Modulation of eIF1A and RPS10 by small molecules unveil novel translation regulatory mechanisms with antitumor and antiviral effects

Scanning and start codon selection phases of translation initiation are regulated by eIF1A, which dynamically interacts with the ribosome through its N- and C-terminal tails. Here, we investigated the regulatory function of eIF1A-ribosome interactions in mammalian translation initiation. Through high-throughput drug screen targeting eIF1A-RPS10 interaction, we identified inhibitors - 1Ais - that directly bind to eIF1A, RPS10, or both and disrupt eIF1A interaction with the 48S in vitro and in cells. 1Ais affect translation akin to eIF1A knockdown, inhibiting scanning, start codon fidelity, and cap-proximal initiation, providing faster and effective perturbation means. Polysome profiling and Ribo-seq analyses confirmed 1Ais impact on translation initiation, revealing downregulated genes characterized by a C at position 5 relative to the AUG. Notably, this position is near eIF1A NTT in the 48S structure. Affected genes are also enriched with uORFs, implicating eIF1A in re-initiation regulation. In xenograft models of ovarian cancer, 1Ais reduce tumor growth without apparent toxicity. Additionally, an RPS10 binder 1Ai showed antiviral SARS-CoV-2 effects by controlling a regulatory CUG initiation in the sub-genomic 5UTR. Our study highlights the multifaceted roles of eIF1A-RPS10 in translation initiation and suggests their targeted inhibition as a potential therapy for cancer and viral infections.