Project description:This study supports an active role for PLZF and RARα-PLZF in leukemogenesis, identifies upregulation of CRABPI as a novel mechanism contributing to retinoid resistance and reveals the ability of the reciprocal fusion gene products to mediate distinct epigenetic effects contributing to the leukemic phenotype. Keywords: Disease state analysis
Project description:We defined the RARα interactome in the MDA-MB453 breast cancer cell line genetically engineered to over-express an N-terminally tagged version of the nuclear retinoic acid receptor. Twenty eight nuclear proteins which interact with RARα and whose interaction is stimulated or reduced by the pan-RAR ligand, all-trans retinoic acid (ATRA) were identified. Given the potential significance of the S100A3 calcium-binding protein in the control of tumor progression, we focused our attention on this factor. Using the two models represented by the ATRA-sensitive SKBR3 and MCF7 breast cancer cell lines characterized by constitutive expression of S100A3 and RARα, we demonstrate that the endogenous forms of S100A3 and RARα interact in physiological conditions. The interaction of S100A3 with RARα is cell context independent and it is observed not only in breast cancer but also in acute promyelocytioc leukemia (APL) cells, characterized by expression of the RARα-derived PML-RARα oncogene, which is the product of the t(15:17) chromosomal translocation. S100A3 interacts directly and specifically with RARα and PML-RARα, being unable to bind other members of the RAR/RXR family of retinoid nuclear receptors. The interaction surface maps to the carboxyl-terminal region of the RARα ligand binding domain. Binding of S100A3 to RARα and PML-RARα controls the constitutive and ATRA-dependent degradation of the two receptors. Silencing of the S100A3 gene decreases the amounts of RARα in breast SK-BR-3 and lung A549 cancer cells, rendering them more refractory to the anti-proliferative action of ATRA. In SK-BR-3 cells, this effect is accompanied by a decrease in the lactogenic/differentiating action of ATRA. In APL-derived NB4 cells, S100A3 knock-down reduces the amounts of both RARα and PML-RARα. Contemporaneous down-regulation of the two receptors is associated with an increase in the basal and ATRA-induced expression of many granulocytic differentiation markers. Opposite on RARα and PML-RARα levels as well as ATRA induced differentiation markers are observed upon over-expression of S100A3 in NB4 cells.
Project description:This study supports an active role for PLZF and RARα-PLZF in leukemogenesis, identifies upregulation of CRABPI as a novel mechanism contributing to retinoid resistance and reveals the ability of the reciprocal fusion gene products to mediate distinct; epigenetic effects contributing to the leukemic phenotype. Experiment Overall Design: 5 patients with t(11;17) or t(7;17) translocations and with the RARA-PLZF status known were analysed for changes in expression related to the reciprocal status. This is a rare disease.
Project description:Acute promyeloid leukemia (APL) is characterized by the oncogenic fusion protein PML/RARα, a major etiological agent in APL. Although PML/RARα is critical, the molecular mechanisms remains largely unknown. Here, using an inducible system, we comprehensively analyzed the 3D genome organization in myloid cells and its reorganizationn after PML/RARα induction, and performed additional analysis in patient-derived APL cells with native PML/RARα. We discovered that PML/RARα mediate extensive chromatin interactions genome-wide. Globally, it redefine the chromatin topology of the in myloid genome toward a more condensed configuration in APL cells; locally, it intrude RNAPII-associated interaction dmains, interrupt myeloid-specific transcription factors binding at enhancers and super-enahncers, and lead to transcriptional repression of genes critical for myeloid differentiation and maturation. Together, our results provide novel insights of a topological framework for PML/RARα’s roles in transforming myeloid into leukemia, likely a general mechanism for oncogenic fusion proteins in cancers.
Project description:Acute promyeloid leukemia (APL) is characterized by the oncogenic fusion protein PML/RARα, a major etiological agent in APL. Although PML/RARα is critical, the molecular mechanisms remains largely unknown. Here, using an inducible system, we comprehensively analyzed the 3D genome organization in myloid cells and its reorganizationn after PML/RARα induction, and performed additional analysis in patient-derived APL cells with native PML/RARα. We discovered that PML/RARα mediate extensive chromatin interactions genome-wide. Globally, it redefine the chromatin topology of the in myloid genome toward a more condensed configuration in APL cells; locally, it intrude RNAPII-associated interaction dmains, interrupt myeloid-specific transcription factors binding at enhancers and super-enahncers, and lead to transcriptional repression of genes critical for myeloid differentiation and maturation. Together, our results provide novel insights of a topological framework for PML/RARα’s roles in transforming myeloid into leukemia, likely a general mechanism for oncogenic fusion proteins in cancers.
Project description:Acute promyeloid leukemia (APL) is characterized by the oncogenic fusion protein PML/RARα, a major etiological agent in APL. Although PML/RARα is critical, the molecular mechanisms remains largely unknown. Here, using an inducible system, we comprehensively analyzed the 3D genome organization in myloid cells and its reorganizationn after PML/RARα induction, and performed additional analysis in patient-derived APL cells with native PML/RARα. We discovered that PML/RARα mediate extensive chromatin interactions genome-wide. Globally, it redefine the chromatin topology of the in myloid genome toward a more condensed configuration in APL cells; locally, it intrude RNAPII-associated interaction dmains, interrupt myeloid-specific transcription factors binding at enhancers and super-enahncers, and lead to transcriptional repression of genes critical for myeloid differentiation and maturation. Together, our results provide novel insights of a topological framework for PML/RARα’s roles in transforming myeloid into leukemia, likely a general mechanism for oncogenic fusion proteins in cancers.
Project description:Acute promyelocytic leukemia (APL) is characterized by a specific t(15;17) chromosome translocation that generates the promyelocytic leukemia/retinoic acid receptor-α (PML/RARα) fusion gene. However, the mechanism underlying PML/RARα mediated transcriptional dysregulation remain unclear. Here, we performed the transcription profiling of BRD4 in NB4, an APL patient-derived cell line.
Project description:Acute promyelocytic leukemia (APL) is characterized by a specific t(15;17) chromosome translocation that generates the promyelocytic leukemia/retinoic acid receptor-α (PML/RARα) fusion gene. However, the global association between PML/RARα and transcriptional co-regulators, and the rules of their association in governing the key processes during the leukemogenesis remain obscure. Here, we performed the genome-wide binding profiling of PML/RARα, HDAC1 and P300, in NB4, an APL patient-derived cell line. We found that PML/RARα targets could be classified into two classes. Moreover, we also performed ChIP-seq of H3K27ac to determine super-enhancers in NB4. We identified a novel function of PML/RARα in super-enhancer regulation during the leukemogenesis of APL.
Project description:Histone demethylase KDM3B is considered to play a critical role in leukemogenesis. To the best of our knowledge, this study is the first attempt to probe the detailed genetic and epigenetic mechanisms underlying the regulation of KDM3B in the development of APL from the perspectives of multi-layer omics. Results of the present study demonstrate that KDM3B exerts anti-APL effect by directly modulating H3K9me1/me2 levels to maintain compact chromatin status, but also indicate the interaction between KDM3B and PML/RARα regulates degradation of PML/RARα.
Project description:Histone demethylase KDM3B is considered to play a critical role in leukemogenesis. To the best of our knowledge, this study is the first attempt to probe the detailed genetic and epigenetic mechanisms underlying the regulation of KDM3B in the development of APL from the perspectives of multi-layer omics. Results of the present study demonstrate that KDM3B exerts anti-APL effect by directly modulating H3K9me1/me2 levels to maintain compact chromatin status, but also indicate the interaction between KDM3B and PML/RARα regulates degradation of PML/RARα.