LncRNA MEG8 promotes TNF-α expression by sponging miR-454-3p in bone-invasive pituitary adenomas

Abstract

There are few studies on the mechanism of pituitary adenoma (PA) destroying bone. The current study aimed to investigate the role of MEG8/miR-454-3p/TNF-α in bone-invasive pituitary adenomas (BIPAs). In this study, we report that lncRNA MEG8 and TNF-α are upregulated in BIPA tissues while miR-454-3p is downregulated, which is associated with poor progression-free survival (PFS). Functional assays revealed the role of up-regulated MEG8 and down-regulated miR-454-3p in promoting bone destruction. Mechanistically, MEG8 promotes TNF-α expression by sponging miR-454-3p, which ultimately leads to the occurrence of bone destruction. The mechanism is confirmed in vivo and in vitro. Therefore, our data illustrated a new regulatory mechanism of MEG8/miR-454-3p/TNF-α in BIPAs. It may provide a useful strategy for diagnosis and treatment for BIPA patients.

Keywords: BIPAs; TNF-α; ceRNAs; lncRNA MEG8; miR-454-3p.

Figure 1

The expression of TNF-α, MEG8 and miR-454-3p in PAs and the relationship between the expression of TNF-α and the prognosis of patients. (A) The preoperative images of NIPAs and BIPAs. Western blot (B) and IHC (C) were used to detect the expression of TNF-α in BIPAs and NIPAs. (D) Kaplan-Meier plotter was used to analyze the regrowth-free curves of patients in TNF-α high/low groups. (E) RT-qPCR was used to detect the expression of TNF-α, MEG8 and miR-454-3p in BIPAs and NIPAs. ***P < 0.001.

Figure 2

The relationship between TNF-α expression and prognosis and the correlation between TNF-α, MEG8 and miR-454-3p. The correlation between MEG8 and miR-454-3p (A), miR-454-3p and TNF-α (B), MEG8 and TNF-α (C) in PAs was analyzed according to RT-qPCR results. The correlation between MEG8 and miR-454-3p (D), miR-454-3p and TNF-α (E), MEG8 and TNF-α (F) in BIPAs was analyzed according to RT-qPCR results.

Figure 3

TNF-α was targeted by miR-454-3p in 293T cells. (A) The predicted binding site between TNF-α and miR-454-3p. (B) The predicted miR-454-3p binding site (TNF-α-wt) and its matched mutant site (TNF-α-mut). (C) Luciferase activity detection. (D) RT-qPCR analyses measured relative miR-454-3p and TNF-α expression levels. (E) RT-qPCR analyses measured TNF-α expression levels. (F) Elisa analyses measured TNF-α expression levels. (G) Scanning electron microscope results of bone slices (500x). (H) Volume of resorption/pit (x10³ um³). **P < 0.01, ***P < 0.001.

Figure 4

MEG8 sponged miR-454-3p in 293T cells. (A) The predicted binding site between MEG8 and miR-454-3p. (B) The predicted miR-454-3p binding site (MEG8-wt) and its matched mutant site (MEG8-mut). (C) Luciferase activity detection. (D, E) RT-qPCR analyses measured relative MEG8, miR-454-3p and TNF-α expression levels. (F) Elisa analyses measured TNF-α expression levels. (G) RT-qPCR analyses measured TNF-α expression levels. (H) Scanning electron microscope results of bone slices (500x). (I) Volume of resorption/pit (x10³ um³). *P < 0.05, **P < 0.01, ***P < 0.001.

Figure 5

Overexpression of MEG8 promoted tumorigenesis and tumor progression in vivo. (A) Mice models, tumor volume and bone slices. (B) Scanning electron microscope results of bone slices (500x). (C) RT-qPCR analyses measured relative MEG8, miR-454-3p and TNF-α expression levels.

Figure 6

Mechanism and function of TNF-α in BIPAs progress. LncRNA MEG8 promotes TNF-α expression by sponging miR-454-3p, and then TNF-α directly induce osteoclast differentiation in BIPAs, which further leads to bone destruction.