Abstract 5393: Exosomal microRNA profiles in peritoneal fluids as a therapeutic biomarker for peritoneal metastasis of gastric cancer

Abstract

Abstract Background: Repeated intraperitoneal chemotherapy (IPC) using taxane is highly effective for peritoneal metastasis. Peritoneal fluids are supposed to contain various factors derived from tumor cells seeded in peritoneal cavity. This study aimed to explore possible biomarkers for suitable IPC using exosomal miRNA profiles derived from malignant ascites or peritoneal lavages. Methods: Peritoneal fluid samples were obtained from 11 patients with peritoneal metastasis (PM+) and 14 patients who received gastrectomy for early gastric cancer (PM-). Exosomal fractions were isolated using ultracentrifuge method and total RNAs were extracted. The pooled RNA samples in both groups were mixed and expression of miRNAs were analyzed using miRNome miScript miRNA PCR Array (QIAGEN). Based on these results, we constructed the custom miRNA PCR panel and evaluates expression of miRNAs in individual samples. Results: The comprehensive PCR analysis showed that total of 56 and 54 miRNAs were strongly expressed in exosomes in PM+ and PM- peritoneal fluid sample, respectively. In analysis of individual samples, 7 upregulated miRNAs (miR-150-5p, miR-223-3p, miR-204-5p, miR-720, and miR-92a, miR-21-5p, miR-4301, and miR-342-3p) and 3 downregulated miRNAs (miR-29a-3p, miR-29b-3p, and miR-29c-3p) were identified in PM+ samples. Conclusion: In patients who receive IPC, peritoneal fluids can be repeatedly obtained from peritoneal access port. Exosomal miRNA profiles of peritoneal fluid samples might be a useful biomarker to determine the therapeutic efficacy as well as to predict the outcome in those patients with peritoneal metastasis. Citation Format: Hideyuki Ohzawa, Yuko Kumagai, Hironori Yamaguchi, Yoshinori Hosoya, Naohiro Sata, Joji Kitayama. Exosomal microRNA profiles in peritoneal fluids as a therapeutic biomarker for peritoneal metastasis of gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5393.