Myricetin reverses epithelial-endothelial transition and inhibits vasculogenic mimicry and angiogenesis of hepatocellular carcinoma by directly targeting PAR1.

Most antiangiogenic inhibitors targeting endothelium-dependent vessels cannot inhibit tumor growth but promote tumor invasion and metastasis in some patients. Vasculogenic mimicry (VM) employs mechanisms that differ from those used to construct endothelium-dependent vessels. Inhibiting VM may be a novel antiangiogenic strategy against alternative tumor vascularization. In this paper, myricetin was selected from among several flavonoid compounds as an effective PAR1 antagonist. In two different hepatocellular carcinoma (HCC) cell lines high-expressed PAR1, myricetin inhibited cell migration, invasion and VM formation and reversed the expression of epithelial-endothelial transition (EET) markers by inhibiting PAR1 activation. Knockout of PAR1 inhibited HCC cell invasion and metastasis and weakened the inhibitory effect of myricetin on HCC cells. The migration, invasion and tube formation ability of PLC-PRF-5 cells were enhanced after PAR1 overexpression, and the inhibitory effect of myricetin was enhanced. A docking assay revealed that myricetin binds to Leu258 and Thr261 in the PAR1 activity pocket. Mutation of Leu258 and Thr261 inhibited the antitumor effect of myricetin in vitro and in vivo. In summary, myricetin reverses PAR1-mediated EET and inhibits HCC cell invasion, metastasis, VM formation and angiogenesis by targeting PAR1, and Leu258 and Thr261 of PAR1 participate in VM and angiogenesis in HCC tissues.

Bergenin attenuates bleomycin-induced pulmonary fibrosis in mice via inhibiting TGF-ß1 signaling pathway.

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease characterized by epithelial cell damage, fibroblast activation, and collagen deposition. IPF has high mortality and limited therapies, which urgently needs to develop safe and effective therapeutic drugs. Bergenin, a compound derived from a variety of medicinal plants, has demonstrated multiple pharmacological activities including anti-inflammatory and anti-tumor, also acts as a traditional Chinese medicine to treat chronic bronchitis, but its effect on the pulmonary fibrosis is unknown. In this study, we demonstrated that bergenin could attenuate bleomycin (BLM)-induced pulmonary fibrosis in mice. In vitro studies indicated that bergenin inhibited the transforming growth factor-ß1 (TGF-ß1)-induced fibroblast activation and the extracellular matrix accumulation by inhibiting the TGF-ß1/Smad signaling pathway. Further studies showed that bergenin could induce the autophagy formation of myofibroblasts by suppressing the mammalian target of rapamycin signaling and that bergenin could promote the myofibroblast apoptosis. In vivo experiments revealed that bergenin substantially inhibited the myofibroblast activation and the collagen deposition and promoted the autophagy formation. Overall, our results showed that bergenin attenuated the BLM-induced pulmonary fibrosis in mice by suppressing the myofibroblast activation and promoting the autophagy and the apoptosis of myofibroblasts.

Antifibrotic Mechanism of Cinobufagin in Bleomycin-Induced Pulmonary Fibrosis in Mice.

Idiopathic pulmonary fibrosis (IPF) is a progressive and usually fatal lung disease that is characterized by fibroblast proliferation and extracellular matrix remodeling, which result in irreversible distortion of the lung's architecture and the formation of focal fibrous hyperplasia. The molecular mechanism by which pulmonary fibrosis develops is not fully understood, and no satisfactory treatment currently exists. However, many studies consider that aberrant activation of TGF-ß1 frequently promotes epithelial-mesenchymal transition (EMT) and fibroblast activation in pulmonary fibrosis. Cinobufagin (CBG), a traditional Chinese medicine, has been widely used for long-term pain relief, cardiac stimulation, and anti-inflammatory and local anesthetic treatments. However, its role in pulmonary fibrosis has not yet been established. We investigated the hypothesis that cinobufagin plays an inhibitory role on TGF-ß1 signaling using a luciferase-reporter assay. We further explored the effect of cinobufagin on pulmonary fibrosis both in vitro and in vivo. The in vitro experiments showed that cinobufagin suppresses TGF-ß1/Smad3 signaling in a dose-dependent manner, attenuates the activation and differentiation of lung fibroblasts and inhibits EMT induced by TGF-ß1 in alveolar epithelial cells. The in vivo experiments indicated that cinobufagin significantly alleviates bleomycin-induced collagen deposition and improves pulmonary function. Further study showed that cinobufagin could attenuate bleomycin-induced inflammation and inhibit fibroblast activation and the EMT process in vivo. In summary, cinobufagin attenuates bleomycin-induced pulmonary fibrosis in mice via suppressing inflammation, fibroblast activation and epithelial-mesenchymal transition.

Synthesis and discovery of a drug candidate for treatment of idiopathic pulmonary fibrosis through inhibition of TGF-ß1 pathway.

In this study, anti-IPF lead compounds 42 and 44, derived from natural sesquiterpene lactones Isoalantolactone and alantolactone, were discovered by screening from a high-throughput TGF-ß1 reporter luciferase assay. Notably, they could reduce the myofibroblast activation and extracellular matrix deposition both in vitro and in vivo. Additionally, compounds 42 and 44 could significantly attenuate bleomycin-induced pulmonary fibrosis in mice. Further validation of pharmacokinetics study and toxicity evaluation indicated that compound 44 might be a promising anti-IPF drug candidate.