Corrigendum: The Ethyl Acetate Extract From Celastrus Orbiculatus Promotes Apoptosis of Gastric Cancer Cells Through Mitochondria Regulation by PHB.

[This corrects the article DOI: 10.3389/fphar.2021.635467.].

The Ethyl Acetate Extract From Celastrus orbiculatus Promotes Apoptosis of Gastric Cancer Cells Through Mitochondria Regulation by PHB.

Objective: To investigate the effect of ethyl acetate extract from Celastrus orbiculatus (COE) on gastric cancer cell apoptosis and reveal its underlying molecular mechanism. In addition, it was aimed to stablish a theoretical basis for the clinical application of Celastrus orbiculatus in the gastric cancer treatment. Material and Methods: Western blot and RT-qPCR were used to detect mRNA and protein expression of PHB in gastric cancer and adjacent tissues. MTT method was used to detect the COE effect on the proliferation of AGS cells and to determine the 50% inhibitory concentration COE on these cells. COE effect on AGS apoptosis was evaluated by flow cytometry. Changes in apoptosis-related proteins expression in AGS cells were detected by western blot and changes in mitochondrial membrane potential were detected by JC-1 fluorescence staining. PHB expression was knocked down in AGS cells by lentiviral-mediated RNA interference. The COE antitumor effect was assessed in vivo using a subcutaneous transplantation tumor model in nude mice and in vivo fluorescence tracing technique in small animals. Results: The clinical samples analysis results showed that the PHB expression in gastric cancer samples was significantly higher than in corresponding adjacent tissues. MTT results showed that the AGS cell proliferation was significantly inhibited. RT-qPCR and western blot results showed that COE can significantly inhibit the PHB mRNA and protein expression, respectively. Flow cytometry analysis showed that COE was able to significantly promote AGS cell apoptosis. Western blot results also indicated that apoptosis-related protein expression changed significantly; BCL-2 expression significantly reduced while the Caspase-3 and Bax expression significantly increased after COE treatment. JC-1 fluorescence staining results showed that COE changed the mitochondrial membrane potential and activated the mitochondrial apoptosis pathway. Furthermore, in vivo experiments results demonstrated that the growth of subcutaneous transplanted tumor was significantly inhibited by the PHB knockdown and by the COE intragastric administration. Conclusion: COE can significantly promote apoptosis of human gastric cancer cells, which can be achieved by inhibiting PHB expression, thus altering the structure and function of mitochondria and activating the mitochondria apoptosis pathway. The antitumor effect of COE has also been proved in vivo.

Polypharmacological Profiles Underlying the Antitumor Property of Salvia miltiorrhiza Root (Danshen) Interfering with NOX-Dependent Neutrophil Extracellular Traps.

Danshen, the dried root of Salvia miltiorrhiza, one of the most investigated medicinal plants with well-defined phytochemical constituents, has shown prominent clinical outcomes for antioxidant, anti-inflammatory, and anticoagulant activities to attain vascular protection and additional benefits for cancer therapy. More recently, activation of neutrophil and excessive formation of neutrophil extracellular traps (NETs) have been observed in pathological conditions of metastatic cancers; thus, we hypothesized that suppression of NETs could account for an essential cellular event underlying Danshen-mediated reduction of the incidence of metastasis. Using an experimental pulmonary metastases model of red fluorescent protein- (RFP-) labeled gastric cancer cells in combination with macroscopic ex vivo live-imaging system, our data indicated that Danshen impaired the fluorescent intensity and quantity of metastatic nodules. Moreover, Danshen could prevent neutrophil trafficking to the metastatic sites with decreased plasma levels of neutrophil elastase (NE) and procoagulant potential featured by fibrinogen. We further established phorbol 12-myristate 13-acetate- (PMA-) induced NET formation of human neutrophils and screened representative active compounds derived from the hydrophilic and hydrophobic fractions of Danshen using qualitative and quantitative methods. As a result, we found that salvianolic acid B (Sal B) and 15,16-dihydrotanshinone I (DHT I) exhibited superior inhibitory activities on NET formation and significantly attenuated the levels of citrullinated histone H3 (citH3), a biomarker for NET formation. Multitarget biochemical assays demonstrated that Sal B and DHT I distinctly modulated the enzymatic cascade involved in NET formation. Sal B and DHT I could disrupt NET formation at the earlier stage by blocking the activities of myeloperoxidase (MPO) and NADPH oxidase (NOX), respectively. Lastly, combining treatment of Sal B and DHT I under subED50 doses displayed remarkable synergism effect on NET inhibition. Altogether, these data provide insight into how promiscuous compounds from herbal medicine can be effectively targeted NETs towards hematogenous metastasis of certain tumors.

Anticancer efficacy of the ethyl acetate extract from the traditional Chinese medicine herb Celastrus orbiculatus against human gastric cancer.

ETHNOPHARMACOLOGICAL RELEVANCE: The traditional Chinese medicine (TCM) herb Celastrus orbiculatus is an important folk medicinal plant in China that has been used as an anti-inflammatory, antitumor, and analgesic in various diseases. The ethyl acetate extract of C. orbiculatus (C. orbiculatus extract, COE) was reported to show significant antitumor effects. However, no study in China or abroad has reported the effect and mechanism of COE in triggering apoptosis of gastric cancer (GC) cells. AIM OF STUDY: To further uncover the molecular mechanism underlying COE's apoptotic and anti-proliferative effects and lay a foundation for the development of novel, effective antitumor TCM agents. MATERIALS AND METHODS: The effect of COE on AGS and BGC-823 GC cell viability was examined using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis of AGS and BGC-823 cells induced by COE was analyzed using flow cytometry and a mitochondrial membrane potential assay kit (JC-1). The proliferating GC cells were identified and examined using a 5-bromo-2'-deoxyuridine (BrdU) staining kit and flow cytometric analysis. A western blot assay was used to detect the effect of COE on apoptosis-related proteins, B-cell lymphoma-2 (Bcl-2), Bcl-extra-large (Bcl-xL), Bcl-2-like protein 12 (Bcl-L12), Bcl-2-associated X protein (Bax), and caspase as well as proliferation-related proteins, phosphoinositide 3-kinase (PI3K)/Akt/mechanistic target of rapamycin (mTOR)/p70s6k. Transmission electron microscopy (TEM) and an animal imaging technique were used to evaluate the microstructure of apoptotic GC cells and the effect of COE on tumor cell growth in vivo, respectively. RESULTS: The results indicate that COE significantly inhibited proliferation and induced apoptosis of GC AGS and BGC-823 cell lines both in vivo and in vitro. COE significantly decreased the cell mitochondrial membrane potential. Moreover, COE downregulated the levels of Bcl-2, Bcl-xL, and PI3K/Akt/mTOR/p70s6k while those of Bax and caspase were upregulated. More interestingly, COE altered the microstructure of the mitochondria. CONCLUSION: All these data collectively indicate that COE not only has significant antiproliferative effects but also has both in vivo and in vitro apoptotic effects. In addition, COE altered the structure and function of the mitochondria, which is another potential pathway for the antitumor activity of COE. These findings may provide a basis for the development of new anticancer TCM candidates.