RNAseq profiling of circRNA expression in radiation-treated A549 cells and bioinformatics analysis of radiation-related circRNA-miRNA networks

With the development of new biochemical and computational methods, circular RNAs (circRNAs) have been identified as microRNA sponges. circRNAs are associated with many diseases, particularly cancer. The present study aimed to investigate the expression profile of circRNAs in irradiated A549 lung cancer cells using high-throughput sequencing. Bioinformatics analyses were used to examine the potential functions of circRNAs. RNA sequencing data demonstrated that 1,875 circRNA targets were differentially expressed in A549 cells in response to irradiation. A total of 30 circRNAs were upregulated and 37 circRNAs were downregulated significantly in irradiation-treated A549 cells (fold change ≥2.0; P<0.05). The top 5 upregulated and downregulated circRNAs were successfully validated by reverse transcription-quantitative PCR. In addition, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis suggested that differentially expressed circRNAs might be pivotal in biological irradiation responses to irradiation. circRNA-microRNA co-expression networks highlighted the biological significance of circRNA_0002174 and circRNA_0036627, which require further study. In conclusion, the present study is, to the best of the authors' knowledge, the first to describe the differentially expressed profile of circRNAs in response to irradiation in A549 cells. These results provide a new perspective to elucidate insight into the molecular mechanisms by which A549 cells respond to radiation, and a basis for a more in-depth analysis of the potential application of circRNAs in the treatment of lung cancer therapy.