A label-free screening approach targeted protease-activated receptor 1 based on dynamic mass redistribution in living cells

Protease-activated receptor 1 (PAR-1) antagonists strongly inhibit thrombin-induced platelet aggregation and are proved to be effective as anti-thrombotic drugs. Traditional screening assays for PAR-1 antagonists require molecular labeling or cell engineering technique. Here, a label-free approach was developed for the screening of active compounds targeting PAR-1 through monitoring integrated live-cell responses in whole cells. To characterize the cellular response, the cellular dynamic mass redistribution (DMR) was detected with a resonant waveguide grating (RWG) biosensor using PAR-1 known agonists and antagonists. The human epidermoid carcinoma A431 cell line was selected to establish a cell phenotypic profiling model for screening the PAR-1 antagonists from 80 natural products. Results showed that five compounds were screened out as candidate bioactive compounds. Two compounds, parthenolide and sanguinarine, were identified to possess anti-platelet aggregation activities in vitro. These results indicate that the label-free DMR screening approach is effective and useful for screening bioactive compounds targeting PAR-1.