Nobuyuki Akita1, Ning Ma2, Takayuki Okamoto3, Kunihiro Asanuma4, Kakunoshin Yoshida4, Junji Nishioka5, Motomu Shimaoka3, Koji Suzuki6, Tatsuya Hayashi7. 1. Faculty of Medical Engineering, Suzuka University of Medical Science, Suzuka-city, Mie, Japan. 2. Faculty of Health Science, Suzuka University of Medical Science, Suzuka-city, Mie, Japan. 3. Department of Molecular Pathobiology and Cell Adhesion Biology, Mie University Graduate School of Medicine, Tsu-city, Mie, Japan. 4. Department of Orthopedic Surgery, Mie University Graduate School of Medicine, Tsu-city, Mie, Japan. 5. Department of Clinical Nutrition, Suzuka University of Medical Science, Suzuka-city, Mie, Japan. 6. Faculty of Pharmaceutical Science, Suzuka University of Medical Science, Suzuka-city, Mie, Japan. 7. Department of Biochemistry, Mie Prefectural College of Nursing, Tsu-city, Mie, Japan. Electronic address: tatsuya.hayashi@mcn.ac.jp.
Abstract
INTRODUCTION: Protein C inhibitor (PCI), a member of the serine protease inhibitor family, is expressed in various human tissues, including liver and kidneys. In the plasma, PCI physiologically inhibits an anticoagulant serine protease, activated protein C (APC). PCI expressed by cancer cells suppresses tumor invasion by inhibiting urokinase-type plasminogen activator, and inhibits tumor growth and metastasis, which are independent of its protease-inhibitory activity. In the present study, we clarified the effects of host PCI on growth and metastasis of B16 melanoma (B16) cells by comparing between wild-type mice and mice transgenic for human PCI gene (hPCI-TG), which have a tissue distribution of PCI similar to that observed in humans. MATERIALS AND METHODS: Growth of intracutaneously-injected B16 cells was evaluated by measuring the tumor volume, and metastatic behavior of intravenously-injected B16 cells by counting the number of metastatic lung nodules. RESULTS: Growth of intracutaneously injected B16 cells was significantly faster in wild-type mice than in hPCI-TG mice; however, hPCI-TG mice developed more metastatic nodules of B16 cells in the lungs. Immunohistochemical analysis using anti-mouse fibrinogen antibody revealed more fibrin deposition in the lung in hPCI-TG mice than in wild-type mice. Furthermore, the more invasive behavior observed in hPCI-TG mice was reduced by rabbit anti-human PCI IgG, APC, or soluble TM administration for 3 consecutive days including the day that B16 cells were injected. CONCLUSIONS: Our results suggest that like PCI expressed in tumor cells, host PCI also inhibits tumor growth, but host PCI promotes tumor metastasis via its procoagulant properties.
INTRODUCTION:Protein C inhibitor (PCI), a member of the serine protease inhibitor family, is expressed in various human tissues, including liver and kidneys. In the plasma, PCI physiologically inhibits an anticoagulant serine protease, activated protein C (APC). PCI expressed by cancer cells suppresses tumor invasion by inhibiting urokinase-type plasminogen activator, and inhibits tumor growth and metastasis, which are independent of its protease-inhibitory activity. In the present study, we clarified the effects of host PCI on growth and metastasis of B16 melanoma (B16) cells by comparing between wild-type mice and mice transgenic for humanPCI gene (hPCI-TG), which have a tissue distribution of PCI similar to that observed in humans. MATERIALS AND METHODS: Growth of intracutaneously-injected B16 cells was evaluated by measuring the tumor volume, and metastatic behavior of intravenously-injected B16 cells by counting the number of metastatic lung nodules. RESULTS: Growth of intracutaneously injected B16 cells was significantly faster in wild-type mice than in hPCI-TGmice; however, hPCI-TGmice developed more metastatic nodules of B16 cells in the lungs. Immunohistochemical analysis using anti-mouse fibrinogen antibody revealed more fibrin deposition in the lung in hPCI-TGmice than in wild-type mice. Furthermore, the more invasive behavior observed in hPCI-TGmice was reduced by rabbit anti-humanPCI IgG, APC, or soluble TM administration for 3 consecutive days including the day that B16 cells were injected. CONCLUSIONS: Our results suggest that like PCI expressed in tumor cells, host PCI also inhibits tumor growth, but host PCI promotes tumor metastasis via its procoagulant properties.