Multicolor Fluorescence Based on FRET Regulated by Functional Peptides To Screen High Metastatic Potential Cancer Cells

The activation and execution of cancer invasion and metastasis involves a complex network of intracellular and extracellular molecule levels (such as reactive oxygen species (ROS), matrix metalloproteinases (MMPs)) and signaling cascades. Fluorescence sensing is a powerful detection tool for analytes. However, for imaging the intracellular signal cascades involving multiple molecules, traditional fluorescence probes are unsuitable, because most of them can only determine the change of species rather than response of multiple species simultaneously. Herein we constructed a novel probe: a H2O2-responding fluorophore donor was linked to a MMP2-sensitive peptide tagged with a FRET Cy5 acceptor. Upon addition of H2O2, the system was subjected to green fluorescence emission (555 nm), further triggering a brighter red fluorescent emission (672 nm, belonging to Cy5 acceptor), owing to FRET. In contrast, in the presence of MMP2, the FRET was turned off, due to the special cleavage of the peptide linker. The stimulation with H2O2 made the probe-loaded living cells emit multicolor fluorescence, mainly red fluorescence in normal RAW264.7 cells and poorly invasive MCF7 cells, and only green fluorescence in highly invasive MDA-MA-231 cells, owing to overexpressed MMP2. This means that after the activation with H2O2, the probe can be used to distinguish MDA-MA-231 cells from RAW264.7 macrophages and MCF7 cells. Therefore, this multicolor fluorescent probe is a powerful tool in monitoring cancer invasion and metastasis, which will provide precision information for cancer control and cure.