MB-3   Click here for help

GtoPdb Ligand ID: 8393

Synonyms: α-methylene-γ-butyrolactone 3
Compound class: Synthetic organic
Comment: MB-3 is reported as a cell-permeable small-molecule inhibitor of the histone acetyltransferase enzyme, general control nonderepressible 5 (GCN5, gene symbol KAT2B) [1]. In vitro, MB-3 has been shown to inhibit GCN5-driven acetylation of the chimeric oncoprotein E2A-PBX1 [4]. E2A-PBX1 is a non-histone target of GCN5 [5].
A 2017 article by Dahlin et al. suggests that the thiol-reactivity of MB-3 brings in to question its activity as a selective HAT inhibitor [3].
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2D Structure
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Physico-chemical Properties
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Hydrogen bond acceptors 5
Hydrogen bond donors 1
Rotatable bonds 3
Topological polar surface area 80.67
Molecular weight 186.05
XLogP 0.49
No. Lipinski's rules broken 0
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Canonical SMILES CCCC1OC(=O)C(=O)C1C(=O)O
Isomeric SMILES CCC[C@@H]1OC(=O)C(=O)[C@H]1C(=O)O
InChI InChI=1S/C8H10O5/c1-2-3-4-5(7(10)11)6(9)8(12)13-4/h4-5H,2-3H2,1H3,(H,10,11)/t4-,5-/m0/s1
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Mechanism Of Action and Pharmacodynamic Effects Click here for help
E2A-PBX1 (pre-B-cell leukemia transcription factor) is a fused oncoprotein which results from a t(1;19)(q23;q13) chromosomal translocation. E2A-PBX1 is found in more than 20% of patients with pediatric pre-B ALL (acute lymphoblastic leukemia) [2]. GCN5-induced acetylation of E2A-PBX1 stablises the oncoprotein and leads to oncogenic transformation in B-cells. MB-3 inhibits this process and results in increased E2A-PBX1 degradation via a E3 ubiquitin ligase HDM2 mechanism [4].