Pseudolaric acid B inhibits the secretion of hepatitis B virus

Dihydroartemisinin inhibited interleukin-18 expression by decreasing YAP1 in hepatocellular carcinoma cells

BACKGROUND

Yes-associated protein 1 (YAP1) is highly expressed in liver cancer and has been used as an independent prognostic marker for hepatocellular carcinoma (HCC), while inhibition of YAP1 slows down the progression of HCC. Interleukin-18 (IL-18) also tends to be highly expressed in liver cancer. Previous research has proved that dihydroartemisinin (DHA) plays an important role in HCC treatment by reducing YAP1 expression. However, the relationship between YAP1 and IL-18 has not been reported in HCC, especially during DHA therapy.

OBJECTIVE

The purpose of this study was to clarify the relationship between YAP1 and IL-18 in HCC cells, and to explicit the role of IL-18 in the treatment of HCC by DHA.

METHODS AND RESULTS

We found that YAP1 and IL-18 were highly expressed in patients with hepatocellular carcinoma by bioinformatics analysis. Moreover, YAP1 was positively correlated with IL18 in liver cancer. YAP1 and IL18 correlated with immune cell infiltration, notably T cell exhaustion. YAP1 knockdown decreased IL-18 expression, while YAP1 overexpression increased the IL-18 expression in HCC cells. DHA reduced IL-18 expression through YAP1 in HCC cells. Further, DHA reduced the growth of Hepa1-6 cells subcutaneous xenograft tumors by inhibiting the expression of YAP1 and IL-18. However, DHA improved IL-18 in serum and adjacent tissues from DEN/TCPOBOP-induced liver tumor model in C57BL/6 mice.

CONCLUSION

YAP1 was positively correlated with IL-18 in HCC. DHA reduced the expression of IL-18 by inhibiting YAP1 and plays a role in the treatment of HCC. Our study suggested that IL-18 is a potential target for the treatment of HCC, and DHA is a promising drug for HCC therapy.

DATA AVAILABILITY

The dataset that supports the findings of this study is available from the corresponding author upon reasonable request.

Caspase-3 inhibitor inhibits enterovirus D68 production

Enterovirus D68 (EVD68) is an emerging pathogen that recently caused a large worldwide outbreak of severe respiratory disease in children. However, the relationship between EVD68 and host cells remains unclear. Caspases are involved in cell death, immune response, and even viral production. We found that caspase-3 was activated during EVD68 replication to induce apoptosis. Caspase-3 inhibitor (Z-DEVD-FMK) inhibited viral production, protected host cells from the cytopathic effects of EVD68 infection, and prevented EVD68 from regulating the host cell cycle at G0/G1. Meanwhile, caspase-3 activator (PAC-1) increased EVD68 production. EVD68 infection therefore activates caspase-3 for virus production. This knowledge provides a potential direction for the prevention and treatment of disease related to EVD68.

Effect of pseudolaric acid B on biochemical and physiologic characteristics in Colletotrichum gloeosporioides

In our previous study on natural products with fungicidal activity, pseudolaric acid B (PAB) isolated from Pseudolarix amabilis was examined to inhibit significantly mango anthracnose (Colletotrichum gloeosporioides) in vivo and in vitro. In the current study, sensitivity of 17 plant pathogenic fungi to PAB was determined. Mycelial growth rate results showed that PAB possessed strong antifungal activities to eleven fungi with median effective concentration (EC₅₀) values ranging from 0.087 to 1.927μg/mL. EC₅₀ of PAB against spore germination was greater than that of mycelium growth inhibition, which suggest that PAB could execute antifungal activity through mycelial growth inhibition. Further action mechanism of PAB against C. gloeosporioides was investigated, in which PAB treatment inhibited mycelia dry weight, decreased the mycelia reducing sugar and soluble protein. Furthermore, PAB induced an increase in membrane permeability, inhibited the biosynthesis of ergosterol, caused the extreme alteration in ultrastructure as indicated by the thickened cell wall and increased vesicles. These results will increase our understanding of action mechanism of PAB against plant pathogenic fungi.

Pseudolaric acid B induced autophagy, but not apoptosis, in MRC5 human fibroblast cells

Autophagy and apoptosis are closely associated. In previous studies, pseudolaric acid B (PAB), a diterpene acid isolated from the root and trunk bark of Pseudolarix kaempferi Gordon (Pinaceae), was demonstrated to induce apoptosis in various cell lines. However, in L929 murine fibrosarcoma and SW579 human thyroid squamous cell carcinoma cells, only autophagy was induced. In the present study, another cell line, MRC5 human lung fibroblast cells, was identified in which PAB only induced autophagy. The relationship between apoptosis and autophagy subsequent to PAB treatment in MRC5 cells was explored. When autophagy was inhibited by 3-methyladenine (3MA), apoptosis was induced in the PAB-treated MRC5 cells. To study the mechanism for the promotion of apoptosis by 3MA in the PAB-treated cells, the expression of members from the apoptotic signal pathways was assessed. As Bcl-2, Bcl-2 associated X and pro-caspase-9 expression following PAB treatment was not affected by 3MA treatment, it was determined that apoptosis was induced independent of the mitochondrial pathway of apoptosis. As Fas and pro-caspase-8 expression following PAB treatment were not altered by 3MA, it was further determined that the death receptor pathway was not induced. However, the phosphorylation of c-Jun-N-terminal kinase and the expression of pro-caspase-3 were upregulated, and the phosphorylation of extracellular signal-regulated kinase downregulated, by the combination of PAB and 3MA treatment compared with PAB alone. It was also observed that 3MA did not affect the microtubule aggregation ability of PAB. Therefore, inhibiting autophagy in MRC5 cells did not affect the role of PAB in microtubule aggregation, while apoptosis was induced. This may present a strategy to enhance the anti-tumor effects of PAB.