Figure 5.
Cetuximab persisted longer in the stroma-rich area than in the stroma-poor area. A representative immunofluorescence (IF) image shows the histology of the tumor collected at the end of the bioluminescence resonance energy transfer (BRET) imaging study, revealing the spatial distribution of the antibody (Cyan DY605-CTX), tumor-associated fibroblast (GFP Fibroblasts), and EGFR-positive tumor cells (TRITC EGFR and DAPI). Area P represents the tumor area without many stroma cells and with evenly distributed tumor cells. Area R represents the stroma-rich area, where tumor cells were surrounded by tumor-associated fibroblasts. Cyan signal denoted the total antibodies, including free DY605-CTX and bound DY605-CTX. As the white arrows indicate, residual antibodies are present at the tumor cell surfaces and largely overlap with EGFR staining, indicating the bound DY605-CTX. Scale bar = 100 .