The work centres on PRMT5, a key enzyme that regulates gene expression and is an important target in oncology. Around 10-15% of human cancers lack a metabolic gene called MTAP, causing a molecule known as MTA to accumulate within tumour cells. This altered metabolic landscape changes the way PRMT5 responds to potential drugs and creates a therapeutic vulnerability that researchers hope to exploit.
Until now, tools to directly quantify how PRMT5 inhibitors behave in the distinct metabolic environments of tumour versus normal cells have been lacking. Existing approaches provided only indirect readouts or relied on studying purified proteins outside their natural cellular context.
The University of Oxford team designed and developed CBH-002, a cell-permeable small molecule BRET probe that binds to a genetically encoded PRMT5-NanoLuc biosensor to report drug target engagement in live cells.
Dr Elisabeth Mira Rothweiler, Postdoctoral Researcher, Centre for Medicines Discovery, University of Oxford, and co-first author, says: "CBH-002 could measure various PRMT5 inhibitor types in live cells, prompting us to test its sensitivity to the cofactor SAM. When we discovered the probe's ability to sense metabolite levels, it established its utility as a metabolic biosensor. Working with Promega, we showed how MTA influences drug selectivity, revealing why certain inhibitors are so effective in MTAP-deleted cancers.”
Professor Kilian Huber, co-senior author of the study, said: “Our biosensor lets us examine, in living cells, how different PRMT5 inhibitors behave under the specific metabolic conditions that make some tumours uniquely vulnerable. This provides unprecedented insight into why certain inhibitors are much more effective in cancers lacking MTAP, and paves the way for highly targeted cancer treatment in the future. It’s like turning on the lights inside the cell so we can finally see which key actually fits the lock.”
Read the full story on the Nuffield Department of Medicine website.