Expression of microRNA-646 in A549 cells treated by lipopolysaccharide and its function

Objective To measure the expression of microRNA-646( miR-646 ) in A549 cells under different concentrations of lipopolysaccharide(LPS) treatment, and to explore the possible mechanism of miR-646 in A549 cells under LPS treatment. Methods A549 cells were divided into control group and experimental groups.A549 cells from the control group were treated with RPMI-1640 and A549 cells from the experimental groups were treated with LPS(5 mg/L, 10 mg/L, 15 mg/L) in a duration of 24 hours.Immunocytochemical method and Western blot were used to detect the changes in surfactant protein A (SP-A) and surfactant protein C (SP-C), and quantitative real-time polyme-rase chain reaction was used to detect the changes in miR-646 in all groups. Results Compared with control group, the expression of SP-A in cytoplasm of A549 cells were decreased in experimental groups (all P<0.05), and LPS in diffe-rent concentrations induced the expression of SP-A in A549 cells in a dose-dependent manner.Compared with control group, the expression of SP-C in cytoplasm of A549 cells was decreased in experimental groups (all P<0.05). The expression of SP-C was the lowest in 10 mg/L LPS treatment group.The relative expression level of the control group of miR-646 was 0.9597±0.0200, in 5 mg/L LPS treatment group it was 1.6319±0.1325, in 10 mg/L LPS treatment group it was 2.4762±0.1380, and in 15 mg/L LPS treatment group it was 1.6642±0.0938.There were statistically significant differences between the experimental groups and control group (all P<0.01). Conclusion miR-646 may have a biological function in acute respiratory distress syndrome through inhibiting the transcription of SP-C. Key words: microRNA-646; Acute respiratory distress syndrome; Surfactant protein C; A549 cell