Genome-wide gene expression profile analysis of MCL1 over-expressing B-NHL cells
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ABSTRACT: To get insight into the mechanisms of MCL1-induced survival and transformation, we screened 41,000 human genes in a genome-wide gene expression profile analysis of MCL1 over-expressing B-NHL cells. Keywords: MCL1-induced gene expression
Project description:To get insight into the mechanisms of MCL1-induced survival and transformation, we screened 41,000 human genes in a genome-wide gene expression profile analysis of MCL1 over-expressing B-NHL cells. Experiment Overall Design: Two-color (Cy5-CTP/ Cy3-CTP) microarray-based gene expression formats presenting high-density oligonucleotide probes printed on a single glass slide were used (Agilent technologies, Cat No# G4112A whole human genome 41K). Total RNAs from MCL1 over-expressing RAMOS RA-1 and Z-138 B-cells were labeled with Cy5-CTP, whereas RNAs from references (empty vector/ RAMOS RA-1 and empty vector/ Z-138 B-cells) were labeled with Cy3-CTP. After competitive hybridization [RNA-Cy5 from MCL1 over-expressing RAMOS RA-1 or MCL1 over-expressing Z-138 versus RNA-Cy3 from either empty vector/ RAMOS RA-1 or empty vector/ Z-138 respectively] gene expression data were pre-processed using Feature Extraction software and GEPAS tools (http://gepas.bioinfo.cipf.es/).
Project description:MCL1 is an anti-apoptotic member of the BCL2 family that is deregulated in various solid and hematological malignancies. However, its role in the molecular pathogenesis of diffuse large B-cell lymphoma (DLBCL) is unclear. We analyzed gene expression profiling data from 350 DLBCL patient samples and detected that activated B-cell-like (ABC) DLBCLs express MCL1 at significantly higher levels compared to germinal center B-cell-like (GCB) DLBCL patient samples (p=2.7 x 10(-10)) [PMID 23257783]. Immunohistochemistry confirmed high MCL1 protein expression predominantly in ABC DLBCL in an independent patient cohort (n=249; p=0.001). To elucidate molecular mechanisms leading to aberrant MCL1 expression, we analyzed array comparative genomic hybridization (aCGH) data of 203 DLBCL samples [GSE11318] and identified recurrent chromosomal gains/amplifications of the MCL1 locus that occurred in 26% of ABC DLBCLs. In addition, aberrant STAT3 signaling contributed to high MCL1 expression in this subtype. Knockdown of MCL1 as well as treatment with the BH3-mimetic obatoclax induced apoptotic cell death in MCL1 positive DLBCL cell lines. In summary, MCL1 is deregulated in a significant fraction of ABC DLBCLs and contributes to therapy resistance. These data suggest that specific inhibition of MCL1 might be utilized therapeutically in a subset of DLBCLs. This GEO dataset is comprised of aCGH measurements for DLBCL cell lines, which are used in the above-mentioned paper. Cell lines were measured against the DNA of a healthy male donor who in turn was measured against a pool of healthy DNAs to correct for individual CNVs of the donor.
Project description:MCL1 is an anti-apoptotic member of the BCL2 family that is deregulated in various solid and hematological malignancies. However, its role in the molecular pathogenesis of diffuse large B-cell lymphoma (DLBCL) is unclear. We analyzed gene expression profiling data from 350 DLBCL patient samples and detected that activated B-cell-like (ABC) DLBCLs express MCL1 at significantly higher levels compared to germinal center B-cell-like (GCB) DLBCL patient samples (p=2.7 x 10(-10)) [PMID 23257783]. Immunohistochemistry confirmed high MCL1 protein expression predominantly in ABC DLBCL in an independent patient cohort (n=249; p=0.001). To elucidate molecular mechanisms leading to aberrant MCL1 expression, we analyzed array comparative genomic hybridization (aCGH) data of 203 DLBCL samples [GSE11318] and identified recurrent chromosomal gains/amplifications of the MCL1 locus that occurred in 26% of ABC DLBCLs. In addition, aberrant STAT3 signaling contributed to high MCL1 expression in this subtype. Knockdown of MCL1 as well as treatment with the BH3-mimetic obatoclax induced apoptotic cell death in MCL1 positive DLBCL cell lines. In summary, MCL1 is deregulated in a significant fraction of ABC DLBCLs and contributes to therapy resistance. These data suggest that specific inhibition of MCL1 might be utilized therapeutically in a subset of DLBCLs.
Project description:The anti-apoptotic MCL1 protein is a member of the pro-survival BCL2 family and is frequently amplified or elevated in human cancers. MCL1 protein is highly unstable, with its stability being regulated by phosphorylation and ubiquitination. We attempted to identify acetylation as another critical post-translational modification regulating MCL1 protein stability. To this end, 293T cells were transfected with HA-humanMCL1 and Myc-p300. The whole-cell lysates were immunoprecipitated with anti-HA agarose beads. The immunoprecipitated material was resolved by SDS-PAGE, and the MCL1 band was excised for tryptic digestion followed by the MS analysis.
Project description:We profiled 40 NHL cell lines to determine gene expression patterns and molecular subtypes. Experiment Overall Design: RNA profiles of NHL cell lines.
Project description:Specialized chromatin exists at centromeres and must be precisely transmitted during DNA replication. The mechanisms involved in the propagation of these structures remain elusive. Fission yeast centromeres are composed of two chromatin domains: the central CENP-ACnp1 kinetochore domain and flanking heterochromatin domains. Here we show that fission yeast Mcl1, a DNA polymerase ? (Pol?) accessory protein, is critical for maintenance of centromeric chromatin. In a screen for mutants that alleviate both central domain and outer repeat silencing, we isolated several cos mutants, of which cos1 is allelic to mcl1. The mcl1-101 mutation causes reduced CENP-ACnp1 in the central domain and an aberrant increase in histone acetylation in both domains. These phenotypes are also observed in a mutant of swi7+, which encodes a catalytic subunit of Pol?. Mcl1 forms S-phase-specific nuclear foci, which colocalize with those of PCNA and Pol?. These results suggest that Mcl1 and Pol? are required for propagation of centromere chromatin structures during DNA replication. Keywords: ChIP-chip analysis, S. pombe Antibodies used were ?-acetyl-histone H4 antiserum (Upstate) and ?-histone H4 pan antibody (Upstate). ChIP-on-chip was carried out using IVT amplification method. ChIP-chip data were comfirmed by real-time PCR.
Project description:To identify the differentially expressed miRs in the plasmas of non-Hodgkin's lymphoma (NHL) patients, we screened NHL samples using microarrays.
Project description:Most human B cell lymphomas (B-NHL) are derived from germinal centers (GCs), the structure where B-cells undergo class switch recombination (CSR) and somatic hypermutation (SHM) and are selected for high-affinity antibody production. The pathogenesis of B-NHL is associated with distinct genetic lesions, including chromosomal translocations and aberrant somatic hypermutation, which appear to arise from mistakes occurring during CSR and SHM. To ascertain the role of CSR and SHM in lymphomagenesis, we crossed three oncogene-driven (MYC, BCL6, MYC/BCL6) mouse models of B cell lymphoma with mice lacking activation-induced cytidine deaminase (AID), the enzyme required for both processes. We show that AID deficiency prevents BCL6-dependent, GC-derived B-NHL, while it has no impact on the formation of MYC-driven, pre-GC lymphomas. Accordingly, abrogation of AID is associated with the disappearance of both CSR- and SHM-mediated structural alterations, including cMYC-IgH chromosomal translocations and aberrant SHM. These results demonstrate that AID is required for GC-derived lymphomagenesis, providing direct support to the notion that errors in AID-mediated antigen-receptor gene modification events represent major contributors to the pathogenesis of human B-NHL. Keywords: Phenotypic characterization of tumors developing in oncogene-driven mouse models of lymphomas
Project description:Specialized chromatin exists at centromeres and must be precisely transmitted during DNA replication. The mechanisms involved in the propagation of these structures remain elusive. Fission yeast centromeres are composed of two chromatin domains: the central CENP-ACnp1 kinetochore domain and flanking heterochromatin domains. Here we show that fission yeast Mcl1, a DNA polymerase α (Polα) accessory protein, is critical for maintenance of centromeric chromatin. In a screen for mutants that alleviate both central domain and outer repeat silencing, we isolated several cos mutants, of which cos1 is allelic to mcl1. The mcl1-101 mutation causes reduced CENP-ACnp1 in the central domain and an aberrant increase in histone acetylation in both domains. These phenotypes are also observed in a mutant of swi7+, which encodes a catalytic subunit of Polα. Mcl1 forms S-phase-specific nuclear foci, which colocalize with those of PCNA and Polα. These results suggest that Mcl1 and Polα are required for propagation of centromere chromatin structures during DNA replication. Keywords: ChIP-chip analysis, S. pombe