Use of α_v Integrin Linked to GFP to Image Molecular Dynamics in Trafficking Cancer-Cell Emboli

Human osteosarcoma cells with an α_v integrin green fluorescent protein (GFP) fusion gene were previously established and imaged in vitro and in vivo. In the present study, we imaged the interaction of α_v integrin-GFP in osteosarcoma cells and collagen fibers in vascular-trafficking osteosarcoma emboli in nude mice. Human 143B osteosarcoma cells, expressing α_v integrin-GFP, were injected by a vascular route in an abdominal skin flap in nude mice. Osteosarcoma cells were fluorescently imaged in the epigastric cranialis vein in the abdominal skin flap by confocal microscopy. Collagen fibers were imaged in reflectance mode. At early stages of tumor embolus-formation, cancer cells adhered firmly to each other, diffusely expressing α_v integrin-GFP. Two weeks after injection, collagen fiber scaffolds were visualized at the margins of tumor emboli or within them. Four weeks after injection, cancer cells invading from emboli were strongly expressing α_v integrin-GFP, and were aligned along collagen fibers. The results suggest α_v integrin and collagen fiber scaffolds are important for tumor embolus formation, which are potential seeds of metastasis. J. Cell. Biochem. 118: 26–30, 2017.