Purpose: Circular RNA (circRNA) plays an important role in various biological processes. However, their functions in cigarette smoke extract (CSE) induced human normal lung epithelial cells (BEAS-2B) injury remain vague. The study aimed to explore circRNA expression profiles and reveal their potential roles in CSE-treated BEAS-2B cells.
Methods: 5% CSE exposure for 24 hours were used to build the BEAS-2B cells ferroptosis model. Differentially expressed circRNAs (DECs) were identified by next-generation RNA sequencing. Six randomly selected DECs were validated via quantitative reverse transcription polymerase chain reaction (qRT-PCR). Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and Gene Ontology (GO) analysis were conducted to clarify the potential functions of the DECs. Furthermore, the role of hsa_circ_0025843 in CSE-related BEAS-2B cells ferroptosis was confirmed.
Results: 5% CSE exposure induced BEAS-2B cells ferroptosis. Fifty-one up-regulated cirRNAs and 80 down-regulated circRNAs were revealed in CSE-treated BEAS-2B cells. Hsa_circ_0003461, hsa_circ_0007548, hsa_circ_0025843, hsa_circ_0068896, hsa_circ_0005832, and hsa_circ_0053378 were selected randomly to validate the reliability of next-generation RNA sequencing by qRT-PCR. After KEGG pathway analysis, DECs were found to participate in the process of EGFR tyrosine kinase inhibitor resistance and glycerophospholipid metabolism. The knockdown of hsa_circ_0025843 significantly alleviated CSE-induced BEAS-2B cells ferroptosis.
Conclusion: The study indicated the circRNA expression profiles in CSE-treated BEAS-2B cells. Hsa_circ_0025843 alleviated CSE induced BEAS-2B cells ferroptosis, which might be a potential therapeutic target of CSE related lung injury.

Keywords: cigarette smoke extract, Circular RNA, next-generation RNA sequencing, lung injury, ferroptosis