Whole-body imaging of tumor cells by azaelectrocyclization: visualization of metastasis dependence on glycan structure.

Noninvasive imaging of cancer metastasis through the efficient cell labeling constitutes a major technological breakthrough for cancer research and patient monitoring post-surgery. In the current work, we expanded our cell surface labeling technique on the whole-body fluorescence imaging of tumor metastasis in BALB/c nude mice. Four kinds of human cancer cells (two cancer cell lines, MKN45 and HCT116, and their transfected versions expressing surface glycan-related genes, MKN45-GnT-V and HCT116-GMDS) were labeled by azaelectrocyclization with Hilyte Fluor 750 for 10 min and without affecting cell viability. Fluorescence-labeled cancer cells were injected into the abdominal cavities of BALB/c mice and whole-body scans were performed with an eXplore Optix device. In accordance with previous findings, the fluorescence imaging clearly showed that tumor metastasis was dependent upon the cell surface glycans: A larger polylactosamine structure or the loss of fucosylation on the cancer cell surfaces, respectively, enhanced the metastatic potential of the tumor cells. Our noninvasive technique provides the landmark opportunity for sensitively monitoring the dynamics of the cancer cells depending on their surface structures and/or the host environments, thus impacts on the cancer prognosis and the therapeutic applications.