Project description:The transcription factor c-JUN and its upstream kinase JNK1 have been implicated in BCR-ABL induced leukemogenesis. JNK1 has been shown to regulate BCL2 expression thereby altering leukemogenesis, but the impact of c-JUN remained unclear. In this study we show that JNK1 and c-JUN promote leukemogenesis via separate pathways, since lack of c-JUN impairs proliferation of p185BCR-ABL transformed cells without affecting viability. The decreased proliferation of c-JunD/D cells is associated with the loss of cyclin dependent kinase 6 (CDK6) expression. In c-JunD/D cells CDK6 expression becomes down-regulated upon BCR-ABL induced transformation which correlates with CpG island methylation within the 5´ region of Cdk6. We verified the impact of Cdk6 deficiency by using Cdk6-/- mice that developed BCR-ABL induced B-lymphoid leukemia with significantly increased latency and an attenuated disease phenotype. In addition we show that re-expression of CDK6 in BCR-ABL transformed c-JunD/D cells reconstitutes proliferation and tumor formation in Nu/Nu mice. In summary, our study reveals a novel function for the AP-1 transcription factor c-JUN in leukemogenesis by antagonizing promoter methylation. Moreover, we identify CDK6 as relevant and critical target of AP-1 regulated DNA methylation upon BCR-ABL induced transformation, thereby accelerating leukemogenesis. Overall, 8 samples consisting of 4 wild type and 4 c-jun knock out samples were hybridized to MoGene-1_0-st-v1 microarrays.
Project description:The transcription factor c-JUN and its upstream kinase JNK1 have been implicated in BCR-ABL induced leukemogenesis. JNK1 has been shown to regulate BCL2 expression thereby altering leukemogenesis, but the impact of c-JUN remained unclear. In this study we show that JNK1 and c-JUN promote leukemogenesis via separate pathways, since lack of c-JUN impairs proliferation of p185BCR-ABL transformed cells without affecting viability. The decreased proliferation of c-JunD/D cells is associated with the loss of cyclin dependent kinase 6 (CDK6) expression. In c-JunD/D cells CDK6 expression becomes down-regulated upon BCR-ABL induced transformation which correlates with CpG island methylation within the 5´ region of Cdk6. We verified the impact of Cdk6 deficiency by using Cdk6-/- mice that developed BCR-ABL induced B-lymphoid leukemia with significantly increased latency and an attenuated disease phenotype. In addition we show that re-expression of CDK6 in BCR-ABL transformed c-JunD/D cells reconstitutes proliferation and tumor formation in Nu/Nu mice. In summary, our study reveals a novel function for the AP-1 transcription factor c-JUN in leukemogenesis by antagonizing promoter methylation. Moreover, we identify CDK6 as relevant and critical target of AP-1 regulated DNA methylation upon BCR-ABL induced transformation, thereby accelerating leukemogenesis.
Project description:The aim of this experiment was to study the DNA interaction of a kinase-dead mutant of the cell cycle kinase CDK6 (CDK6-K43M) in a murine model of BCR-ABL driven leukemia.
Project description:The aim of this experiment was to study the effects of a kinase-dead mutant of the cell cycle kinase CDK6 (CDK6-K43M) on gene expression in a murine model of BCR-ABL driven leukemia.
Project description:We performed methylation analyses in BCR-ABL+ cells either expressing or lacking CDK6 using the next-generation sequencing approach RRBS and identified DNA methylation changes towards both hyper- and hypomethylation. CDK6 mediated methylation changes are largely reverted by CDK6 re-expression in this experimental system.
Project description:Metabolic reprogramming and cell cycle deregulation are hallmarks of cancer cells. We here investigate the role of the cell cycle kinase CDK6 in the regulation of cellular energetics in BCR-ABL+ leukemia. Gene expression data and ChIP-Seq analysis from murine BCR-ABL+ cell lines expressing kinase-inactive CDK6 or no CDK6 highlight an activating role for the kinase in regulating the oxidative phosphorylation gene set by interacting with respective promoter regions. Our data imply a competition of CDK6 and Nrf-1, a master regulator of genes required for mitochondrial respiration, at the same sites. In line, cells expressing kinase- inactive CDK6 show signs of a defective electron transport chain and morphologically changed mitochondria. An enhanced cytoplasm/mitochondria ATP ratio together with high levels of pyruvate and lactate point towards a metabolic switch to glycolysis in those cells. Combinatorial treatment of BCR-ABL+ cell lines with the clinically used CDK4/6 inhibitor palbociclib and the glycolysis inhibitor 2-deoxyglocose (2-DG) reduced proliferation and led to enhanced apoptosis compared to single-agent treatments. Our data, suggest a new therapeutic avenue for hematologic malignancies with high CDK6 expression.
Project description:Using BCR-ABL-induced chronic myeloid leukemia (CML) as a disease model for leukemia stem cells (LSCs), we showed that BCR-ABL down-regulates the B lymphoid kinase (Blk) gene in leukemia stem cells in CML mice and that Blk functions as a tumor suppressor in LSCs and suppresses LSC function. Inhibition of this Blk pathway accelerates CML development, whereas increased activity of the Blk pathway delays CML development. To identify the pathways in which Blk regulates function of LSCs, we performed a comparative DNA microarray analysis using total RNA isolated from non-BCR-ABL-expressing Lin-Sca-1+c-Kit+, BCR-ABL- and BCR-ABL-Blk expressing LSCs. This analysis revealed a large group of candidate genes that exhibited changes in the levels of transcription in the Blk expressing LSCs, and uncovered the molecular mechanisms by which Blk suppresses LSCs and CML development. Bone marrow cells were transduced with GFP, BCR-ABL-GFP or BCR-ABL-Blk-GFP, followed by transplantation into recipient mice. Fourteen days after transplantation, bone marrow cells were isolated and LSCs were sorted by FACS for isolation of total RNA for DNA microarray analysis.
Project description:BCR-ABL was used to transform Cdk6+/+, Cdk6-K43M or Cdk6-/- bone marrow cells. RNA was isolated from individual colonies formed in methylcellulose at day 10 post-transduction
Project description:Using BCR-ABL-induced chronic myeloid leukemia (CML) as a disease model for leukemia stem cells (LSCs), we showed that BCR-ABL down-regulates the B lymphoid kinase (Blk) gene in leukemia stem cells in CML mice and that Blk functions as a tumor suppressor in LSCs and suppresses LSC function. Inhibition of this Blk pathway accelerates CML development, whereas increased activity of the Blk pathway delays CML development. To identify the pathways in which Blk regulates function of LSCs, we performed a comparative DNA microarray analysis using total RNA isolated from non-BCR-ABL-expressing Lin-Sca-1+c-Kit+, BCR-ABL- and BCR-ABL-Blk expressing LSCs. This analysis revealed a large group of candidate genes that exhibited changes in the levels of transcription in the Blk expressing LSCs, and uncovered the molecular mechanisms by which Blk suppresses LSCs and CML development.