Resection of Primary Osteosarcoma Tumor Enhances the Pulmonary Metastasis through the Activation of Angiogenesis

It is well known that more than 50% of the patients with osteosarcoma affected pulmonary metastasis at the time of diagnosis of the primary lesion although such a dormant micrometastasis is often asymptomatic and clinically undetectable until relapse. There are several clinical evidences showing that some of these patients relapse of pulmonary metastasis within months after the removal of the primary lesion. Howevwe, little is known about the molecular mechanism of the early relapse of the pulmonary metastasis of osteosarcoma. Thus, to clarify the moleculae mechanism of this phenomenon, we have examined whether removal of osteosarcoma can enhance the establishment of pulmonary metastasis. In addition, we assessed that the removal of the primary osteosarcoma tumor enhance the angiogenic activity. Furthermore, we investigated whether s.c. delivery of TNP-470, an angiogenesis inhibitor, inhibited the progression of pulmonary metastasis after the removal of primary osteosarcoma tumor.