Dynamic analysis of lung metastasis by mouse osteosarcoma LM8: VEGF is a candidate for anti-metastasis therapy

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RESEARCH PAPER

Dynamic analysis of lung metastasis by mouse osteosarcoma LM8: VEGF is a candidate for anti-metastasis therapy Takaaki Tanaka • Yoshihiro Yui • Norifumi Naka • Toru Wakamatsu • Kiyoko Yoshioka • Nobuhito Araki Hideki Yoshikawa • Kazuyuki Itoh



Received: 25 May 2012 / Accepted: 1 October 2012 / Published online: 18 October 2012 Ó The Author(s) 2012. This article is published with open access at Springerlink.com

Abstract Osteosarcoma (OS) is the most common malignant bone tumor and the prognosis depends on pulmonary metastases, which arise from multi-step progression of malignant tumors. We herein aimed to clarify the critical step of pulmonary metastasis using the syngeneic mouse spontaneous highly metastatic OS LM8 and parental Dunn cell lines, to identify new candidate molecules to suppress pulmonary metastasis. We first investigated the chronological detection of circulating tumor cells (CTCs) from mice with either cell line. LM8 CTCs appeared faster, at a higher rate and with a greater number compared to Dunn CTCs. Cultured cells from CTCs of LM8 showed higher proliferative ability than cells from the primary site Electronic supplementary material The online version of this article (doi:10.1007/s10585-012-9543-8) contains supplementary material, which is available to authorized users. T. Tanaka (&)  Y. Yui  N. Naka  T. Wakamatsu  K. Yoshioka  K. Itoh (&) Department of Biology, Osaka Medical Center of Cancer and Cardiovascular Diseases, 1-3-3 Nakamichi, Higashinari-ku, Osaka 537-8511, Japan e-mail: [email protected] K. Itoh e-mail: [email protected] T. Tanaka  N. Naka  T. Wakamatsu  H. Yoshikawa Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, Japan

in suspension culture, which mimicked the environment of the bloodstream for CTCs. The proliferative ability of LM8 cells was also higher than that of Dunn cells in 3D collagen culture with low stiffness (-150 Pa; close to conditions in the lung). We next focused on the extravasation step. LM8 showed higher migration ability compared to Dunn with transendothelial migration assay. We also found a disruption in endothelial barrier function throughout co-culture with LM8 using time-lapse imaging. In addition, LM8 secreted high levels of vascular endothelial growth factor (VEGF), while VEGF signal inhibition with a small molecule tyrosine kinase inhibitor (pazopanib) decreased disruption of the vascular barrier and transendothelial migration of LM8. Finally, daily oral administration of pazopanib reduced the rate and size of pulmonary metastasis in vivo. Collectively, these results show anti-VEGF therapy as a candidate for pulmonary metastasis of OS. Keywords Osteosarcoma  Metastasis  Circulating tumor cells  Vascular endothelial growth factor  Transendothelial migration  Pazopanib Abbreviations CTCs Circulating tumor cells 3D Three dimensions VEGF Vascular endothelial growth factor

Y. Yui Department of Surgery, University of California, San Francisco, 513 Parnas