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αv Integrin is involved in various steps of cancer metastasis. In this report, we describe real-time imaging of αv integrin molecular dynamics in human 143B osteosarcoma cells in vitro and in vivo. We first generated osteosarcoma cells expressing αv integrin green fluorescent protein (GFP) by transfection of an αv integrin GFP fusion vector (pCMV6-AC-ITGAV-GFP) into 143B cells. Confocal laser-scanning microscopy demonstrated that αv integrin immunofluorescence staining co-localized with αv integrin-GFP fluorescence in 143B cells. When αv integrin-GFP-expressing 143B osteosarcoma cells were seeded on a dish coated with fibronectin, which is bound by αv integrin, punctate αv integrin-GFP was observed by confocal laser-scanning microscopy. When the 143B αv integrin-GFP cells were seeded onto uncoated plastic, αv integrin-GFP was diffuse within the cells. When αv integrin-GFP 143B osteosarcoma cells (1×10(6)) were orthotopically transplanted into the tibia of nude mice, the cells aligned along the collagen fibers within the tumor and had punctuate expression of αv integrin-GFP. In the orthotopic model, the invading osteosarcoma cells had punctate αv integrin-GFP in the muscle tissue at the primary tumor margin. These results show that αv integrin-GFP enables the imaging of the molecular dynamics of αv integrin in osteosarcoma cells in vitro and in vivo.

We have previously demonstrated that ultraviolet (UV) light treatment is effective against various types of cancer cells expressing fluorescent proteins. In order to further understand the efficacy of UV treatment of cancer cells, we determined the kinetics of focus formation by imaging of a DNA damage-response (DDR) protein after UVC irradiation of human pancreatic cancer cells. A fusion protein consisting of the DDR protein 53BP1 and green fluorescent protein (GFP) (GFP-53BP1) was used as a live-cell imaging marker for cellular response after UVC irradiation. GFP-53BP1 foci were observed after UVC irradiation of MiaPaCa-2 human pancreatic cancer cells. During live-cell imaging, GFP-53BP1 foci were observed in the cells within 15 min after UVC irradiation, and some of the foci remained stable for at least three hours. GFP-53BP1 focus formation was observed in the pancreatic-cancer cells irradiated by 25-200 J/m(2) UVC. Our results indicate that an early response to DNA damage caused by UVC irradiation can be visualized by increased GFP-53BP1 focus formation by pancreatic cancer cells.

The integrin family of proteins has been shown to be involved in the malignant behavior of cells. We report here development of a color-coded imaging model that can visualize the interaction between αv integrin linked to green fluorescent protein (GFP) in osteosarcoma cells and blood vessels in Gelfoam® vascularized after implantation in red fluorescent protein (RFP) transgenic nude mice. Human 143B osteosarcoma cells expressing αv integrin-GFP were generated by transfection with an αv integrin-GFP vector. Gelfoam® (5×5 mm) was transplanted subcutaneously in transgenic RFP nude mice. The implanted Gelfoam® became highly vascularized with RFP vessels within 14 days. Skin flaps were made at days 7, 14, 21, 28 after transplantation of Gelfoam® for observing vascularization of the Gelfoam® using fluorescence imaging. Gelfoam® is a useful tool to observe angiogenesis in vivo. 143B cells (5 × 10(5)) expressing αv integrin-GFP were injected into the Gelfoam® seven days after transplantation of Gelfoam®. Seven days after cancer-cell injection, cancer cells and blood vessels were observed in the Gelfoam® by color-coded confocal microscopy via the skin flap. The 143B cells expressing αv integrin-GFP proliferated into the Gelfoam®, which contained RFP-expressing blood vessels. Strong expression of αv integrin-GFP in 143B cells was observed near RFP vessels in the Gelfoam®. The observation of the behavior of αv integrin-GFP and blood vessels will allow further understanding of the role of αv integrin in cancer cells.

Malignant glioma is the most common type of primary central nervous system cancer. Gliomas are very difficult to completely resect due to their invasiveness. In the present study, we compared fluorescence-guided and standard bright-light resection of a human glioma orthotopically implanted in nude mice. U87 human glioma cells, expressing red fluorescent protein (RFP), were injected stereotactically into the nude mouse brain through a craniotomy open window. Two weeks after cancer-cell implantation, gliomas were resected under fluorescence guidance or under bright light. U87-RFP tumors were clearly visualized with a long-working distance fluorescence microscope. Almost all cancer cells were removed using fluorescence-guided navigation without damage to the brain tissue. In contrast, brain tumors were difficult to visualize under bright light and many residual cancer cells remained in the brain after bright-light surgery. Fluorescence-guided surgery significantly extended the survival of the mice compared to those who underwent bright-light surgery. These results suggest that fluorescence-guided surgery has significant potential for brain cancer treatment.