Design of nucleotide-mimetic and non-nucleotide inhibitors of the translation initiation factor eIF4E: Synthesis, structural and functional characterisation

Abstract

Eukaryotic translation initiation factor 4E (eIF4E) is considered as the corner stone in the cap-dependent translation initiation machinery. Its role is to recruit mRNA to the ribosome through recognition of the 5′-terminal mRNA cap structure (m7GpppN, where G is guanosine, N is any nucleotide). eIF4E is implicated in cell transformation, tumourigenesis, and angiogenesis by facilitating translation of oncogenic mRNAs; it is thus regarded as an attractive anticancer drug target. We have used two approaches to design cap-binding inhibitors of eIF4E by modifying the N7-substituent of m7GMP and replacing the phosphate group with isosteres such as squaramides, sulfonamides, and tetrazoles, as well as by structure-based virtual screening aimed at identifying non-nucleotide cap-binding antagonists. Phosphomimetic nucleotide derivatives and highly ranking virtual hits were evaluated in a series of in vitro and cell-based assays to identify the first non-nucleotide eIF4E cap-binding inhibitor with activities in cell-based assays, N-[(5,6-dihydro-6-oxo-1,3-dioxolo[4,5-g]quinolin-7-yl)methyl]-N′-(2-methyl-propyl)-N-(phenyl-methyl)thiourea (14), including down-regulation of oncogenic proteins and suppression of RNA incorporation into polysomes. Although we did not observe cellular activity with any of our modified m7GMP phosphate isostere compounds, we obtained X-ray crystallography structures of three such compounds in complex with eIF4E, 5′-deoxy-5′-(1,2-dioxo-3-hydroxycyclobut-3-en-4-yl)amino-N7-methyl-guanosine (4a), N7-3-chlorobenzyl-5′-deoxy-5′-(1,2-dioxo-3-hydroxy-cyclobut-3-en-4-yl)amino-guanosine (4f), and N7-benzyl-5′-deoxy-5′-(trifluoromethyl-sulfamoyl)guanosine (7a). Collectively, the data we present on structure-based design of eIF4E cap-binding inhibitors should facilitate the optimisation of such compounds as potential anticancer agents.

Integrated docking and enhanced sampling-based selection of repurposing drugs for SARS-CoV-2 by targeting host dependent factors

“…SARS-CoV-2 meticulously exploits this epigenetic mechanism for the production of ACE2 enzyme (virus receptor on the host’s lung epithelial cells) (Schäfer & Baric, 2017 ; Tutuncuoglu et al, 2020 ). Interestingly, therapeutic targeting of the host translation machinery (initiation and elongation factors; EF1A1, IF4E, IF4E2) may also prevent viral protein production and inhibit the viral replication (Soukarieh et al 2016 ).…”

Integrated Docking and Enhanced Sampling Based Selection of Repurposing Drugs for SARS-CoV-2 by Targeting Host Dependent Factors

“…23,24 Interestingly, therapeutic targeting of the host translation machinery (initiation and elongation factors; EF1A1, IF4E, IF4E2) may also prevent viral protein production and inhibit the viral replication. 25…”

Monitoring flux in signalling pathways through measurements of 4EBP1-mediated eIF4F complex assembly

“…These findings underline the importance of eIF4F complex disruption in mediating the actions of these therapies. Other strategies that have been pursued to interfere with the activity of the eIF4F complex are the development of ASOs (antisense oligonucleotides) to reduce eIF4E expression [22], the discovery of chemical inhibitors of the eIF4A helicase [22] and exploration of cap analogues to prevent recruitment to capped mRNA [22, 29, 30].…”