Anticancer pyrroloquinazoline LBL1 targets nuclear lamins.

Target identification of bioactive compounds is critical for understanding their mechanism of action. We previously discovered a novel pyrroloquinazoline compound LBL1 with significant anticancer activity. However, its molecular targets remain to be established. Herein, we developed a clickable photoaffinity probe based on LBL1. By extensive chemical, biochemical and cellular studies with this probe and LBL1, we found that LBL1 targets nuclear lamins, which are type V intermediate filament (IF) proteins. Further studies showed that LBL1 binds to the coiled-coil domain of lamin A. These results revealed that IF proteins can also be targeted with appropriate small molecules besides two other cytoskeletal proteins actin filaments and microtubules, providing a novel avenue to investigate lamin biology and a novel strategy to develop distinct anticancer therapies.