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Oligomerization of the ABL tyrosine kinase by the Ets protein TEL in human leukemia.

ABSTRACT: TEL is a member of the Ets family of transcription factors which are frequently rearranged in human leukemia. The mechanism of TEL-mediated transformation, however, is unknown. We report the cloning and characterization of a chromosomal translocation associated with acute myeloid leukemia which fuses TEL to the ABL tyrosine kinase. The TEL-ABL fusion confers growth factor-independent growth to the marine hematopoietic cell line Ba/F3 and transforms Rat-1 fibroblasts and primary murine bone marrow cells. TEL-ABL is constitutively tyrosine phosphorylated and localizes to the cytoskeleton. A TEL-ABL mutant containing an ABL kinase-inactivating mutation is not constitutively phosphorylated and is nontransforming but retains cytoskeletal localization. However, constitutive phosphorylation, cytoskeletal localization, and transformation are all dependent upon a highly conserved region of TEL termed the helix-loop-helix (HLH) domain. TEL-ABL formed HLH-dependent homo-oligomers in vitro, a process critical for tyrosine kinase activation. These experiments suggest that oligomerization of TEL-ABL mediated by the TEL HLH domain is required for tyrosine kinase activation, cytoskeletal localization, and transformation. These data also suggest that oligomerization of Ets proteins through the highly conserved HLH domain may represent a previously unrecognized phenomenon.

SUBMITTER: Golub TR

PROVIDER: S-EPMC231407 | biostudies-other | 1996 Aug

REPOSITORIES: biostudies-other

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Oligomerization of the ABL tyrosine kinase by the Ets protein TEL in human leukemia.

Golub T R TR Goga A A Barker G F GF Afar D E DE McLaughlin J J Bohlander S K SK Rowley J D JD Witte O N ON Gilliland D G DG

Molecular and cellular biology 19960801 8

TEL is a member of the Ets family of transcription factors which are frequently rearranged in human leukemia. The mechanism of TEL-mediated transformation, however, is unknown. We report the cloning and characterization of a chromosomal translocation associated with acute myeloid leukemia which fuses TEL to the ABL tyrosine kinase. The TEL-ABL fusion confers growth factor-independent growth to the marine hematopoietic cell line Ba/F3 and transforms Rat-1 fibroblasts and primary murine bone marro ...[more]

PMID: 8754809

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Project description:Background In the ongoing battle against BCR-ABL+ leukemia, despite significant advances with tyrosine kinase inhibitors (TKIs), the persistent challenges of drug resistance and the enduring presence of leukemic stem cells (LSCs) remain formidable barriers to achieving a cure. Methods In this study, we demonstrated that Disulfiram (DSF) induces ferroptosis to synergize with TKIs in inhibiting BCR-ABL+ cells, particularly targeting resistant cells and LSCs, using cell models, mouse models, and primary cells from patients. We elucidated the mechanism by which DSF promotes GPX4 degradation to induce ferroptosis through immunofluorescence, co-immunoprecipitation (CO-IP), RNA sequencing, lipid peroxidation assays, and rescue experiments. Results Here, we present compelling evidence elucidating the sensitivity of DSF, an FDA-approved drug for alcohol dependence, towards BCR-ABL+ cells. Our findings underscore DSF's ability to selectively induce a potent cytotoxic effect on BCR-ABL+ cell lines and effectively inhibit primary BCR-ABL+ leukemia cells. Crucially, the combined treatment of DSF with TKIs selectively eradicates TKI-insensitive stem cells and resistant cells. Of particular note is DSF's capacity to disrupt GPX4 stability, elevate the labile iron pool, and intensify lipid peroxidation, ultimately leading to ferroptotic cell death. Our investigation shows that BCR-ABL expression induces alterations in cellular iron metabolism and increases GPX4 expression. Additionally, we demonstrate the indispensability of GPX4 for LSC development and the initiation/maintenance of BCR-ABL+ leukemia. Mechanical analysis further elucidates DSF's ability to circumvent resistance by reducing GPX4 levels through the disruption of its binding with HSPA8, thereby promoting GPX4 ubiquitination and subsequent degradation. Furthermore, the combined treatment of DSF with TKIs effectively targets both BCR-ABL+ blast cells and drug-insensitive LSCs, conferring a significant survival advantage in mouse models. Conclusion In summary, the dual inhibition of GPX4 and BCR-ABL presents a promising therapeutic strategy to synergistically target blast cells and drug-insensitive LSCs in patients, offering potential avenues for advancing leukemia treatment.

Project description:Previously, it has been stated that the BCR-ABL fusion-protein is sufficient to induce Chronic Myeloid Leukemia (CML), but additional genomic-changes are required for disease progression. Hence, we profiled control and tyrosine kinase inhibitors (TKI) alone or in combination with other drug-treated CML-samples in different phases, categorized as drug-sensitive and drug-resistant on the basis of BCR-ABL transcripts, the marker of major molecular-response. Molecular-profiling was done using the molecular-inversion probe-based-array, Human Transcriptomics-Array2.0, and Axiom-Biobank genotyping-arrays. At the transcript-level, clusters of control, TKI-resistant and TKI-sensitive cases were correlated with BCR-ABL transcript-levels. Both at the gene- and exon-levels, up-regulation of MPO, TPX2, and TYMS and down-regulation of STAT6, FOS, TGFBR2, and ITK lead up-regulation of the cell-cycle, DNA-replication, DNA-repair pathways and down-regulation of the immune-system, chemokine- and interleukin-signaling, TCR, TGF beta and MAPK signaling pathways. A comparison between TKI-sensitive and TKI-resistant cases revealed up-regulation of LAPTM4B, HLTF, PIEZO2, CFH, CD109, ANGPT1 in CML-resistant cases, leading to up-regulation of autophagy-, protein-ubiquitination-, stem-cell-, complement-, TGFβ- and homeostasis-pathways with specific involvement of the Tie2 and Basigin signaling-pathway. Dysregulated pathways were accompanied with low CNVs in CP-new and CP-UT-TKI-sensitive-cases with undetectable BCR-ABL-copies. High CNVs (previously reported gain of 9q34) were observed in BCR-ABL-independent and -dependent TKI, non-sensitive-CP-UT/AP-UT/B-UT and B-new samples. Further, genotyping CML-CP-UT cases with BCR-ABL 0-to-77.02%-copies, the identified, rsID239798 and rsID9475077, were associated with FAM83B, a candidate for therapeutic resistance. The presence of BCR-ABL, additional genetic-events, dysregulated-signaling-pathways and rsIDs associated with FAM83B in TKI-resistant-cases can be used to develop a signature-profile that may help in monitoring therapy.

Dataset Information

Oligomerization of the ABL tyrosine kinase by the Ets protein TEL in human leukemia.

Publications

Oligomerization of the ABL tyrosine kinase by the Ets protein TEL in human leukemia.

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