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Expression profile of CREB knockdown in myeloid leukemia cells.

ABSTRACT: The cAMP Response Element Binding Protein, CREB, is a transcription factor that regulates cell proliferation, differentiation, and survival in several model systems, including neuronal and hematopoietic cells. We demonstrated that CREB is overexpressed in acute myeloid and leukemia cells compared to normal hematopoietic stem cells. CREB knockdown inhibits leukemic cell proliferation in vitro and in vivo, but does not affect long-term hematopoietic reconstitution.To understand downstream pathways regulating CREB, we performed expression profiling with RNA from the K562 myeloid leukemia cell line transduced with CREB shRNA.By combining our expression data from CREB knockdown cells with prior ChIP data on CREB binding we were able to identify a list of putative CREB regulated genes. We performed extensive analyses on the top genes in this list as high confidence CREB targets. We found that this list is enriched for genes involved in cancer, and unexpectedly, highly enriched for histone genes. Furthermore, histone genes regulated by CREB were more likely to be specifically expressed in hematopoietic lineages. Decreased expression of specific histone genes was validated in K562, TF-1, and primary AML cells transduced with CREB shRNA.We have identified a high confidence list of CREB targets in K562 cells. These genes allow us to begin to understand the mechanisms by which CREB contributes to acute leukemia. We speculate that regulation of histone genes may play an important role by possibly altering the regulation of DNA replication during the cell cycle.

SUBMITTER: Pellegrini M

PROVIDER: S-EPMC2647550 | biostudies-literature | 2008 Sep

REPOSITORIES: biostudies-literature

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Expression profile of CREB knockdown in myeloid leukemia cells.

Pellegrini Matteo M Cheng Jerry C JC Voutila Jon J Judelson Dejah D Taylor Julie J Nelson Stanley F SF Sakamoto Kathleen M KM

BMC cancer 20080918

<h4>Background</h4>The cAMP Response Element Binding Protein, CREB, is a transcription factor that regulates cell proliferation, differentiation, and survival in several model systems, including neuronal and hematopoietic cells. We demonstrated that CREB is overexpressed in acute myeloid and leukemia cells compared to normal hematopoietic stem cells. CREB knockdown inhibits leukemic cell proliferation in vitro and in vivo, but does not affect long-term hematopoietic reconstitution.<h4>Methods</h ...[more]

PMID: 18801183

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Project description:Background. The cAMP Response Element Binding Protein, CREB, is a transcription factor that regulates cell proliferation, differentiation, and survival in several model systems, including neuronal and hematopoietic cells. We demonstrated that CREB is overexpressed in acute myeloid and leukemia cells compared to normal hematopoietic stem cells. CREB knockdown inhibits leukemic cell proliferation in vitro and in vivo, but does not affect long-term hematopoietic reconstitution. Therefore, we propose CREB to be a potential target for therapy. To understand downstream pathways regulating CREB, we performed expression profiling with RNA from the K562 myeloid leukemia cell line. Results. By combining our expression data from CREB knockdown cells with prior ChIP data on CREB binding we were able to identify a list of putative CREB regulated genes. We performed extensive analyses on the top genes in this list as high confidence CREB targets. We found that this list is enriched for genes involved in cancer, and unexpectedly, highly enriched for histone genes. Furthermore, histone genes regulated by CREB were more likely to be specifically expressed in hematopoietic lineages. The transcription factor Elk-1 was upregulated in response to CREB deletion. Conclusions. We have identified a high confidence list of CREB targets in K562 cells. These genes allow us to begin to understand the mechanisms by which CREB contributes to acute leukemia. In particular, we speculate that the regulation of histone genes may play an important role in this process, by possibly altering the regulation of DNA replication during the cell cycle. Experiment Overall Design: Cell lines. The following human leukemia cell lines were transduced with shRNAs: K562 (Iscoves + 10% FCS) and TF-1 (RPMI + 10%FCS + rhGM-CSF. Cells were cultured at 37oC, 5% CO2 and split every 3 to 4 days. Primary AML bone marrow samples were processed as previously described [12]. All human samples were obtained with approval from the Institutional Review Board and consents were signed, according to the Helsinki protocol. Experiment Overall Design: shRNA sequence design and constructs. The CREB specific shRNA sequences were selected and validated based on accepted parameters established by Tuschl et al. [25-27]; CREB shRNA-1, CREB shRNA-2, CREB shRNA-3. Controls included empty vector, luciferase shRNA, and scrambled shRNA. shRNA sequences are: CREB shRNA-1(5âGCAAATGACAGTTCAAGCCC3â), shRNA-2 (5âGTACAGCTGGCTAACAATGG3â), shRNA-3 (5âGAGAGAGGTCCGTCTAATG3â), Luciferase shRNA (5âGCCATTCTATCCTCTAGAGGA3â), Scramble shRNA (5âGGACGAACCTGCTGAGATAT3â). Short-hairpin sequences were synthesized as oligonucleotides and annealed according to standard protocol. Annealed shRNAs were then subcloned into pSICO-R shRNA vectors from the Jacks laboratory at MIT [28]. The second generation SIN vector HIV-CSCG was used to produce human shRNA vectors [29]. Experiment Overall Design: Microarray analysis. Total RNA (10 Î¼g) was extracted from K562 cells transduced with vector alone or CREB shRNA was submitted to the UCLA DNA Microarray Facility. RNA samples were labeled and hybridized by standard protocol to Affymetrix GeneChip Human Genome U133+ Array Set HG-U133A array. Gene expression values were calculated using the MAS5 software. The expression values are quantile normalized across all arrays. We obtained the expression profiles for a control set and CREB downregulated K562 cells. These are first quantile normalized, and then a t-test is performed between the two groups to identify significantly differentially regulated genes. The analysis was performed using Matlab (Mathworks, Inc.). A normal quantile plot of T is shown in figure qqplot.tiff. Data points with t-scores < 1/(2N) display with red circles, were N is the total number of genes. We therefore see that there are a significant number of differentially expressed genes, which are either direct or indirect targets of CREB.

Project description:UnlabelledBackgroundThe Real-time PCR Array System is the ideal tool for analyzing the expression of a focused panel of genes. In this study, we will analyze the gene expression profile of pediatric acute myeloid leukemia with real-time PCR arrays.MethodsReal-time PCR array was designed and tested firstly. Then gene expression profile of 11 pediatric AML and 10 normal controls was analyzed with real-time PCR arrays. We analyzed the expression data with MEV (Multi Experiment View) cluster software. Datasets representing genes with altered expression profile derived from cluster analyses were imported into the Ingenuity Pathway Analysis Tool.ResultsWe designed and tested 88 real-time PCR primer pairs for a quantitative gene expression analysis of key genes involved in pediatric AML. The gene expression profile of pediatric AML is significantly different from normal control; there are 19 genes up-regulated and 25 genes down-regulated in pediatric AML. To investigate possible biological interactions of differently regulated genes, datasets representing genes with altered expression profile were imported into the Ingenuity Pathway Analysis Tool. The results revealed 12 significant networks. Of these networks, Cellular Development, Cellular Growth and Proliferation, Tumor Morphology was the highest rated network with 36 focus molecules and the significance score of 41. The IPA analysis also groups the differentially expressed genes into biological mechanisms that are related to hematological disease, cell death, cell growth and hematological system development. In the top canonical pathways, p53 and Huntington's disease signaling came out to be the top two most significant pathways with a p value of 1.5E-8 and2.95E-7, respectively.ConclusionsThe present study demonstrates the gene expression profile of pediatric AML is significantly different from normal control; there are 19 genes up-regulated and 25 genes down-regulated in pediatric AML. We found some genes dyes-regulated in pediatric AML for the first time as FASLG, HDAC4, HDAC7 and some HOX family genes. IPA analysis showed the top important pathways for pediatric AML are p53 and Huntington's disease signaling. This work may provide new clues of molecular mechanism in pediatric AML.

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Expression profile of CREB knockdown in myeloid leukemia cells.

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Expression profile of CREB knockdown in myeloid leukemia cells.

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