Abstract 3085: Expression profiling of exosomal miRNAs derived from human esophageal cancer cells by Solexa high-through sequencing.

Abstract

Abstract Background: Exosomes are small membrane vesicles of endocytic origin that are released into the extracellular environment on fusion of multivesicular bodies (MVB) with the plasma membrane. Studies showed that inside exosomes, cellular gene products including proteins, mRNAs, and microRNAs (miRNAs) are packaged and these molecules can be transferred to recipient cells to deliver their molecular signaling. Objective: To explore the miRNA expression profile and distribution characteristics of exosomes derived from human esophageal cancer cells by Solexa high-throughput sequencing. Methods: Exosomes were extracted from cell culture supernatants by ultracentrifugation. Exosomes were identified by transmission electronic microscopy and western blot assay with anti-CD63 antibody. The types and abundance of known and novel miRNAs in cells and exosomes were identified by Solexa high-throughput sequencing. Results:There were 56421(2.94%) unique sequences in cells and 7727(0.63%) in exosomes matched the known miRNAs(Table 1). 64 in cells and 32 in exosomes novel miRNAs were predicted. Further analysis revealed extensive sequence variations (isomiRs) of cell and exosome miRNAs. The known miRNAs showed an increased expression in cells compared with exosomes. The expression level of hsa-miR-chr15_4885 and hsa-miR-chr18_7463 in exosomes were significantly higher than cells, with an average fold-change of 10 while hsa-miR-chr7_20613 and hsa-miR-chr19_8205 in cells were significantly higher than exosomes, with an average fold-change of thousands. Conclusion: The miRNA expression profile in exosomes is different from that in cells. It suggested that the significantly enriched miRNAs in exosomes may be the result of an active uptaken by exosomes. These specific miRNAs expressed in exosomes may play an important role in intercellular communication. Table 1. Distribution of sequence counts for the different classes of small RNAs in cells and exosomes Classification Unique RNA in cells Percentage (%) in cells Unique RNA in exosomes Percentage (%) in exosomes miRNA 56,421 2.94 7,727 0.63 mRNA 59,655 3.11 5,988 0.49 Repbase 31,421 1.64 5,066 0.41 rRNA 260,307 13.56 85,303 6.95 tRNA 80,635 4.20 119,500 9.74 snRNA 27,935 1.45 1,823 0.15 Unknown RNA 1,403,576 73.10 1,001,499 81.63 Total 1,919,950 100.00 1,226,905 100.00 Citation Format: Juan Liao, Ran Liu, Lihong Yin. Expression profiling of exosomal miRNAs derived from human esophageal cancer cells by Solexa high-through sequencing. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3085. doi:10.1158/1538-7445.AM2013-3085 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.