image: (A) The levels of the METTL3 protein in MV4.11, MOLM13, and NB4 cells treated with ZW27941 for 24 h detected by Western blot. METTL3 band intensity was normalized against ACTIN in each sample and DC50 (the drug concentration causing 50 % protein degradation) concentration was calculated. (B) Viability of MOLM13 and MV4.11 cells after they were treated with increasing concentrations of ZW27941 for 72 h. EC50 values are the average of three independent experiments. EC50 values were calculated based on the percentage of viable cells, normalized to control, as determined by CCK8 assay. (C) Western blot analysis of METTL3, METTL14, METTL16, WTAP, and RBM15 in NB4 cells after treated with 1 μM ZW27941 for 24 h. (D) The effect of UZH2 or ZW27941 (1 μM) treatment on global mRNA m6A levels in MOLM13 cells detected by dot-blot assay. (E) Quantification of m6A levels on polyA mRNA following 24 h treatment of MOLM13 cells with UZH2 or ZW27941 (1 μM). Data shown were mean ± standard deviation of triplicate experiments; ∗∗∗P < 0.001, ∗∗∗∗P < 0.0001. (F) Cellular thermal shift assay (CETSA) was conducted with MOLM13 cell lysate to monitor cellular target engagement. The cell lysate was incubated with either vehicle (DMSO) or ZW27941 (100 μM) for 30 min before melting at the indicated temperatures. The assay was performed in duplicate and western blots of METTL3 are shown. (G) Immunoblot analysis of METTL3 expression in MV4.11 cells after they were treated with 1 μM ZW27941 for various durations as indicated. Densitometric analysis of METTL3 expression is presented on the bottom panel as the mean of two independent experiments. (H) Analysis of METTL3 expression by immunoblot in MV4.11 cells treated with ZW27941 for 12 h followed by drug withdrawal and then culturing without ZW27941 for 0–24 h.
Credit: Genes & Diseases
Acute myeloid leukemia (AML) is an aggressive blood cancer characterized by the uncontrolled proliferation of malignant hematopoietic stem and progenitor cells. METTL3, a key catalytic component within the m6A methyltransferase complex (alongside METTL14), is overexpressed in AML cells and plays a crucial role in promoting cancer. However, effective pharmacological targeting of the RNA m6A transferase core complex remains a challenge.
This new research published in the Genes & Diseases journal by a team from the University of Florida evaluates the anti-leukemic activity of a Von Hippel-Lindau (VHL)-recruiting METTL3 PROteolysis TArgeting Chimera (PROTAC), ZW27941.
The research team initially screened a library of VHL-directed METTL3 degraders against a panel of AML cell lines and identified ZW27941. ZW27941 was shown to degrade METTL3/METTL14 in a concentration- and time-dependent manner, requiring proteasomal and ubiquitin ligase activities and VHL binding. In vitro studies demonstrated that ZW27941 not only exhibited anti-tumor effects on AML cell lines but also inhibited cancer cell proliferation, promoted cell apoptosis, and triggered G0/G1 cell cycle arrest.
Further analysis demonstrated a dose-dependent reduction in c-Myc expression following ZW27941 treatment, which implicates the likely involvement of METTL3 in c-Myc regulation. Differential expression of 1911 genes was noted in AML cells following ZW27941 treatment, with a notable proportion being down-regulated. Additionally, this study also suggests that METTL3 plays a role in regulating translation through an m6A-independent mechanism. Furthermore, GO and KEGG analyses indicated that the down-regulated genes following ZW27941 treatment were enriched in metabolic processes, cell cycle regulation, and RNA processing pathways.
Importantly, ZW27941 demonstrated synergistic or additive effects when combined with standard AML therapeutics, such as cytarabine and venetoclax.
Although this study warrants further optimization and validation in animal models to fully establish the therapeutic potential and safety of these degraders in vivo, it also presents an exciting case for the use of selective METTL3 degraders in the context of leukemia. In conclusion, this research holds promise as a novel therapeutic approach for AML, particularly when used in combination with existing treatments to enhance efficacy and overcome resistance mechanisms.
Reference
Title of Original Paper: Targeting METTL3 protein by proteolysis-targeting chimeras: A novel therapeutic approach for acute myeloid leukemia
Journal: Genes & Diseases
Genes & Diseases is a journal for molecular and translational medicine. The journal primarily focuses on publishing investigations on the molecular bases and experimental therapeutics of human diseases. Publication formats include full length research article, review article, short communication, correspondence, perspectives, commentary, views on news, and research watch.
DOI: https://doi.org/10.1016/j.gendis.2024.101452
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Genes & Diseases publishes rigorously peer-reviewed and high quality original articles and authoritative reviews that focus on the molecular bases of human diseases. Emphasis is placed on hypothesis-driven, mechanistic studies relevant to pathogenesis and/or experimental therapeutics of human diseases. The journal has worldwide authorship, and a broad scope in basic and translational biomedical research of molecular biology, molecular genetics, and cell biology, including but not limited to cell proliferation and apoptosis, signal transduction, stem cell biology, developmental biology, gene regulation and epigenetics, cancer biology, immunity and infection, neuroscience, disease-specific animal models, gene and cell-based therapies, and regenerative medicine.
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