Abstract 456: Identification of circulating tumor-derived microRNA signatures in osteosarcoma

Introduction: The lack of useful biomarkers is one of the most important clinical problems of bone and soft tissue sarcomas, although early detection of recurrent or metastatic disease and early decision making according to tumor response to chemotherapy is important to improve patient prognosis. The recent discovery of circulating cell-free microRNAs (miRNAs) in human blood has represented a new approach for the diagnostic screening for malignant diseases. In this study, we investigated whether the serum miRNA levels could be used as novel biomarkers for osteosarcoma (OS) patients. Methods: Global miRNA profiling was performed using the serum samples collected from OS patients, age-matched non-OS patients and healthy volunteers. The expression levels of extracted miRNA were confirmed in human OS cell lines (SaOS2, U2OS, HOS, 143B), human mesenchymal stem cell (hMSC), and their culture media. The miRNA candidates were evaluated using the serum samples of the validation set. Results: The miRNA expression profile of the serum samples of 10 OS patients, 10 age-matched non-OS patients, and 10 healthy controls identified 236 serum miRNAs to be highly expressed in the OS compared to the non-OS patients and healthy controls. Among these miRNAs, 8 miRNAs were overlapped with the secretory miRNAs in the culture medium of 7 osteosarcoma cell lines. Quantitative RT-PCR revealed that two candidates were significantly upregulated in the OS cells and culture medium, compared to MSCs. The expression of these miRNAs in the culture media from all OS cell lines increased along with culture time and tumor cell numbers, indicating that it is an important secretory miRNA derived from OS cells. The serum concentration of these miRNAs in OS patients was significantly higher than those in healthy volunteers and non-OS patients. Our ROC analyses revealed that an AUC value based on the miRNA expression was 0.868 (95% confidence interval = 0.743 to 0.993), which was was higher than that of alkaline phosphatase (ALP). Finally, the detected serum miRNA expression levels markedly decreased at the postoperative status in operative cases, while gradually decreased during neoadjuvant chemotherapy, which revealed that serum miRNA expression levels correlated with the tumor burden and drug sensitivity. Conclusions: We identified circulating tumor-derived miRNA signatures in the serum obtained from the OS patients. Furthermore, the definitive miRNA reflected tumor burden in OS patients. Evaluating the serum miRNA expression may thus have important clinical implications for risk stratification and the planning of post-therapeutic surveillance. Citation Format: Tomohiro Fujiwara, Koji Uotani, Aki Yoshida, Takuya Morita, Tadashi Komatsubara, Kazuhisa Sugiu, Toshinori Omori, Ken Takeda, Toshiyuki Kunisada, Yutaka Nezu, Akira Kawai, Hirotaka Kanzaki, Takahiro Ochiya, Toshifumi Ozaki. Identification of circulating tumor-derived microRNA signatures in osteosarcoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 456.