Activation of the unfolded protein response contributed to the selective cytotoxicity of oroxylin A in human hepatocellular carcinoma HepG2 cells

Inhibition of hepatocellular carcinoma cell proliferation through regulation of the Cell Cycle, AGE-RAGE, and Leptin signaling pathways by a compound formulation comprised of andrographolide, wogonin, and oroxylin A derived from Andrographis Paniculata(Burm.f.) Nees

ETHNOPHARMACOLOGICAL RELEVANCE

In 2020, liver cancer contributed to approximately 0.9 million new cases and 0.83 million deaths, making it the third leading cause of mortality worldwide. Andrographis paniculata (Burm.f.) Nees(APN), a traditional Chinese or ethnic medicine extensively utilized in Asia, has been historically employed for treating hepatitis and liver cancer. However, the precise molecular mechanism responsible for its therapeutic efficacy remains unclear.

AIM OF THE STUDY

To identify and replace the active components of APN on liver cancer, which is investigate the potential of a Multi-Component Chinese Medicine derived from Andrographis paniculata (Burm.f.) Nees(APN-MCCN) for the treatment of liver cancer.

MATERIALS AND METHODS

Firstly, the TCMSP database and two liver cancer disease databases were utilized to optimize the chemical constituents of APN and the disease-related targets of liver cancer. The network was constructed using Cytoscape to visualize the relationships between them. Subsequently, the optimal combination of components in APN-MCCN for the treatment of liver cancer was determined using the contribution index method. HPLC analysis was performed to measure the content of each component. Pathway enrichment and gene annotation were conducted using the ClueGo plugin. In vivo efficacy was evaluated by transplanting S180 and H22 tumor-bearing mouse models. In vitro efficacy was determined through MTT assay, morphological observations, flow cytometry analysis, and scratch tests. Western blotting was used to validate the protein expression. The transfection techniques were employed to knockdown the expressions of key protein in different pathway.

RESULTS

We obtained 24 effective compounds, with andrographolide contributing 20.78%, wogonin contributing 41.85%, and oroxylin A contributing 30.26% to the overall composition. Based on the predicted enrichment degree and correlation with liver cancer, we identified a total of 27 pathways, among which the Leptin signaling pathway, AGE-RAGE signaling pathway, and Cell Cycle signaling pathway were selected for further investigation. The content of andrographolide, oroxylin A, and wogonin in APN was found to be 0.104%, 0.0024%, and 0.0052%, respectively. In vivo experiments demonstrated that APN-MCCM significantly reduced tumor weight in S180 tumor-bearing mice and prolonged the survival time of H22 liver cancer-bearing mice. APN-MCCM exhibited inhibitory effects on the proliferation, apoptosis, and migration of liver cancer cells while arresting them in the G2/M phase. Furthermore, APN-MCCM down-regulated the protein expression of NCOA1, PTPN1, and GSK3B in the Leptin signaling pathway, NOS2 and NOS3 in the AGE-RAGE signaling pathway, CCNA2, CDK1, CDK2, and CDK7 in the Cell Cycle signaling pathway. Additionally, it upregulated the protein phosphorylation of p-P38 and p-JUN in the AGE-RAGE signaling pathway. Knockout experiments revealed that the inhibitory effect of APN-MCCM on liver cancer cell migration was prevented when the MAPK or NCOA1 genes were knocked out. Similarly, knocking out the CDK7 gene blocked the G2/M phase arrest induced by APN-MCCM in liver cancer cells.

CONCLUSIONS

APN-MCCM, consisting of andrographolide, wogonin, and oroxylin A, exhibits inhibitory effects on the cell proliferation of liver cancer cells by targeting the cell cycle pathway. Additionally, it suppresses the migration of liver cancer cells through the AGE-RAGE and Leptin signaling pathways.

Modulation of diverse oncogenic signaling pathways by oroxylin A: An important strategy for both cancer prevention and treatment

BACKGROUND

Regardless of major advances in diagnosis, prevention and treatment strategies, cancer is still a foreboding cause due to factors like chemoresistance, radioresistance, adverse side effects and cancer recurrence. Therefore, continuous development of unconventional approaches is a prerequisite to overcome foregoing glitches. Natural products have found their way into treatment of serious health conditions, including cancer since ancient times. The compound oroxylin A (OA) is one among those with enormous potential against different malignancies. It is a flavonoid obtained from the several plants such as Oroxylum indicum, Scutellaria baicalensis and S. lateriflora, Anchietea pyrifolia, and Aster himalaicus.

PURPOSE

The main purpose of this study is to comprehensively elucidate the anticancerous effects of OA against various malignancies and unravel their chemosensitization and radiosensitization potential. Pharmacokinetic and pharmacodynamic studies of OA have also been investigated.

METHOD

The literature on antineoplastic effects of OA was searched in PubMed and Scopus, including in vitro and in vivo studies and is summarized based on a systematic review protocol prepared according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The term "oroxylin A" was used in combination with "cancer" and all the title, abstracts and keywords appeared were considered.

RESULTS

In Scopus, a total of 157 articles appeared out of which 103 articles that did not meet the eligibility criteria were eliminated and 54 were critically evaluated. In PubMed, from the 85 results obtained, 26 articles were eliminated and 59 were included in the preparation of this review. Mounting number of studies have illustrated the anticancer effects of OA, and its mechanism of action.

CONCLUSION

OA is a promising natural flavonoid possessing wide range of pleiotropic properties and is a potential anticancer agent. It has a great potential in the treatment of multiple cancers including brain, breast, cervical, colon, esophageal, gall bladder, gastric, hematological, liver, lung, oral, ovarian, pancreatic and skin. However, lack of pharmacokinetic studies, toxicity assessments, and dose standardization studies and adverse effects limit the optimization of this compound as a therapeutic agent.

Oroxylin A ameliorates AKI-to-CKD transition through maintaining PPARα-BNIP3 signaling-mediated mitochondrial homeostasis

Background: Acute kidney injury (AKI) occurs in approximately 7–18% of all hospitalizations, but there are currently no effective drug therapy for preventing AKI or delaying its progression to chronic kidney disease (CKD). Recent studies have shown that Scutellaria baicalensis, a traditional Chinese herb, could attenuate cisplatin-induced AKI, although the mechanism remains elusive. Further, it is unknown whether its major active component, Oroxylin A (OA), can alleviate kidney injury.

Methods: The therapeutic effect of OA was evaluated by using ischemia-reperfusion (IR) and cisplatin mediated-AKI mice and HK-2 cells under hypoxia-reoxygenation (HR) conditions. HE staining, transmission electron microscopy, flow cytometry, immunofluorescence, qPCR, Western blot, PPARα inhibitor, BNIP3 siRNA and ChIP assay were used to explore the role and mechanism of OA in AKI.

Results: OA ameliorated tubular damage and dramatically decreased serum creatinine (Scr) and urea nitrogen (BUN), and the expressions of renal injury markers (Kim-1, Ngal) in AKI mice induced by both IR injury and cisplatin, as well as attenuating AKI-to-CKD transition. In vitro experiments showed that OA alleviated HR-induced mitochondrial homeostasis imbalance in renal tubular epithelial cells. Mechanistically, OA dose-dependently induced the expression of Bcl-2/adenovirus E1B 19-kDa interacting protein (BNIP3), while knockdown of BNIP3 expression reversed the protection of OA against HR-mediated mitochondrial injury. Network pharmacological analysis and experimental validation suggested that OA enhanced BNIP3 expression via upregulating the expression of peroxisome proliferator activated receptor alpha (PPARα), which induced the transcription of BNIP3 via directly binding to its promoter region. Both in vitro and in vivo experiments confirmed that the renoprotective effect of OA was dramatically reduced by GW6471, a PPARα antagonist.

Conclusion: Our findings revealed that OA ameliorates AKI-to-CKD transition by maintaining mitochondrial homeostasis through inducing PPARα-BNIP3 signaling pathway, indicating that OA may serve as a candidate therapeutic strategy for alleviating AKI and CKD.

Antidepressant-like activity of oroxylin A in mice models of depression: A behavioral and neurobiological characterization

Depression is a mood disorder which causes a huge economic burden to both families and societies. However, those monoamine-based antidepressants used in clinical practice have been found to have various limitations. Therefore, currently it is very necessary to explore novel antidepressant targets and medications. As a main active component extracted from Scutellariae radix, oroxylin A possesses many pharmacological functions such as anti-cancer, anti-inflammation and neuroprotection. Here, the present study aims to investigate whether oroxylin A possess antidepressant-like actions using the chronic unpredictable mild stress (CUMS) and chronic restraint stress (CRS) models of depression, forced swim test, tail suspension test, open field test, sucrose preference test, western blotting, immunofluorescence and viral-mediated gene interference. Our results revealed that treatment of oroxylin A fully prevented both the CUMS-induced and CRS-induced depressive-like behaviors in mice. Moreover, the protecting effects of oroxylin A against CUMS and CRS on mice behaviors were accompanied with a significant enhancement on the levels of brain-derived neurotrophic factor (BDNF), phosphorylated tyrosine kinase B (pTrkB), phosphorylated cAMP-response element binding protein (pCREB) and neurogenesis in the hippocampus. Furthermore, genetic knockdown of BDNF and TrkB in the hippocampus remarkably abolished the antidepressant-like efficacy of oroxylin A in both the CUMS and CRS models of depression, proving that the hippocampal BDNF-TrkB system participates in the antidepressant mechanism of oroxylin A. In summary, our findings are the first evidence showing that oroxylin A possesses potential of being an antidepressant candidate.

Novel CDK9 inhibitor oroxylin A promotes wild-type P53 stability and prevents hepatocellular carcinoma progression by disrupting both MDM2 and SIRT1 signaling

Hepatocellular carcinoma (HCC) is one of the most lethal tumours worldwide. However, the effects of first-line sorafenib treatment in advanced HCC fail to prolong patients' survival due to the highly heterogeneous characteristics of HCC etiology. Cyclin-dependent kinase 9 (CDK9) is an important target in the continuous development of cancer therapy. Here, we demonstrate that CDK9 is closely associated with the progression of HCC and can serve as an HCC therapeutic target by modulating the recovery of wild-type p53 (wt-p53) function. We prove that mouse double minute 2 homologue (MDM2) and Sirtuin 1 (SIRT1) are phosphorylated by CDK9 at Ser166 and Ser47, respectively. Inhibition of CDK9 not only reduces the MDM2-mediated ubiquitination and degradation of wt-p53 but also increases wt-p53 stability by suppressing deacetylase activity of SIRT1. Thus, inhibition of CDK9 promotes the wt-p53 stabilization and prevents HCC progression. However, excessive inhibition by high concentrations of specific CDK9 inhibitors counteracts the promotion of p53 stability and reduces their anti-HCC activity because of extreme general transcription repression. The effects of a novel CDK9 inhibitor named oroxylin A (OA) from Scutellaria baicalensis are explored, with the results indicating that OA shows moderate and controlled inhibition of CDK9 activity and expression, and stabilizes wt-p53 by inhibiting CDK9-regulated MDM2 and SIRT1 signaling. These outcomes indicate the high therapeutic potential of OA against HCC and its low toxicity in normal tissue. This study demonstrates a novel mechanism for the regulation of wt-p53 by CDK9 and indicates that OA is a potential candidate for HCC therapy.

Pharmacognostic Study on Elsholtzia ciliata (Thumb.) Hyl: Anatomy, Phytochemistry and Pharmacological Activities

Elsholtzia ciliata (Thunb.) Hyl, family Lamiaceae, is an important and popular anti-bacterial and anti-inflammatory Traditional Chinese Medicine (TCM). However, there are limited scientific studies on its anatomy and pharmacological activities. Moreover, the information of chemical constituents in relation to its non-volatile constituents are still missing. The current study aimed to evaluate the anatomic, pharmacological and phytochemical profile of Elsholtzia ciliata, providing means for the quality control of this herbal drug. The methodology designed for this study included the preparation of anatomic sections and their description, extraction, chromatography, structural elucidation of isolated compounds by NMR techniques and their quantification by HPLC using pharmacological assays (Formalin, hot plate, DPPH, antimicrobial-Gram positive, Gram Negative and fungus, and MTT assays) to confirm the activities described for this species. Results of the anatomic study are aligned with the pattern expected for plants belonging to the Lamiaceae family; Ursolic acid and Oroxylin were isolated from this plant species. The findings observed in this study indicate that Elsholtzia ciliata possess anti-inflammatory, antinociceptive, antioxidant, antimicrobial and anticancer activities. The chemical compounds isolated from its leaves and the anatomy profile of its parts provide the basis for further quality control for this plant.

Network Pharmacology-Based Study on the Mechanism of Scutellariae Radix for Hepatocellular Carcinoma Treatment

Hepatocellular carcinoma (HCC) is a malignant tumor without effective therapeutic drugs for most patients in advanced stages. Scutellariae Radix (SR) is a well-known anti-inflammatory and anticarcinogenic herbal medicine. However, the mechanism of SR against HCC remains to be clarified. In the present study, network pharmacology was utilized to characterize the mechanism of SR on HCC. The active components of SR and their targets were collected from the traditional Chinese medicine systems pharmacology database and the traditional Chinese medicine integrated database. HCC-related targets were acquired from the liver cancer databases OncoDB.HCC and Liverome. The gene ontology and the Kyoto Encyclopedia of Genes and Genomes pathway were analyzed using the Database for Annotation, Visualization, and Integrated Discovery. Component-component target and protein-protein interaction networks were set up. A total of 143 components of SR were identified, and 37 of them were considered as candidate active components. Fifty targets corresponding to 29 components of SR were mapped with targets of HCC. Functional enrichment analysis indicated that SR exerted an antihepatocarcinoma effect by regulating pathways in cancer, hepatitis B, viral carcinogenesis, and PI3K-Akt signaling. The holistic approach of network pharmacology can provide novel insights into the mechanistic study and therapeutic drug development of SR for HCC treatment.

Oroxylin A Exerts Its Antitumor Effects in Human Gallbladder Cancer via Inhibition of the PTEN/PI3K/AKT Signaling Pathway

Gallbladder carcinoma (GBC) is one of the most common carcinomas of the biliary tract and is associated with aggressive malignancy and poor prognosis. Current therapeutic strategies, including surgery, radiotherapy, and chemotherapy, are not sufficient for the treatment of GBC, and new therapeutic strategies are urgently needed. The antitumor effects of oroxylin A (OrA), a natural flavonoid extracted from the dried roots of medicinal plants such as Scutellariae species (Radix Scutellariae), have been widely reported in various cancers. In this study, we first evaluated the antitumor activity and the underlying mechanism of action of OrA on GBC cells in vitro. Our results revealed that OrA significantly attenuated the proliferation, migration, and invasion of GBC cells, simultaneously promoting their apoptosis. Suppression of the phosphate on and tension homology deleted chromosome ten (PTEN)/phosphatidylinositol-3 kinase (PI3K)/protein kinase B (AKT) signaling pathway was found to be the underlying mechanism involved in the antitumor activity of OrA. In addition, experiments using a tumor xenograft mouse model confirmed the antitumor effects of OrA in vivo. Taken together, our findings indicate that OrA could be a potential antitumor agent for the prospective treatment of GBC.

Capsaicin-induced TRIB3 upregulation promotes apoptosis in cancer cells

Background

Capsaicin (8-methyl-N-vanillyl-6-nonenamide) is one of the main pungent components of chili peppers and has been shown to exert various effects on numerous physiological processes. Recent studies have focused on the chemopreventive effects of capsaicin, which can combat growth in various human cancer cell systems. The tribbles-related protein 3 (TRIB3) is evolutionarily conserved from Drosophila to humans. In the latter, TRIB3 is a key determinant in numerous cellular processes, including apoptosis.

Purpose

The aim of this study was to examine the importance of TRIB3 in the antitumor efficacy of capsaicin in human cancer cells, and further assess potential mechanism(s) underlying the capsaicin-induced upregulation of TRIB3.

Methods

Human cancer cell lines were treated with capsaicin, then evaluated for levels of TRIB3 and molecules related to apoptosis or signaling pathways. The impact of TRIB3 on capsaicin-induced apoptosis was investigated using si-RNA or overexpression of TRIB3.

Results

It is the first time to show that TRIB3 is targeted by capsaicin to promote apoptosis. Capsaicin promotes apoptotic cell death by upregulating TRIB3 expression in cancer cells. Overexpression of TRIB3 enhances capsaicin-induced apoptosis, and TRIB3 knockdown experiments demonstrate that the effect of capsaicin in apoptotic cell death is correlated with the induction of TRIB3 in cancer cells. Finally, enhancements in gene expression and protein stability are involved in the capsaicin-induced upregulation of TRIB3.

Conclusion

Our results show that the capsaicin-induced upregulation of TRIB3 triggers apoptosis and thereby contributes to the suppression of cell growth in cancer cell lines.

The Potential and Action Mechanism of Polyphenols in the Treatment of Liver Diseases

Liver disease, involving a wide range of liver pathologies from fatty liver, hepatitis, and fibrosis to cirrhosis and hepatocellular carcinoma, is a serious health problem worldwide. In recent years, many natural foods and herbs with abundant phytochemicals have been proposed as health supplementation for patients with hepatic disorders. As an important category of phytochemicals, natural polyphenols have attracted increasing attention as potential agents for the prevention and treatment of liver diseases. The striking capacities in remitting oxidative stress, lipid metabolism, insulin resistance, and inflammation put polyphenols in the spotlight for the therapies of liver diseases. It has been reported that many polyphenols from a wide range of foods and herbs exert therapeutic effects on liver injuries via complicated mechanisms. Therefore, it is necessary to have a systematical review to sort out current researches to help better understand the potentials of polyphenols in liver diseases. In this review, we aim to summarize and update the existing evidence of natural polyphenols in the treatment of various liver diseases by in vitro, in vivo, and clinical studies, while special attention is paid to the action mechanisms.

Oroxylin A activates PKM1/HNF4 alpha to induce hepatoma differentiation and block cancer progression

Liver cancer is the second cause of death from cancer worldwide, without effective treatment. Traditional chemotherapy for liver cancer has big side effects for patients, whereas targeted drugs, such as sorafenib, commonly have drug resistance. Oroxylin A (OA) is the main bioactive flavonoids of Scutellariae radix, which has strong anti-hepatoma effect but low toxicity to normal tissue. To date, no differentiation-inducing agents have been reported to exert a curative effect on solid tumors. Here our results demonstrated that OA restrained the proliferation and induced differentiation of hepatoma both in vitro and in vivo, via inducing a high PKM1 (pyruvate kinase M1)/PKM2 (pyruvate kinase M2) ratio. In addition, inhibited expression of polypyrimidine tract-binding protein by OA was in charge of the decrease of PKM2 and increase of PKM1. Further studies demonstrated that increased PKM1 translocated into the nucleus and bound with HNF-4α (hepatocyte nuclear factor 4 alpha) directly, promoting the transcription of HNF-4α-targeted genes. This work suggested that OA increased PKM1/PKM2 ratio, resulting in HNF-4α activation and hepatoma differentiation. Especially, OA showed reliable anticancer effect on both human primary hepatocellular carcinoma cells and patient-derived tumor xenograft model for hepatoma, and slowed down the development of primary hepatoma, suggesting that OA could be developed into a novel differentiation inducer agent for hepatoma.

Oroxylin A suppresses the development and growth of colorectal cancer through reprogram of HIF1α-modulated fatty acid metabolism

The occurrence and progress of colon cancer are closely associated with obesity. Therefore, the lipid metabolism, especially fatty acid metabolism, is a significant section of energy homeostasis in colon cancer cells, and it affects many important cellular processes. Oroxylin A is one of the main bioactive flavonoids of Scutellariae radix, which has a strong anticancer effect but low toxicity to normal tissue. In previous studies, we have proved that oroxylin A reprogrammes metabolism of cancer cells by inhibiting glycolysis. Here, we further investigated the metabolism-modulating effects of oroxylin A on the fatty acid metabolism in colon cancer cells under hypoxia. We found that HIF1α upregulated adipophilin, fatty acid synthase and sterol regulatory element-binding protein 1, and downregulated carnitine palmitoyltransferase 1 (CPT1), resulting in the promoted lipid uptake and transport, increased de novo fatty acid synthesis and suppressed fatty acid oxidation. Oroxylin A inactivated HIF1α and reprogrammed fatty acid metabolism of HCT116 cells, decreasing intracellular fatty acid level and enhancing fatty acid oxidation. Furthermore, the rapid decrease of fatty acid level caused by oroxylin A inhibited the nuclear translocation of β-cantenin and inactivated the Wnt pathway, arousing cell cycle arrest in G2/M phase. In vivo studies demonstrated that high-fat diet increased the incidence of colon cancer and accelerated tumor development. Importantly, besides the growth inhibitory effects on colon cancer xenograft, oroxylin A prevented carcinogenesis and delayed progress of primary colon cancer as well. Our studies enriched the metabolic regulatory mechanism of oroxylin A, and suggested that oroxylin A was a potent candidate for the treatment and prevention of colorectal cancer.

Hyperthermia enhances 17-DMAG efficacy in hepatocellular carcinoma cells with aggravated DNA damage and impaired G2/M transition

Due to the lack of effective treatment, hepatocellular carcinoma (HCC) is one of the malignancies with low survival rates worldwide. Combination of hyperthermia and chemotherapy has shown promising results in several abdominal tumours, but high expression of HSP90 in tumours attenuated the efficacy of hyperthermia. Thus a combination of hyperthermia and inhibition of HSP90 might be a feasible therapeutic strategy for HCC. One hepatic cell line (L02) and two HCC cell lines (Huh7 and HepG2) were heated at 42 °C for 0, 0.5 or 4 h with or without 100 nM 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG). HCC cells of the combination group exhibited more G2/M arrest and higher apoptotic rates which might result from suffering from more reactive oxygen species and serious DNA damage. Heat shock/17-DMAG co-treatment of HCC cells also destabilized CDK1, Cyclin B1 and CDC25C with a concomitant decreased proportion of cells in the M phase. Furthermore, co-treatment impaired the interaction of HSP90α with CDC37 and with CDK1, accompanied with decreased soluble CDK1. Combination of 17-DMAG with a 1.5-h whole body hyperthermia treatment attenuated tumour growth in xenograft mice models. These results suggest hyperthermia sensitize HCC to 17-DMAG, and combination of hyperthermia with 17-DMAG might be a potential therapeutic strategy for HCC.

Overview of Oroxylin A: A Promising Flavonoid Compound

Oroxylin A is one of the main active components extracted from Scutellariae radix. It has been proved that oroxylin A possesses a broad spectrum of pharmacological functions, including anti-cancer, antiinflammation, neuroprotective, anti-coagulation and so on. The pharmacological activity of oroxylin A has been studied in vitro and on animal models, which reflected its promising potency in disease treatment. This review aims to recapitulate the pharmacological function and the molecular mechanisms of oroxylin A, as well as its sources, extraction, synthesis and toxicity study. These data confirmed the therapeutic potential of oroxylin A and provided reference for further development. Copyright © 2016 John Wiley & Sons, Ltd.

Antiviral Activity of Oroxylin A against Coxsackievirus B3 Alleviates Virus-Induced Acute Pancreatic Damage in Mice

The flavonoids mosloflavone, oroxylin A, and norwogonin, which were purified from Scutellaria baicalensis Georgi, significantly protected Vero cells against Coxsackievirus B3 (CVB3)-induced cell death. To investigate the in vivo antiviral activity of oroxylin A, we intraperitoneally inoculated CVB3 into 4-week-old BALB/c mice. Body weights and blood glucose levels of the mice were decreased after CVB3 infection, and these changes were attenuated by the administration of oroxylin A. Importantly, treatment of mice with oroxylin A reduced viral titers in the pancreas and decreased the serum levels of the inflammatory cytokines including interleukin-6 (IL-6) and tumor necrosis factor (TNF)-α. Additionally, the administration of oroxylin A mitigated the histological pancreatic lesions and apoptotic cell death induced by CVB3 infection and increased the levels of phospho-eIF2α in infected pancreata. The results suggest that oroxylin A may represent a potent antiviral agent against CVB3 infection.

Novel Investigations of Flavonoids as Chemopreventive Agents for Hepatocellular Carcinoma

We would like to highlight the application of natural products to hepatocellular carcinoma (HCC). We will focus on the natural products known as flavonoids, which target this disease at different stages of hepatocarcinogenesis. In spite of the use of chemotherapy and radiotherapy in treating HCC, patients with HCC still face poor prognosis because of the nature of multidrug resistance and toxicity derived from chemotherapy and radiotherapy. Flavonoids can be found in many vegetables, fruits, and herbal medicines that exert their different anticancer effects via different intracellular signaling pathways and serve as antioxidants. In this review, we will discuss seven common flavonoids that exert different biological effects against HCC via different pathways.

Oroxylin A inhibits glycolysis-dependent proliferation of human breast cancer via promoting SIRT3-mediated SOD2 transcription and HIF1α destabilization

Alterations of cellular metabolism play a central role in the development and progression of cancer. Oroxylin A, an active flavonoid of a Chinese traditional medicinal plant, was previously shown to modulate glycolysis in cancer cells. However, the mechanism by which oroxylin A regulates glycolysis is still not well defined. Here, we show that oroxylin A inhibits glycolysis in breast cancer cells via the Sirtuin 3 (SIRT3)-mediated destabilization of hypoxia-inducible factor 1α (HIF1α), which controls glycolytic gene expression. Oroxylin A promotes superoxide dismutase (SOD2) gene expression through SIRT3-regulated DNA-binding activity of FOXO3a and increases the activity of SOD2 by promoting SIRT3-mediated deacetylation. In vivo, oroxylin A inhibits the growth of transplanted human breast tumors associated with glycolytic suppression. These data indicate that oroxylin A inhibits glycolysis-dependent proliferation of breast cancer cells, through the suppression of HIF1α stabilization via SIRT3 activation, providing preclinical information for the cancer therapies of SIRT3 stimulation.

ER stress and ER stress-mediated apoptosis are involved in manganese-induced neurotoxicity in the rat striatum in vivo

Manganese (Mn) is an essential trace element found in many enzymes, however, excessive Mn-exposure can result in manganism which is similar to Parkinson's movement disorder. The mechanisms of manganism are not well-known. The present in vivo study was carried out to determine whether endoplasmic reticulum stress (ER stress) and ER stress-mediated apoptosis are involved in manganese-induced neurotoxicity. Sixty-four SD rats were randomly divided into four groups and were administered intraperitoneally with normal saline (NS, as control) or MnCl₂ (7.5, 15 and 30 mg/kg body weight, respectively) for 4 weeks. We found that MnCl₂ dose-dependently accumulate in striatal. HE staining and TUNEL assay results indicated that MnCl₂ induced striatal neurocytes apoptosis in both male and female rats. The alterations of ultrastructures showed that MnCl₂ resulted in chromatin condensation, mitochondria and ER tumefaction in rat striatal neurocytes. Furthermore, MnCl₂ increased the expressions of p-IRE-1, ATF-6α, PERK, GRP78, Sigma-1R, CHOP, Bim, Bax, caspase-12 and caspase-3, and decreased the expression of Bcl-2 in rat striatal neurocytes. In conclusion, MnCl₂ could induce ER stress and ER stress-mediated apoptosis in rat striatal neurocytes, which might be one of the important mechanisms of Mn-induced neurotoxicity.

Oroxylin A inhibits ATRA-induced IL-6 expression involved in retinoic acid syndrome by down-regulating CHOP

Production of IL-6 constituted the major cause of death in the ATRA trial called retinoic acid syndrome (RAS). LAP and LIP are active and inactive isoforms of C/EBPβ, respectively. Inactive LIP dimerized with LAP to eliminate its activity. Following treatment with ATRA, CHOP expression was increased and dimerized with LIP more preferentially than LAP to rescue function of LAP. Oroxylin A has been reported to activate CHOP, a key mediator of unfolded protein response (UPR) pathway, and resulted in apoptosis. Interestingly, we found that low concentration of oroxylin A (≦ 40 μM) showed no apoptosis effect on NB4 and HL-60 cells and decreased the CHOP protein level via promoting its degradation. MG132 was utilized to conform the effect of oroxylin A on degrading CHOP. Our results showed that oroxylin A decreased the level of IL-6 secretion of NB4 cells with or without ATRA treatment while the effect was eliminated by C/EBPβ siRNA. We conclude that oroxylin A possessed abilities of inhibiting the ATRA-induced IL-6 production via modulation of LAP/LIP/CHOP in leukemia cell lines, which could providing a therapeutic strategy for RAS.

The unfolded protein response in fatty liver disease

The unfolded protein response (UPR) is a protective cellular response activated under conditions of endoplasmic reticulum (ER) stress. The hepatic UPR is activated in several forms of liver disease including nonalcoholic fatty liver disease (NAFLD). Recent data defining the role of the UPR in hepatic lipid metabolism have identified molecular mechanisms that may underlie the association between UPR activation and NAFLD. It has become increasingly evident that the IRE1α/Xbp1 pathway of the UPR is critical for hepatic lipid homeostasis, and dysregulation of this evolutionarily conserved pathway is associated with human nonalcoholic steatohepatitis (NASH). Although increasing evidence has delineated the importance of UPR pathway signaling in fatty liver disorders, the regulation of the hepatic UPR in normal physiology and fatty liver disorders remains incompletely understood. Understanding the role of the UPR in hepatic lipid metabolism may lead to the identification of novel therapeutic targets for the treatment of NAFLD.

Wogonin induced cytotoxicity in human hepatocellular carcinoma cells by activation of unfolded protein response and inactivation of AKT

AIM

To investigate the potential anticancer effects of the natural flavonoid wogonin on human hepatocellular carcinoma (HCC) cells and tumor xenografts and the contribution of the unfolded protein response (UPR) and AKT pathways to the cytotoxicity of wogonin.

METHODS

The HCC cell lines HepG2, SMMC-7721 and Hep3B were treated with wogonin. 3-(4 5-Dimethylthiazol-2-yl)-2 5-diphenyltetrazolium bromide assays were used to evaluate the cell viability. Flow cytometry assays were used to identify the cell death types and measure the concentrations of intracellular H2 O2 and Ca(2+) . Western blotting assays were used to detect the protein expression levels of members in the UPR and AKT pathways. Relative quantitative real-time polymerase chain reaction assays were used to analysis the mRNA expression levels of chop and trb3. Furthermore, the male BALB/c nude mice with SMMC-7721 xenografts were treated with wogonin. The tumor volume, tumor weight and bodyweight were monitored during the tumorigenicity assays.

RESULTS

Wogonin significantly inhibited the viability of HCC cells by inducing apoptosis and necrosis. This cytotoxicity was at least partially attributed to the activation of the UPR pathway and consequent inactivation of AKT signaling, which resulted from the production of intracellular H2 O2 and causal release of endoplasmic reticulum Ca(2+) . Moreover, wogonin evidently repressed the growth of xenografts but slightly influenced the bodyweight of mice.

CONCLUSION

Wogonin is a prospect for improving the systemic chemotherapy strategy on HCC by concurrently rectifying the aberrant UPR and AKT signaling pathways, which are crucial to the biology of HCC.

V8, a newly synthetic flavonoid, induces apoptosis through ROS-mediated ER stress pathway in hepatocellular carcinoma

Natural flavonoids from plants have been demonstrated to possess promising chemopreventive activities against various diseases. 7-{4-[Bis-(2-hydroxy-ethyl)-amino]-butoxy}-5-hydroxy-8-methoxy-2-phenyl-chromen-4-one (V8), a newly synthesized derivative of wogonin may have antioxidant, antiviral, anti-inflammatory and anti-tumor potentials as wogonin. Based on the recent findings of V8, the anti-tumor activities and fundamental mechanisms by which V8 inhibits growth of hepatocellular carcinoma were further investigated in this study. After the treatment of V8, a significant inhibition of HepG2 cell proliferation was observed in a dose-dependent manner with the IC50 value of 23 μM using MTT assay. The exposure to V8 also resulted in apoptosis induction and an accumulation of ROS and Ca(2+). Meanwhile, a release of cytochrome c (Cyt-c), activation of BH-3 only proteins and Bax, decrease in mitochondrial membrane potential ΔΨ, as well as a suppression of Bcl-2, pro-caspase9 and pro-caspase3 expression were shown. Moreover, knocking down CHOP partly decreased the effect of V8-mediated apoptosis and activation of GRP78, p-PERK, p-eIF2α, ATF4 and CHOP modulated ER stress triggered by V8. In vivo, V8 inhibited the transplanted mice H22 liver carcinomas in a dose-dependent manner. Compared with wogonin, V8 exhibited stronger anti-proliferative effects both in vitro and in vivo. The underlying mechanism of activating PERK-eIF2α-ATF4 pathway by which V8 induces apoptosis was verified once again in vivo. The apoptosis induction via the mitochondrial pathway by modulating the ROS-mediated ER signaling pathway might serve to provide support for further studies of V8 as a possible anticancer drug in the clinical treatment of cancer.