Expression of TGF-β Superfamily Receptor ALK-5 Is Associated with Decreased Overall Survival of AML Patients Receiving Standard AML Chemotherapy.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1604-1604
Author(s):  
Jasmin Otten ◽  
Lisa Schmitz ◽  
Eik Vettorazzi ◽  
Alexander Schultze ◽  
Jürgen Krauter ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bone Marrow ◽  
Overall Survival ◽  
Endothelial Cells ◽  
Target Genes ◽  
Downstream Target ◽  
Alk 5 ◽  
Tgf Β1 ◽  
Pai 1 ◽  
Acute Myeloid

Abstract Abstract 1604 Poster Board I-630 Introduction Bone marrow neoangiogenesis plays an important role in acute myeloid leukaemia. TGF-β has been shown to be involved in angiogenesis. TGF-β receptors are comprised of class I, class II and accessory receptors. Class I TGF-β receptor ALK-1 is mainly expressed on endothelial cells whereas ALK-5 is found on endothelial cells and various cell types including tumor cells. Patients and Methods m-RNA and protein expression of ALK-1 and ALK-5 were studied in several leukemic cell lines by PCR and FACS analysis. Expression of both receptors and their respective ligands, bone morphogenic proteins (BMP) -9 and -10 and TGF-β1, were analyzed by real-time quantitative PCR in pretherapeutic samples from 93 acute myeloid leukaemia (AML) patients enrolled into the AMLSG 07-04 study of the Austrio-German AMLSG study group. To evaluate ALK-1 and ALK-5 receptor activation, expression of downstream target genes ID-1 and PAI-1 were also determined by quantitative PCR. Uni- and multivariate analyses were performed using clinical and gene expression variables. Results ALK-1 and ALK-5 were expressed by several leukemic cells lines including KG-1 and UKE-1 where endothelial cells (HUVECs and OECs) served as positive controls. Expression of ALK-1 and ALK-5 were found in the majority of AML patients (82 % and 88 %, respectively). All patients expressed TGF-β1, whereas the percentage of BMP-expressing patients was low (8 % for BMP-9, 13 % for BMP-10). Expression of downstream targets ID-1 and PAI-1 was detected in almost all patients (99 % and 100 %, respectively). The impact of gene expression on achievement of CR and event-free (EFS), relapse-free (RFS) and overall survival (OS), was analyzed. Due to low numbers of patients with BMP-9 and -10 expression and inconclusive PCR results for ALK-1 and PAI-1 in several patients, these variables were only studied by univariate analysis. No effect of ALK-1, PAI-1, BMP-9 or -10 expression on clinical outcome was detected. Patients with low vs. high ALK-5 expression achieved a CR rate 63 % vs. 27 %, respectively. Multivariate analysis included ALK-5, TGF-β1 and ID-1 gene expression as well as the baseline variables sex, age, karyotype and FLT3 mutation status. During the stepwise procedure of the Cox regression, several variables were eliminated. Only ALK-5 and the karyotype showed a significant impact on event-free, relapse-free and overall survival (ALK-5: p=0,001 for EFS, p<0,001 for RFS, p=0,008 for OS; karyotype: p<0,001 for EFS, p<0,001 for RFS, p=0,008 for OS). Conclusion ALK-1 and ALK-5 expression is found in bone marrow and peripheral blood samples from the majority of AML patients. Both receptors are found on endothelial cells and on leukemic blasts. Both receptors are in an activated state as demonstrated by expression of downstream target genes. High ALK-5 expression results in a low CR rate which translates into reduced EFS, RFS and OS of AML patients. Therefore ALK-5 expression represents a new prognostic marker in AML. Recently published data (Shao, Blood. 2009 Jun 8. [Epub ahead of print]) demonstrate involvement of both ALK-1 and ALK-5 in the regulation of vascular endothelial growth factor which is believed to be the central growth factor in angiogenesis. Hence, the ALK-1/ALK-5 pathway might represent a novel therapeutic target in AML. Disclosures No relevant conflicts of interest to declare.

High Serum Level of Placental Growth Factor (PlGF) Predicts Adverse Overall Survival in Patients with Acute Myeloid Leukemia Treated with Standard Chemotherapy

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3972-3972
Author(s):  
Agnieszka Wierzbowska ◽  
Anna Krawczynska ◽  
Ewa Wawrzyniak ◽  
Agnieszka Pluta ◽  
Anna Wolska ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Overall Survival ◽  
Endothelial Cells ◽  
Acute Myeloid Leukemia ◽  
Growth Factor ◽  
Myeloid Leukemia ◽  
Univariate Analysis ◽  
Placental Growth Factor ◽  
Healthy Controls ◽  
Acute Myeloid

Abstract Background: Angiogenesis plays an important role in the pathogenesis of acute myeloid leukemia (AML) and vascular endothelial growth factor (VEGF) is an essential positive regulator of this process. Placental growth factor (PlGF) is a member of VEGF family that exerts its angiogenic action by synergizing with VEGF. There is also evidence that PlGF may be survival factor for angiogenic endothelial cells. The role of PlGF in patients with acute leukemia have not been investigated at all. Material and methods: We measured the plasma concentrations of VEGF and PlGF in 61 patients with newly diagnosed AML and 22 healthy controls using the ELISA assay. Additionally, in AML patients we correlated the plasma levels of angiogenic cytokines with the number of viable (CEC) and apoptotic (CECAnnV+) circulating endothelial cells, known prognostic factors, response to induction therapy as well as overall survival (OS). The AML group consisted of 34 women and 27 men with a median age of 49 years (range 25–76 years). All patient received standard induction chemotherapy (according to 3+7 protocol). Statistical analysis included the following variables: VEGF and PlGF levels, age, sex, performance status, cytogenetic risk group according SWOG, presence of multilineage dysplasia, WBC and PLT count, hemoglobin level, LDH activity, % of bone marrow blasts and CEC as well as CECAnnV+ number. Results: The PlGF and VEGF median levels (23,6 pg/ml and 45,1 pg/ml respectively) were significantly higher in the AML at diagnosis than in the healthy subjects (9,5 pg/ml; p&lt;0,0001 and 25,2 pg/ml; p&lt;0,03 respectively). Moreover, the VEGF level at diagnosis in patients who did not respond to induction chemotherapy was significantly higher than in patients who achieved complete remission (CR) (84,7 vs 31,2 pg/ml; p&lt;0,01). The significant negative correlation between the VEGF and percentage of apopototic CECAnnV+ was also observed. Median follow-up was 12,1 months (range: 1– 43 months). 50 patients (82%) achieved CR. The CR rate in low and high VEGF expressors was respectively 86% and 70% (p=0.07). The CR rate in high- and low PlGF expressors did not differ significantly (74% and 80% respectively). In univariate analysis poor cytogenetics was the only factor associated with increased risk of treatment failure. The median time of OS in analysed group was 15 months. In the univariate analysis high (over median) PlGF levels was associated with shorter OS (p=0.005) (Figure1). Shorter OS was also associated with age&gt;40 years (p=0.009), failure to achieve CR (p=0.009) and higher (&gt;50%) bone marrow infiltration with leukemic blasts (p=0.005). In the multivariate Cox proportional hazard model the elevated PlGF plasma level was strongly associated with shorter OS (p&lt;0.007). The other factors found to influence shorter OS were: high bone marrow infiltration with leukemic blasts (p=0.02), age&gt;40 years (p=0.04), failure to achieve CR (p=0.04). Conclusions: In conclusion we can state that the high plasma concentration of PlGF is associated with poor prognosis in AML patients. Observed in our study significantly higher PlGF level in AML patients compared to healthy controls may indicate that this angiogenic cytokine plays an important, independent of VEGF role in pathogenesis of AML Figure Figure

Enasidenib: First Mutant IDH2 Inhibitor for the Treatment of Refractory and Relapsed Acute Myeloid Leukemia

2019 ◽  
Vol 18 (14) ◽  
pp. 1936-1951 ◽  
Author(s):  
Raghav Dogra ◽  
Rohit Bhatia ◽  
Ravi Shankar ◽  
Parveen Bansal ◽  
Ravindra K. Rawal
Keyword(s):  
Clinical Trial ◽  
Bone Marrow ◽  
Overall Survival ◽  
Acute Myeloid Leukemia ◽  
Adverse Effects ◽  
Blood Cells ◽  
Myeloid Leukemia ◽  
White Blood Cells ◽  
Phase Iii ◽  
Acute Myeloid

Background: Acute myeloid leukemia is the collective name for different types of leukemias of myeloid origin affecting blood and bone marrow. The overproduction of immature myeloblasts (white blood cells) is the characteristic feature of AML, thus flooding the bone marrow and reducing its capacity to produce normal blood cells. USFDA on August 1, 2017, approved a drug named Enasidenib formerly known as AG-221 which is being marketed under the name Idhifa to treat R/R AML with IDH2 mutation. The present review depicts the broad profile of enasidenib including various aspects of chemistry, preclinical, clinical studies, pharmacokinetics, mode of action and toxicity studies. Methods: Various reports and research articles have been referred to summarize different aspects related to chemistry and pharmacokinetics of enasidenib. Clinical data was collected from various recently published clinical reports including clinical trial outcomes. Result: The various findings of enasidenib revealed that it has been designed to allosterically inhibit mutated IDH2 to treat R/R AML patients. It has also presented good safety and efficacy profile along with 9.3 months overall survival rates of patients in which disease has relapsed. The drug is still under study either in combination or solely to treat hematological malignancies. Molecular modeling studies revealed that enasidenib binds to its target through hydrophobic interaction and hydrogen bonding inside the binding pocket. Enasidenib is found to be associated with certain adverse effects like elevated bilirubin level, diarrhea, differentiation syndrome, decreased potassium and calcium levels, etc. Conclusion: Enasidenib or AG-221was introduced by FDA as an anticancer agent which was developed as a first in class, a selective allosteric inhibitor of the tumor target i.e. IDH2 for Relapsed or Refractory AML. Phase 1/2 clinical trial of Enasidenib resulted in the overall survival rate of 40.3% with CR of 19.3%. Phase III trial on the Enasidenib is still under process along with another trial to test its potency against other cell lines. Edasidenib is associated with certain adverse effects, which can be reduced by investigators by designing its newer derivatives on the basis of SAR studies. Hence, it may come in the light as a potent lead entity for anticancer treatment in the coming years.

scholarly journals si-SNHG5-FOXF2 inhibits TGF-β1-induced fibrosis in human primary endometrial stromal cells by the Wnt/β-catenin signalling pathway

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Limin Liu ◽  
Guobin Chen ◽  
Taoliang Chen ◽  
Wenjuan Shi ◽  
Haiyan Hu ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Stromal Cells ◽  
Target Genes ◽  
Cell Model ◽  
Ex Vivo ◽  
Signalling Pathway ◽  
Endometrial Stromal Cells ◽  
Downstream Target ◽  
Related Proteins ◽  
Tgf Β1

Abstract Background Intrauterine adhesions (IUAs) are manifestations of endometrial fibrosis characterized by inflammation and fibrinogen aggregation in the extracellular matrix (ECM). The available therapeutic interventions for IUA are insufficiently effective in the clinical setting for postoperative adhesion recurrence and infertility problems. In this study, we investigated whether si-SNHG5-FOXF2 can serve as a molecular mechanism for the inhibition of IUA fibrosis ex vivo. Methods FOXF2, TGF-β1 and collagen expression levels were measured by microarray sequencing analysis in three normal endometrium groups and six IUA patients. We induced primary human endometrial stromal cells (HESCs) into myofibroblasts (MFs) to develop an IUA cell model with various concentrations of TGF-β1 at various times. Downstream target genes of FOXF2 were screened by chromatin immunoprecipitation combined with whole-genome high-throughput sequencing (ChIP-seq). We investigated ECM formation, cell proliferation and Wnt/β-catenin signalling pathway-related proteins in primary HESCs with FOXF2 downregulation by quantitative reverse transcription-polymerase chain reaction (qRT-PCR), western blotting (WB), immunohistochemistry (IHC), flow cytometry, ethylenediurea (EdU) and CCK8 assays. We identified long noncoding RNAs (lncRNA) SNHG5 as the upstream regulatory gene of FOXF2 through RNA immunoprecipitation (RIP), RNA pulldown and fluorescence in situ hybridization (FISH). Finally, we examined FOXF2 expression, ECM formation, cell proliferation and Wnt/β-catenin signalling pathway-related proteins in primary HESCs upon FOXF2 downregulation. Results FOXF2 was highly expressed in the endometrium of patients with IUA. Treatment of primary HESCs with 10 ng/ml TGF-β1 for 72 h was found to be most effective for developing an IUA cell model. FOXF2 regulated multiple downstream target genes, including collagen, vimentin (VIM) and cyclin D2/DK4, by ChIP-seq and ChIP-PCR. FOXF2 downregulation inhibited TGF-β1-mediated primary HESC fibrosis, including ECM formation, cell proliferation and Wnt/β-catenin signalling pathway-related protein expression. We identified lncRNA SNHG5 as an upstream gene that directly regulates FOXF2 by RIP-seq, qRT-PCR, WB and FISH. SNHG5 downregulation suppressed FOXF2 expression in the IUA cell model, resulting in synergistic repression of the Wnt/β-catenin pathway, thereby altering TGF-β1-mediated ECM aggregation in endometrial stromal cells ex vivo. Conclusions Regulation of the Wnt/β-catenin signalling pathway and ECM formation by si-SNHG5-FOXF2 effectively inhibited the profibrotic effect of TGF-β1 on primary HESCs. This finding can provide a molecular basis for antagonizing TGF-β1-mediated fibrosis in primary HESCs.

scholarly journals SETDB1 mediated histone H3 lysine 9 methylation suppresses MLL-fusion target expression and leukemic transformation

Haematologica ◽  
2019 ◽  
Vol 105 (9) ◽  
pp. 2273-2285 ◽  
Author(s):  
James Ropa ◽  
Nirmalya Saha ◽  
Hsiangyu Hu ◽  
Luke F. Peterson ◽  
Moshe Talpaz ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Target Genes ◽  
Critical Role ◽  
High Expression ◽  
Leukemia Cells ◽  
Biological Impact ◽  
Hematopoietic Stem ◽  
Acute Myeloid

Epigenetic regulators play a critical role in normal and malignant hematopoiesis. Deregulation, including epigenetic deregulation, of the HOXA gene cluster drives transformation of about 50% of acute myeloid leukemia. We recently showed that the Histone 3 Lysine 9 methyltransferase SETDB1 negatively regulates the expression of the pro-leukemic genes Hoxa9 and its cofactor Meis1 through deposition of promoter H3K9 trimethylation in MLL-AF9 leukemia cells. Here, we investigated the biological impact of altered SETDB1 expression and changes in H3K9 methylation on acute myeloid leukemia. We demonstrate that SETDB1 expression is correlated to disease status and overall survival in acute myeloid leukemia patients. We recapitulated these findings in mice, where high expression of SETDB1 delayed MLL-AF9 mediated disease progression by promoting differentiation of leukemia cells. We also explored the biological impact of treating normal and malignant hematopoietic cells with an H3K9 methyltransferase inhibitor, UNC0638. While myeloid leukemia cells demonstrate cytotoxicity to UNC0638 treatment, normal bone marrow cells exhibit an expansion of cKit+ hematopoietic stem and progenitor cells. Consistent with these data, we show that bone marrow treated with UNC0638 is more amenable to transformation by MLL-AF9. Next generation sequencing of leukemia cells shows that high expression of SETDB1 induces repressive changes to the promoter epigenome and downregulation of genes linked with acute myeloid leukemia, including Dock1 and the MLL-AF9 target genes Hoxa9, Six1, and others. These data reveal novel targets of SETDB1 in leukemia that point to a role for SETDB1 in negatively regulating pro-leukemic target genes and suppressing acute myeloid leukemia.

Quantification of MDM2 Gene Expression Level by RQ-PCR Is Predictive of the First Complete Remission in Adulte Acute Myeloid Leukaemia.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1068-1068 ◽  
Author(s):  
Nathalie Gachard ◽  
Pascal Turlure ◽  
Franck Trimoreau ◽  
Stephane Moreau ◽  
Magali Donnard ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bone Marrow ◽  
Complete Remission ◽  
P53 Gene ◽  
Low Doses ◽  
Mdm2 Gene ◽  
Expression Levels ◽  
Mdm2 Expression ◽  
Gene Expression Levels ◽  
Acute Myeloid

Abstract The overall survival of patients with p 53 mutated gene acute myeloid leukaemia (AML) is significantly shorter than those of patients without mutations. The frequency of p53 gene mutations in AML ranges from 4 to 15% in populations from USA and Europe, thus this is not a useful criteria in the vast majority of patients with a poor prognosis. Mdm2 is the natural functional inhibitor of p53, but very few studies have assessed its prognosis value in AML, and this was done only at the protein level, suffering major lacking of precision. In this study, we have quantified gene expression levels of both MDM2 and p53 by RQ-PCR in a series of 18 patients with more that 50% blast cell in the bone marrow: 4 AML1, 6 AML2 (one with multilineage dysplasia), 4 AML4 (one AML4 Eos), 4 AML5. Median age was 57 years, ranging 39–84. Eight patients had a white cell blood count over 30 G/L. Eleven patients had a normal karyotype, 3 had a complex caryotype, 2 had an inv(16). FLT3 amplification was found in 2 cases. Two patients died immediately following the diagnosis because of an immediate massive global failure of vital functions. Three patients were treated with low doses of Aracytine because of the performance status. Thirteen patients were treated with intensive chemotherapy according classical scheme, and complete remission was obtained in 6 cases. After total RNA extraction of bone marrow mononuclear cells, assessment of MDM2 and p53 gene expression levels was done in duplicate on an ABI PRISM 7000 automat using the TaqManR Assay on demandTM gene expression reference system. The Abl1 gene was used as a reference gene for the control of amplification. The relative expression levels of the genes were calculated as follow: briefly, for each gene, the cycle threshold (CT) was defined for a delta Rn of 10−1. Then, the delta CT (DCT) was calculated as the CT of the gene minus the CT of Abl1 (expected CT for Abl1 ranged from 22 to 24). For each experimental condition, the delta delta CT (DDCT) was calculated as the DCT of the given condition minus the DCT of the RNA pool. For each gene and in each experimental condition, the calculated relative gene expression level was equal to 2−DDCT. No correlation was found between p53 gene expression levels and any of the other clinical, biological or genetic prognosis marker. By contrast, complete remission was obtained for all patients with low levels MDM2 expression and MDM2 expression was markedly increased in 5 out the 7 patient without remission (t-test, p=0,01). It is noteworthy that, among the 3 patients treated with low doses of Aracytine, the patient with the shortest survival was the only one with increased levels of MDM2. No correlation was found between MDM2 gene expression levels and other biological prognosis markers. This suggests that quantification of MDM2 mRNA by RQ-PCR could be an interesting prognosis factor in AML.

Identification of Distinct inv(16) Subclasses in Adult Acute Myeloid Leukemia Based on Gene Expression Profiling.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2037-2037
Author(s):  
Lars Bullinger ◽  
Claudia Scholl ◽  
Eric Bair ◽  
Konstanze Dohner ◽  
Stefan Frohling ◽  
...  
Keyword(s):  
Gene Expression ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Target Genes ◽  
Expression Patterns ◽  
Rank Test ◽  
Survival Times ◽  
Strong Trend ◽  
Candidate Target ◽  
Acute Myeloid

Abstract Recurrent cytogenetic aberrations have been shown to constitute markers of diagnostic and prognostic value in acute myeloid leukemia (AML). However, even within the well-defined cytogenetic AML subgroup with an inv(16) we see substantial biological and clinical heterogeneity which is not fully reflected by the current classification system. To better characterize this cytogenetic group on the molecular level we profiled gene expression in a series of adult AML patients (n=26) with inv(16) using 42k cDNA microarrays. By unsupervised hierarchical clustering we observed that samples with inv(16) separated primarily into two different subgroups. These showed no significant differences regarding known risk factors like age, WBC, LDH, etc. However, these newly defined inv(16)-subgroups were characterized by distinct clinical behavior. There was a strong trend towards unfavorable outcome with shorter overall survival times in one group (P=0.09, log rank test). Since the primary translocation/inversion events themselves are not sufficient for leukemogenesis, distinct patterns of gene expression found within each of these cytogenetic groups may suggest alternative cooperating mutations and deregulated pathways leading to transformation. Therefore, we performed a supervised analysis to determine the characteristic gene expression patterns underlying the cluster-defined subgroups. This Significance Analysis of Microarrays (SAM) method identified 260 genes significantly differentially expressed between the two newly defined inv(16)-subgroups (false discovery rate = 0.002). High expression levels of JUN, JUNB, JUND, FOS and FOSB characterized the first inv(16) subgroup (having less favorable prognosis). FOS gene family members can dimerize with proteins of the JUN family, forming the transcription factor complex AP-1 which has been implicated in the regulation of cell proliferation, differentiation, and transformation. Among the second subgroup, the proto-oncogene ETS1,displayed elevated expression, possibly resulting from aberrant MEK/ERK pathway activation as these cases also showed an over-expression of MAP3K1 and MAP3K2. In conclusion, both supervised and unsupervised methods provide numerous insights into the pathogenesis of AML with inv(16), identifying clinically significant patterns of gene expression, as well as candidate target genes involved in leukemogenesis.

Global Gene Expression Analysis Demonstrates that Transforming Growth Factor β1 (TGF-β1) Signals Exclusively through Receptor Complexes Involving TGF-β Receptor I and Identifies Numerous Targets of TGF-β Signaling.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2178-2178
Author(s):  
Goran Karlsson ◽  
Yingchun Liu ◽  
Marie-José Goumans ◽  
Jonas Larsson ◽  
Ju-Seog Lee ◽  
...  
Keyword(s):  
Gene Expression ◽  
Expression Analysis ◽  
Gene Expression Analysis ◽  
Target Genes ◽  
Global Gene Expression ◽  
Differentially Expressed ◽  
Global Gene Expression Analysis ◽  
Β Receptor ◽  
Tgf Β1

Abstract In the hematopoietic system, TGF-β1 is one of the most potent extrinsic regulators, affecting both early progenitors and committed cells. At the top of the hematopoietic hierarchy, TGF-β1 maintains hematopoietic stem cells (HSCs) in quiescence in vitro through transcriptional regulation of genes encoding proteins important in the cell cycle. We have shown that TGF-β receptor I (TβRI) −/− HSCs exhibit increased proliferative capacity in vitro and that TβRII−/− mice develop a multifocal autoimmune disease, mainly mediated by T-cells (Larsson et al, 2003, Levéen et al 2002). The mechanisms of TGF-β signaling in hematopoietic cells are poorly understood and many target genes of TGF-β signaling remain elusive. In this study we have used global gene expression analysis to investigate whether all TGF-β signaling is mediated by TβRI and II. Furthermore, we asked what target genes are affected upon TGF-β stimulation in normal and TGF-β signaling deficient murine embryonic fibroblasts (MEFs). MEFs were grown with and without TGF-β1 stimulation and proliferation, transcriptional responses and expression analysis were performed. We demonstrate through Western Blot analysis, luciferase reporter assays and cell expansion experiments how these cells lack functional TβRI. Additionally, transcriptional assays show that no other Smad activity is triggered by TGF-β1 stimulation. Furthermore, we demonstrate through quantitative RT-PCR that the inhibitor of differentiation family of genes, known targets of TGF-β signaling, are not affected by TGF-β1 in TβRI−/− MEFs, while wt cells downregulate these genes 4–8.5 fold in response to stimulation. In order to completely exclude alternative receptors outside the TGF-β superfamily and signaling pathways activated through TβRII alone, we performed global gene expression profiling on TGF-β1 stimulated TβRI−/− MEFs with unstimulated TβRI deficient cells as reference. Very few (0.05 %) of the more than 37,000 spots on the microarray had a >2 fold differential expression in the two experiments conducted. Similar experiments performed on wt cells resulted in differential expression of between 2.6–3.9 % of the genes printed. From this data we conclude that no signaling affecting gene expression occur in the absence of TβRI in these cells. Additionally we present transcriptional profiles of MEF cell lines that either are normal or are TβRI deficient. By means of cDNA microarray technology, we have identified genes that were differentially expressed when TβRI deficient fibroblasts were compared to wt cells stimulated with TGF-β1. Our results create a data base of 461 significantly differentially expressed (p<0.01) target genes of TGF-β signaling. These include genes potentially responsible for the growth arrest induced by TGF-β1, like Gadd45g, Gas5, Id1, Id2 and Id3. However, the most significantly enriched number of differentially expressed genes are involved in protein folding and chaperone activities (Hspa9a, Hsp105, Hspe1, Hsp60, Cct2, Cct3, Cct8, Tcp1 and Dnaja1. Studies to identify TGF-β signaling responsive genes in HSCs are in progress.

Williams-Beuren Syndrome Critical Region-5/Non-T Cell Activation Linker: A Novel Target Gene of AML1/ETO.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2898-2898
Author(s):  
Michael Lübbert ◽  
Michael Stock ◽  
Tobias Berg ◽  
Manfred Fliegauf
Keyword(s):  
Gene Expression ◽  
T Cell ◽  
T Cell Activation ◽  
Critical Region ◽  
Cell Activation ◽  
Target Genes ◽  
Chromosome 8 ◽  
Chromosome 21 ◽  
Acute Myeloid

Abstract The chromosomal translocation (8;21) fuses the AML1 gene on chromosome 21 and the ETO gene on chromosome 8 in human acute myeloid leukemias, resulting in expression of the chimeric transcription factor AML1/ETO. AML1/ETO-mediated dysregulation of target genes critical for hematopoietic differentiation and proliferation is thought to contribute to the leukemic phenotype. Several mechanisms, including recruitment of histone deacetylases (HDACs) to AML1 target genes, may be responsible for altered gene expression. We used an ecdysone-inducible expression system in the human monoblastic U-937 cell line to isolate genes that were differentially expressed upon induction of AML1/ETO expression. By representational difference analysis (cDNA-RDA), we identified 26 genes whose expression levels were significantly modulated following AML1/ETO induction for 48 hours. None of these genes has previously been described as a target of AML1, ETO or AML1/ETO. One gene down-regulated by AML1/ETO in vitro, Williams Beuren Syndrome critical region 5 (WBSCR5), was expressed in primary t(8;21) negative AML blasts but not in primary t(8;21) positive AML blasts, strongly implying a role of this gene in the phenotype of t(8;21) positive AML. WBSCR5 is part of the critical region located on chromosome 7q11.23 that is deleted in the Williams Beuren syndrome (OMIM 194050), an autosomal dominant disorder comprising vascular, neurological, behavioral and skeletal abnormalities. WBSCR5 has recently been shown to have a role in the activation and differentiation of B cells (Brdicka et al., J. Exp. Med. 196:1617, 2002) and thus was also termed Non-T cell activation linker.. WBSCR5 as well as seven other regulated genes were further studied using all-trans-retinoic acid (ATRA), an inducer of differentiation of U-937 cells, and Trichostatin A (TSA), an HDAC inhibitor. WBSCR5 and two other out of these eight genes were regulated during ATRA-induced monocytic differentiation of U-937 cells, however none of them antagonistically, upon both ATRA-treatment and AML1/ETO-induction. Since repression of WBSCR5 might be mediated by recruitment of HDACs through the fusion gene, cells were treated with TSA prior to transgene induction. However, the AML1/ETO-associated dysregulation of WBSCR5 gene expression (as well as that of the other seven genes studied) was not mediated by a TSA-sensitive mechanism. The identified genes provide a useful model to study the mechanism by which the AML1/ETO fusion protein exerts its function in transcriptional dysregulation in acute myeloid leukemia. The role of WBSCR5 in malignant hematopoietic cells warrants further study.

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