Targeting CDK6 and BCL2 exploits the "MYB Addiction" of Ph+ acute lymphoblastic leukemia
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PROVIDER: PRJNA415464 | ENA |
REPOSITORIES: ENA
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Project description:Transcriptome analysis of two Ph+ acute lymphoblastic leukemia cell lines after doxycycline induced silencing of MYB. Current treatment options for Ph+ acute lymphoblastic leukemia (ALL) do not result in long term remission. MYB transcription factor has been shown to be selectively important for Ph+ ALL cell survival and proliferation however the mechanisms for this oncogene addiction are poorly understood and no bona-fide MYB inhibitors currently exist. To overcome these limitations, we analyzed the transcriptome of MYB silenced Ph+ ALL in search for genes regulated by MYB that could serve as potential pharmacological targets. We observed that among MYB-regulated genes, those involved in cell cycle regulation are significantly over-represented. We found that CDK6 and BCL2 are MYB targets pivotal for MYB dependent regulation of proliferation and survival respectively. Furthermore, their inhibition suppresses leukemia growth in vitro and in vivo thus providing a potential treatment approach for patients that fails or do not respond to conventional treatments.
2018-01-17 | GSE105826 | GEO
Project description:Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) is currently treated with BCR-ABL1 tyrosine kinase inhibitors (TKI) in combination with chemotherapy. However, most patients develop resistance to TKI through BCR-ABL1-dependent and -independent mechanisms. Newly developed TKI can target Ph+ ALL cells with BCR-ABL1-dependent resistance; however, overcoming BCR-ABL1-independent mechanisms of resistance remains challenging because transcription factors, which are difficult to inhibit, are often involved. We show here that (i) the growth of Ph+ ALL cell lines and primary cells is highly dependent on MYB-mediated transcriptional upregulation of CDK6, cyclin D3, and BCL2, and (ii) restoring their expression in MYB-silenced Ph+ ALL cells rescues their impaired proliferation and survival. Levels of MYB and CDK6 were highly correlated in adult Ph+ ALL (P = 0.00008). Moreover, Ph+ ALL cells exhibited a specific requirement for CDK6 but not CDK4 expression, most likely because, in these cells, CDK6 was predominantly localized in the nucleus, whereas CDK4 was almost exclusively cytoplasmic. Consistent with their essential role in Ph+ ALL, pharmacologic inhibition of CDK6 and BCL2 markedly suppressed proliferation, colony formation, and survival of Ph+ ALL cells ex vivo and in mice. In summary, these findings provide a proof-of-principle, rational strategy to target the MYB "addiction" of Ph+ ALL.Significance: MYB blockade can suppress Philadelphia chromosome-positive leukemia in mice, suggesting that this therapeutic strategy may be useful in patients who develop resistance to imatinib and other TKIs used to treat this disease. Cancer Res; 78(4); 1097-109. ©2017 AACR.
| S-EPMC5815914 | biostudies-literature
Project description:Aberrant gene expression is a hallmark of acute leukemias. However, therapeutic strategies for its blockade are generally lacking, in large part due to the pharmacologic challenges of drugging transcription factors. MYB-driven gene trans-activation with CREB-binding protein (CBP) is required for the initiation and maintenance of a variety of acute lymphoblastic and myeloid leukemias, including refractory MLL-rearranged leukemias. Using structure-guided molecular design, we developed a prototypical peptidomimetic inhibitor MYBMIM that interferes with the assembly of the molecular MYB:CBP complex at ¼M concentrations and rapidly accumulates in the nuclei of AML cells. We found that treatment of AML cells with MYBMIM, but not with its inactive near-isosteric analogue TG3, led to the displacement and dissociation of MYB:CBP complex in cells, displacement of MYB from oncogenic enhancers and promoters enriched for MYB binding sites, and rapid downregulation of MYB-dependent gene expression, including of MYC and BCL2 oncogenes. Both human MLL-rearranged and non-rearranged AML cells, but not normal CD34+ umbilical cord blood progenitor cells, underwent sustained mitochondrial apoptosis in response to MYBMIM treatment, an effect that could be partially rescued by ectopic expression of BCL2. We observed that MYBMIM treatment impeded leukemia growth and extended survival of immunodeficient mice engrafted with primary patient-derived MLL-rearranged leukemia cells. These findings emphasize the exquisite dependence of human AML on MYB:CBP transcriptional dysregulation, and establish a pharmacologic approach for its therapeutic blockade.
2018-02-23 | GSE94240 | GEO
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.
2011-02-04 | E-GEOD-27028 | biostudies-arrayexpress
Project description:We describe a critical role for Cdk6 in JAK2V617F+ MPN evolution. The absence of Cdk6 ameliorates clinical symptoms and prolongs survival of JAK2V617F fl/+ vav-Cre mice. The Cdk6 protein interferes with three hallmarks of disease: besides regulating malignant stem cell quiescence, it promotes NFkB signaling and contributes to cytokine production while inhibiting apoptosis. The treatment with palbociclib did not mirror these effects, showing that the functions of Cdk6 in MPN pathogenesis are largely kinase-independent.
2019-06-10 | GSE123401 | GEO
Project description:The cell cycle kinase CDK6 interacts with a variety of proteins including cyclins and members of the INK4 and Cip/Kip families. These interactions are thought to involve primarily the N-lobe of the protein. Less is known about the role of the C-lobe for the function of CDK6. In this experiment we assessed the function of the C-lobe in CDK6's interaction with transcriptional complexes. We generated cell lines by retroviral over-expression of BCR-ABL1 in bone marrow cells from CDK6 knock-out mice. We then introduced HA-tagged variants of CDK6 - either wildtype CDK6 (CDK6_WT) or a C-terminally truncated variant of CDK6 lacking the last 32 amino acids of the protein (CDK6_delta-C). ChIP was performed with an antibody against the HA tag. CDK6 KO cell lines were used as controls.
2024-06-30 | E-MTAB-13798 | biostudies-arrayexpress
Project description:Dertermination of chromatin accessibility in murine BCR-ABL+ CDK6-wt and CDK6-KO cells
2020-11-24 | GSE156966 | GEO
Project description:Earlier we have shown important roles of MYB in pancreatic tumor pathobiology. To better understand the role of MYB in the tumor microenvironment and identify MYB-associated secreted biomarker proteins, we conducted mass spectrometry analysis of the secretome from MYB-modulated and control pancreatic cancer cell lines. We also performed in silico analyses to determine MYB-associated biofunctions, gene networks and altered biological pathways. We further investigated the secreted proteins for their potential biomarker properties.
2021-09-08 | PXD015126 | Pride
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.
2011-02-04 | GSE27028 | GEO
Project description:Most E2F-binding sites repress transcription through the recruitment of Retinoblasoma (RB) family members until the end of the G1 cell-cycle phase. Although the MYB promoter contains an E2F-binding site, its transcription is activated shortly after the exit from quiescence, before RB family members inactivation, by unknown mechanisms. We had previously uncovered a nuclear factor distinct from E2F, Myb-sp, whose DNA-binding site overlapped the E2F element and had hypothesized that this factor might overcome the transcriptional repression of MYB by E2F-RB family members. We have purified Myb-sp and discovered that Myc-associated zinc finger proteins (MAZ) are major components. We show that various MAZ isoforms are present in Myb-sp and activate transcription via the MYB-E2F element. Moreover, while forced RB or p130 expression repressed the activity of a luciferase reporter driven by the MYB-E2F element, co-expression of MAZ proteins not only reverted repression, but also activated transcription. Finally, we show that MAZ binds the MYB promoter in vivo, that its binding site is critical for MYB transactivation, and that MAZ knockdown inhibits MYB expression during the exit from quiescence. Together, these data indicate that MAZ is essential to bypass MYB promoter repression by RB family members and to induce MYB expression.
2017-10-04 | PXD006857 | Pride