Cigarette smoke is a major cause of chronic obstructive pulmonary disease (COPD). Circular RNAs (circRNAs) are involved in regulating various biological processes. This study aimed to explore the role and molecular basis of hsa_circ_0006872 in cigarette smoke extract (CSE)-induced cell injury. HPMECs and BEAS-2B cells were treated with CSE to mimic COPD in vitro. The levels of hsa_circ_0006872 and miR-145-5p were measured by quantitative real-time polymerase chain reaction. Cell proliferation was assessed via Cell Counting Kit-8 (CCK-8) and colony formation assays. Flow cytometry was used to evaluate apoptosis and cell cycle. The levels of inflammatory factors were assayed via enzyme-linked immunosorbent assay (ELISA). The levels of oxidative stress markers were determined via commercial kits. The interaction between hsa_circ_0006872 and miR-145-5p was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation assay. Protein expression was measured using Western blot assay. Hsa_circ_0006872 level was elevated in COPD patients and was negatively correlated with miR-145-5p level. CSE exposure promoted apoptosis, inflammation and oxidative stress of HPMECs and BEAS-2B cells, while hsa_circ_0006872 down-regulation undermined the effects. In addition, hsa_circ_0006872 silencing inhibited CSE-induced cell injury via regulating miR-145-5p. Moreover, CSE contributed to the activation of NF-kappa B pathway through hsa_circ_0006872/miR-145-5p axis. Hsa_circ_0006872 facilitated CSE-triggered apoptosis, inflammation and oxidative stress in HPMECs and BEAS-2B cells by regulating miR-145-5p/NF-kappa B pathway. (C) 2020 Published by Elsevier Inc.