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The amino acid response (AAR) and unfolded protein response (UPR) pathways converge on eIF2α phosphorylation, which is catalyzed by Gcn2 and Perk, respectively, under different stresses. This close interconnection makes it difficult to specify different functions of AAR and UPR. Here, we generated a zebrafish model in which loss of threonyl-tRNA synthetase (Tars) induces angiogenesis dependent on Tars aminoacylation activity. Comparative transcriptome analysis of the tars-mutant and wild-type embryos with/without Gcn2- or Perk-inhibition reveals that only Gcn2-mediated AAR is activated in the tars-mutants, whereas Perk functions predominantly in normal development. Mechanistic analysis shows that, while a considerable amount of eIF2α is normally phosphorylated by Perk, the loss of Tars causes an accumulation of uncharged tRNAThr, which in turn activates Gcn2, leading to phosphorylation of an extra amount of eIF2α. The partial switchover of kinases for eIF2α largely overwhelms the functions of Perk in normal development. Interestingly, although inhibition of Gcn2 and Perk in this stress condition both can reduce the eIF2α phosphorylation levels, their functional consequences in the regulation of target genes and in the rescue of the angiogenic phenotypes are dramatically different. Indeed, genetic and pharmacological manipulations of these pathways validate that the Gcn2-mediated AAR, but not the Perk-mediated UPR, is required for tars-deficiency induced angiogenesis. Thus, the interconnected AAR and UPR pathways differentially regulate angiogenesis through selective functions and mutual competitions, reflecting the specificity and efficiency of multiple stress response pathways that evolve integrally to enable an organism to sense/respond precisely to various types of stresses.

Twenty batches of Aurantii Fructus Immaturus(AFI) were collected, with their peel and pulp taken as research objects. Ultra-high performance liquid chromatography(UPLC) fingerprints of peel and pulp of AFI were established with 17 common peaks in peel and 10 in pulp. Six kinds of flavonoids were identified, i.e., narirutin, naringin, rhoifolin, hesperidin, neohesperidin and nobiletin. The Similarity Evaluation System for Chromatographic Fingerprint of Traditional Chinese Medicine was employed for similarity analysis, which showed that the chromatographic peaks of peel and pulp were basically similar to their respective reference fingerprints, with all similarities greater than 0.90. The similarity between peel and pulp of the same batch of AFI ranged from 0.850 to 0.983. Cluster analysis(CA), principal component analysis(PCA), and orthogonal partial least squares discriminant analysis(OPLS-DA) were conducted on the common peaks of peel and pulp of AFI with SPSS 17.0 and SIMCA 14.1. Combined with the reference fingerprints, these analyses revealed 12 differential components regarding peel and pulp. Further, the content of the 6 flavonoids and synephrine was determined. The proposed method integrating UPLC fingerprint and multicomponent quantitative analysis is applicable to the quality evaluation of AFI. The results provide a certain basis for the scientific connotation about the appearance characteristic of AFI.

Myelodysplastic syndrome (MDS) includes a group of diseases characterized by dysplasia of bone marrow myeloid lineages with ineffective hematopoiesis and frequent evolution to acute myeloid leukemia (AML). Whole-genome sequencing was performed in CD34(+) hematopoietic stem/progenitor cells (HSPCs) from eight cases of refractory anemia with excess blasts (RAEB), the high-risk subtype of MDS. The nucleotide substitution patterns were found similar to those reported in AML, and mutations of 96 protein-coding genes were identified. Clonal architecture analysis revealed the presence of subclones in six of eight cases, whereas mutation detection of CD34(+) versus CD34(-) cells revealed heterogeneity of HSPC expansion status. With 39 marker genes belonging to eight functional categories, mutations were analyzed in 196 MDS cases including mostly RAEB (n = 89) and refractory cytopenia with multilineage dysplasia (RCMD) (n = 95). At least one gene mutation was detected in 91.0% of RAEB, contrary to that in RCMD (55.8%), suggesting a higher mutational burden in the former group. Gene abnormality patterns differed between MDS and AML, with mutations of activated signaling molecules and NPM1 being rare, whereas those of spliceosome more common, in MDS. Finally, gene mutation profiles also bore prognostic value in terms of overall survival and progression free survival.

Context: Graves disease (GD) is a common autoimmune disease triggered by genetic predisposition and environmental factors. However, the mechanisms of interaction between genetic and environmental factors contributing to the development of GD remain unknown. Objective: We aimed to identify GD susceptibility variants and genes on Xq21.1 locus and interpret the contribution of interaction between genetic predisposition on Xq21.1 and environmental factors to GD. Design: We performed refining study on Xq21.1 in a 2-stage study and carried out expression quantitative trait locus analysis of the best association signal with GD. Setting and Participants: A total of 4316 GD patients and 4374 sex-matched controls were collected from the Chinese Han population by cooperation with multiple hospitals. Results: We identified that rs3827440 or its linkage single nucleotide polymorphisms (SNPs) were probably the causal variant in the Xq21.1 locus, with the most substantial association with GD in our combined cohorts (P = 2.45 × 10−15). The genotypes of rs3827440 were correlated with the expression of ITM2A in monocytes and peripheral blood mononuclear cells (PBMCs) from healthy volunteers. Notably, the expression of ITM2A in monocytes after lipopolysaccharide (LPS) and interferon-γ (INF-γ) stimulation showed substantial difference among the volunteers that carried different genotypes of rs3827440 (P = 9.40 × 10−7 and P = 1.26 × 10−5 for 24 hours’ LPS and INF-γ stimulation, respectively). Moreover, ITM2A expression was significantly decreased in PBMCs from untreated GD patients than that from controls. Conclusion: The results suggest that ITM2A might be a susceptibility gene for GD in the Xq21.1 locus, and environmental factors, such as viral and bacterial infections, probably contribute to GD pathogenesis by interacting with the risk SNP rs3827440 mediating the regulation of ITM2A expression.

To evaluate the prognostic value of genetic mutations for acute myeloid leukemia (AML) patients, we examined the gene status for both fusion products such as AML1 (CBFα)–ETO, CBFβ-MYH11, PML-RARα, and MLL rearrangement as a result of chromosomal translocations and mutations in genes including FLT3, C-KIT, N-RAS, NPM1, CEBPA, WT1, ASXL1, DNMT3A, MLL, IDH1, IDH2, and TET2 in 1185 AML patients. Clinical analysis was mainly carried out among 605 cases without recognizable karyotype abnormalities except for 11q23. Of these 605 patients, 452 (74.7%) were found to have at least 1 mutation, and the relationship of gene mutations with clinical outcome was investigated. We revealed a correlation pattern among NPM1, DNMT3A, FLT3, IDH1, IDH2, CEBPA, and TET2 mutations. Multivariate analysis identified DNMT3A and MLL mutations as independent factors predicting inferior overall survival (OS) and event-free survival (EFS), whereas biallelic CEBPA mutations or NPM1 mutations without DNMT3A mutations conferred a better OS and EFS in both the whole group and among younger patients < 60 years of age. The use of molecular markers allowed us to subdivide the series of 605 patients into distinct prognostic groups with potential clinical relevance.

Abnormal epigenetic regulation has been implicated in oncogenesis. We report here the identification of somatic mutations by exome sequencing in acute monocytic leukemia, the M5 subtype of acute myeloid leukemia (AML-M5). We discovered mutations in DNMT3A (encoding DNA methyltransferase 3A) in 23 of 112 (20.5%) cases. The DNMT3A mutants showed reduced enzymatic activity or aberrant affinity to histone H3 in vitro. Notably, there were alterations of DNA methylation patterns and/or gene expression profiles (such as HOXB genes) in samples with DNMT3A mutations as compared with those without such changes. Leukemias with DNMT3A mutations constituted a group of poor prognosis with elderly disease onset and of promonocytic as well as monocytic predominance among AML-M5 individuals. Screening other leukemia subtypes showed Arg882 alterations in 13.6% of acute myelomonocytic leukemia (AML-M4) cases. Our work suggests a contribution of aberrant DNA methyltransferase activity to the pathogenesis of acute monocytic leukemia and provides a useful new biomarker for relevant cases.

Stress-induced angiogenesis enormously contributes to both normal development and pathogenesis of various diseases including cancer. Among many stress response pathways implicated in regulation of angiogenesis, the amino acid response (AAR) and the unfolded protein response (UPR) pathways are closely interconnected, as they converge on the common target, eIF2α, which is a key regulator of protein translation. Two kinases, namely Gcn2 (Eif2ak4) and Perk (Eif2ak3), are responsible for transducing signals from AAR and UPR, respectively, to phosphorylation of eIF2α. Even though numerous studies have been performed, this close interconnection between AAR and UPR makes it difficult to clearly distinguish different contributions of these two pathways in regulation of angiogenesis. In this study, we generated a zebrafish angiogenic model harboring a loss-of-function mutation of the threonyl-tRNA synthetase (tars) gene. Tars belongs to a family of evolutionarily conserved enzymes, aminoacyl-tRNA synthetases (aaRSs), which control the first step of protein translation through coupling specific amino acids with their cognate tRNAs. Deficiencies of several aaRSs in zebrafish have been shown to cause increased branching of blood vessels, and this angiogenic phenotype has roughly been explained by activation of AAR and UPR; however, it is unclear whether both AAR and UPR are required and to what extent they contribute to this process. To address this issue, we first performed RNA-seq analyses of Tars-mutated and control zebrafish embryos, as well as those with knockdown of either Gcn2 or Perk in both genotypes. We found that the AAR target genes are dramatically activated in the Tars-mutants, whereas the genes associated with the three UPR sub-pathways (i.e., Perk-, Ire1- and Atf6-mediated pathways) remain inactive, except for very few genes (e.g., Atf3, Atf4, Asns and Igfbp1) that are shared in both AAR and UPR, thus suggesting activation of AAR, but not UPR, in the Tars-mutants. In support of this notion, knockdown of the AAR-associated kinase Gcn2 in the Tars-mutants largely represses the activated genes, while the Perk knockdown shows very little effect. Nonetheless, in contrast to the apparently dispensable role of Perk in Tars-mutants, knockdown of Perk in control embryos leads to specific gene expression alterations, suggesting that Perk effectively functions in homeostatic states (i.e., controls), but, in the stress condition (i.e., Tars-mutants), its function is largely overwhelmed by activation of the Gcn2-mediated AAR. To validate these observations, we investigated the angiogenic phenotypes of the zebrafish models upon genetic and pharmacological interference with the AAR and UPR pathways. A transgenic zebrafish line, Tg(flk1:EGFP), was crossed with the Tars-mutants to visualize angiogenesis in vivo. We observed increased branching of blood vessels in the Tars-mutants, which is rescued by tars mRNA but not an enzymatically dead version. Importantly, knockdown of Gcn2 in the Tars-mutants rescues this phenotype. In contrast, knockdown of Perk, or knockdown of two other known eIF2α kinases, Hri (Eif2ak1) or Pkr (Eif2ak2), shows no effect. Furthermore, knockdown of either one of two major factors downstream to eIF2α, namely Atf4 and Vegfα, or inhibition of Vegf receptor with the drug SU5416, also rescue the phenotype. Thus, these results confirm that AAR, but not UPR, is required for the Tars-deficiency-induced angiogenesis. Taken together, this study demonstrates that, despite being closely interconnected and even sharing a common downstream target, the Gcn2-mediated AAR and the Perk-mediated UPR can be activated independently in different conditions and differentially regulate cellular functions such as angiogenesis. This notion reflects the specificity and efficiency of multiple stress response pathways that are evolved integrally to benefit the organism by ensuring sensing and responding precisely to different types of stresses. This study also provides an example of combining systematic gene expression profiling and phenotypic validations to distinguish activities of such interconnected pathways. Further clarification of the mechanisms shall advance our understanding of how the organisms respond to diverse stresses and how the abnormalities in these regulatory machineries cause cellular stress-related diseases such as cancer, diabetes and immune disorders. Disclosures No relevant conflicts of interest to declare.

Background The FIP1L1-PDGFRalpha fusion gene plays an important role in the pathogenesis of chronic eosinophilic leukemia (CEL) and is a direct therapeutic target of the tyrosine kinase inhibitor imatinib mesylate. Methods In 24 hypereosinophilic syndromes (HES) patients, using reverse transcriptase-polymerase chain reaction (RT-PCR), nested PCR and sequence analysis, we investigated the frequency of FIP1L1-PDGFRalpha and other abnormalities of tyrosine kinase family genes like PDGFRalpha, PDGFRbeta, C-KIT, FGFR1, ABL and FLT3 as well as gene mutation "hotspots", like MPL515 and JAK2V617F, frequently involved in myeloproliferative diseases. Fluorescence in situ hybridization was used to confirm the 4q12 deletion. Results The FIP1L1-PDGFRalpha fusion transcript was found in 8 (33%) of 24 patients with HES, corresponding to the chromosome 4q12 deletion identified by FISH. The FIP1L1-PDGFRalpha-associated patients diagnosed with CEL, frequently had hepatosplenomegaly, eosinophil-related tissue damage, anemia, thrombocytopenia, myelofibrosis and a short overall survival time. Nevertheless, imatinib mesylate induced rapid and complete hematological responses in treated FIP1L1-PDGFRalpha cases, followed by molecular remission and reversal of myelofibrosis. FIP1L1-PDGFRalpha fusion could co-exist with other mutations of tyrosine kinase family genes, like FLT3 or PDGFRbeta. We also demonstrated that the SNPs of PDGFRbeta were associated with selective splicing of exon 19 in case 20. Conclusions Correlating the CEL genotype with phenotype, FIP1L1-PDGFRalpha emerges as a relatively homogeneous clinicobiological entity that co-exists with other abnormalities of tyrosine kinase family genes. It reflects the disease progression and there is a good response to imatinib. Detection of the FIP1L1-PDGFRalpha fusion gene is valid for both CEL diagnosis and therapy surveillance.

MassARRAY assay: a more accurate method for JAK2V617F mutation detection in Chinese patients with myeloproliferative disorders

Natural-killer/T cell lymphoma (NKTCL) is a malignant proliferation of CD56+/cytoCD3+ lymphocytes and constitutes a heterogeneous group of aggressive lymphoma prevalent in Asian and South American populations. NKTCL represents a distinct clinicopathologic entity of non-Hodgkin’s lymphoma, characterized by male predominance, strong association with Epstein-Barr virus (EBV) infection, prominent tissue necrosis and aggressive clinical course. However, molecular pathogenesis of NKTCL remains largely elusive. Here we identified somatic mutations by whole-exome sequencing in 25 NKTCL patients and extended validation through targeted sequencing in an additional 80 cases. Functional experiments including RNA unwinding test, colony forming assay, cell proliferation assay and gene expression profiling were also performed. Overall, 50.5% of NKTCL patients displayed somatic mutations of RNA helicase family, tumor suppressors (TP53 and MGA), and/or epigenetic modifiers (MLL2, ARID1A, EP300 and ASXL3). Recurrent mutations were most frequently discovered in RNA helicase gene DDX3X (21/105 cases, 20.0%). Mutations of DDX3X were seldom overlapped with those of TP53. Functionally, DDX3X mutants exhibited reduced RNA unwinding activity and enhanced cell proliferation. Similar stimulatory effect on cell proliferation was observed in cells transfected with specific siRNA targeting DDX3X. Gene expression profiling revealed an association of DDX3X mutations with activation of NF-kB and MAPK pathways. The clinical follow-up data showed that DDX3X-mutated patients presented a poor prognosis. Our work suggests the heterogeneity of gene mutational spectrum of NKTCL and provides a potential therapeutic target for relevant cases. Disclosures No relevant conflicts of interest to declare.

To explore the genetic abnormalities that cooperate with AML1-ETO ( AE ) fusion gene to cause acute myeloid leukemia (AML) with t(8;21), we screened a number of candidate genes and identified 11 types of mutations in C-KIT gene ( mC-KIT ), including 6 previously undescribed ones among 26 of 54 (48.1%) cases with t(8;21). To address a possible chronological order between AE and mC-KIT, we showed that, among patients with AE and mC-KIT , most leukemic cells at disease presentation harbored both genetic alteration, whereas in three such cases investigated during complete remission, only AE , but not mC-KIT , could be detected by allele-specific PCR. Therefore, mC-KIT should be a subsequent event on the basis of t(8;21). Furthermore, induced expression of AE in U937-A/E cells significantly up-regulated mRNA and protein levels of C-KIT. This may lead to an alternative way of C-KIT activation and may explain the significantly higher C-KIT expression in 81.3% of patients with t(8;21) than in patients with other leukemias. These data strongly suggest that t(8;21) AML follows a stepwise model in leukemogenesis, i.e., AE represents the first, fundamental genetic hit to initiate the disease, whereas activation of the C-KIT pathway may be a second but also crucial hit for the development of a full-blown leukemia. Additionally, Gleevec suppressed the C-KIT activity and induced proliferation inhibition and apoptosis in cells bearing C-KIT N822K mutation or overexpression, but not in cells with D816 mC-KIT . Gleevec also exerted a synergic effect in apoptosis induction with cytarabine, thus providing a potential therapeutic for t(8;21) leukemia.

Development of resistance to 1-beta-arabinofuranosylcytosine (AraC) is a major obstacle in the treatment of patients with acute myeloid leukaemia (AML). Deficiency of functional deoxycytidine kinase (dCK) plays an important role in AraC resistance in vitro. We screened 5378 bp sequences of the dCK gene, including all exons and the 5' flanking region, and identified two single nucleotide polymorphisms (SNPs) in the regulatory region (rSNPs) with high allele frequencies. These two rSNPs (-201C>T and -360C>G) formed two major haplotypes. Genotyping with sequencing and MassARRAY system among 122 AML patients showed that those with -360CG/-201CT and -360GG/-201TT compound genotypes (n = 41) displayed a favourable response to chemotherapy whereas those with -360CC/-201CC (n = 81) tended to have a poor response (P = 0.025). Moreover, real-time quantitative reverse transcriptase-polymerase chain reaction showed that patients with -360CG/-201CT and -360GG/-201TT genotypes expressed higher level of dCK mRNA compared to those with the -360CC/-201CC genotype (P = 0.0034). Luciferase-reporter assay showed that dCK 5' regulatory region bearing -360G/-201T genotype alone had an eight-fold greater transcriptional activation activity compared to that with -360C/-201C genotype, whereas co-transfection of both -360G/-201T and -360C/-201C constructs mimicked the heterozygous genotype, which exhibited a four-fold greater activity compared to that with -360C/-201C. These results indicate that rSNP haplotypes of dCK gene may serve as a genetic marker for predicting drug responsiveness, which will be beneficial in establishing more effective AML chemotherapeutic regimens.

The clinical significance of low-frequency microsatellite instability (MSI-L) in gastric cancer (GC) has not been well established. The aim of this study was to evaluate the clinicopathological features of MSI-L in GC. We investigated microsatellite instability (MSI) in 5 di-nucleotide repeat sequences in 210 unselected GC patients. High-resolution fluorescent microsatellite analysis assay was utilized to detect MSI. Clinicopathological variables were compared among groups with different microsatellite statuses. The overall survival (OS) was analyzed by Kaplan-Meier method. Multivariable analysis was performed to identify prognostic factors and variables correlated with lymph node metastasis. High-frequency microsatellite instability (MSI-H), MSI-L, and microsatellite stable were identified, respectively, in 10.5, 10.0, and 79.5% of unselected GC cases. Tumors with MSI-H were less invasive, and these patients showed a better OS. MSI-L was correlated with more advanced tumor Node Metastasis stage, and more frequent lymph node metastasis. The unfavorable prognosis predicted by MSI-L was ascribed to its correlation with lymphatic invasion. MSI-L characterized by di-nucleotide markers represents a distinct subcategory of GC with aggressive clinicopathological features, which are particularly affiliated to lymphatic system and correlated with a poor prognosis. MSI-L could be beneficial for predicting the clinical outcome of GC.

The refractoriness of acute promyelocytic leukemia (APL) with t (11;17)(q23;q21) to all- trans retinoic acid (ATRA)-based therapy concerns clinicians and intrigues basic researchers. By using a murine leukemic model carrying both promyelocytic leukemia zinc finger/retinoic acid receptor-α ( PLZF/RARα ) and RARα/PLZF fusion genes, we discovered that 8-chlorophenylthio adenosine-3′, 5′-cyclic monophosphate (8-CPT-cAMP) enhances cellular differentiation and improves gene trans -activation by ATRA in leukemic blasts. Mechanistically, in combination with ATRA, 8-CPT-cAMP activates PKA, causing phosphorylation of PLZF/RARα at Ser765 and resulting in increased dissociation of the silencing mediator for retinoic acid and thyroid hormone receptors/nuclear receptor corepressor from PLZF/RARα. This process results in changes of local chromatin and transcriptional reactivation of the retinoic acid pathway in leukemic cells. Meanwhile, 8-CPT-cAMP also potentiated ATRA-induced degradation of PLZF/RARα through its Ser765 phosphorylation. In vivo treatment of the t (11;17) APL mouse model demonstrated that 8-CPT-cAMP could significantly improve the therapeutic effect of ATRA by targeting a leukemia-initiating cell activity. This combined therapy, which induces enhanced differentiation and oncoprotein degradation, may benefit t (11;17) APL patients.

BACKGROUND: Via sequencing the genes of apelin/angiotensin receptor-like 1 (apelin/APJ) pathway, we have recently identified and validated four common polymorphisms (rs3761581, rs56204867, rs7119375, and rs10501367) implicated in the development of hypertension. Extending these findings, we, in Chinese hypertensive patients, sought to investigate the association of these four polymorphisms and one additional promising candidate (rs9943582) from this pathway with the risk of developing coronary artery disease (CAD). METHODOLOGY/PRINCIPAL FINDINGS: Genotypes were obtained from 994 sporadic CAD patients and 708 age- and sex-matched controls. All participants were hypertensives and angiographically-confirmed. Data were analyzed by Haplo.Stats and multifactor dimensionality reduction (MDR) softwares. Genotype distributions of five examined polymorphisms satisfied Hardy-Weinberg equilibrium in controls of both genders. Single-locus analyses exhibited no significant differences in the genotype/allele frequencies of examined polymorphisms between CAD patients and controls (P>0.05), even after controlling traditional cardiovascular confounders. In haplotype analyses, low-penetrance haplotype G-A (in order of rs56204867 and rs3761581 from apelin gene) was significantly overrepresented in controls (1.73%) relative to in CAD patients (0.4%) in males (P = 0.047). Further interaction analyses suggested an overall best MDR model including rs3761581 in males (P = 0.0408) and including rs7119375 and rs9943582 in females (P

Abnormalities of chromosome 11 involving mixed lineage leukemia (MLL) on 11q23 are often seen in acute myeloid leukemia (AML)-M5 or AML-M4. The fusion gene of MLL-PTD and MLL plays a critical role in the pathogenesis of these AML. However, rare chromosome abnormalities have been identified in this type of leukemia. To explore whether there were other MLL gene mutations at M4 and M5, in this study all of the MLL exons were sequenced at cDNA level. 25 patients with de novo AML-M4 or M5 with normal karyotypes excluding M4eo and MLL fusion gene or MLL-PTD were selected, the amplification and direct sequencing analysis of full length MLL gene exons were carried out, then the mutations found were verified at genomic DNA level. Furthermore, the point mutations were tested in normal samples and a larger group of AML patients using the platform of Mass Array. The results showed that high-frequency deletion/insertion and point mutations in RD, PHD, TAD and SET domains of MLL were found, while these alterations in normal samples and other subtypes of AML samples were also verified, and without significant difference (P0.05). It is concluded that a variety of deletions/insertions in MLL mRNA and point mutations are respectively alternative splicing of MLL gene at transcriptional level and single nucleotide polymorphism. These alternations together constituted genetic polymorphisms of MLL. Although these variations may not play a direct role in the molecular pathogenesis of AML-M4 or M5, their correlations to clinical treatment and prognosis need to be further explored.

This study was aimed to investigate the clinical feasibility of using multiplex PT-PCR assay for screening rare/cryptic chromosome translocations in patients with de novo acute myeloid leukemia. For 126 patients with de novo AML-M4/M5 without common chromosome translocations including t(15;17), t(8;21) and t(16;16), 3 parallel multiplex RT-PCR assays were set up to detect 6 mll-related gene rearrangements (mll/af10, mll/af17, mll/ell, mll/af9, mll/af6 and mll/enl) with low detection rate and 4 rare fusion genes (dek/can, tls/erg, aml1/mds (evi1) and npm/mlf1). The results showed that 11 patients with positive result from 126 patients were detected which involved in 5 molecular abnormalities. Among them, 10 cases were AML-M5 (16.67%), 1 cases AML-M4 (1.51%). The marker chromosomes were observed in 2 cases out of 11 cases through conventional karyotyping analysis, the karyotyping analysis in 1 case was not performed because this case had 1 mitotic figure only, no any cytogenetic aberrations were found in other 8 cases through R-band karyotyping analysis. It is concluded that multiplex RT-PCR designed in this study can quickly, effectively and accurately identify the rare/cryptic chromosome translocations and can be used in clinical detection.

Common genetic variations in genes involved in DNA repair or response to genotoxic stress may influence both cancer susceptibility and treatment response individually or interactively. However, in acute myeloid leukemia (AML), the relevance of these genetic variations remains to be fully established. In this study, we analyzed 42 genetic variations among 15 candidate genes in 307 AML patients and 560 age-sex matched controls. Their associations with chemotherapy response were further evaluated in combination with other well-established prognostic factors. An increased risk of AML was found in individuals heterozygous for XPD 2251A>C (rs13181) with an odds ratio (OR) of 1.637 (95% confidence interval [CI]: 1.118-2.395), and the increased risk could be attributed to C allele (OR = 1.505, 95% CI: 1.061-2.134). Postchemotherapy response analysis revealed that AML patients heterozygous for ATM 4138C>T (rs3092856) or GG homozygous for TP53 215C>G (rs1042522) were independently linked to inferior treatment outcomes. These results uncover novel prognostic factors for AML patients treated with chemotherapy and may also indicate an etiological role of XPD in this disease.

To determine whether genetic heterogeneity exists in patients with Graves' disease (GD), the cytotoxic T-lymphocyte associated 4 (CTLA-4) gene, which is implicated a susceptibility gene for GD by considerable genetic and immunological evidence, was used for association analysis in a Chinese Han cohort recruited from various geographic regions. Our association study for the SNPs in the CTLA4 gene in 2640 GD patients and 2204 control subjects confirmed that CTLA4 is the susceptibility gene for GD in the Chinese Han population. Moreover, the logistic regression analysis in the combined Chinese Han cohort revealed that SNP rs231779 (allele frequencies p = 2.81x10(-9), OR = 1.35, and genotype distributions p = 2.75x10(-9), OR = 1.42) is likely the susceptibility variant for GD. Interestingly, the logistic regression analysis revealed that SNP rs35219727 may be the susceptibility variant to GD in the Shandong population; however, SNP, rs231779 in the CTLA4 gene probably independently confers GD susceptibility in the Xuzhou and southern China populations. These data suggest that the susceptibility variants of the CTLA4 gene varied between the different geographic populations with GD.

AML1-ETO fusion gene is generated from chromosomal translocation t(8;21) mainly in acute myeloid leukemia M2 subtype (AML-M2). Its spliced variant transcript, AML1-ETO9a, rapidly induces leukemia in murine model. To evaluate its clinical significance, AML1-ETO9a expression was assessed in 118 patients with t(8;21) AML-M2, using qualitative and nested quantitative reverse transcriptase (RT)-PCR methods. These cases were accordingly divided into the AML1-ETO9a-H group (n=86, positive for qualitative RT-PCR, with higher level of AML1-ETO9a by quantitative RT-PCR) and the AML1-ETO9a-L group (n=32, negative for qualitative RT-PCR, with lower but still detectable level of AML1-ETO9a by quantitative RT-PCR). C-KIT expression was significantly increased in the AML1-ETO9a-H group, as compared with the AML1-ETO9a-L group. Of the 36 patients harboring C-KIT mutations, 32 patients overexpressed AML1-ETO9a (P=0.0209). Clinically, AML1-ETO9a-H patients exhibited significantly elevated white blood cells count, less bone marrow aberrant myelocytes, increased CD56 but decreased CD19 expression (P=0.0451, P=0.0479, P=0.0149 and P=0.0298, respectively). Moreover, AML1-ETO9a overexpression was related to short event-free and overall survival time (P=0.0072 and P=0.0076, respectively). Taken together, these data suggest that AML1-ETO9a is correlated with C-KIT overexpression/mutations and indicates poor disease outcome in t(8;21) AML-M2.

Graves' disease (GD) is one of the most common human autoimmune diseases, and recent data estimated a prevalence of clinical hyperthyroidism of 0.25-1.09% in the population. Several reports have linked GD to the region 5q12-q33; and a locus between markers D5s436 and D5s434 was specifically linked to GD susceptibility in the Chinese population. In the present study, association analysis was performed using a large number of single-nucleotide polymorphisms (SNPs) at this locus in 2811 patients with GD recruited from different geographic regions of China. The strongest associations with GD in the combined Chinese Han cohorts were mapped to two SNPs in the promoter (pSNP) of SCGB3A2 [SNP76, rs1368408, P = 1.43 x 10(-6), odds ratio (OR) = 1.28 and SNP75, -623 - -622, P = 7.62 x 10(-5), OR = 1.32, respectively], a gene implicated in immune regulation. On the other hand, pSNP haplotypes composed of the SNP76 (rs1368408)+SNP74 (rs6882292) or SNP76+SNP75 (-623 approximately -622, AG/T) variants are correlated with high disease susceptibility (P = 0.0007, and P = 0.0192, respectively) in this combined Chinese Han cohort. Furthermore, these haplotypes were associated with reduced SCGB3A2 gene expression levels in human thyroid tissue, while functional analysis revealed a relatively low efficiency of SCGB3A2 promoters of the SNP76+SNP75 and SNP76+SNP74 haplotypes in driving gene expression. These results suggest that the SCGB3A2 gene may contribute to GD susceptibility.

Chronic myeloid leukemia (CML) progression is characterized by occurrence of new cytogenetic and molecular abnormalities. In the previous study, we have shown the important role of GATA-2 L359 V mutation in CML progression. To further ascertain the truth of transcription factor GATA-2 in hematological malignancies, we expanded our study to GATA-2 full length by directly sequencing and applied MassARRAY assay into GATA-2 L359 V mutation analysis. Finally, no GATA-2 L359 V mutation was found in 270 acute myeloid leukemia, 30 myelodysplastic syndrome, 50 acute lymphoblastic leukemia, 12 chronic lymphocytic leukemia, 40 CML chronic phase and 286 BCR/ABL negative myeloproliferative disorders except CML blast crisis. A new variation of GATA-2 resulted in P250A change was identified, which was not found to have statistical difference between patients with hematological malignancies and healthy control. Hence, we concluded GATA-2 L359 V is exclusively associated with CML progression but not other hematological malignancies and P250A is a new single nucleotide polymorphism.

The FIP1L1-PDGFRalpha fusion gene plays an important role in the pathogenesis of chronic eosinophilic leukemia (CEL) and is a direct therapeutic target of the tyrosine kinase inhibitor imatinib mesylate.In 24 hypereosinophilic syndromes (HES) patients, using reverse transcriptase-polymerase chain reaction (RT-PCR), nested PCR and sequence analysis, we investigated the frequency of FIP1L1-PDGFRalpha and other abnormalities of tyrosine kinase family genes like PDGFRalpha, PDGFRbeta, C-KIT, FGFR1, ABL and FLT3 as well as gene mutation "hotspots", like MPL515 and JAK2V617F, frequently involved in myeloproliferative diseases. Fluorescence in situ hybridization was used to confirm the 4q12 deletion.The FIP1L1-PDGFRalpha fusion transcript was found in 8 (33%) of 24 patients with HES, corresponding to the chromosome 4q12 deletion identified by FISH. The FIP1L1-PDGFRalpha-associated patients diagnosed with CEL, frequently had hepatosplenomegaly, eosinophil-related tissue damage, anemia, thrombocytopenia, myelofibrosis and a short overall survival time. Nevertheless, imatinib mesylate induced rapid and complete hematological responses in treated FIP1L1-PDGFRalpha cases, followed by molecular remission and reversal of myelofibrosis. FIP1L1-PDGFRalpha fusion could co-exist with other mutations of tyrosine kinase family genes, like FLT3 or PDGFRbeta. We also demonstrated that the SNPs of PDGFRbeta were associated with selective splicing of exon 19 in case 20.Correlating the CEL genotype with phenotype, FIP1L1-PDGFRalpha emerges as a relatively homogeneous clinicobiological entity that co-exists with other abnormalities of tyrosine kinase family genes. It reflects the disease progression and there is a good response to imatinib. Detection of the FIP1L1-PDGFRalpha fusion gene is valid for both CEL diagnosis and therapy surveillance.

Acquisition of additional genetic and/or epigenetic abnormalities other than the BCR / ABL fusion gene is believed to cause disease progression in chronic myeloid leukemia (CML) from chronic phase to blast crisis (BC). To gain insights into the underlying mechanisms of progression to BC, we screened DNA samples from CML patients during blast transformation for mutations in a number of transcription factor genes that are critical for myeloid–lymphoid development. In 85 cases of CML blast transformation, we identified two new mutations in the coding region of GATA-2 , a negative regulator of hematopoietic stem/progenitor cell differentiation. A L359V substitution within zinc finger domain (ZF) 2 of GATA-2 was found in eight cases with myelomonoblastic features, whereas an in-frame deletion of 6 aa (Δ341–346) spanning the C-terminal border of ZF1 was detected in one patient at myeloid BC with eosinophilia. Further studies indicated that L359V not only increased transactivation activity of GATA-2 but also enhanced its inhibitory effects on the activity of PU.1, a major regulator of myelopoiesis. Consistent with the myelomonoblastic features of CML transformation with the GATA-2 L359V mutant, transduction of the GATA-2 L359V mutant into HL-60 cells or BCR / ABL -harboring murine cells disturbed myelomonocytic differentiation/proliferation in vitro and in vivo , respectively. These data strongly suggest that GATA-2 mutations may play a role in acute myeloid transformation in a subset of CML patients.

The positive regulatory domain I (PRDM1) is a master regulator in the differentiation of mature B lymphocytes to plasma cells. It has 2 isoforms, PRDM1alpha and PRDM1beta, and is regulated by the transcriptional regulator nuclear factor kappa (NF)-kappaB. PRDM1 protein expression was recently demonstrated in a subset of diffuse large B-cell lymphoma (DLBCL) with aggressive behavior, a type of lymphoma for which rituximab associated with chemotherapy (R-CHOP) is now widely indicated. Using laser microdissection combined with reverse transcription-polymerase chain reaction (RT-PCR) amplification, PRDM1 gene expression was assessed in 82 DLBCL patients. The results showed that both PRDM1alpha and PRDM1beta transcripts were expressed in microdissected lymphoma cells only in the non-germinal center B-cell-like (non-GCB) subtype of DLBCL. PRDM1beta gene expression was correlated with short survival time in the non-GCB patients treated with CHOP but not with R-CHOP. In vitro, B-lymphoma cells resistant to chemotherapy expressed PRDM1beta. Rituximab suppressed PRDM1beta expression, which was concomitant with NF-kappaB inactivation. The value of PRDM1beta expression as a prognostic marker in non-GCB DLBCL might thus be considered. This study confirms the efficiency of rituximab on DLBCL and allows a better understanding of one of its biologic actions.

We investigate the role of mutations of receptor tyrosine kinases as well as their downstream scaffold molecules in leukemogenesis of acute myeloid leukemia (AML) in Chinese patients. Genes of interest included FLT3, PDGFRbeta, KDR, CSF2Rbeta, SOCS1, PIAS3 and SHIP. The coding sequence of these genes was analysed by the reverse transcription-polymerase chain reaction to search novel mutations. A novel mutation (AT, Q1154L) of SHIP (1 of 192, 0.52%) was identified and another novel mutation (CT, R685C) of PDGFRbeta (2 of 192, 1.04%). In addition, FLT3 mutations were seen in three of five patients with AML following myelodysplastic syndrome (60%) and 39 of 268 (14.6%) de novo AML patients (P0.05). No mutations were found in the coding sequence regions of KDR, CSF2Rbeta, SOCS1 or PIAS3.

To investigate the significance of mutation and single nucleotide polymorphism (SNP) of class III receptor tyrosine kinases such as PDGFRbeta and SHIP in acute myeloid leukemia (AML) patients.Screening of the mutation and SNP of PDGFRbeta and SHIP by genomic PCR, RT-PCR, directly sequencing and Mass-ARRAY system was carried out in 273 AML patients.The mutations of PDGFRbeta R685C and SHIP Q1153L were detected for the first time in AML patients. The positivity ratio was 0.73% and 0.36% respectively.The mutations of PDGFRbeta R685C and SHIP Q1153L may contribute to leukemogenesis of AML.

Purpose: NOTCH signaling pathway is essential in T-cell development and NOTCH1 mutations are frequently present in T-cell acute lymphoblastic leukemia (T-ALL). To gain insight into its clinical significance, NOTCH1 mutation was investigated in 77 patients with T-ALL. Experimental Design: Detection of NOTCH1 mutation was done using reverse transcription-PCR amplification and direct sequencing, and thereby compared according to the clinical/biological data of the patients. Results: Thirty-two mutations were identified in 29 patients (with dual mutations in 3 cases), involving not only the heterodimerization and proline/glutamic acid/serine/threonine domains as previously reported but also the transcription activation and ankyrin repeat domains revealed for the first time. These mutations were significantly associated with elevated WBC count at diagnosis and independently linked to short survival time. Interestingly, the statistically significant difference of survival according to NOTCH1 mutations was only observed in adult patients (>18 years) but not in pediatric patients (≤18 years), possibly due to the relatively good overall response of childhood T-ALL to the current chemotherapy. NOTCH1 mutations could coexist with HOX11, HOX11L2, or SIL-TAL1 expression. The negative effect of NOTCH1 mutation on prognosis was potentiated by HOX11L2 but was attenuated by HOX11. Conclusion: NOTCH1 mutation is an important prognostic marker in T-ALL and its predictive value could be even further increased if coevaluated with other T-cell-related regulatory genes. NOTCH pathway thus acts combinatorially with oncogenic transcriptional factors on T-ALL pathogenesis.

BACKGROUND B-lineage acute lymphoblastic leukemia (B-ALL) represents the most common subtype in ALL. Genomic sequence information has been lacking in adult B-ALL, whose outcome remains dismal, while a comparison between genomic abnormalities in adult and pediatric groups is useful to further decipher disease mechanisms. METHODS We used whole exome sequencing (WES), copy number variation and molecular cytogenetics to catalog somatic mutations in 95 B-ALL patients (43 adults and 52 children).WES was conducted with appropriate depths for paired genomic DNA from bone marrow mononuclear cells at diagnosis and their matched peripheral blood samples during complete remission (CR) or saliva samples. Targeted deep sequencing (TDS) was performed in a validation cohort of 179 adult and 199 pediatric B-ALLs. RESULTS Eighty-four recurrent gene mutations were revealed by WES. Integrative analysis identified the involvement of 9 functional categories of genes: key fusions (KFs), epigenetic modifiers (EMs), signaling molecules (SMs), transcription factors (TFs), tumor suppressors (TSs), actin binding/cytoskeletons (ABCs), ion binding proteins (IBPs), trans-membrane proteins (TPs) and the others. Mutually cooperative or exclusive relationships were revealed among some of these categories. Genomic landscapes suggested two distinct mechanisms involved in the leukemogenesis: one is mainly driven by KFs together with mutations of TFs and TSs; the other results from the abnormalities of TFs and TSs, in cooperation with mutations of EMs, SMs, ABCs and IBPs recapitulating the role of KFs. A panel of histone/DNA methylation modifiers (HMMs) were revealed to bear potential value of relatively favorable prognosis in both adult and childhood patients. CONCLUSIONS We described the genome-wide abnormality patterns in adult B-ALL patients in comparison with those of pediatric cases, contributing to the understanding of leukemogenesis and the identification of potential new prognostic markers. Disclosures No relevant conflicts of interest to declare.

Both all-trans retinoic acid (ATRA) and arsenic trioxide (As 2 O 3 ) have proven to be very effective in obtaining high clinical complete remission (CR) rates in acute promyelocytic leukemia (APL), but they had not been used jointly in an integrated treatment protocol for remission induction or maintenance among newly diagnosed APL patients. In this study, 61 newly diagnosed APL subjects were randomized into three treatment groups, namely by ATRA, As 2 O 3 , and the combination of the two drugs. CR was determined by hematological analysis, tumor burden was examined with real-time quantitative RT-PCR of the PML-RAR α (promyelocytic leukemia - retinoic acid receptor α) fusion transcripts, and side effects were evaluated by means of clinical examinations. Mechanisms possibly involved were also investigated with cellular and molecular biology methods. Although CR rates in three groups were all high (≥90%), the time to achieve CR differed significantly, with that of the combination group being the shortest one. Earlier recovery of platelet count was also found in this group. The disease burden as reflected by fold change of PML-RARα transcripts at CR decreased more significantly in combined therapy as compared with ATRA or As 2 O 3 mono-therapy ( P < 0.01). This difference persisted after consolidation ( P < 0.05). Importantly, all 20 cases in the combination group remained in CR whereas 7 of 37 cases treated with mono-therapy relapsed ( P < 0.05) after a follow-up of 8–30 months (median: 18 months). Synergism of ATRA and As 2 O 3 on apoptosis and degradation of PML-RARα oncoprotein might provide a plausible explanation for superior efficacy of combinative therapy in clinic. In conclusion, the ATRA/As 2 O 3 combination for remission/maintenance therapy of APL brings much better results than either of the two drugs used alone in terms of the quality of CR and the status of the disease-free survival.

Abstract 2382 Epigenetic modification process is required for the development of hematopoietic cells. DNA methyltransferase DNMT3A, responsible for de novo DNA methylation, was newly reported to have a high frequency of mutations in hematopoietic malignancies. Conditional knock-out of DNMT3A promoted self-renewal activity of murine hematopoietic stem cells (HSCs). However, the role of mutated DNMT3A in hematopoiesis and its regulative mechanism of epigenetic network mostly remain unknown. Here we showed that the Arg882His (R882H) hotspot locus on DNMT3A impaired the normal function of this enzyme and resulted in an abnormal increase of primitive hematopoietic cells. In both controlled in vivo and in vitro assays, we found that the cells transfected by R882H mutant promoted cell proliferation, while decreased the differentiation of myeloid lineage compared to those with wild type. Analysis of bone marrow (BM) cells from mice transduced by R882H reveals an expansion of Lin−Sca-1+C-kit+ populations and a reduction of mature myeloid cells. Meanwhile, a cluster of upregulated genes and downregulated lineage-specific differentiation genes associated with hematopoiesis were discovered in mice BM cells with R882H mutation. We further evaluated the association of mutated DNMT3A and HOXB4 which was previously detected to be highly expressed in clinical samples carrying R882 mutation. Compared with wildtype DNMT3A, R882H mutation disrupted the repression of HOXB4 by largely recruiting tri-methylated histone 3 lysine 4 (H3K4). Taken together, our results showed that R882H mutation disturbed HSC activity through H3K4 tri-methylation, and transcriptional activation of HSC-related genes. Disclosures: No relevant conflicts of interest to declare.

Abstract 2187 Poster Board II-164 Chronic myeloid leukemia (CML) progression is characterized by occurrence of new cytogenetic and molecular abnormalities. In the previous study, we have shown the important role of GATA-2 L359V mutation in CML progression. To further ascertain the truth of transcription factor GATA-2 in hematological malignancies, we expanded our study to GATA-2 full length by directly sequencing and applied MassARRAY assay into GATA-2 L359V mutation analysis. Finally, no GATA-2 L359V mutation was found in 270 acute myeloid leukemia, 30 myelodysplastic syndrome, 50 acute lymphoblastic leukemia, 12 chronic lymphocytic leukemia, 40 CML chronic phase and 286 BCR/ABL negative myeloproliferative disorders except CML blast crisis. A new variation of GATA-2 resulted in P250A change was identified, which was not found to have statistical difference between patients with hematological malignancies and healthy control. Hence, we concluded GATA-2 L359V is exclusively associated with CML progression but not other hematological malignancies and P250A is a new single nucleotide polymorphism. Disclosures: No relevant conflicts of interest to declare.

In recent three years the new notable progress associated with myeloproliferative disorder (MPD) was the identification of JAK2 and MPL mutations, which have been confirmed to be the major molecular mechanism and marker of BCR/ABL negative MPD. Multiple techniques including allele-specific PCR, conventional DNA sequencing, pyrosequencing as well as BsaXI restriction analysis have been used to detect these mutations. The previous data of Shanghai Group had demonstrated the sensitivity and preliminary result of JAK2 V617F in 162 Chinese patients with MPD using MassARRAY assay. To generally identify the frequency of these mutations in Chinese MPD patients, we continued to employ this technique-MassARRAY assay to detect JAK2 V617F, JAK2 K539L as well as MPL W515L mutation in a larger scale of Chinese MPD patients. A total of 204 Chinese MPD patients were enrolled in our study. These patients were referred to polycythemia vera (PV) (n=55), essential thrombocythemia (ET) (n=110), primary myelofibrosis (PMF) (n=29) and hypereosinophilic syndrome (HES) (n=10). 2 ml peripheral blood was obtained with informed consent and genomic DNA was isolated. The diagnosis of MPD was established according to the 2001 WHO diagnostic criteria. Finally, 187 patient samples with good signal can be analyzed for JAK2 V617F mutation. Among the available 101 signals of ET patients, 30 were heterozygous mutation and 9 were homozygous mutation. Among 52 PV patients, 25 were heterozygous mutation and 14 were homozygous mutation. Among 25 PMF patients, 9 were heterozygous mutation and 5 were homozygous mutation. None of HES patients was found harboring JAK2 V617F. In addition, we identified a PV patient harboring JAK2 K539L but not V617F mutation (1/52, 1.9%), and an ET patient harboring MPL W515L mutation (1/101, 1%). Both results were further confirmed by sequence analysis. Hence, we concluded that JAK2 V617F underlie the major molecular pathogenesis of Chinese MPD patients especially PV, however, JAK2 K539L and MPL W515L are rare events in these patients.

Chronic Myeloid Leukemia (CML) is a hematopoietic stem cell disease with distinct biology and clinical features. According to clinical and biology process, CML can be divided as two different phase: the initial chronic phase (CP) and progression phase including accelerated phase (AP) followed by blast crisis (BC). In a previous study, we have identified the transcription factor GATA-2 L359V mutation in CML BC patients but not CP and its pivotal role in CML progression (PNAS 2008 105:2076–2081). Here, we continued to explore the occurrence of GATA-2 L359V mutation in other hematological malignancies using Mass-ARRAY assay and sequence analysis. A total of 652 patient samples were included in our study. These patients were referred to 270 Acute Myeloid Leukemia (AML) including M1–M7, 30 Myelodysplastic Syndrome (MDS), 50 Acute Lymphoblastic Leukemia (ALL), 12 Chronic Lymphocytic Leukemia (CLL), 40 CML CP and 250 BCR/ABL negative Myeloproliferative Disorder (MPD) patients. 5 ml bone marrow sample before therapy was collected with informed consent and genomic DNA was isolated. The diagnosis of AML, ALL, CML, CLL, MDS and MPD was established according to the 2001 WHO diagnostic criteria. In addition, 8 samples of CML BC harboring GATA-2 L359V were supplied into our study as positive control and 100 peripheral blood samples of healthy adult as normal control. As a result, no L359V mutation was detected in AML, ALL, MDS, CLL, BCR/ABL negative MPD and CML CP. Our data strongly suggested that GATA-2 L359V is solely associated with CML progression but not other hematological malignancies. Therefore, we favored this idea, i.e., BCR/ABL underlies the pathogenic basis of CML CP; However, subsequent genomic instabilities contribute to mutation of key transcription factor such as GATA-2 which ultimately trigger the blastic transformation of CML.

Acquisition of additional genetic and/or epigenetic abnormalities other than BCR/ABL fusion gene is believed to cause disease progression in chronic myeloid leukemia (CML) from chronic phase to blast phase. To gain insights into the underlying mechanisms, we screened DNA samples from CML patients during acute transformation for alterations in a number of transcription factor genes crucial to myeloid-lymphoid development. In 85 cases of CML blast transformation, we identified two new mutations in the coding region of GATA-2, a negative regulator of hematopoietic stem/progenitor cell differentiation. L359V within zinc finger domain (ZF) 2 of GATA-2 was found in 8 cases with myelo-monoblastic features, while an in-frame deletion of six amino acids (D341–346) across the border of ZF1 was detected in 1 patient at blast crisis with eosinophilia. Further studies showed that L359V not only increased transactivation activity, but also enhanced inhibitory effects on the major myelopoietic regulator PU.1. Consistent with the myelo-monoblastic features of CML patients with GATA-2 L359V mutant, transduction of GATA-2 L359V mutant into HL-60 cells or BCR/ABL-harboring mouse model disturbed myelo-monocytic differentiation/proliferation in vitro and in vivo, respectively. These data suggest that GATA-2 mutations may be involved in acute myeloid transformation in some CML patients.

The NUP98 gene has been reported to be fused with at least 17 partner genes in leukemia with 11p15 translocation. An adult patient with de novo acute myeloid/T lymphocytic leukemia harboring t(3;11)(q29q13;p15) has been investigated to characterize the genes involved in that translocation. Through molecular cytogenetic analysis, we identified a fusion transcript between NUP98 gene and a novel partner gene named as NUP98 related gene (NRG) at 3q29. Further molecular analysis showed that exon 13 of NUP98 was fused in-frame to exon 10 of NRG. Moreover, the segment from 3q13 to 3q29 translocated at 11p15 had been inverted and accompanied by the deletion of the distal portion of breakpoint at chromosome 3q29. Interestingly, the NUP98-NRG protein showed nuclear and cytoplasmic distribution, a pattern different from that of wild type NUP98 or NRG. When assayed in a GAL 4 reporter system, the fusion gene showed an aberrant trans-regulatory activity. Transfection in HL-60 cells demonstrated that NUP98-NRG could promote cell proliferation, survival and arrest differentiation. Therefore, NUP98-NRG may exert transforming effects by interfering with the cellular mechanism of transcriptional regulation. Our data provide thus new evidence that NUP98-related molecular abnormality is a recurrent genetic event in leukemogenesis.