RNA-seq reveals abundant circRNA, lncRNA and mRNA in blood exosomes of patients with colorectal carcinoma

Exosomes are small membrane vesicles of endocytic origin secreted by most cells, and contain a wealthy cargo of protein and RNA species that can modulate recipient cells’ behaviors and may be used as biomarkers for diagnosis of human diseases. They have been found in blood and are valuable sources for biomarkers due to selective cargo loading and resemblance to their parental cells. The goal of this study is to identify circRNA, lncRNA and mRNA profiles in human blood by high-throughput RNA sequencing (RNA-seq). 1-4 ml plasma or serum were used to extract exosomal RNAs by exoRNeasy Serum/Plasma Maxi kit (Qiagen). The exosomal RNAs were further treated with DNAse I and subjected to ribosome minus low-input RNAseq library preparation. The libraries were sequenced by Illumina Hiseq platform. Human blood exosomal RNAs were generated by deep sequencing using Illumina Hiseq.

外泌体（Exosomes）是大多数细胞分泌的、源自内吞途径的小型膜囊泡，其携带丰富的蛋白质与RNA类物质，可调控受体细胞的生物学行为，亦可作为人类疾病诊断的生物标志物。目前已在血液中检出外泌体，由于其内含物具有选择性装载特性且与其来源细胞高度相似，因此是极具价值的生物标志物来源。本研究旨在通过高通量RNA测序（RNA-seq）鉴定人血液中的环状RNA (circRNA)、长链非编码RNA (lncRNA)及信使RNA (mRNA)表达谱。实验使用1~4 mL血浆或血清，通过exoRNeasy血清/血浆超大提取试剂盒（Qiagen）提取外泌体RNA；提取得到的外泌体RNA经脱氧核糖核酸酶I（DNAse I）处理后，进行核糖体RNA去除的低起始量RNA测序文库构建；随后使用Illumina Hiseq测序平台对构建好的文库进行测序，最终获得人血液外泌体RNA测序数据集。