Modular FRET sensor for site-specific detection of protein arginine methylation in living cells

To evaluate a modular fluorescence resonance energy transfer (FRET) biosensor for site-specific real-time detection of protein arginine methylation and to explore its translational relevance using a synthetic oncology cohort.

A synthetic cohort of 200 patients with breast, colorectal, and lung cancer was generated to reflect real-world demographics and clinical distribution. A modular FRET biosensor (composed of donor-receptor fluorophores linked by a methylarginine recognition domain) was used to quantify the methylation index of different tumor subgroups.

The FRET biosensor demonstrated superior diagnostic accuracy in identifying tumors with high methylation burden. The definition of high methylation burden was based on a clinically informed threshold (≥0.65) optimized using receiver operating characteristic (ROC) and was supported by survival relevance. Patients with elevated FRET-derived methylation indices showed significantly shorter progression-free survival (8.9 months vs. 14.6 months; hazard ratio (HR) 1.92, 95% confidence interval (CI) 1.41-2.63, P<0.001) and overall survival (OS) (21.4 months vs. 36.2 months; HR 2.11, 95% confidence interval (CI) 1.55-2.87, P<0.001). In the hypermethylation subgroup, the addition of a protein arginine methyltransferase inhibitor was associated with a higher objective response rate (38% vs. 21%, P=0.008), but showed no significant trend towards improved survival.

This study demonstrates the potential translational application value of modular FRET biosensors in the dynamic monitoring of protein arginine methylation. Although the study was based on a synthetic cohort, the results highlight the potential of FRET-based methylation sensing technology as a research and biomarker development tool, and warrant validation in future real-world clinical settings.