A Cooperatively Activatable, DNA‐based Fluorescent Reporter for Imaging of Correlated Enzymatic Activities

The dynamic variation of the expression profile and spatial landscape of multiple enzymes are crucial factors influencing tumor progression and drug treatment. However, the comprehensive analysis of these events has been hampered by the limitations of existing imaging technologies. Here we report a cooperatively activatable, DNA-based fluorescent reporter programmed to detect the correlated activity of dual enzymes, telomerase (TE) and apurinic/apyrimidinic endonuclease 1 (APE1), both in vitro and in vivo. The conformational change of the DNA probe can be orthogonally triggered through TE-induced DNA elongation and APE1-mediated specific cleavage, producing a fluorescent signal for imaging the activity of the two enzymes in an AND-gated manner. Furthermore, we demonstrate the capability of the system for specific tumor imaging through "dual lock-and-key" strategy, and visualizing the correlated enzymatic activities during drug treatment of cancer.