Downregulating lncRNA PRNCR1 ameliorates LPS-induced pulmonary vascular endothelial cell injury by modulating miR-330-5p/TLR4 axis.

Pulmonary vascular endothelial cell (PVEC) injury following acute lung injury or acute respiratory distress syndrome seriously affects disease development. Recently, accumulating evidence has suggested that long noncoding RNA (lncRNA) exerts significant effects in vascular endothelial cell injury. However, PRNCR1, a novel lncRNA, remains scarcely understood in terms of its functions in PVEC injury. Both in vivo and in vitro models of PVEC injury were constructed by lipopolysaccharide (LPS) administration. The relative expressions of PRNCR1, miR-330-5p, and TLR4 were detected by quantitative reverse transcription-polymerase chain reaction, Western blot, and immunohistochemistry. Besides, gain and loss assays of PRNCR1/miR-330-5p were conducted to verify their effects on LPS-induced PVEC injury. Cell Counting Kit-8 assay used to measure cell viability and flow cytometry was used to detect apoptosis. Besides, the protein levels of caspase 3, nuclear factor-κB (NF-κB), and inflammatory cytokines (including tumor necrosis factor-α, interleukin-1β [IL-1β], and IL-6) were evaluated via Western blot and enzyme-linked immunosorbent assay. Moreover, a dual-luciferase activity experiment and RNA immunoprecipitation were applied to confirm the targeting relationship between PRNCR1 and miR-330-5p, miR-330-5p, and TLR4. PRNCR1 and TLR4 levels were significantly upregulated in LPS-treated PVEC, both in vivo and in vitro, while miR-330-5p were downregulated. Inhibiting PRNCR1 or overexpressing miR-330-5p markedly attenuated LPS-induced PVEC injury, expressions of TLR4, NF-κB, and inflammatory cytokines. Mechanistically, PRNCR1 functioned as a competitive endogenous RNA by sponging miR-330-5p and then promoting TLR4 expression. PRNCR1 was upregulated in LPS-induced PVEC and aggravated its injury via modulating the miR-330-5p/TLR4 axis.