Mechanism through which the hsa-circ_0000992- hsa- miR- 936-AKT3 regulatory network promotes the PM_2.5-induced inflammatory response in human bronchial epithelial cells

Background: Studies have shown that fine particulate matter (PM_2.5) remains a significant problem in developing countries and plays a critical role in the onset and progression of respiratory illnesses. Circular RNAs (circRNAs) are involved in many pathophysiological processes,but their relationship to PM_2.5 pollution is largely unexplored.

Objectives: To elucidate the functional role of hsa_circ_0000992 in PM_2.5-induced inflammation in a human bronchial epithelial cell line (16HBE) and to clarify whether the competing endogenous RNA (ceRNA) mechanism is involved in the interrelationships between hsa_circ_0000992 and hsa-miR-936 and the inflammatory signaling pathways.

Methods: Detection of inflammatory factors in 16HBE cells exposed to PM_2.5 by RT-qPCR and ELISA.High throughput sequencing and bioinformatics analysis methods were used to screen circRNA.The bioinformatics analysis method western blotting and dual-luciferase reporter gene system were used to verify mechanisms associated with circRNA.

Results: PM_2.5 cause inflammation in the 16HBE cells. High throughput sequencing and RT-qPCR result revealed that the expression of hsa_circ_0000992 was markedly up-regulated in 16HBE exposed to PM_2.5. The binding sites between hsa_circ_0000992 and hsa-miR-936 was confirmed by dual-luciferase reporter gene system.Western blotting and RT-qPCR showed that hsa_circ_0000992 can interact with hsa-miR-936 to regulate AKT serine/threonine kinase 3(AKT3),thereby activating the PI3K/AKT pathway and ultimately promoting the expression of interleukin (IL)- 1β and IL-8.

Conclusion: PM_2.5 can induce the inflammatory response in 16HBE cells by activating the PI3K/AKT pathway. The expression of hsa_circ_0000992 increased when PM_2.5 stimulated 16HBE cells,and the circRNA could then regulate the inflammatory response.Hsa_circ_0000992 regulates the hsa-miR-936/AKT3 axis through the ceRNA mechanism,thereby activating the PI3K/AKT signaling pathway,increasing the expression of cellular inflammatory factors,and promoting PM_2.5-induced respiratory inflammation.