Targeted Delivery of an Activatable Fluorescent Probe for the Detection of Furin Activity in Living Cells.

Furin, a protein convertase, plays a crucial role in the progression of tumors. In this work, a new fluorescent probe consisting of a peptide, Arg-Val-Arg-Arg (RVRR), and an aminoluciferin fluorophore was designed and prepared for the responsive and activatable detection of furin activity in vitro and in living cells. We demonstrated that this probe could be responsive toward furin with an "off-on" florescence signal and generated an approximately 3.58-fold enhancement in the fluorescence intensity in vitro. Fluorescence imaging in MDA-MB-468 and LoVo cells showed that the probe could be cleaved by overexpressed furin with fluorescence turn-on in MDA-MB-468 cells, and this probe was also found to be capable of discriminating between furin-overexpressing and furin-deficient cell lines. Our research indicates that this probe has great potential for the detection of furin activity in living cells.