Abstract 2765: Exosomal miRNAs as circulating biomarkers for prediction of metastasis in stage II/III gastric cancer

Abstract

Abstract Background: Metastasis is the fatal character of cancer, leading to mortality of gastric cancer. In recent years, exosomes have been reported as extracellular vesicles secreted by cells. They contain various biological molecules including miRNAs from the original cells. Exosomal miRNAs are significant for pre-metastatic niche formation, as they can change the microenvironment and make it favorable for future metastasis. Therefore, the aim of this study was to identify dysregulated exosomal miRNAs as circulating biomarkers for prediction of metastasis of gastric cancer. Materials and Methods: Pre-treatment serum samples of 36 metastatic patients and 55 non-metastatic patients with stage II/III gastric cancer were collected. Exosomes were extracted and validated by western blot, transmission electron microscope and nanoparticle tracking analysis. MiRCURY LNATM miRNA miRNome PCR Array (containing 752 miRNAs) was performed in three pairs of serum exosomes. Each pair samples were with the same stage, race, gender and similar age. These three pairs of samples represented stage II, IIIA or IIIB gastric cancer, respectively. A panel of commonly dysregulated exosomal miRNAs was released from the PCR Array. Expressions of exosomal miRNAs were validated in the remaining 33 metastatic and 52 non-metastatic patients by RT-qPCR, as well as in gastric cancer cell culture medium and cell lines. Results: By comparing the expressions of exosomal miRNAs between the metastatic patients and matched non-metastatic ones, 13 upregulated and 6 downregulated miRNAs were released after normalization with miR-16-5p and miR-93-5p. Among these miRNAs, 7 of them were selected for further validation according to their fold changes, p-values and association with cancer development. MiR-379-5p and miR-410-3p were validated to be significantly upregulated in metastatic patients (P<0.01). Sensitivity, specificity and AUC were 67.31%, 69.70% and 0.6894 for miR-379-5p, and 65.38%, 66.67% and 0.6719 for miR-410-3p. Higher expression of serum exosomal miR-379-5p or miR-410-3p showed shorter overall survival of the patients (P<0.05). It was also found that miR-379-5p and miR-410-3p expressed significantly higher in gastric cancer cell culture medium comparing with gastric cancer cells. Conclusions: Exosomal miRNAs are dysregulated in the serum of metastatic gastric cancer patients before they are clinically diagnosed. Upregulation of serum exosomal miR-379-5p and/or miR-410-3p are promising circulating biomarkers for prediction of metastasis in stage II/III gastric cancer. Citation Format: Xin Liu, Kent-Man Chu. Exosomal miRNAs as circulating biomarkers for prediction of metastasis in stage II/III gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2765.