GSH/GSSG redox couple plays central role in aryl hydrocarbon receptor-dependent modulation of cytochrome P450 1A1

Baicalein antagonises Rhopilema esculentum toxin-induced oxidative stress and apoptosis by modulating ROS-MAPK-NF-κB and inhibiting PLA2 activity

The toxicity of jellyfish Rhopilema esculentum (R. esculentum), an edible jellyfish that releases venom, has been controversial. The aim of this comprehensive study was to investigate the toxic effects of jellyfish tentacle extract (TE), which was evaluated in vivo and in vitro using ICR mice and RAW264.7 cells respectively. A library of natural compounds was screened for their ability to antagonize phospholipase A2 (PLA2) activity to identify potential protective agents and mechanisms. Of the 20 natural compounds evaluated, baicalein was found to have the strongest PLA2 antagonistic and cytoprotective effects. In vivo, experiments showed that TE at a dose of 7.02 mg/kg only resulted in a 50% survival rate in mice. However, pretreatment with 30 mg/kg baicalein significantly increased the survival rate to 75%, while also attenuating TE-induced cardiac and hepatic injuries, and ameliorating TE-induced elevations in LDH, CK-MB, and AST levels. In vitro studies found that baicalein reduced cellular ROS and MDA levels, increased the expression of CAT, SOD, and GSH/GSSG to enhance cellular antioxidant defenses against TE-induced oxidative stress, and also inhibited TE-induced upregulation of TNF-α, IL-6, IL-1β, and CXCL10. Importantly, baicalein was found to modulate dysregulated MAPK and NF-κB signaling pathways disrupted by TE. Taken together, these findings suggest that baicalein can antagonize R. esculentum toxin-induced oxidative stress and apoptosis by modulating ROS/MAPK/NF-κB, which provides a viable therapeutic strategy to control the deleterious effects of jellyfish stings and associated inflammation.

Involvement of Nrf2 Signaling in Lead-induced Toxicity

Nuclear factor erythroid 2-related factor 2 (Nrf2) is used as one of the main protective factors against various pathological processes, as it regulates cells resistant to oxidation. Several studies have extensively explored the relationship between environmental exposure to heavy metals, particularly lead (Pb), and the development of various human diseases. These metals have been reported to be able to, directly and indirectly, induce the production of reactive oxygen species (ROS) and cause oxidative stress in various organs. Since Nrf2 signaling is important in maintaining redox status, it has a dual role depending on the specific biological context. On the one hand, Nrf2 provides a protective mechanism against metal-induced toxicity; on the other hand, it can induce metalinduced carcinogenesis upon prolonged exposure and activation. Therefore, the aim of this review was to summarize the latest knowledge on the functional interrelation between toxic metals, such as Pb and Nrf2 signaling.

The microbiota catabolites of quercetin glycosides concertedly enhance the resistance against acetaldehyde-induced oxidative stress

3,4-Dihydroxyphenylacetic acid (DOPAC) and 3-hydroxyphenylacetic acid (OPAC) are the predominant catabolites of quercetin glycosides, such as quercetin 4'-O-β-glucoside from the onion, produced by intestinal microbiota. Although each catabolite has been reported to protect the cells from acetaldehyde-induced cytotoxicity, the effect of their combination remains to be clarified. The purpose of this study was to determine whether the combination of DOPAC and OPAC enhances the resistance against the acetaldehyde-induced oxidative stress in the cultured hepatocytes. The pretreatment of the combination of DOPAC (5 μM) and OPAC (5 μM) showed significant protection against the acetaldehyde- and hydrogen peroxide-induced cytotoxicity, even though each compound at the same concentration did not. This combination also significantly inhibited the intracellular dichlorofluorescin diacetate-detectable reactive oxygen species (ROS) level, whereas the solo treatment did slightly, suggesting that reducing mechanisms of ROS or compounds that enhance ROS production are involved in the cytoprotective effect. The combinatory treatment significantly enhanced the gene expression of not only the aldehyde dehydrogenases (ALDHs), but also glutamate-cysteine ligase, catalytic subunit, the first rate-limiting enzyme of glutathione (GSH) synthesis. Accordingly, both the intracellular GSH level and the total ALDH activity were enhanced by DOPAC plus OPAC. Involvement of GSH in the cytoprotection as well as ALDH up-regulation by the combination was confirmed by the experiments using a GSH biosynthesis inhibitor, buthionine sulfoximine. Taken together, the present results suggested that the quercetin microbiota catabolites concertedly protect the cells from acetaldehyde through a pre-enhanced resistance against oxidative stress by the GSH-dependent up-regulation of ALDHs.

Effects of β-HgS on cell viability and intracellular oxidative stress in PC-12 cells

Traditional Tibetan medicines containing β-HgS have been used to treat chronic ailments for thousands of years. The effects were studied of β-HgS on cell viability and intracellular oxidative stress in PC-12 cells.

6-Formylindolo[3,2-b]carbazole (FICZ) Enhances The Expression of Tumor Suppressor miRNAs, miR-22, miR-515-5p, and miR-124-3p in MCF-7 Cells

Objective

microRNAs (miRNAs) play bifunctional roles in the initiation and progression of cancer, and recent evidence has confirmed that unusual expression of miRNAs is required for the progress of breast cancer. The regulatory role of aryl hydrocarbon receptor (AhR) and its endogenous ligand, 6-formylindolo[3,2-b]carbazole (FICZ) on the expression of tumor suppressor miRNAs, miR-22, miR-515-5p and miR-124-3p, as well as their association with the estrogen receptor alpha (ERα) were the aims of this study.

Materials and Methods

In this experimental study, the expression levels of miR-22, miR-515-5p, miR-124-3p and miR-382-5p in MCF-7 cells were determined using the quantificational real time polymerase chain reaction (qRT-PCR) assay.

Results

Our results revealed that miR-22, miR-515-5p, and miR-124-3p expressions were significantly increased in cells transfected with ERα siRNA. Our data also showed that miR-22, miR 515-5p, and miR-124-3p expression levels were significantly increased following FICZ treatment. Here, we found that AhR/ERα cross-talk plays a critical role in the expression of miR-22, miR-515-5p and miR-124-3p in MCF-7 cells.

Conclusion

Overall, our data demonstrated that FICZ, as an AhR agonist could induce the expression of tumor suppressor miRNAs, miR-22, miR-515-5p, and miR-124-3p; thus, FICZ might be regarded as a potential therapeutic agent for breast cancer treatment.