The antibiotic drug trimethoprim suppresses tumour growth and metastasis via targeting Snail.

Background and Purpose: The zinc finger transcription factor Snail is aberrantly activated in many human cancers and strongly associated with poor prognosis. As a transcription factor, Snail has been traditionally considered an 'undruggable' target. Here, we identified a potent small-molecule inhibitor of Snail, namely trimethoprim, and investigated its potential antitumour effects and the underlying mechanisms.
Experimental Approach: The inhibitory action of trimethoprim on Snail protein and the related molecular mechanisms were revealed by molecular docking, biolayer interferometry, immunoblotting, immunoprecipitation, qRT-PCR, pull-down and cycloheximide pulse-chase assays. The anti-proliferative and anti-metastatic effects of trimethoprim via targeting Snail were tested in multiple cell-based assays and animal models.
Key Results: This study identified trimethoprim, an antimicrobial drug, as a potent antitumour agent via targeting Snail. Molecular modelling analysis predicted that trimethoprim directly binds to the arginine-174 pocket of Snail protein. We further discovered that trimethoprim strongly interrupts the interaction of Snail with CREB-binding protein (CBP)/p300, which consequently suppresses Snail acetylation and promotes Snail degradation through the ubiquitin-proteasome pathway. Furthermore, trimethoprim sufficiently inhibited the proliferation, epithelial-mesenchymal transition (EMT) and migration of cancer cells in vitro via specifically targeting Snail. More importantly, trimethoprim effectively reduced Snail-driven tumour growth and metastasis to vital organs such as lung, bone and liver.
Conclusions and Implications: These findings indicate, for the first time, that trimethoprim suppresses tumour growth and metastasis via targeting Snail. This study provides insights for a better understanding of the anticancer effects of trimethoprim and offers a potential anticancer therapeutic agent for clinical treatment.
(© 2021 The British Pharmacological Society.)