RNA-Seq profiling of circular RNAs in colorectal cancer and circST7L as a potential biomarker
Aberrant expression of circular RNAs (circRNAs) has been reported in a variety of cancers. CircRNAs may serve as candidate biomarkers and have implications for cancer diagnosis and treatment. RNA-sequencing (RNA-seq) was applied to detect circRNA expression in five CRC and paired normal tissues. Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was performed to measure circRNA expression, and the receiver operating characteristic curve was used to assess the diagnostic value of circRNA as a biomarker in 50 patients. A total of 1602 circRNAs were differentially expressed, including 743 upregulated and 859 downregulated circRNAs in CRC. CircST7L (hsa_circ_0110464) has a high diagnostic value for CRC. The expression of circST7L was closely associated with tumor size (P=0.024), grade (P=0.017), depth of invasion (P=0.034) and lymph node metastasis (P=0.001). In addition, prediction of circRNA-miRNA interactions identified miR-6821-5p, miR-1908-3p, and miR-6748-5p as pivotal targets of differentially expressed circRNAs. Finally, we predicted 7 miRNAs that may bind to circST7L and 13 target genes for these miRNAs. This study demonstrated that circRNAs were differentially expressed between CRC and normal tissues, and suggested that circST7L might be a promising diagnostic biomarker for CRC. Overall design: Comparative circular RNA expression profiling analysis of RNA-seq data for colorectal cancer tissues and adjacent normal tissues in human