IL-6/STAT3 signaling in mice with dysfunctional type-2 ryanodine receptor

Anthelmintic niclosamide attenuates pressure-overload induced heart failure in mice

The heart is a high energy demand organ and enhancing mitochondrial function is proposed as the next-generation therapeutics for heart failure. Our previous study found that anthelmintic drug niclosamide enhanced mitochondrial respiration and increased adenosine triphosphate (ATP) production in cardiomyocytes, therefore, this study aimed to determine the effect of niclosamide on heart failure in mice and the potential molecular mechanisms. The heart failure model was induced by transverse aortic constriction (TAC) in mice. Oral administration of niclosamide improved TAC-induced cardiac hypertrophy, cardiac fibrosis, and cardiac dysfunction in mice. Oral administration of niclosamide reduced TAC-induced increase of serum IL-6 in heart failure mice. In vitro, niclosamide within 0.1 μM increased mitochondrial respiration and ATP production in mice heart tissues. At the concentrations more than 0.1 μM, niclosamide reduced the increased interleukin- 6 (IL-6) mRNA expression in lipopolysaccharide (LPS)-stimulated RAW264.7 and THP-1 derived macrophages. In cultured primary cardiomyocytes and cardiac fibroblasts, niclosamide (more than 0.1 μM) suppressed IL-6- and phenylephrine-induced cardiomyocyte hypertrophy, and inhibited collagen secretion from cardiac fibroblasts. In conclusion, niclosamide attenuates heart failure in mice and the underlying mechanisms include enhancing mitochondrial respiration of cardiomyocytes, inhibiting collagen secretion from cardiac fibroblasts, and reducing the elevated serum inflammatory mediator IL-6. The present study suggests that niclosamide might be therapeutic for heart failure.

MicroRNA‑19b inhibitors can attenuate the STAT3 signaling pathway in NPC C666‑1 cells

MicroRNA (miR)-19b is expressed in various types of tumors and may serve as a potential therapeutic target. The miR‑17‑92 cluster is upregulated in nasopharyngeal carcinoma (NPC) tissues and cells. miR‑19b is a member of the miR‑17‑92 cluster; however, its expression and function in NPC are largely unknown. The present study aimed to investigate the expression and function of miR‑19b in NPC cells. The miRCURY LNATM miRNA Inhibitor (miR‑19b inhibitor and negative control) were transfected into C666‑1 cells. The proliferation, apoptosis and migration of the cells were subsequently detected by the Cell Counting Kit‑8 assay, flow cytometry and Transwell assay, respectively. Additionally, the expression of STAT3 signaling pathway‑associated proteins [STAT3, pSTAT3 and suppressor of cytokine signaling 1 (SOCS1)] and the transcriptional targets of pSTAT3 [Bcl‑2, myeloid leukemia protein 1 (Mcl‑1) and cyclin D1] were detected by western blotting. The miR‑19b inhibitor inhibited proliferation and migration and induced apoptosis of C666‑1 cells. Furthermore, the miR‑19b inhibitor upregulated the expression of SOCS1, a predicted target gene of miR‑19b, and decreased the phosphorylation of STAT3 at Tyr705 and Ser727. These data indicated that upregulation of SOCS1, an endogenous inhibitor of STAT3 phosphorylation, attenuated the STAT3 signaling pathway in C666‑1 cells. Moreover, the expression level of the proproliferative protein cyclin D1 and antiapoptotic proteins Mcl‑1 and Bcl‑2 was significantly decreased following transfection with the miR‑19b inhibitor. The aforementioned three proteins are downstream transcriptional targets of the activated STAT3 signaling pathway. The results of the present study revealed that inhibition of miR‑19b negatively modulated the malignant behavior of NPC cells via the STAT3 signaling pathway. Therefore, miR‑19b inhibition may serve as a novel therapeutic target for the treatment of NPC.

GABA, γ-Aminobutyric Acid, Protects Against Severe Liver Injury

BACKGROUND

Acute liver failure (ALF) from severe acute liver injury is a critical condition associated with high mortality. The purpose of this study was to investigate the impact of preemptive administration of γ-aminobutyric acid (GABA) on hepatic injury and survival outcomes in mice with experimentally induced ALF.

MATERIALS AND METHODS

To induce ALF, C57BL/6NHsd mice were administered GABA, saline, or nothing for 7 d, followed by intraperitoneal administration of 500 μg of tumor necrosis factor α and 20 mg of D-galactosamine. The study mice were humanely euthanized 4-5 h after ALF was induced or observed for survival. Proteins present in the blood samples and liver tissue from the euthanized mice were analyzed using Western blot and immunohistochemical and histopathologic analyses. For inhibition studies, we administered the STAT3-specific inhibitor, NSC74859, 90 min before ALF induction.

RESULTS

We found that GABA-treated mice had substantial attenuation of terminal deoxynucleotidyl transferase dUTP nick end labeling-positive hepatocytes and hepatocellular necrosis, decreased caspase-3, H2AX, and p38 MAPK protein levels and increased expressions of Jak2, STAT3, Bcl-2, and Mn-SOD, with improved mitochondrial integrity. The reduced apoptotic proteins led to a significantly prolonged survival after ALF induction in GABA-treated mice. The STAT3-specific inhibitor NSC74859 eliminated the survival advantage in GABA-treated mice with ALF, indicating the involvement of the STAT3 pathway in GABA-induced reduction in apoptosis.

CONCLUSIONS

Our results showed that preemptive treatment with GABA protected against severe acute liver injury in mice via GABA-mediated STAT3 signaling. Preemptive administration of GABA may be a useful approach to optimize marginal donor livers before transplantation.