Knockdown of the long non‑coding RNA MALAT1 ameliorates TNF‑α‑mediated endothelial cell pyroptosis via the miR‑30c‑5p/Cx43 axis

Long noncoding RNAs (lncRNAs) are related to the development of atherosclerosis (AS). However, the role of lncRNA metastasis associated lung adenocarcinoma transcript 1 (MALAT1) in tumor necrosis factor-α (TNF-α)-induced rat aortic endothelial cell (RAOEC) pyroptosis, as well as the underlying mechanisms, remain unclear. RAOEC morphology was assessed using an inverted microscope. The mRNA and/or protein expression levels of MALAT1, microRNA(miR)-30c-5p and connexin 43 (Cx43) were assessed using reverse transcription-quantitative PCR (RT-qPCR) and/or western blotting, respectively. The relationships among these molecules were validated by dual-luciferase reporter assays. Biological functions, such as LDH release, pyroptosis-associated protein levels and the proportion of PI-positive cells, were evaluated using a LDH assay kit, western blotting and Hoechst 33342/PI staining, respectively. The present study demonstrated that compared with the control group, the mRNA expression levels of MALAT1 and protein expression levels of Cx43 were significantly up-regulated, whereas miR-30c-5p mRNA expressions levels were significantly decreased in TNF-α-treated RAOEC pyroptosis. Knockdown of MALAT1 or Cx43 significantly attenuated the increase in LDH release, pyroptosis-associated protein expression and PI-positive cell numbers among RAOEC treated using TNF-α, whereas an miR-30c-5p mimic exerted the opposite effect. Furthermore, miR-30c-5p was demonstrated to be a negative regulator of MALAT1 and could also target Cx43. Finally, co-transfection with siMALAT1 and miR-30c-5p inhibitor could attenuate the protective effect of MALAT1 knockdown against TNF-α-mediated RAOEC pyroptosis by upregulation of Cx43 expression. In conclusion, MALAT1 might serve an important role in TNF-α-mediated RAOEC pyroptosis by regulating the miR-30c-5p/Cx43 axis, which would provide a potential novel diagnostic and therapeutic target for AS.