HDAC inhibitor, MS-275, increases vascular permeability by suppressing Robo4 expression in endothelial cells

Roundabout guidance receptor 4 (Robo4) is an endothelial-specific membrane protein that suppresses pathological angiogenesis and vascular hyperpermeability by stabilizing endothelial cells. Robo4 suppresses severe systemic inflammation induced by pathogens and endotoxins and inhibits tumor growth and metastasis, therefore serving as a potential therapeutic target. Although the regulation of Robo4 expression through transcription factors and epigenetic mechanisms has been studied, the role of histone deacetylases (HDACs) has not been explored. In the present study, we investigated the involvement of HDACs in the regulation of Robo4 expression. An HDAC inhibitor, MS-275, which inhibits HDAC1, HDAC2, and HDAC3, was found to suppress Robo4 expression in endothelial cells. Small interfering RNA (siRNA)-mediated knockdown of HDAC3, but not of HDAC1 and 2, also decreased its expression level. MS-275 downregulated the expression of the transcription factor complex GABP, in addition to suppressing Robo4 promoter activity. GABP expression was also downregulated by the siRNA against HDAC3. MS-275 decreased the transendothelial electrical resistance of a monolayer of mouse endothelial cells and increased the rate of leakage of Evans blue dye in the mouse lungs. In addition, MS-275 accelerated cell migration through the endothelial cell monolayer and augmented cell extravasation in the mouse lungs. Taken together, we demonstrated that MS-275 suppresses Robo4 expression by inhibiting HDAC3 in endothelial cells and enhances endothelial and vascular permeability. Thus, we demonstrated a novel mechanism regulating Robo4 expression and vascular permeability, which is anticipated to contribute to future therapies for infectious and inflammatory diseases.

LncRNA LINC-PINT Inhibits Malignant Behaviors of Laryngeal Squamous Cell Carcinoma Cells via Inhibiting ZEB1

Objective: Laryngeal squamous cell carcinoma (LSCC) belongs to head and neck squamous cell carcinoma (HNSCC), with dismal prognosis. Here, this study aims to disclose the role of LINC-PINT in cancer development, which may contribute to improving the clinical outcomes of LSCC treatment.

Methods: LINC-PINT expression in LSCC tissues and in TU-177 and Hep-2 cells was quantified, and subsequently, the association between LINC-PINT and LSCC malignancies was analyzed. pcDNA3.1-LINC-PINT or pcDNA3.1-EZH2 was introduced into Hep-2 and TU-177 cells. qRT-PCR and Western blot analyses examined the levels of proteins related to the AKT/mTOR pathway and their phosphorylated proteins in Hep-2 and TU-177 cells. The viability as well as migration and invasion abilities of Hep-2 and TU-177 cells were determined. Also, the distribution of LINC-PINT in Hep-2 cells was investigated as well as the interplay between LINC-PINT and EZH2. The downstream genes that might interact with EZH2 were screened.

Results: LINC-PINT expression was inhibited in LSCC tissues and in Hep-2 and TU-177 cells, whose downregulation was associated with unsatisfactory prognosis. LINC-PINT overexpression suppressed the proliferative, migratory and invasive capacities of Hep-2 and TU-177 cells. LINC-PINT, mainly expressing in nuclei, could enrich EZH2 to silence ZEB1. In Hep-2 and TU-177 cells, the inhibition of LINC-PINT or overexpression of ZEB1 could enhance cell proliferation, migration and invasion. The phosphorylated levels of proteins related to the AKT/mTOR pathway were declined in cells with LINC-PINT overexpression, and the levels of these phosphorylated proteins were increased in cells with LINC-PINT inhibition.

Conclusion: LINC-PINT enriches EZH2 to silence ZEB1 and thus inhibits the proliferative, migratory, and invasive capacities of Hep-2 and TU-177 cells. In addition, LINC-PINT might exert its biological function through the AKT/mTOR pathway.

DZNep attenuates allergic airway inflammation in an ovalbumin-induced murine model

BACKGROUND

Growing evidence shows that enhancer of zeste homolog 2 (EZH2) plays a role in various physiological functions and cancer pathogenesis. However, its contribution to allergic diseases remains controversial. We sought to investigate the role of EZH2 in the pathogenesis of allergic airway inflammation.

METHODS

3-Deazaneplanocin A (DZNep), an indirect inhibitor of EZH2, was administered via intraperitoneal injection in an ovalbumin (OVA)-induced murine model of allergic airway inflammation. The expression of EZH2 in the allergic airway tissues was examined by immunohistochemistry (IHC) and western blot. The inflammatory cell infiltration and the goblet cell hyperplasia in the murine nose and lung were detected by hematoxylin and eosin (H&E) staining and periodic acid-Schiff (PAS) staining. Levels of cytokines, including IL-4, IFN-γ, IL-6, and IL-10, were evaluated in the bronchoalveolar lavage fluid (BALF) using Enzyme-linked immune sorbent assay (ELISA).

RESULTS

EZH2 expression was inhibited by DZNep treatment (P < 0.05). The administration of DZNep significantly inhibited the inflammatory cell infiltration (P < 0.0001) and goblet cell hyperplasia (P < 0.001). Moreover, it suppressed the secretion of IL-4 (P < 0.0001) and IL-6 (P < 0.01) in the BALF.

CONCLUSIONS

Our findings demonstrate that DZNep attenuates allergic airway inflammation and could be a new therapeutic option for allergic rhinitis and asthma.