Potential role of lncRNA HULC/miR-128-3p/RAC1 axis in the inflammatory response during LPS-induced sepsis in HMEC-1 cells

Abstract

Sepsis is a serious clinical condition characterized by systemic inflammation. The long noncoding RNA (lncRNA ) highly upregulated in liver cancer (HULC ) was validated to partake in the development of sepsis. The present study aimed to investigate the potential mechanism of HULC in lipopolysaccharide (LPS)-induced sepsis. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR ) and western blot analysis was employed to examine the expression of HULC , microRNA (miR)-128-3p, Rac family small GTPase 1 (RAC1) and pro-inflammatory factors [IL-6, TNF-α, intercellular adhesion molecule (ICA M1) and vascular cell adhesion molecule (VCA M1)] in the serum of patients with sepsis or LPS-induced human dermal microvascular endothelial cells (HMEC- 1). Flow cytometry and western blot assays were performed to detect cell apoptosis. The targeted relationship among HULC, miR-128-3p and RAC1 was confirmed by a dual-luciferase reporter assay, RNA binding protein immunoprecipitation (RI P) assay and RNA pull-down assay. HULC and RAC 1 were found to be upregulated, and miR- 128-3p was downregulated in the serum of patients with sepsis and LPS-stimulated HMEC- 1 cells. LPS promoted apoptosis and inflammation, which were decreased by silencing of HULC. HULC targeted miR- 128-3p and negatively regulated its expression. HULC knockdown protected HMEC- 1 cells from LPS-induced injury by upregulating miR- 128-3p. RAC 1 was a target of miR- 128-3p, and gain of RAC 1 also relieved the silencing of HULC- mediated suppressive effects on apoptosis and inflammation in LPS-stimulated HMEC-1 cells. In conclusion, HULC knockdown partially reversed LPS-induced sepsis via the regulation of miR- 128-3p/RAC 1 axis.