scholarly journals Comparison of the Transcriptomic Signatures in Pediatric and Adult CML

Cancers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 6263
Author(s):  
Minyoung Youn ◽  
Stephanie M. Smith ◽  
Alex Gia Lee ◽  
Hee-Don Chae ◽  
Elizabeth Spiteri ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Rna Sequencing ◽  
Differentially Expressed Genes ◽  
High Throughput ◽  
Myeloid Leukemia ◽  
Differentially Expressed ◽  
Molecular Characteristics ◽  
Healthy Controls ◽  
Cd34 Cells ◽  
Transcriptomic Signature

Children with chronic myeloid leukemia (CML) tend to present with higher white blood counts and larger spleens than adults with CML, suggesting that the biology of pediatric and adult CML may differ. To investigate whether pediatric and adult CML have unique molecular characteristics, we studied the transcriptomic signature of pediatric and adult CML CD34+ cells and healthy pediatric and adult CD34+ control cells. Using high-throughput RNA sequencing, we found 567 genes (207 up- and 360 downregulated) differentially expressed in pediatric CML CD34+ cells compared to pediatric healthy CD34+ cells. Directly comparing pediatric and adult CML CD34+ cells, 398 genes (258 up- and 140 downregulated), including many in the Rho pathway, were differentially expressed in pediatric CML CD34+ cells. Using RT-qPCR to verify differentially expressed genes, VAV2 and ARHGAP27 were significantly upregulated in adult CML CD34+ cells compared to pediatric CML CD34+ cells. NCF1, CYBB, and S100A8 were upregulated in adult CML CD34+ cells but not in pediatric CML CD34+ cells, compared to healthy controls. In contrast, DLC1 was significantly upregulated in pediatric CML CD34+ cells but not in adult CML CD34+ cells, compared to healthy controls. These results demonstrate unique molecular characteristics of pediatric CML, such as dysregulation of the Rho pathway, which may contribute to clinical differences between pediatric and adult patients.

scholarly journals Comparison of the Transcriptomic Signature of Pediatric Vs. Adult CML and Normal Bone Marrow Stem Cells

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 4246-4246 ◽  
Author(s):  
Hee-Don Chae ◽  
Lara C. Murphy ◽  
Michele Donato ◽  
Alex G. Lee ◽  
E. Alejandro Sweet-Cordero ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Tyrosine Kinase ◽  
Differentially Expressed Genes ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
Kinase Inhibitors ◽  
Differentially Expressed ◽  
False Discovery ◽  
Cd34 Cells ◽  
Transcriptomic Signature

Abstract Introduction Pediatric chronic myeloid leukemia (CML) accounts for 10 to 15% of children with myeloid leukemia and 2 to 9% of all pediatric leukemias. Prior to the discovery of tyrosine kinase inhibitors (TKI) such as imatinib, stem cell transplantation was the only curative treatment for both adults and children with CML. However, due to the small numbers of patients, standardized treatment approaches for pediatric CML have not been established. There are several unique characteristics of CML diagnosed in children and adolescents, and young adults (AYA; 16-29 years), compared to adults. Children and AYA with CML present with a higher white blood count and have larger spleens, higher peripheral blast counts, and lower hemoglobin levels, suggesting that the biology of pediatric CML is different than adult CML. In addition, potential side effects of TKIs unique to pediatric CML patients include impaired bone growth, fertility and immune function, however none have been extensively studied. We hypothesize that the differences in clinical presentation of pediatric CML patients are due to unique molecular characteristics that are absent in adult CML patients. To test this hypothesis, we studied the transcriptomic signature of pediatric CD34+ CML cells compared to adult CML and normal age-matched bone marrow CD34+ cells. Methods CD34+ cells were isolated from pediatric CML (n=7), adult CML (n=8), pediatric normal (n=2) and adult normal (n=3) bone marrow samples. Total RNA was isolated from cells, and then cDNA libraries were generated. Prepared libraries were sequenced on the Illumina HiSeq 4000 instrument. We aligned reads using the HISAT2 alignment software, and mapped to genes with HT-Seq. We removed genes that had zero reads across all the samples, resulting in a set of 4,696 genes that were detected in one or more samples. In case of technical replicates, we used mean of replicates. We performed three differential expression comparisons with edgeR: (1) Pediatric CML vs Adult CML, (2) Adult CML vs Adult Normal, and (3) Pediatric CML vs Pediatric Normal. We used a False Discovery Rate (FDR) of £ 20% and absolute log2 fold-change ³ 1 for selecting differentially expressed genes in each comparison. We used Fisher's exact test to identify significant KEGG pathways for the differentially expressed genes in each comparison. Results Pediatric CML vs Adult CML We found 24 differentially expressed genes (15 over- and 9 under-expressed). Though no pathway was found to be significant at the false discovery rate (FDR) £ 20%, we identified a number of sub-pathways that are relevant. For example, the Chemokine Signaling pathway shows at the top of the list (ordered by raw p-value) because of two genes, XCR1 and HCK, associated with VEGF and MAPK pathways involved in cell proliferation, angiogenesis, DNA repair, and cancer pathogenesis. Adult CML vs Adult Normal We found 60 genes (30 over- and 30 under-expressed) differentially expressed when comparing adult CML patients to normal adults. Ten genes overlapped with 24 genes we identified when comparing pediatric and adult CML patients. We found 11 pathways as significant at FDR £ 10%. Multiple pathways, including Cell adhesion, allograft rejection, Graft versus Host Disease, and Type I diabetes pathways, showed downregulation of MHC, with subsequent downstream reduction in expression of apoptosis-related genes. The IL-17 pathway makes sense, as MAPK, well-known to be associated with various cancers, is down-regulated. Lastly, in the NK pathway the gene DAP12 is up-regulated. This gene is known as a tyrosine kinase binding protein, and although tyrosine kinase inhibitors are the standard treatment for CML, the role of DAP12 in relation to leukemia has not yet been described. Pediatric CML vs Pediatric Normal We found 509 genes (350 over- and 159 under-expressed) differentially expressed in pediatric CML patients compared to normal. Interestingly, transcriptional regulators are differentially enriched in the hematopoietic stem cell differentiation function group including GATA1, GATA2, KLF1 and KLF2. RFC is down-regulated. RFC is a mismatch repair gene known to be involved in colorectal cancer. Many of the significant pathways are involved in glucose and fatty acid metabolism. Our pilot study identified novel molecular features of pediatric CML bone marrow stem cells, providing new insights into the novel biomarkers and pathogenesis of pediatric CML. Disclosures Gotlib: Blueprint Medicines: Consultancy, Honoraria, Research Funding; Promedior: Research Funding; Deciphera: Consultancy, Honoraria, Research Funding; Incyte: Consultancy, Honoraria, Research Funding; Kartos: Consultancy; Celgene: Consultancy, Honoraria, Research Funding; Gilead: Consultancy, Research Funding; Novartis: Consultancy, Honoraria, Research Funding.

scholarly journals Differentially expressed genes responsible for insensitivity of CD34+ cells to kinase inhibitors in patients with chronic myeloid leukemia

2013 ◽  
Vol 7 (S2) ◽  
Author(s):  
Caroline FA Moreira-Nunes ◽  
Tereza CB Azevedo ◽  
Ana CS Beltrão ◽  
Larissa TVM Francês ◽  
Rodrigo GMA Sousa ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Differentially Expressed Genes ◽  
Myeloid Leukemia ◽  
Kinase Inhibitors ◽  
Differentially Expressed ◽  
Cd34 Cells

Drug Efflux Transporters and Imatinib Mesylate Insensitivity in Chronic Myeloid Leukemia

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 4424-4424
Author(s):  
Caroline Fátima Aquino Moreira-Nunes ◽  
Ana Cristina Simões Beltrão ◽  
Larissa Tatiana Valente Martins Francês ◽  
Rodrigo Guarischi Mattos Amaral Sousa ◽  
Israel Tojal Silva ◽  
...  
Keyword(s):  
Stem Cells ◽  
Chronic Myeloid Leukemia ◽  
Imatinib Mesylate ◽  
Differentially Expressed Genes ◽  
Myeloid Leukemia ◽  
Molecular Therapy ◽  
Differentially Expressed ◽  
Drug Efflux ◽  
Pool Sample ◽  
Cd34 Cells

Abstract Abstract 4424 Background. Chronic Myeloid Leukemia represents the first human cancer in which a molecular therapy produces an effective clinical response (Holtz Blood 99:3792-800, 2002). The imatinib mesylate (IM) (Novartis Pharmaceuticals™) is a drug, that was designated to inhibit selectively certain tyrosine kinase proteins involved in the process of oncogenesis (Guilhot, The Oncologist, 9:271-81, 2004). In 2005, Michor (Nature 435:1267-70), through mathematical model, concluded that imatinib efficiently reduces the differentiated leukemic cells population, but it has not the same effect on the cell population that drives this disease, the CD34+ leukemic stem cells, which can be kept alive during the treatment. The search for the main causes of imatinib resistance has been intensified in recent years, with a special focus on the possible role of drug transporters (Apperley, Lancet Oncol 8:1018–29, 2007; Baker and Reddy, Mount Sinai J Med, 77:573–86, 2010). These proteins are the main determinants of the intracellular drug concentration, and how they actively regulating the traffic of small molecules through the cell membrane (Melo, Blood 108:1116-7, 2006). Thus, a cell can be resistant to a drug, because the optimum amount of the drug does not stay inside it to a significant effect to be achieved (Kim, Toxicology 182:291-7, 2002). Purpose. Identify differentially expressed genes in CD34+ and CD66b+ cells as candidates for IM transport. Methods. Samples of bone marrow (BM) and peripheral blood (PB) were obtained from five patients with CML treated with imatinib in better then optimal response according to European LeukemiaNet criteria (Baccarani, Blood 108:1809-20, 2006). Cells Isolation and RNA extraction. CD34+ cells were isolated from BM of five patients with CML. Likewise, mature CD66b+ PB cells were isolated from the same patients. SOLiD sequencing and sequence analysis. cDNA was sequenced according to the manufacturer's protocols for the SOLiD Total RNA-Seq kit for whole transcriptome. Data Analysis. To characterize the class genes, we analyzed the Gene Ontology (GO) annotation (Ashburner, Nature Genetics 25:25-9, 2000), and the software Cufflinks (Trapnell, Nature Biotechnology 28:511–15, 2010) were used to identify the differential expression of genes in both samples, in patients (BM × PB) and in control (BM × PB). The difference in gene expression between compared samples, were calculated based on P < 0.05 significance, were called differentially expressed genes those who submit P ≤ 0.05. Results. In pool sample of patients, it was possible to identify the genes SLC22A1 (OCT1) – in both, BM and PB pool samples, without any significant change (p ≤ 0,05) - and SLCO1A2 (OATP1A2) – only in PB sample. Thus its presence could not be identified in any of the control samples, which may reinforce the fact that these channels are actually responsible for the influx of imatinib in cells from patients undergoing treatment (Crossman, Blood:1133-4, 2005; Hu, Clin Cancer Res 14:3141–8, 2008). The presence of ABC gene family (ABCB1; ABCG2; ABCC1), described in the literature as being responsible for imatinib efflux (Jordanides, Blood 108: 1370–3, 2006; Brendel, Leukemia 21:1267–75, 2007) were found only in BM cells of patients. The presence of other two genes responsible for the drug efflux was also found exclusively in BM pool sample of patients, SLC47A1 and SLC47A2. These genes known as Human multidrug and toxin extrusion (MATE1 and MATE2) have also being identified as one important efflux mechanism of various drugs (Yonezawa and Inui, British J Pharmacol, 164:1817–25, 2011; Minematsu and Giacomini, Mol Cancer Ther, 10:531–9, 2011). Conclusion. The presence of more drug influx channels - the SLC family (OCT1 and OATP1A2) in mature cell - and absence of drug efflux channels - family ABC (ABCB1, ABCG2, ABCC1) and MATE genes (SLC47A1 and SLC47A2) - and the reverse in stem cells (CD34+) of patients with CML analyzed in this study may be the answer of why the insensitivity of CD34+ cells to treatment with IM and consequent failure to eliminate minimal residual disease. These genes can be candidates to therapeutic targets in CML. Disclosures: Lemos: Novartis of Brazil: Research Funding.

scholarly journals Transcriptome Analysis of Orbital Adipose Tissue in Active Thyroid Eye Disease Using Next Generation RNA Sequencing Technology

2018 ◽  
Vol 12 (1) ◽  
pp. 41-52 ◽  
Author(s):  
Bradford W. Lee ◽  
Virender B. Kumar ◽  
Pooja Biswas ◽  
Audrey C. Ko ◽  
Ramzi M. Alameddine ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Differential Expression ◽  
Rna Sequencing ◽  
Differentially Expressed Genes ◽  
Thyroid Eye Disease ◽  
Differentially Expressed ◽  
Eye Disease ◽  
Healthy Controls ◽  
Rna Seq ◽  
Next Generation

Objective: This study utilized Next Generation Sequencing (NGS) to identify differentially expressed transcripts in orbital adipose tissue from patients with active Thyroid Eye Disease (TED) versus healthy controls. Method: This prospective, case-control study enrolled three patients with severe, active thyroid eye disease undergoing orbital decompression, and three healthy controls undergoing routine eyelid surgery with removal of orbital fat. RNA Sequencing (RNA-Seq) was performed on freshly obtained orbital adipose tissue from study patients to analyze the transcriptome. Bioinformatics analysis was performed to determine pathways and processes enriched for the differential expression profile. Quantitative Reverse Transcriptase-Polymerase Chain Reaction (qRT-PCR) was performed to validate the differential expression of selected genes identified by RNA-Seq. Results: RNA-Seq identified 328 differentially expressed genes associated with active thyroid eye disease, many of which were responsible for mediating inflammation, cytokine signaling, adipogenesis, IGF-1 signaling, and glycosaminoglycan binding. The IL-5 and chemokine signaling pathways were highly enriched, and very-low-density-lipoprotein receptor activity and statin medications were implicated as having a potential role in TED. Conclusion: This study is the first to use RNA-Seq technology to elucidate differential gene expression associated with active, severe TED. This study suggests a transcriptional basis for the role of statins in modulating differentially expressed genes that mediate the pathogenesis of thyroid eye disease. Furthermore, the identification of genes with altered levels of expression in active, severe TED may inform the molecular pathways central to this clinical phenotype and guide the development of novel therapeutic agents.

ETS1 Expression Is Upregulated in Chronic Myeloid Leukemia (CML) and the ETS1 Transcriptional Program Correlates with Disease Progression Towards Blast Crisis

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 442-442
Author(s):  
Christophe Desterke ◽  
Maud Voldoire ◽  
Nathalie Sorel ◽  
Marie Laure Bonnet ◽  
Sarah Pagliaro ◽  
...  
Keyword(s):  
Stem Cell ◽  
Chronic Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Blast Crisis ◽  
Leukemic Cells ◽  
P Value ◽  
Healthy Controls ◽  
Transcriptional Program ◽  
Chip Sequencing ◽  
Cd34 Cells

Abstract Chronic myeloid leukemia is a clonal myeloproliferative neoplasm characterized by the occurrence of the Ph1 chromosome in a primitive hematopoietic stem cell with a major amplification of myeloid compartment. Despite the major progress obtained by the use of tyrosine kinase inhibitors (TKI), resistances to these drugs occur with progression towards blast crisis (BC) during which there is an increase of BCR-ABL expression. To evaluate the potential targets of BCR-ABL in this context, a gene profiling analysis of the UT7-11 cell line overexpressing BCR-ABL fusion protein was performed using a whole transcriptome microarray. One of the highly upregulated genes was ETS1 with a fold change of +35.86. ETS1 proto-oncogene, the founder member of the ETS-domain family of transcription factors such as TEL and FLI1, is the human homolog of the avian erythroblastosis virus E26. They play a crucial role in stem cell biology, tumorigenesis and ETS1 has been shown to be involved in the regulation of granulocytic differentiation. Its role in CML pathophysiology has not been studied so far. We first showed by Western blots that ETS1 protein was highly increased in UT7-11 cells as compared to parental UT7 cells. Using a DOX-Inducible BCR-ABL system, we have shown that ETS1 expression was downregulated upon inhibition of BCR-ABL expression. ETS1 expression was a tyrosine kinase dependent event as its expression was reduced in the presence of TKI. To determine if ETS1 expression is upregulated in primary leukemic cells, we have analyzed leukemic cells of CML patients at diagnosis (n= 40) as compared to healthy controls (n= 30) showing an increase of ETS1 mRNA expression in primary CML cells in a highly significant manner (p < 0.0007). We then analyzed ETS1 targets using chip-sequencing in K562 cells, performed on HG19 human genome allowing to predict 3209 proximal promoters (-3000 upstream pb, + 50pb around Transcription Starting Sites) which represents a promoter enrichment of +33.68 (p-value=4.9E-324) as compared to the distribution of peaks in the whole genome. Chromosomes 19, 16, 17, 11, 12 and 1 were found over-represented with ETS1 bound events in Chip-sequencing. Integration of BCR-ABL transcriptome with ETS1 promoters identified by Chip-Sequencing led to the identification of 130 ETS1-targets activated by BCR-ABL, allowing reclassification of BCR-ABL transfected samples with transcriptome data by unsupervised classification. ETS1 transcriptional program regulated by BCR-ABL analysis performed on CD34+ from CML patients during progression of the disease (GSE47927) allowed discrimination of the different states of the progression (from the chronic phase to accelerated phase and BC p-value=1.63E-33). This analysis was also found significant by Gene Set Enrichment Analysis ETS1_BC specific geneset (NES=+1.52, p-value<0.0001). Among this ETS1 program specific of BC, we identified 2 targets that are discriminant for CD34+ cells of CML patients without cytogenetic response under Imatinib therapy. These two genes were Dynamin 3 (DNM3) and LIMS1/ PINCH1. Dynamin 3 is a member of the motor proteins implicated in cell motility and cytokinesis and it is implicated in megakaryocyte development whereas LIMS1 / PINCH1 is essentially involved in cell migration and adhesion. In order to validate ETS1 and its target expressions in a novel cohort of CML patients, we have analyzed the expression of DNM3 and PINCH1 in whole blood samples in CML patients ( n= 60 ) as compared to healthy controls (n= 32). We have found that, similar to ETS1, DNM3 and LIMS1 / PINCH1 mRNA were highly upregulated in primary CML and this increase was highly significant. In this new cohort of patients, DNM3 transcript levels were inversely correlated to WBC count (r=-0.32, p-value=0.011) and especially in male gender (r=-0.43, p-value=0.012). The expression of LIMS1 was inversely correlated with the age at diagnosis and the major molecular response at 12 months. Thus, our results show for the first time the major upregulation of ETS1 transcriptional program in CML. ETS1 transcriptional program has been found to correlate with the gene expression pattern involved in the progression of the disease in the transcriptomic analysis of CML CD34+ cells. The novel druggable targets that we identified in the BCR-ABL-activated transcriptional program is currently under investigation to determine their use in patients with resistance to targeted therapies. Disclosures No relevant conflicts of interest to declare.

RNA sequencing analysis reveals differential gene expression of CXCL2 in ACPA-positive and ACPA-negative rheumatoid arthritis

2020 ◽  
Author(s):  
Lin Sun ◽  
Xinyu Wang ◽  
Ning He ◽  
Zhuo An ◽  
Ruohan Yu ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Gene Expression ◽  
Rna Sequencing ◽  
Differentially Expressed Genes ◽  
Differentially Expressed ◽  
Enzyme Linked Immunosorbent Assay ◽  
Sequencing Analysis ◽  
Healthy Controls ◽  
Raw264.7 Macrophages

Abstract Background. Anti-citrullinated protein/peptide antibodies (ACPA) play important roles in the pathogenesis of rheumatoid arthritis (RA), and are associated with RA severity. It has been suggested that ACPA-positive (ACPA+) and ACPA-negative (ACPA-) RA are different disease subsets with distinct differences in genetic variation and clinical outcomes. The aims of the present study were to compare gene expression profiles in ACPA + and ACPA- RA and identify novel candidate gene signatures that might serve as therapeutic targets. Methods. Comprehensive transcriptome analysis of peripheral blood mononuclear cells (PBMCs) from ACPA + and ACPA- RA patients, and healthy controls was performed via RNA sequencing. Genes with significantly different expressions were analyzed by cluster analysis, Gene Ontology analysis and Ingenuity Pathway analysis. A validation cohort was used to further investigate differentially expressed genes via real-time PCR and enzyme-linked immunosorbent assay. Spearman's correlation test was used to evaluate the correlation of differentially expressed genes and the clinical and laboratory data of the patients. The role of differentially expressed genes in osteoclastogenesis was further investigated. Results. There were significant differences in the expression levels of both genes and gene isoforms between ACPA + and ACPA- RA samples. Expression of C-X-C motif chemokine ligand 2 (CXCL2) was significantly increased in ACPA + RA patients than in ACPA- RA patients and healthy controls. Validation of candidate genes expression showed that CXCL2 levels in PBMCs and serum were higher in ACPA + RA patients than in ACPA- RA patients and healthy controls. CXCL2 promoted the migration of CD14 + monocytes and increased osteoclast differentiation in RA patients. RAW264.7 macrophages were used to investigate specific mechanisms, and the results suggested that CXCL2 stimulated osteoclastogenesis via ERK MAPK and NFκB pathways. Conclusion. Novel pathways associated with ACPA + RA were identified via RNA sequencing, and CXCL2 was highly expressed in ACPA + RA than in ACPA- RA. These results reveal a previously unreported role of CXCL2 during osteoclastogenesis in RA, and suggest that the blockade of CXCL2 might be a novel strategy for the treatment of RA.

scholarly journals Gene Expression Analysis of CML Patients across the Age Spectrum

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 1473-1473
Author(s):  
Minyoung Youn ◽  
Stephanie M. Smith ◽  
Alex Gia Lee ◽  
Hee-Don Chae ◽  
Elizabeth Spiteri ◽  
...  
Keyword(s):  
Gene Expression ◽  
Differentially Expressed Genes ◽  
Pathway Analysis ◽  
Adult Patients ◽  
Negative Regulator ◽  
Differentially Expressed ◽  
Molecular Characteristics ◽  
P Values ◽  
Cell Counts ◽  
Cd34 Cells

Abstract Chronic myeloid leukemia (CML) accounts for 2-9% of leukemias in children and adolescents, and occurs with much greater frequency in adults. Compared to adults, children with CML tend to present with higher white blood cell counts and larger spleens, suggesting that the biology of pediatric CML is different from adult CML. We hypothesize that the differences in clinical presentation of pediatric CML are due to unique molecular characteristics that differ from adult CML. To test this hypothesis, we compared the transcriptomic signature of pediatric and adult CML CD34+ cells and healthy age-matched CD34+ cells. CD34+ cells were isolated by FACS from pediatric CML (n=9), adult CML (n=10), pediatric healthy (n=10), and adult healthy (n=10) bone marrow samples. Prepared libraries were sequenced on the Illumina HiSeq 4000 instrument. Raw sequences were trimmed and aligned to the hg38 reference genome with STAR/2.5.1b aligner. Gene level counts were determined with STAR -quantMode option using gene annotations from GENCODE (p5). Differential gene expression and pathway analysis were conducted with R/3.5.3. Counts were normalized with trimmed mean of M-values from the EdgeR/ 3.24.3 package and further transformed with VOOM from the Limma/ 3.38.3 package. A linear model using the empirical Bayes analysis pipeline also from Limma was then used to obtain p-values, adjusted p-values and log-fold changes. Four comparisons were performed: (1) pediatric CML vs pediatric healthy, (2) adult CML vs adult healthy, (3) pediatric CML vs adult CML, and (4) pediatric healthy vs adult healthy. A False Discovery Rate of ≤ .05 and absolute log2 fold-change &gt; 1 was used to define differentially expressed genes (DEGs) in each comparison. To identify potentially unique pathways based on DEG, pathway over-representation was calculated with either goana from the limma package or clueGO. At diagnosis, pediatric patients had higher platelet counts (p=0.001) and larger spleen sizes (p=0.010) than adult patients. Median WBC counts were 273,000 and 143,000 in pediatric and adult patients respectively. A total of 1352 genes were differentially expressed in either adult or pediatric CML CD34+ cells compared to healthy CD34+ cells, 174 of which were expressed similarly in pediatric and adult CML CD34+ cells (54 up- and 120 down-regulated). There were 746 differentially expressed genes (325 up- and 421 down-regulated) in adult CML CD34+ cells compared to adult healthy CD34+ cells, and 432 differentially expressed genes (156 up- and 276 down-regulated) in pediatric CML CD34+ cells compared to pediatric healthy CD34+ cells. In direct comparison of pediatric and adult CML CD34+ cells, 446 genes (270 up and 176 down) were dysregulated in pediatric CML CD34+ cells. Pathway analysis showed that Rho signaling pathway was downregulated in pediatric CML CD34+ cells and several genes in Rho pathway were uniquely dysregulated. ARHGAP27 and VAV2 were significantly upregulated in adult CML CD34+ cells by 3.7-fold (p=0.0453) and 11-fold (p=0.0072), respectively, compared to pediatric CML CD34+ cells. In addition, several genes involved in the NADPH oxidase pathway, one of the best-characterized Rho GTPase-regulated systems, were differently expressed in CML. NCF1, CYBB, and S100A8 were significantly upregulated in adult CML CD34+ cells by 4-fold (p=0.0045), 3.26-fold (p&lt;0.0001), and 3.09-fold (p&lt;0.0001), respectively, compared to pediatric CML CD34+ cells. Furthermore, DLC1, which is known as a negative regulator of Rho pathway, was significantly upregulated in pediatric CML CD34+ cells by 2.47-fold (p=0.0493) compared to adult CML CD34+ cells. These results demonstrate unique molecular characteristics of pediatric CML that may contribute to the clinical differences at presentation between adult and pediatric disease. A better understanding of the molecular biology of CML across the ages will provide new insights into the pathogenesis of pediatric CML and potentially inform future treatment decisions. Disclosures Davis: Jazz Pharmaceuticals: Research Funding; Novartis Pharmaceuticals: Honoraria. Hijiya: Novartis: Consultancy; Stemline Therapeutics: Consultancy.

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