Long non-coding RNA CASC2 improved acute lung injury by regulating miR-144-3p/AQP1 axis to reduce lung epithelial cell apoptosis

Background and objective: Apoptosis of lung epithelial cell is implicated in the pathogenesis of acute lung injury (ALI). To study the protective effect and mechanism of cancer susceptibility candidate 2 (CASC2) on reducing lung epithelial cell apoptosis after LPS inducing acute lung injury in mice. Methods and results: The ALI mice model was performed by intratracheally instilling with lipopolysaccharide (LPS). The CASC2 expression detected by quantitative real-time polymerase chain reaction was significantly decreased in LPS-induced A549 cell and ALI mice model. LPS induced A549 cell apoptosis, while transfection with pcDNA-CASC2 reversed the increased cell apoptosis, suggesting overexpression of CASC2 inhibited LPS-induced A549 cell apoptosis. In addition, we found that miR-144-3p expression were opposite to CASC2, while Aquaporin-1 (AQP1) expression was opposite to miR-144-3p in LPS-induced A549 cell and ALI mice model. The RNA immunoprecipitation and RNA pull-down assay demonstrated that CASC2 could function as a miR-144-3p decoy. The luciferase reporter assay revealed that AQP1 was a target of miR-144-3p in A549 cell. And then, further in vitro studied showed that CASC2 controlled AQP1 expression by regulating miR-144-3p, and LPS induced A549 cell apoptosis by regulating CASC2/miR-144-3p/AQP1 axis. At last, after injection with lentivirus-expressing CASC2 or control lentivirus, the mice were intratracheally instilled with LPS. Comparing to the mice injected with pcDNA, the mice injected with pcDNA-CASC2 had a significantly reduced lung wet-dry weight ratio. Conclusions: Long non-coding RNA CASC2 improved acute lung injury by regulating miR-144-3p/AQP1 axis to reduce lung epithelial cell apoptosis.