Abstract 969: Circulating cell-free microRNA as a novel biomarker for synovial sarcoma patients (2016)

Abstract INTRODUCTION Synovial sarcoma (SS) is characterized by the SS18-SSX fusion gene, and the presence of this chromosomal translocation is clinically useful as a diagnostic marker. However, SS18-SSX does not reflect disease progression and can be detected only with tumor specimens surgically resected. Therefore, novel non-invasive biomarkers would help clinicians to diagnose or detect tumor progression, which could improve patients’ prognosis. We investigated the expression of the serum microRNA (miRNA) of SS patients, and evaluated its significance using in vitro and in vivo experimental models. METHODS In the screening phase, global analysis by miRNA microarray was performed using extracted RNA derived from patients’ serum and culture medium. The serum samples were collected from SS patients, age-matched non-SS patients, and healthy volunteers. The culture mediums were obtained from human SS cell lines and human mesenchymal stem cells (hMSCs) as controls. In the validation phase, the expression levels of miRNA derived from culture medium were evaluated by quantitative real-time PCR (qRT-PCR) to determine the secretory potential of miRNA candidates. SS cell lines and hMSCs were cultured and the culture medium was collected at 0, 24, and 48 hours. Furthermore, serum miRNA levels of SS-bearing mice were analyzed by qRT-PCR according to the tumor growth and tumor resection. RESULTS A miRNA microarray profiling revealed that four miRNAs were significantly highly expressed (p &amp;lt; 0.05) in SS patients’ serum and cell culture medium, compared to control samples, which were selected as candidates for further analysis. We then identified that one miRNA expression among four candidates in the culture medium from all SS cell lines increased with time and with increasing numbers of tumor cells. These data suggested that the detected miRNA is a secretory miRNA derived from SS cells. Next, we investigated whether the serum expression of the detected miRNA correlates with tumor progression using SS-bearing mice, which demonstrated that the detected miRNA expression in mice serum increased size-dependently (R = 0.78, p &amp;lt; 0.05). Moreover, it significantly reduced after tumor resection (p &amp;lt; 0.05), indicating that the detected serum miRNA level reflects tumor burden in vivo. Furthermore, the expression of the detected miRNA in serum collected from SS patients was significantly higher compared with that in serum collected from other soft tissue sarcoma patients. CONCLUSIONS Our results indicate that the serum expression of the detected miRNA could be useful for tumor monitoring as a non-invasive biomarker for SS. Moreover, the detected miRNA may contribute to SS progression. Citation Format: Koji Uotani, Tomohiro Fujiwara, Aki Yoshida, Takuya Morita, Yutaka Nezu, Tadashi Komatsubara, Kazuhisa Sugiu, Takenori Uehara, Toshinori Omari, Ken Takeda, Toshiyuki Kunisada, Junya Toguchida, Akira Kawai, Takahiro Ochiya, Toshifumi Ozaki. Circulating cell-free microRNA as a novel biomarker for synovial sarcoma patients. [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 969.