Identification of Serum Exosomal hsa-circ-0004771 as a Novel Diagnostic Biomarker of Colorectal Cancer.

Bei Pan,Tao Xu,Xiaoxiang Chen,Xueni Xu,Kaixuan Zeng,Jian Qin,Mu Xu,Yuqin Pan,Shukui Wang,Bangshun He,Huiling Sun,Li Sun,Xiangxiang Liu,Xuhong Wang

doi:10.3389/fgene.2019.01096

Abstract

Background: Exosomal circular RNAs (circRNAs) in peripheral blood are considered as emerging diagnostic biomarkers of cancers. Owing to the lack of sensitive and specific biomarkers, a large number of colorectal cancer (CRC) patients were diagnosed in advanced stages leading to high mortality. This study aimed to identify circulating exosomal circRNAs as novel diagnostic biomarkers of CRC.Materials and Methods: Candidate circRNA was selected by integrating analysis of Gene Expression Omnibus (GEO) database with online program GEO2R. A total of 170 patients and 45 healthy controls were enrolled to assess the diagnostic value of circRNAs for CRC. Exosomes isolated from the serum of participants and cell cultured media were confirmed by transmission electron microscope (TEM), Nanoparticle Tracking Analysis and western blot. The expression and the diagnostic utility of circRNA were tested by qRT-PCR and receiver operating characteristic (ROC) analysis, respectively.Results: The circulating exosomal hsa-circ-0004771 with most abundant among the top ten differentially expressed circRNAs (fold change ≥1.5) was selected for further study based on the results of GEO dataset analysis. The up-regulated exosomal hsa-circ-0004771 was verified in serum of CRC patients compared to healthy controls (HCs) and patients with benign intestinal diseases (BIDs) by qRT-PCR. The area under the ROC curves (AUCs) of circulating exosomal hsa-circ-0004771 were 0.59 (95%CI, 0.457–0.725), 0.86 (95%CI, 0.785–0.933) and 0.88 (95%CI, 0.815–0.940) to differentiate BIDs, stage I/II CRC patients and CRC patients from HCs, respectively. The AUC was 0.816 (95%CI, 0.728–0.9) to differentiate stage I/II CRC patients from patients with BIDs. In addition, the elevated expression of exosomal hsa-circ-0004771 in the serum of CRC patients was tumor-derived. It was found that the expression of exosomal hsa-circ-0004771 was down-regulated expression of in the serum of postoperative CRC patients as well as cultured media of CRC cells treated with GW4869.Conclusions: Circulating exosomal hsa-circ-0004771 was significantly up-regulated in CRC patients and served as a novel potential diagnostic biomarker of CRC.

Highlights

Colorectal cancer (CRC) is the third most common cancer and the second leading cause of death globally (Bray et al, 2018)
It was found that the expression of exosomal hsa-circ-0004771 was down-regulated expression of in the serum of postoperative CRC patients as well as cultured media of CRC cells treated with GW4869
Circulating exosomal hsa-circ-0004771 was significantly up-regulated in CRC patients and served as a novel potential diagnostic biomarker of CRC

Summary

Introduction

Colorectal cancer (CRC) is the third most common cancer and the second leading cause of death globally (Bray et al, 2018). Almost 90% of deaths might be preventable if CRC patients were diagnosed at an early stage (Smith et al, 2001). Sensitive diagnostic biomarkers for early detection of CRC are urgently needed. Increasing findings have indicated that exosome-delivered RNAs involve in the occurrence and progress of cancers, which involved in epithelial–mesenchymal transition (Wang et al, 2014), angiogenesis (Umezu et al, 2014), premetastatic niche (Grange et al, 2011), immune response and therapeutic resistance (Xie et al, 2019). Exosomal circular RNAs (circRNAs) in peripheral blood are considered as emerging diagnostic biomarkers of cancers. Owing to the lack of sensitive and specific biomarkers, a large number of colorectal cancer (CRC) patients were diagnosed in advanced stages leading to high mortality. This study aimed to identify circulating exosomal circRNAs as novel diagnostic biomarkers of CRC

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