synthetic lethal screening provides a rational approach for selecting drugs for use in combination therapy and warrants clinical evaluation of the efficacy of the combination of topotecan and bortezomib or other NF-κB inhibitors in patients with high risk neuroblastoma.
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http://dx.doi.org/10.1186/1471-2407-12-101DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3364855PMC
March 2012

Exon array analysis reveals neuroblastoma tumors have distinct alternative splicing patterns according to stage and MYCN amplification status.

BMC Med Genomics 2011 Apr 18;4:35. Epub 2011 Apr 18.

Oncogenomics Section, Pediatric Oncology Branch, National Cancer Institute, National Institute of Health, Gaithersburg, MD 20877, USA.

Background: Neuroblastoma (NB) tumors are well known for their pronounced clinical and molecular heterogeneity. The global gene expression and DNA copy number alterations have been shown to have profound differences in tumors of low or high stage and those with or without MYCN amplification. RNA splicing is an important regulatory mechanism of gene expression, and differential RNA splicing may be associated with the clinical behavior of a tumor.

Methods: In this study, we used exon array profiling to investigate global alternative splicing pattern of 47 neuroblastoma samples in stage 1 and stage 4 with normal or amplified MYCN copy number (stage 1-, 4- and 4+). The ratio of exon-level expression to gene-level expression was used to detect alternative splicing events, while the gene-level expression was applied to characterize whole gene expression change.

Results: Principal component analysis (PCA) demonstrated distinct splicing pattern in three groups of samples. Pairwise comparison identified genes with splicing changes and/or whole gene expression changes in high stage tumors. In stage 4- compared with stage 1- tumors, alternatively spliced candidate genes had little overlap with genes showing whole gene expression changes, and most of them were involved in different biological processes. In contrast, a larger number of genes exhibited either exon-level splicing, gene-level expression or both changes in stage 4+ versus stage 1- tumors. Those biological processes involved in stage 4- tumors were disrupted to a greater extent by both splicing and transcription regulations in stage 4+ tumors.

Conclusions: Our results demonstrated a significant role of alternative splicing in high stage neuroblastoma, and suggested a MYCN-associated splicing regulation pathway in stage 4+ tumors. The identification of differentially spliced genes and pathways in neuroblastoma tumors of different stages and molecular subtypes may be important to the understanding of cancer biology and the discovery of diagnostic markers or therapeutic targets in neuroblastoma.
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http://dx.doi.org/10.1186/1755-8794-4-35DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3096898PMC
April 2011

Murine rhabdomyosarcoma is immunogenic and responsive to T-cell-based immunotherapy.

Pediatr Blood Cancer 2011 Dec 1;57(6):921-9. Epub 2011 Apr 1.

Immunology Section, Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA.

Background: Immunotherapies targeting cellular immunity are currently approved for treatment of melanoma, renal cell carcinoma, and prostate cancer. Studies on the immunogenicity and immune responsiveness of pediatric tumors are limited, therefore, it remains unclear to what extent T-cell-based immunotherapy holds promise for pediatric solid tumors.

Procedure: A new rhabdomyosarcoma cell line (M3-9-M) was derived from an embryonal rhabdomyosarcoma (ERMS) occurring in a C57BL/6 mouse transgenic for hepatocyte growth factor and heterozygous for mutated p53. Primary tumors and metastases derived from M3-9-M were studied for similarities to human ERMS, and for immunogenicity and immune responsiveness.

Results: Primary and metastatic tumors develop after orthotopic injection of M3-9-M into immunocompetent C57BL/6 mice, which mirror human ERMS with regard to histology, gene expression, and metastatic behavior. Whole cell vaccination using irradiated M3-9-M cells or M3-9-M-pulsed dendritic cells (DC)-induced tumor-specific T-cell responses that prevent tumor growth following low-dose tumor injection, and slow tumor growth following higher doses. Administration of anti-CD25 moAbs to deplete CD4(+)CD25(+)FOXP3(+) regulatory T cells prior to tumor vaccination enhanced the potency of the ERMS tumor vaccine. Adoptive immunotherapy with M3-9-M primed T cells plus DC-based vaccination resulted in complete eradication of day 10 M3-9-M derived tumors.

Conclusions: M3-9-M derived murine ERMS is immunogenic and immunoresponsive; regulatory T cells contribute to immune evasion by murine rhabdomyosarcoma. Adoptive immunotherapy with DC vaccination can eradicate low tumor burdens. Future work will seek to identify the tumor-associated antigens that mediate protective and therapeutic immunity in this model.
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http://dx.doi.org/10.1002/pbc.23048DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7401311PMC
December 2011

Systematic proteome analysis identifies transcription factor YY1 as a direct target of miR-34a.

J Proteome Res 2011 Feb 23;10(2):479-87. Epub 2010 Dec 23.

Oncogenomics Section, Pediatric Oncology Branch, Advanced Technology Center, National Cancer Institute, Gaithersburg, Maryland 20877, USA.

MicroRNA 34a (miR-34a) is a potential tumor suppressor gene and has been identified as a miRNA component of the p53 network. To better understand the biological pathways involved in miR-34a action, a parallel global protein and mRNA expression profiling on miR-34a treated neuroblastoma cells (IMR32) was performed using isotope-coded affinity tags (ICAT) and Affymetrix U133plus2 microarray, respectively. Global profiling showed that miR-34a causes much smaller mRNA expression changes compared to changes at the protein level. A total of 1495 proteins represented by two or more peptides were identified from the quantitative ICAT analysis, of which 143 and 192 proteins are significantly up- or down-regulated by miR-34a, respectively. Pathway analysis of these differentially expressed proteins showed the enrichment of apoptosis and cell death processes in up-regulated proteins but DNA replication and cell cycle processes in the down-regulated proteins. Ribosomal proteins are the most significant set down-regulated by miR-34a. Additionally, biological network analysis to identify direct interactions among the differentially expressed proteins demonstrated that the expression of the ubiquitous transcription factor YY1, as well as its downstream proteins, is significantly reduced by miR-34a. We further demonstrated that miR-34a directly targets YY1 through a miR-34a-binding site within the 3' UTR of YY1 using a luciferase reporter system. YY1 is a negative regulator of p53, and it plays an essential role in cancer biology. Therefore, YY1 is another important direct target of miR-34a which closely regulates TP53 activities.
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http://dx.doi.org/10.1021/pr1006697DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3679541PMC
February 2011

Expression profiling identifies epoxy anthraquinone derivative as a DNA topoisomerase inhibitor.

Cancer Lett 2010 Jul 4;293(1):124-31. Epub 2010 Feb 4.

Oncogenomics Section, Pediatric Oncology Branch, Advanced Technology Center, National Cancer Institute, Gaithersburg, MD, USA.

To discover novel drugs for neuroblastoma treatment, we have previously screened a panel of drugs and identified 30 active agents against neuroblastoma cells. Here we performed microarray gene expression analysis to monitor the impact of these agents on a neuroblastoma cell line and used the connectivity map (cMAP) to explore putative mechanism of action of unknown drugs. We first compared the expression profiles of 10 compounds shared in both our dataset and cMAP database and observed the high connectivity scores for 7 of 10 matched drugs regardless of the differences of cell lines utilized. The screen of cMAP for uncharacterized drugs indicated the signature of Epoxy anthraquinone derivative (EAD) matched the profiles of multiple known DNA targeted agents (topoisomerase I/II inhibitors, DNA intercalators, and DNA alkylation agents) as predicted by its structure. Similar result was obtained by querying against our internal NB-cMAP (http://pob.abcc.ncifcrf.gov/cgi-bin/cMAP), a database containing the profiles of 30 active drugs. These results suggest that Epoxy anthraquinone derivative may inhibit neuroblastoma cells by targeting DNA replication inhibition. Experimental data also demonstrate that Epoxy anthraquinone derivative indeed induces DNA double-strand breaks through DNA alkylation and inhibition of topoisomerase activity. Our study indicates that Epoxy anthraquinone derivative may be a novel DNA topoisomerase inhibitor that can be potentially used for treatment of neuroblastoma or other cancer patients.
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http://dx.doi.org/10.1016/j.canlet.2010.01.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4698332PMC
July 2010

Global genomic and proteomic analysis identifies biological pathways related to high-risk neuroblastoma.

J Proteome Res 2010 Jan;9(1):373-82

Oncogenomics Section, Pediatric Oncology Branch, Advanced Technology Center, National Cancer Institute, 8717 Grovemont Circle, Gaithersburg, Maryland 20877, USA.

Neuroblastoma (NB) is a heterogeneous pediatric tumor. To better understand the biological pathways involved in the development of high-risk neuroblastoma, we performed parallel global protein and mRNA expression profiling on NB tumors of stage 4 MYCN-amplified (4+) and stage 1 MYCN-not-amplified (1-) using isotope-coded affinity tags (ICAT) and Affymetrix U133plus2 microarray, respectively. A total of 1461 proteins represented by 2 or more peptides were identified from the quantitative ICAT analysis, of which 433 and 130 proteins are up- or down-regulated, respectively, in 4+ tumor compared to the 1- tumor. Pathway analysis of the differentially expressed proteins showed the enrichment of glycolysis, DNA replication and cell cycle processes in the up-regulated proteins and cell adhesion, nervous system development and cell differentiation processes in the down-regulated proteins in 4+ tumor; suggesting a less mature neural and a more invasive phenotype of 4+ tumor. Myc targets and ribosomal proteins are overrepresented in the 4+ tumors as expected; functional gene sets reported to be enriched in neural and embryonic stem cells are significantly enriched in the 4+ tumor, indicating the existence of a stemness signature in MYCN-amplified stage 4 tumor. In addition, protein and mRNA expression are moderately correlated (r = 0.51, p < 0.0001), as approximately half of the up-regulated proteins in 4+ tumor have elevated mRNA level (n = 208), and one-third of down-regulated proteins have lower mRNA expression (n = 47). Further biological network analysis revealed that the differentially expressed proteins closely interact with other proteins of known networks; the important role of MYCN is confirmed and other transcription factors identified in the network may have potential roles in the biology of NB tumor. We used global genomic and proteomic analysis to identify biologically relevant proteins and pathways important to NB progression and development that may provide new insights into the biology of advanced neuroblastoma.
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http://dx.doi.org/10.1021/pr900701vDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2801773PMC
January 2010

Identification of FGFR4-activating mutations in human rhabdomyosarcomas that promote metastasis in xenotransplanted models.

J Clin Invest 2009 Nov 5;119(11):3395-407. Epub 2009 Oct 5.

Pulmonary and Vascular Medicine Branch, National Heart, Lung, and Blood Institute (NHLBI), NIH, Bethesda, Maryland 20892-4605, USA.

Rhabdomyosarcoma (RMS) is a childhood cancer originating from skeletal muscle, and patient survival is poor in the presence of metastatic disease. Few determinants that regulate metastasis development have been identified. The receptor tyrosine kinase FGFR4 is highly expressed in RMS tissue, suggesting a role in tumorigenesis, although its functional importance has not been defined. Here, we report the identification of mutations in FGFR4 in human RMS tumors that lead to its activation and present evidence that it functions as an oncogene in RMS. Higher FGFR4 expression in RMS tumors was associated with advanced-stage cancer and poor survival, while FGFR4 knockdown in a human RMS cell line reduced tumor growth and experimental lung metastases when the cells were transplanted into mice. Moreover, 6 FGFR4 tyrosine kinase domain mutations were found among 7 of 94 (7.5%) primary human RMS tumors. The mutants K535 and E550 increased autophosphorylation, Stat3 signaling, tumor proliferation, and metastatic potential when expressed in a murine RMS cell line. These mutants also transformed NIH 3T3 cells and led to an enhanced metastatic phenotype. Finally, murine RMS cell lines expressing the K535 and E550 FGFR4 mutants were substantially more susceptible to apoptosis in the presence of a pharmacologic FGFR inhibitor than the control cell lines expressing the empty vector or wild-type FGFR4. Together, our results demonstrate that mutationally activated FGFR4 acts as an oncogene, and these are what we believe to be the first known mutations in a receptor tyrosine kinase in RMS. These findings support the potential therapeutic targeting of FGFR4 in RMS.
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http://dx.doi.org/10.1172/JCI39703DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769177PMC
November 2009

microRNA profiling identifies cancer-specific and prognostic signatures in pediatric malignancies.

Clin Cancer Res 2009 Sep 25;15(17):5560-8. Epub 2009 Aug 25.

Oncogenomics Section, Pediatric Oncology Branch, Advanced Technology Center, National Cancer Institute, Gaithersburg, Maryland 20877, USA.

Purpose: microRNAs have been shown to be involved in different human cancers. We therefore have performed expression profiles on a panel of pediatric tumors to identify cancer-specific microRNAs. We also investigated if microRNAs are coregulated with their host gene.

Experimental Design: We performed parallel microRNAs and mRNA expression profiling on 57 tumor xenografts and cell lines representing 10 different pediatric solid tumors using microarrays. For those microRNAs that map to their host mRNA, we calculated correlations between them.

Results: We found that the majority of cancer types clustered together based on their global microRNA expression profiles by unsupervised hierarchical clustering. Fourteen microRNAs were significantly differentially expressed between rhabdomyosarcoma and neuroblastoma, and 8 of them were validated in independent patient tumor samples. Exploration of the expression of microRNAs in relationship with their host genes showed that the expression for 43 of 68 (63%) microRNAs located inside known coding genes was significantly correlated with that of their host genes. Among these 43 microRNAs, 5 of 7 microRNAs in the OncomiR-1 cluster correlated significantly with their host gene MIRHG1 (P < 0.01). In addition, high expression of MIRHG1 was significantly associated with high stage and MYCN amplification in neuroblastoma tumors, and the expression level of MIRHG1 could predict the outcome of neuroblastoma patients independently from the current neuroblastoma risk-stratification in two independent patient cohorts.

Conclusion: Pediatric cancers express cancer-specific microRNAs. The high expression of the OncomiR-1 host gene MIRHG1 correlates with poor outcome for patients with neuroblastoma, indicating important oncogenic functions of this microRNA cluster in neuroblastoma biology.
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http://dx.doi.org/10.1158/1078-0432.CCR-08-3287DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2737097PMC
September 2009

Factors in tissue handling and processing that impact RNA obtained from formalin-fixed, paraffin-embedded tissue.

J Histochem Cytochem 2008 Nov 18;56(11):1033-42. Epub 2008 Aug 18.

Tissue Array Research Program, Laboratory of Pathology, National Institutes of Health, Bethesda, Maryland, USA.

Formalin-fixed, paraffin-embedded (FFPE) tissue is the most common specimen available for molecular assays on tissue after diagnostic histopathological examination. RNA from FFPE tissue suffers from strand breakage and cross-linking. Despite excellent extraction methods, RNA quality from FFPE material remains variable. To address the RNA quality factors within FFPE tissues, we studied RNA quality, isolating individual elements of the tissue fixation and processing including length of fixation in formalin and the type of buffer incorporated in the fixative. We examined the impact of the length of the tissue processing cycle as well. The optimal fixation period of 12-24 hr in phosphate-buffered formalin resulted in better-quality RNA. Longer tissue processing times were associated with higher quality RNA. We determined that the middle region of gene suffers less damage by these processes as shown by real-time quantitative RT-PCR. These data provide key information for the development of methods of analysis of gene expression in archival FFPE tissues and contribute to the establishment of objective standards for the processing and handling of tissue in surgical pathology. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.
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http://dx.doi.org/10.1369/jhc.2008.951863DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2569903PMC
November 2008
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