Abstract 4146: The expression of exosomal microRNA in serum of patients with esophageal squamous cell carcinoma

Background: Exosomes are 40 -100 nm membrane vesicles secreted by various cells such as T cells, platelets, and epithelial cells by exocytosis. Exosomes are found in blood, urine, amniotic fluid, and malignant ascites, and contain distinct subsets of microRNAs (miRs) depending upon the tumor from which they are secreted. Exosomes play a major role in cell-to-cell communication, targeting cells to transfer exosomal molecules including proteins, mRNAs, and microRNAs by an endocytosis-like pathway. Recent reports imply that miRNAs can be stably detected in circulating plasma and serum since miRNAs are packaged by exosomes to be protected from RNA degradation. We have previously reported that overexpression of miR-21 was observed in patients with esophageal squamous cell carcinoma. miR-26a is also known to be overexpressed in esophageal cancer. Objective: Aim of this study is to clarify the expression levels of miR-21 and miR-26a in exosomes from the serum of esophageal cancer patients. Patients and method: We extracted exosomes from serum of 20 esophageal cancer patients (ESCC group) and of 20 benign disease cases without inflammation (control group) by September, 2010 from October, 2009. We separated exosomes from serum, and then extracted total RNA including microRNA from exosome. Furthermore, using quantitative quantitative RT-PCR, we analyzed expression of miR-21, miR-26a where overexpression was confirmed in esophageal cancer in a past report. Results: The expression levels of miR-21 in exosomes were significantly higher in ESCC than those in control (P Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4146. doi:1538-7445.AM2012-4146