Undesirable ER stress induced by bavachin contributed to follicular atresia in zebrafish ovary

Fructus psoraleae (FP) is a commonly used herb with potential reproductive toxicity. Bavachin (BV), one of essential active ingredients of FP, was found to exhibit estrogenic activity, but its effect on female reproductive system remains unknown. In this study, the impact of BV on the female zebrafish reproductive system and underlying molecular mechanism were determined in vivo and ex vivo. The results showed that BV could accumulate in zebrafish ovary, leading to obvious follicular atresia and increase in gonadal index and vitellogenin content. Endoplasmic reticulum (ER) swelling and hypertrophy were observed in the BV-treated zebrafish ovary, accompanied by an increase in the expressions of ER stress and unfolded protein response (UPR) related genes, namely atf6, ire-1α and xbp1s. In the ex vivo study, BV was found to decrease the survival rate and maturation rate of oocytes, while increasing the expression of Ca2+. Additionally, BV led to an elevation in the level of estrogen receptor ESR1 and the expressions of genes involved in ER stress and UPR, including atf6, ire-1α, xbp1s, chop and perk. Moreover, molecular docking revealed that BV could directly bind to immunoglobulin heavy chain binding protein (BiP) and estrogen receptor 1 (ESR1). Besides, the alterations induced by BV could be partially reversed by fulvestrant (FULV) and 4-phenylbutyric acid (4-PBA), respectively. Thus, long-termed BV-containing medicine treatment could generate reproductive toxicity in female zebrafish by causing follicular atresia through BiP- and ESR-mediated ER stress and UPR, providing a potential target for the prevention of reproductive toxicity caused by BV.

Bavachin induces liver injury and cell apoptosis by targeting Wnt/β-catenin/DRP1 signaling pathway mediated mitochondrial dysfunction

Psraleae Fructus (PF) is a well-known traditional Chinese medicine in China. While numerous liver injury reports caused by PF limits its clinical application. Bavachin, a flavonoid compound isolated from the fruits of Psoralea corylifolia L., has been validated to induce direct apoptosis in hepatocytes and liver tissues in our previous studies. However, the subcellular mechanisms of bavachin induced liver injury is still elusive. Here, utilizing 6-week-old C57BL/6 J mice and human embryonic hepatocytes (L02 cells), we report that bavachin activates dynamic-related protein 1 (DRP1) mediated excess mitochondrial fission and endoplasmic reticulum (ER) stress related apoptosis via Wnt/β-catenin signaling pathway. Notably, DRP1 knockdown or XAV-939 induced Wnt/β-catenin inhibition decreased bavachin-induced ER stress and cell apoptosis in L02 cells. In addition, bavachin impaired mitochondrial structural and function in the mice liver tissues. Mdivi-1, a mitochondrial fission inhibitor targeting DRP1, prevented bavachin-induced mitochondrial and ER structural damage, ER stress, and liver injury. Our results demonstrated that bavachin induced mitochondrial fission plays a crucial role in bavachin induced ER stress related liver injury, via the mechanism that involved activation of Wnt/β-catenin signaling pathway.

A Scd1-mediated metabolic alteration participates in liver responses to low-dose bavachin

Hepatotoxicity induced by bioactive constituents in traditional Chinese medicines or herbs, such as bavachin (BV) in Fructus Psoraleae, has a prolonged latency to overt drug-induced liver injury in the clinic. Several studies have described BV-induced liver damage and underlying toxicity mechanisms, but little attention has been paid to the deciphering of organisms or cellular responses to BV at no-observed-adverse-effect level, and the underlying molecular mechanisms and specific indicators are also lacking during the asymptomatic phase, making it much harder for early recognition of hepatotoxicity. Here, we treated mice with BV for 7 days and did not detect any abnormalities in biochemical tests, but found subtle steatosis in BV-treated hepatocytes. We then profiled the gene expression of hepatocytes and non-parenchymal cells at single-cell resolution and discovered three types of hepatocyte subsets in the BV-treated liver. Among these, the hepa3 subtype suffered from a vast alteration in lipid metabolism, which was characterized by enhanced expression of apolipoproteins, carboxylesterases, and stearoyl-CoA desaturase 1 (Scd1). In particular, increased Scd1 promoted monounsaturated fatty acids (MUFAs) synthesis and was considered to be related to BV-induced steatosis and polyunsaturated fatty acids (PUFAs) generation, which participates in the initiation of ferroptosis. Additionally, we demonstrated that multiple intrinsic transcription factors, including Srebf1 and Hnf4a, and extrinsic signals from niche cells may regulate the above-mentioned molecular events in BV-treated hepatocytes. Collectively, our study deciphered the features of hepatocytes in response to BV insult, decoded the underlying molecular mechanisms, and suggested that Scd1 could be a hub molecule for the prediction of hepatotoxicity at an early stage.

Bavachin protects against diet-induced hepatic steatosis and obesity in mice

Non-alcoholic fatty liver disease (NAFLD) is a major health concern worldwide, and the incidence of metabolic disorders associated with NAFLD is rapidly increasing because of the obesity epidemic. There are currently no approved drugs that prevent or treat NAFLD. Recent evidence shows that bavachin, a flavonoid isolated from the seeds and fruits of Psoralea corylifolia L., increases the transcriptional activity of PPARγ and insulin sensitivity during preadipocyte differentiation, but the effect of bavachin on glucose and lipid metabolism remains unclear. In the current study we investigated the effects of bavachin on obesity-associated NAFLD in vivo and in vitro. In mouse primary hepatocytes and Huh7 cells, treatment with bavachin (20 μM) significantly suppressed PA/OA or high glucose/high insulin-induced increases in the expression of fatty acid synthesis-related genes and the number and size of lipid droplets. Furthermore, bavachin treatment markedly elevated the phosphorylation levels of AKT and GSK-3β, improving the insulin signaling activity in the cells. In HFD-induced obese mice, administration of bavachin (30 mg/kg, i.p. every other day for 8 weeks) efficiently attenuated the increases in body weight, liver weight, blood glucose, and liver and serum triglyceride contents. Moreover, bavachin administration significantly alleviated hepatic inflammation and ameliorated HFD-induced glucose intolerance and insulin resistance. We demonstrated that bavachin protected against HFD-induced obesity by inducing fat thermogenesis and browning subcutaneous white adipose tissue (subWAT). We revealed that bavachin repressed the expression of lipid synthesis genes in the liver of obese mice, while promoting the expression of thermogenesis, browning, and mitochondrial respiration-related genes in subWAT and brown adipose tissue (BAT) in the mice. In conclusion, bavachin attenuates hepatic steatosis and obesity by repressing de novo lipogenesis, inducing fat thermogenesis and browning subWAT, suggesting that bavachin is a potential drug for NAFLD therapy.

Psoraleae Fructus Ethanol Extract Induced Hepatotoxicity via Impaired Lipid Metabolism Caused by Disruption of Fatty Acid β-Oxidation

Herb-induced liver injury (HILI) is gradually increasing, and Psoraleae Fructus (PF) has been reported to induce hepatotoxicity. However, its underlying toxicity mechanism has been only poorly revealed. In this paper, we attempted to explore the liver injury and mechanism caused by Psoraleae Fructus ethanol extract (PFE). First, we administered PFE to mice for 4 weeks and evaluated their serum liver function indices. H&E staining was performed to observe the pathological changes of the livers. Oil red O staining was used to visualize hepatic lipids. Serum-untargeted metabolomics and liver proteomics were used to explore the mechanism of PF hepatotoxicity, and transmission electron microscopy was determined to assess mitochondria and western blot to determine potential target proteins expression. The results showed that PFE caused abnormal liver biochemical indicators and liver tissue injury in mice, and there was substantial fat accumulation in liver tissue in this group. Furthermore, metabolomic analysis showed that PFE changed bile acid synthesis, lipid metabolism, etc., and eight metabolites, including linoleic acid, which could be used as potential biomarkers of PFE hepatotoxicity. Proteomic analysis revealed that differential proteins were clustered in the mitochondrial transmembrane transport, the long-chain fatty acid metabolic process and purine ribonucleotide metabolic process. Multiomics analysis showed that eight pathways were enriched in both metabolomics and proteomics, such as bile secretion, unsaturated fatty acid biosynthesis, and linoleic acid metabolism. The downregulation of SLC27A5, CPT1A, NDUFB5, and COX6A1 and upregulation of cytochrome C and ABCC3 expressions also confirmed the impaired fatty acid oxidative catabolism. Altogether, this study revealed that PFE induced hepatotoxicity by damaging mitochondria, reducing fatty acid β-oxidation levels, and inhibiting fatty acids ingested by bile acids.

Bavachin induces apoptosis in colorectal cancer cells through Gadd45a via the MAPK signaling pathway

Bavachin is a dihydroflavonoid compound isolated from Psoralea corylifolia, and exhibits anti-bacterial, anti-inflammatory, anti-tumor and lipid-lowering activities. Recent attention has gradually drawn on bavachin-induced apoptosis in many human cancer cell lines. However, the anti-cancer effects and related mechanisms in colorectal cancer remain unknown. Here, we investigated the effects of bavachin on colorectal cancer in vivo and in vitro. The results showed that bavachin inhibited the proliferation of human colorectal cancer cells and induce apoptosis. These changes were mediated by activating the MAPK signaling pathway, which significantly up-regulated the expression of Gadd45a. Furthermore, Gadd45a silencing obviously attenuated bavachin-mediated cell apoptosis. Inhibition of the MAPK signaling pathway by JNK/ERK/p38 inhibitors also weakened the up-regulation of Gadd45a by bavachin. The anticancer effect of bavachin was also validated using a mouse xenograft model of human colorectal cancer. In conclusion, these findings suggest that bavachin induces the apoptosis of colorectal cancer cells through activating the MAPK signaling pathway.

Role of ER Stress in Xenobiotic-Induced Liver Diseases and Hepatotoxicity

The liver is a highly metabolic organ and plays a crucial role in the transportation, storage, and/or detoxication of xenobiotics. Liver damage induced by xenobiotics (e.g., heavy metal, endocrine disrupting chemicals, Chinese herbal medicine, or nanoparticles) has become a pivotal reason for liver diseases, leading to great clinical challenge and much attention for the past decades. Given that endoplasmic reticulum (ER) is the prominent organelle involved in hepatic metabolism, ER dysfunction, namely, ER stress, is clearly observed in various liver diseases. In response to ER stress, a conserved adaptive signaling pathway known as unfolded protein response (UPR) is activated to restore ER homeostasis. However, the prolonged ER stress with UPR eventually leads to the death of hepatocytes, which is a pathogenic event in many hepatic diseases. Therefore, analyzing the perturbation in the activation or inhibition of ER stress and the UPR signaling pathway is likely an effective marker for investigating the molecular mechanisms behind the toxic effects of xenobiotics on the liver. We review the role of ER stress in hepatic diseases and xenobiotic-induced hepatotoxicity, which not only provides a theoretical basis for further understanding the pathogenesis of liver diseases and the mechanisms of hepatotoxicity induced by xenobiotics but also presents a potential target for the prevention and treatment of xenobiotic-related liver diseases.

Bavachin Suppresses Alpha-Hemolysin Expression and Protects Mice from Pneumonia Infection by Staphylococcus aureus

Staphylococcus aureus (S. aureus) infection causes dramatic harm to human health as well as to livestock development. As an important virulence factor, alpha-hemolysin (hla) is critical in the process of S. aureus infection. In this report, we found that bavachin, a natural flavonoid, not only efficiently inhibited the hemolytic activity of hla, but was also capable of inhibiting it on transcriptional and translational levels. Moreover, further data revealed that bavachin had no neutralizing activity on hla, which did not affect the formation of hla heptamers and exhibited no effects on the hla thermal stability. In vitro assays showed that bavachin was able to reduce the S. aureus-induced damage of A549 cells. Thus, bavachin repressed the lethality of pneumonia infection, lung bacterial load and lung tissue inflammation in mice, providing potent protection to mice models in vivo. Our results indicated that bavachin has the potential for development as a candidate hla inhibitor against S. aureus.

Ginsenoside Rb1 Ameliorated Bavachin-Induced Renal Fibrosis via Suppressing Bip/eIF2α/CHOP Signaling-Mediated EMT

The nephrotoxicity of Fructus Psoraleae, an effective traditional Chinese medicine for vitiligo treatment, has been reported. As one of the main toxic components in Fructus Psoraleae, bavachin (BV) was considered to be related to Fructus Psoraleae-caused adverse outcomes, but the direct evidence and molecular mechanism underlying BV-induced nephrotoxicity are not well elucidated. Therefore, this study was designed to confirm whether BV would cause toxic effects on the kidney and explore the possible mode of action. Our results demonstrated that days’ treatment with 0.5 μM BV indeed caused obvious renal fibrosis in the zebrafish kidney. The obvious E- to N-cadherin switch and the expressions of proteins promoting epithelial–mesenchymal transition (EMT) were observed in BV-treated human renal tubular epithelial and zebrafish kidneys. In addition, elevated reactive oxygen species (ROS) levels and Bip/eIF2α/CHOP-mediated endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) were caused by BV, both of which could be reversed by ROS scavenger N-acetyl-L-cysteine (NAC). Also, blocking ER stress-caused cytoplasmic Ca2+ overload with 4-PBA notably alleviated BV-induced alterations in key molecular events related to EMT and renal fibrosis. Furthermore, of the natural compounds subjected to screening, ginsenoside Rb1 significantly downregulated BV-induced ER stress by inhibiting ROS generation and following the activation of Bip/eIF2α/CHOP signaling in HK2 cells. Subsequently, BV-triggered EMT and renal fibrosis were both ameliorated by ginsenoside Rb1. In summary, our findings suggested that BV-induced ROS promoted the appearance of EMT and renal fibrosis mainly via Bip/eIF2α/CHOP-mediated ER stress. This ER stress-related toxic pathway might be a potential intervention target for BV-caused renal fibrosis, and ginsenoside Rb1 would be a promising drug against BV- or Fructus Psoraleae-induced nephrotoxicity.

Isobavachalcone disrupts mitochondrial respiration and induces cytotoxicity through ROS accumulation and Akt suppression

Isobavachalcone (IBC) is one of the flavonoid components in Fructus Psoraleae, and has been found multiple pharmacological effects. However, the hepatotoxicity of IBC has been overlooked and not been carefully studied. We aim to find out the cytotoxicity of IBC on HepG2 cells, and explore the underlying mechanisms. HepG2 cells were treated with IBC for 24 h, then MTT assay and LDH assay were used to detect the cell viability. The apoptosis and reactive oxygen species (ROS) production were reflected by the flow cytometry. Using Seahorse Analyzer, we measured the mitochondrial respiratory capacity. The expression of oxidative stress and mitochondrial apoptosis-related proteins were determined by Western blot. The results showed that IBC induced the cell death and apoptosis of HepG2 cells. IBC initiated the accumulation of ROS in cells and impaired the mitochondrial function, triggered apoptosis and suppressed the phosphorylation of Akt. Additionally, scavenging ROS by the antioxidant N-acetyl-l-cysteine (NAC) reduced IBC-induced mitochondria damage and increased Akt phosphorylation. Taken together, IBC caused mitochondrial damage and induced hepatotoxicity by ROS accumulation and Akt suppression. Targeting oxidative stress and depressing mitochondrial damage may provide a theoretical basis for the treatment and prevention of IBC-induced hepatotoxicity in clinic.

A new strategy for the rapid identification and validation of direct toxicity targets of psoralen-induced hepatotoxicity

The interaction between small-molecule compounds of traditional Chinese medicine and their direct targets is the molecular initiation event, which is the key factor for toxicity efficacy. Psoralen, an active component of Fructus Psoraleae, is toxic to the liver and has various pharmacological properties. Although the mechanism of psoralen-induced hepatotoxicity has been studied, the direct target of psoralen remains unclear. Thus, the aim of this study was to discover direct targets of psoralen. To this end, we initially used proteomics based on drug affinity responsive target stability (DARTS) technology to identify the direct targets of psoralen. Next, we used surface plasmon resonance (SPR) analysis and verified the affinity effect of the 'component-target protein'. This method combines molecular docking technology to explore binding sites between small molecules and proteins. SPR and molecular docking confirmed that psoralen and tyrosine-protein kinase ABL1 could be stably combined. Based on the above experimental results, ABL1 is a potential direct target of psoralen-induced hepatotoxicity. Finally, the targets Nrf2 and mTOR, which are closely related to the hepatotoxicity caused by psoralen, were predicted by integrating proteomics and network pharmacology. The direct target ABL1 is located upstream of Nrf2 and mTOR, Nrf2 can influence the expression of mTOR by affecting the level of reactive oxygen species. Immunofluorescence experiments and western blot results showed that psoralen could affect ROS levels and downstream Nrf2 and mTOR protein changes, whereas the ABL1 inhibitor imatinib and ABL1 agonist DPH could enhance or inhibit this effect. In summary, we speculated that when psoralen causes hepatotoxicity, it acts on the direct target ABL1, resulting in a decrease in Nrf2 expression, an increase in ROS levels and a reduction in mTOR expression, which may cause cell death. We developed a new strategy for predicting and validating the direct targets of psoralen. This strategy identified the toxic target, ABL1, and the potential toxic mechanism of psoralen.

Five Constituents Contributed to the Psoraleae Fructus-Induced Hepatotoxicity via Mitochondrial Dysfunction and Apoptosis

Backgrounds: Psoraleae Fructus (PF)-induced hepatotoxicity has been reported in clinical and animal experiments. However, the hepatotoxic constituents and mechanisms underlying PF-induced toxicity have remained unclear. Therefore, this study explored the potentially toxic PF components and revealed their relative mechanisms.

Methods: The hepatotoxicity of PF water (PFW) and ethanol (PFE) extracts was compared using Kunming mice. The different compositions between PFW and PFE, which were considered toxic compositions, were identified using the UHPLC-Q-Exactive MS method. Then, L02 and HepG2 cell lines were used to evaluate the toxicity of these compositions. Cell viability and apoptosis were determined through the Cell Counting Kit-8 (CCK-8) assay and flow cytometry, respectively. An automatic biochemical analyzer detected the aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP). Lastly, we used high-content screening (HCS) to determine the levels of reactive oxygen species (ROS), lipid, and mitochondrial membrane potential (MMP).

Results: The ethanol extraction process aggravated the hepatotoxicity of PF, causing more severe injuries. The content of psoralen, isopsoralen, bavachin, psoralidin, bavachinin, neobavaisoflavone, and bakuchiol was higher in the PFE than PFW. Bavachin, psoralidin, bavachinin, neobavaisoflavone, and bakuchiol induced cell apoptosis and the AST, ALT, and ALP leakages. Furthermore, these five constituents increased intracellular lipid accumulation and ROS levels but decreased the MMP level.

Conclusion: The ethanol extraction process could induce severe PF hepatotoxicity. Bavachin, psoralidin, bavachinin, neobavaisoflavone, and bakuchiol are the main hepatotoxic ingredients. This mechanism could be associated with oxidative stress and mitochondrial damage-mediated apoptosis. Taken together, this study provides a basis for the clinical application of PF that formulates and improves its herbal standards.

Multi-parametric cellular imaging coupled with multi-component quantitative profiling for screening of hepatotoxic equivalent markers from Psoraleae Fructus

BACKGROUND

The hepatotoxicity of Chinese herbal medicine (CHM) is an important reason for its restrictive application. Psoraleae Fructus (PF), a commonly used CHM for treatment of osteoporosis and vitiligo etc., has caused serious concern due to the frequent occurrence of liver injury incidents. To date, its hepatotoxic equivalent markers (HEMs) and potential mechanisms are still unclear.

PURPOSE

To discover and validate the HEMs of PF and further explore the potential mechanisms of hepatotoxicity.

METHODS

Multi-parametric cellular imaging was performed by high content screening, and multi-component quantitative profiling was conducted by ultra-high performance liquid chromatography coupled with triple-quadrupole mass spectrometry. The correlations between hepatotoxic features and component contents were modeled by chemometrics including partial least square regression, back propagation-artificial neural network, and hierarchical cluster analysis. Then the candidate HEMs of PF were screened out and subjected to hepatotoxic equivalence assessment in primary hepatocytes, zebrafish, and mice, and the hepatotoxic mechanisms of PF were investigated.

RESULTS

The chemical combination of psoralen and isopsoralen was discovered as the HEMs of PF through pre-screening and verifying process. PF was demonstrated to induce oxidative stress, mitochondrial dysfunction and cellular apoptosis.

CONCLUSIONS

This study not only provides a rational strategy for screening HEMs from CHMs like PF, but also contributes to understanding the underlying mechanisms of PF hepatotoxicity.

Bavachin Induces Ferroptosis through the STAT3/P53/SLC7A11 Axis in Osteosarcoma Cells

Ferroptosis is a new form of regulated cell death, which is mediated by intracellular iron. Although it is reported that bavachin has antitumour effects on several tumour cells and prompts the reactive oxygen species (ROS) generation, it is unclear whether ferroptosis can be induced by bavachin in osteosarcoma (OS) cells. In this study, we found that bavachin inhibits the viability of MG63 and HOS OS cell lines along with an increase in the ferrous iron level, ROS accumulation, malondialdehyde overexpression, and glutathione depletion. Moreover, iron chelators (deferoxamine), antioxidants (Vit E), and ferroptosis inhibitors (ferrostatin-1 and liproxstatin-1) reverse bavachin-induced cell death. Bavachin also altered the mitochondrial morphology of OS cells, leading to smaller mitochondria, higher density of the mitochondrial membrane, and reduced mitochondrial cristae. Further investigation showed that bavachin upregulated the expression of transferrin receptor, divalent metal transporter-1, and P53, along with downregulating the expression of ferritin light chain, ferritin heavy chain, p-STAT3 (705), SLC7A11, and glutathione peroxidase-4 in OS cells. More importantly, STAT3 overexpression, SLC7A11 overexpression, and pretreatment with pifithrin-α (P53 inhibitor) rescued OS cell ferroptosis induced by bavachin. The results show that bavachin induces ferroptosis via the STAT3/P53/SLC7A11 axis in OS cells.

Endoplasmic reticulum stress: Multiple regulatory roles in hepatocellular carcinoma

BACKGROUND

Endoplasmic reticulum (ER) stress is a basic cellular stress response that maintains cellular protein homeostasis under endogenous or exogenous stimuli, which depends on the stimulus, its intensity, and action time. The ER produces a corresponding cascade reaction for crosstalk of adaptive and/or pro-death regulation with other organelles. Hepatocellular carcinoma(HCC) is one of the most common malignant solid tumors with an extremely poor prognosis. Viral hepatitis infection, cirrhosis, and steatohepatitis are closely related to the occurrence and development of HCC, and ER stress has gradually been shown to be a major mechanism. Moreover, an increasing need for protein and lipid products and relative deficiencies of oxygen and nutrients for rapid proliferation and endoplasmic reticulum stress are undoubtedly involved. Therefore, to fully and comprehensively understand the regulatory role of endoplasmic reticulum stress in the occurrence and progression of HCC is of vital importance to explore its pathogenesis and develop novel anti-cancer strategies.

METHODOLOGY

We searched for relevant publications in the PubMed databases using the keywords "Endoplasmic reticulum stress", "hepatocellular carcinoma" in last five years,and present an overview of the current knowledge that links ER stress and HCC, which includes carcinogenesis, progression, and anti-cancer strategies, and propose directions of future research.

RESULT

ER stress were confirmed to be multiple regulators or effectors of cancer, which also be confirmed to drive tumorigenesis and progression of HCC. Targeting ER stress signaling pathway and related molecules could play a critical role for anti-HCC and has become a research hotspot for anti-cancer in recent years.

CONCLUSION

ER stress are critical for the processes of the tumorigenesis and progression of tumors. For HCC, ER stress was associated with tumorigenesis, development, metastasis, angiogenesis and drug resistance, targeting ER stress has emerged as a potential anti-tumor strategy.

Potential therapeutic compounds from traditional Chinese medicine targeting endoplasmic reticulum stress to alleviate rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease which affects about 0.5-1% of people with symptoms that significantly impact a sufferer's lifestyle. The cells involved in propagating RA tend to display pro-inflammatory and cancer-like characteristics. Medical drug treatment is currently the main avenue of RA therapy. However, drug options are limited due to severe side effects, high costs, insufficient disease retardation in a majority of patients, and therapeutic effects possibly subsiding over time. Thus there is a need for new drug therapies. Endoplasmic reticulum (ER) stress, a condition due to accumulation of misfolded proteins in the ER, and subsequent cellular responses have been found to be involved in cancer and inflammatory pathologies, including RA. ER stress protein markers and their modulation have therefore been suggested as therapeutic targets, such as GRP78 and CHOP, among others. Some current RA therapeutic drugs have been found to have ER stress-modulating properties. Traditional Chinese Medicines (TCMs) frequently use natural products that affect multiple body and cellular targets, and several medicines and/or their isolated compounds have been found to also have ER stress-modulating capabilities, including TCMs used in RA treatment by Chinese Medicine practitioners. This review encourages, in light of the available information, the study of these RA-treating, ER stress-modulating TCMs as potential new pharmaceutical drugs for use in clinical RA therapy, along with providing a list of other ER stress-modulating TCMs utilized in treatment of cancers, inflammatory diseases and other diseases, that have potential use in RA treatment given similar ER stress-modulating capacity.

Bavachin enhances NLRP3 inflammasome activation induced by ATP or nigericin and causes idiosyncratic hepatotoxicity

Psoraleae Fructus (PF) is a well-known traditional herbal medicine in China, and it is widely used for osteoporosis, vitiligo, and other diseases in clinical settings. However, liver injury caused by PF and its preparations has been frequently reported in recent years. Our previous studies have demonstrated that PF could cause idiosyncratic drug-induced liver injury (IDILI), but the mechanism underlying its hepatotoxicity remains unclear. This paper reports that bavachin isolated from PF enhances the specific stimuli-induced activation of the NLRP3 inflammasome and leads to hepatotoxicity. Bavachin boosts the secretion of IL-1β and caspase-1 caused by ATP or nigericin but not those induced by poly(I:C), monosodium urate crystal, or intracellular lipopolysaccharide. Bavachin does not affect AIM2 or NLRC4 inflammasome activation. Mechanistically, bavachin specifically increases the production of nigericin-induced mitochondrial reactive oxygen species among the most important upstream events in the activation of the NLRP3 inflammasome. Bavachin increases the levels of aspartate transaminase and alanine aminotransferase in serum and hepatocyte injury accompanied by the secretion of IL-1β via a mouse model of lipopolysaccharide-mediated susceptibility to IDILI. These results suggest that bavachin specifically enhances the ATP- or nigericin-induced activation of the NLRP3 inflammasome. Bavachin also potentially contributes to PF-induced idiosyncratic hepatotoxicity. Moreover, bavachin and PF should be evaded among patients with diseases linked to the ATP- or nigericin-mediated activation of the NLRP3 inflammasome, which may be a dangerous factor for liver injury.

Hepatocellular carcinoma (HepG2/C3A) cell-based 3D model for genotoxicity testing of chemicals

The major weakness of the current in vitro genotoxicity test systems is the inability of the indicator cells to express metabolic enzymes needed for the activation and detoxification of genotoxic compounds, which consequently can lead to misleading results. Thus, there is a significant emphasis on developing hepatic cell models, including advanced in vitro three-dimensional (3D) cell-based systems, which better imitate in vivo cell behaviour and offer more accurate and predictive data for human exposures. In this study, we developed an approach for genotoxicity testing with 21-day old spheroids formed from human hepatocellular carcinoma cells (HepG2/C3A) using the dynamic clinostat bioreactor system (CelVivo BAM/bioreactor) under controlled conditions. The spheroids were exposed to indirect-acting genotoxic compounds, polycyclic aromatic hydrocarbon [PAH; benzo(a) pyrene B(a)P], and heterocyclic aromatic amine [PhIP]) at non-cytotoxic concentrations for 24 and 96 h. The results showed that both environmental pollutants B(a)P and PhIP significantly increased the level of DNA strand breaks assessed by the comet assay. Further, the mRNA level of selected genes encoding metabolic enzymes from phase I and II, and DNA damage responsive genes was determined (qPCR). The 21-day old spheroids showed higher basal expression of genes encoding metabolic enzymes compared to monolayer culture. In spheroids, B(a)P or PhIP induced compound-specific up-regulation of genes implicated in their metabolism, and deregulation of genes implicated in DNA damage and immediate-early response. The study demonstrated that this model utilizing HepG2/C3A spheroids grown under dynamic clinostat conditions represents a very sensitive and promising in vitro model for genotoxicity and environmental studies and can thus significantly contribute to a more reliable assessment of genotoxic activities of pure chemicals, and complex environmental samples even at very low for environmental exposure relevant concentrations.

Psoralen induces liver injuries through endoplasmic reticulum stress signaling in female mice

Psoralen is the main coumarin component of Fructus psoraleae. Previously, we have found that psoralen induced hepatocytes apoptosis via PERK and ATF6 related ER stress pathways in vitro. In this study, we investigated the toxicity and ER stress induced by psoralen in female C57 mice. Mice were fed with 80 mg/kg of psoralen intra-gastrically for either 3, 7, or 21 days. Liver and kidney were weighed and their coefficients were calculated. The serum was isolated to examine the biochemical parameters including alanine aminotransferase (ALT) activity, aspartate aminotransferase (AST) activity, alkaline phosphatase (ALP) activity, blood urea nitrogen (BUN), total bile acid (TBA), total bilirubin (TBIL), and creatinine (CRE). The transcription and expression of ER stress-related markers were determined by Wes-automated Protein Simple system, Western blot and RT-PCR. Psoralen administration for 3 days significantly increased liver coefficients but decreased kidney coefficients of mice. Histopathological examination showed minimal inflammatory cell foci and vacuolar degeneration in the liver. Besides, serum levels of ALT, TBA, BUN, and CRE were markedly altered by psoralen. Moreover, psoralen significantly increased expression and transcription levels of ER stress related markers, including Grp78, PERK, eIF2α, ATF4, IRE1α, ATF6, and XBP1. These results illustrated that psoralen induced liver injuries through ER stress signaling in female mice.

Role of Mitofusins and Mitophagy in Life or Death Decisions

Mitochondria entail an incredible dynamism in their morphology, impacting death signaling and selective elimination of the damaged organelles. In turn, by recycling the superfluous or malfunctioning mitochondria, mostly prevalent during aging, mitophagy contributes to maintain a healthy mitochondrial network. Mitofusins locate at the outer mitochondrial membrane and control the plastic behavior of mitochondria, by mediating fusion events. Besides deciding on mitochondrial interconnectivity, mitofusin 2 regulates physical contacts between mitochondria and the endoplasmic reticulum, but also serves as a decisive docking platform for mitophagy and apoptosis effectors. Thus, mitofusins integrate multiple bidirectional inputs from and into mitochondria and ensure proper energetic and metabolic cellular performance. Here, we review the role of mitofusins and mitophagy at the cross-road between life and apoptotic death decisions. Furthermore, we highlight the impact of this interplay on disease, focusing on how mitofusin 2 and mitophagy affect non-alcoholic fatty liver disease.

Bavachin suppresses human placental choriocarcinoma cells by targeting electron transport chain complexes and mitochondrial dysfunction

Phytoestrogens are naturally derived estrogen-like therapeutic compounds that have long been studied for their role as anti-cancer agents and supplements during chemotherapy. Bavachin is a therapeutic phytoestrogen used to treat cancer, inflammation, and diabetes mellitus. Though the therapeutic effects of bavachin on various diseases have been explored, its anti-cancer effects and related mechanisms in human placental choriocarcinoma remain unknown. This is the first study to identify the anti-cancer potential of bavachin on human placental choriocarcinoma cell lines JEG3 and JAR. Placental mitochondria support the elevated energy production required for placental development, through oxidative phosphorylation (OXPHOS). Based on this concept, we hypothesized that mitochondrial targeting by bavachin may contribute to anti-cancer activities in high-OXPHOS subtypes of cancer such as placental choriocarcinoma. Apoptosis and caspase activities were increased by bavachin in placental choriocarcinoma cells. Bavachin altered metabolic phenotypes by regulating electron transport chain complex and OXPHOS to suppress choriocarcinoma cell proliferation. It also led to calcium disruption and endoplasmic reticulum stress accompanied by mitochondrial membrane potential depolarization. It showed synergistic anti-cancer effects with paclitaxel on placental choriocarcinoma cells. Taken together, we suggest that bavachin has therapeutic potential against placental choriocarcinoma and may be used to counter paclitaxel-induced toxicity.

Natural Products Targeting ER Stress, and the Functional Link to Mitochondria

The endoplasmic reticulum (ER) is a dynamic organelle essential for intracellular homeostasis maintenance, controlling synthesis, the folding of secreted and membrane-bound proteins, and transport of Ca²⁺. During cellular stress, ER dysfunction leads to the activation of unfolded protein response (UPR) due to accumulated misfolded proteins in the ER. This condition is referred as ER stress. Mitochondria and ER form a site of close contact (the mitochondria-associated membrane, MAM) which is a major platform exerting important physiological roles in the regulation of intracellular Ca²⁺ homeostasis, lipid metabolism, mitochondrial fission, autophagosome formation, and apoptosis progression. Natural products have been receiving increasing attention for their ability to interfere with ER stress. Research works have focused on the capacity of these bioactive compounds to induce apoptosis by activating ER stress through the ER stress-mediated mitochondrial apoptotic pathway. In this review we discuss the role of natural products in the signaling communication between ER and mitochondria, focusing on the effects induced by ER stress including Ca²⁺ permeability transition and UPR signaling (protein kinase R-like ER kinase/mitofusin 2).

Classification, hepatotoxic mechanisms, and targets of the risk ingredients in traditional Chinese medicine-induced liver injury

Traditional Chinese medicine (TCM) has become a crucial cause of drug-induced liver injury (DILI). Differ from chemical medicines, TCM feature more complex and mostly indefinite components. This review aimed to clarify the classification, underlying mechanisms and targets of the risk components in TCM-induced liver injury to further guide the secure application of TCM. Relevant studies or articles published on the PubMed database from January 2008 to December 2019 were searched. Based on the different chemical structures of the risk ingredients in TCM, they are divided into alkaloids, glycosides, toxic proteins, terpenoids and lactones, anthraquinones, and heavy metals. According to whether drug metabolism is activated or hepatocytes are directly attacked during TCM-induced liver injury, the high-risk substances can be classified into metabolic activation, non-metabolic activation, and mixed types. Mechanisms of the hepatotoxic ingredients in TCM-induced hepatotoxicity, including cytochrome P450 (CYP450) induction, mitochondrial dysfunction, oxidative damage, apoptosis, and idiosyncratic reaction, were also summarized. The targets involved in the risk ingredient-induced hepatocellular injury mainly include metabolic enzymes, nuclear receptors, transporters, and signaling pathways. Our periodic review and summary on the risk signals of TCM-induced liver injury must be beneficial to the integrated analysis on the multi-component, multi-target, and multi-effect characteristics of TCM-induced hepatotoxicity.

Tauroursodeoxycholic acid mediates endoplasmic reticulum stress and autophagy in adrenocortical carcinoma cells

Adrenocortical carcinoma (ACC) is an invasive tumor that occurs in the endocrine system. Increasing evidence has shown that endoplasmic reticulum (ER) stress and autophagy play an important role in tumor formation. Tauroursodeoxycholic acid (TUDCA) is an ER chemical chaperone that can alleviate ER stress. In the present study, TUDCA promoted the proliferation, migration and invasion of ACC SW-13 and NCI-H295R cells. Reverse transcription-quantitative PCR and western blot analysis showed that the expression of glucose-regulated protein 78, a promoter of ER stress, was decreased. The expression levels of protein kinase R (PKR)-like ER kinase and activating transcription factor 6 were correspondingly decreased, and the downstream proteins, C/EBP homologous protein and JNK, were also decreased. The expression levels of the autophagy factor microtubule-associated protein light chain 3-II/I and the anti-apoptotic factor Bcl-2 increased following TUDCA treatment, while the expression of the pro-apoptotic factor Bax decreased. TUDCA alleviated ER stress in ACC SW-13 and NCI-H295R cells and induced autophagy, thereby inhibiting ACC cell apoptosis. ER stress- and autophagy-related signaling pathways are involved in the occurrence of ACC, which may provide potential therapeutic targets for ACC treatment.

Mitofusin-2 regulates inflammation-mediated mouse neuroblastoma N2a cells dysfunction and endoplasmic reticulum stress via the Yap-Hippo pathway

Endoplasmic reticulum (ER) stress is involved in inflammation-induced neurotoxicity. Mitofusin 2 (Mfn2), a member of the GTPase family of proteins, resides in the ER membrane and is known to regulate ER stress. However, the potential role and underlying mechanism of Mfn2 in inflammation-induced neuronal dysfunction is unknown. In our study, we explored the potential of Mfn2 to attenuate inflammation-mediated neuronal dysfunction by inhibiting ER stress. Our data show that Mfn2 overexpression significantly ameliorated tumor necrosis factor alpha (TNFα)-induced ER stress, as indicated by the downregulation of the ER stress proteins PERK, GRP78 and CHOP. Mfn2 overexpression also prevented the TNFα-mediated activation of caspase-3, caspase-12 and cleaved poly (ADP-ribose) polymerase (PARP). Cellular antioxidant dysfunction and reactive oxygen species overproduction were also improved by Mfn2 in the setting of TNFα in mouse neuroblastoma N2a cells in vitro. Similarly, disordered calcium homeostasis, indicated by disturbed levels of calcium-related proteins and calcium overloading, was corrected by Mfn2, as evidenced by the increased expression of store-operated calcium entry (SERCA), decreased levels of inositol trisphosphate receptor (IP3R), and normalized calcium content in TNFα-treated N2a cells. Mfn2 overexpression was found to elevate Yes-associated protein (Yap) expression; knockdown of Yap abolished the regulatory effects of Mfn2 on ER stress, oxidative stress, calcium balance, neural death and inflammatory injury. These results lead us to conclude that re-activation of the Mfn2-Yap signaling pathway alleviates TNFα-induced ER stress and dysfunction of mouse neuroblastoma N2a cells. Our findings provide a better understanding of the regulatory role of Mfn2-Yap-ER stress in neuroinflammation and indicate that the Mfn2-Yap axis may be a focus of research in terms of having therapeutic value for the treatment of neurodegenerative diseases.

New incompatible pair of TCM: Epimedii Folium combined with Psoraleae Fructus induces idiosyncratic hepatotoxicity under immunological stress conditions

Epimedii Folium (EF) combined with Psoraleae Fructus (PF) is a common modern preparation, but liver injury caused by Chinese patent medicine preparations containing EF and PF has been frequently reported in recent years. Zhuangguguanjiewan pills (ZGW), which contain EF and PF, could induce immune idiosyncratic liver injury according to clinical case reports and a nonhepatotoxic dose of lipopolysaccharide (LPS) model. This present study evaluated the liver injury induced by EF or PF alone or in combination and investigated the related mechanism by using the LPS model. Liver function indexes and pathological results showed that either EF or PF alone or in combination led to liver injury in normal rats; however, EF or PF alone could lead to liver injury in LPS-treated rats. Moreover, EF combined with PF could induce a greater degree of injury than that caused by EF or PF alone in LPS-treated rats. Furthermore, EF or PF alone or in combination enhanced the LPS-stimulated inflammatory cytokine production, implying that IL-1β, which is processed and released by activating the NLRP3 inflammasome, is a specific indicator of EF-induced immune idiosyncratic hepatotoxicity. Thus, EF may induce liver injury through enhancing the LPS-mediated proinflammatory cytokine production and activating the NLRP3 inflammasome. In addition, the metabolomics analysis results showed that PF affected more metabolites in glycerophospholipid and sphingolipid metabolic pathways compared with EF in LPS model, suggesting that PF increased the responsiveness of the liver to LPS or other inflammatory mediators via modulation of multiple metabolic pathways. Therefore, EF and PF combination indicates traditional Chinese medicine incompatibility, considering that it induces idiosyncratic hepatotoxicity under immunological stress conditions.