Differential expression of circular RNAs in gefitinib-acquired resistant non-small cell lung cancer cells

Objective: To establish gefitinib-acquired resistant non-small cell lung cancer cell lines, then to screen and analyze the differentially expressed circular RNAs (circRNAs) before and after drug resistance. Methods: The gefitinib-sensitive non-small cell lung cancer cell line H292 (named as H292_S) was used to establish gefitinib-acquired resistant cell line (named as H292_R) by stepwise dose escalation of gefitinib. The inhibitory effect of gefitinib on proliferation of the two cell lines was detected by CCK-8 assay. The differentially expressed circRNA in the two cell lines was screened by RNA sequencing (RNA-Seq) method and confirmed by real-time fluorescent quantitative PCR. The biological functions of host genes of differentially expressed circRNAs were analyzed by statistics and bioinformatics methods. Results: The half inhibition concentrations (IC50) of gefitinib on the proliferation of H292_S and H292_R cells were (108.63±0.32) nmol/L and (982.37±2.62) nmol/L, respectively; the difference was statistically significant (P < 0.05). The drug-resistant index of H292_R cells to gefitinib was 9.04. There were 36 differentially expressed circRNAs between the two cell lines (all P < 0.05) , including 24 up-regulated circRNAs and 12 down-regulated circRNAs in H292_R cells. Gene Ontology (GO) enrichment analysis showed that these abnormal expressed circRNAs mainly involved in the regulations of cell growth and proliferation, protein transport, gene transcription and other biological processes. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that these abnormal circRNAs mainly involved in cytoplasmic DNA-sensing pathway, nuclear factor-kappa B (NF-κB）signaling pathway, endocytosis, apoptosis and so on. Real-time fluorescent quantitative PCR verified that the expressions of hsa_circ_0000567 and hsa_circ_0000620 were significantly up-regulated in drug-resistant H292_R cells (both P < 0.05), which was consistent with RNA-seq results. Conclusion: The differentially expressed circRNAs related to gefitinib-acquired resistance are screened out, which maybe helpful to elucidate the mechanism of drug resistance in non-small cell lung cancer, and provide a biological marker for early diagnosis of drug-resistant non-small cell lung cancer. DOI:10.3781/j.issn.1000-7431.2017.11.474