Long Non-coding RNA XIST Impedes LPS-induced AC16 Cell Inflammation and Apoptosis through Down-regulating miR-370-3p and Regulating PI3K/AKT/mTOR Pathways.

ABSTRACT

BACKGROUND/PURPOSE: Myocarditis is a severe disorder characterized by the inflammation of the heart's muscular walls, thereby leading to sudden death in young adults. Long non-coding RNA X-inactive specific transcripts (LncRNA XIST) are a class of transcripts having a length ˃ 200 nts with the absence of protein-coding abilities. They exert their function of apoptosis in various cancers and inflammatory diseases. OBJECTIVE: The current work intended to investigate the impact and mechanism of XIST on inflammation induced by LPS in AC16 cells. METHODS: An in vitro inflammatory injury model was established by stimulating AC16 cells with LPS. CCK-8 was used to test AC16 cell viability and FCM to detect apoptosis. The Elisa assay was used to measure the level of IL-8, IL-1ß, and TNF-α. The RT-qPCR was used to detect XIST, miR-370-3p, Bax, and Bcl-2 in LPS-stimulated AC16 cells. The Elisa assay was performed to assess the phosphorylation of PI3K, AKT and mTOR in AC16 cells. RESULTS: Our findings showed LPS exposure to significantly reduce AC16 cell viability while increasing inflammation and apoptosis. Also, XIST expression was reduced in AC16 cells stimulated with LPS. Overexpression of XIST in AC16 cells increased cell survival, inhibited apoptosis, and increased the expressions of Bcl-2, Bax, and inflammatory modulators (IL-8, TNF-α, and IL-1ß). Inhibiting XIST in AC16 cells produced opposite outcomes. MiR-370-3p mimics inhibited XIST's effect on inflammation, viability, and apoptosis. Moreover, XIST inhibited the phosphorylation levels of mTOR, AKT, and PI3K in LPS-injured AC16 cells. CONCLUSION: The data elucidate lncRNA XIST to exert its anti-inflammatory and anti-apoptotic effects on AC16 cells stimulated by LPS via down-regulating miR-370-3p and inhibiting PI3K/AKT/mTOR pathways. These findings suggest a novel treatment strategy for myocarditis.