Quercetin prevents liver carcinogenesis by inducing cell cycle arrest, decreasing cell proliferation and enhancing apoptosis

Flavonoids target different molecules of autophagic and metastatic pathways in cancer cells

Despite the success of cancer therapy, it has encountered a major obstacle due to the complicated nature of cancer, namely resistance. The recurrence and metastasis of cancer occur when anti-cancer therapeutic agents fail to eradicate all cancer cells. Cancer therapy aims to find the best agent that targets all cancer cells, including those sensitive or resistant to treatment. Flavonoids, natural products from our diet, show anti-cancer effects in different studies. They can inhibit metastasis and the recurrence of cancers. This review discusses metastasis, autophagy, anoikis in cancer cells, and their dynamic relationship. We present evidence that flavonoids can block metastasis and induce cell death in cancer cells. Our research suggests that flavonoids can serve as potential therapeutic agents in cancer therapy.

Biochemical Profile and In Vitro Therapeutic Properties of Two Euhalophytes, Halocnemum strobilaceum Pall. and Suaeda fruticosa (L.) Forske., Grown in the Sabkha Ecosystem in the Algerian Sahara

This study reports the biochemical profile and in vitro biological activities of the aerial part of two shrubs: Halocnemum strobilaceum and Suaeda fruticosa, a halophytes species native to saline habitats. The biomass was evaluated by determining its physiological properties and approximate composition. Hydro-methanolic extracts from Halocnemum strobilaceum and Suaeda fruticosa have been investigated for the inhibition of bacterial growth, the protection of proteins (albumin) from denaturation, and cytotoxicity to hepatocellular carcinomas (Huh-7 and HepG2). Their antioxidant activity was evaluated by five tests, including one that examined their ability to inhibit hydrogen peroxide (H₂O₂)-induced hemolysis. The profile of their phenolic compounds was also determined. These two euhalophytes had a high moisture content, high levels of photosynthetic pigments, elevated levels of ash and protein, low oxidative damage indices, MDA (Malondialdehyde) and proline, and low lipids levels. Their content was also characterized by a moderate acidity with good electrical conductivity. They contained abundant levels of phytochemicals and varied phenolic contents. Reverse phase high performance liquid chromatography (RP-HPLC) analysis revealed the presence of caffeic acid, p-coumaric acid, rutin, and quercetin in both plant extracts. On the pharmaceutical level, the two euhalophytes had anti-inflammatory, antibacterial, antioxidant, and cytotoxic properties, and therefore it was recommended to isolate and identify biologically active compounds from these plants and evaluate them in vivo.

Apoptotic Mechanisms of Quercetin in Liver Cancer: Recent Trends and Advancements

Due to rising incidence rates of liver cancer and worries about the toxicity of current chemotherapeutic medicines, the hunt for further alternative methods to treat this malignancy has escalated. Compared to chemotherapy, quercetin, a flavonoid, is relatively less harmful to normal cells and is regarded as an excellent free-radical scavenger. Apoptotic cell death of cancer cells caused by quercetin has been demonstrated by many prior studies. It is present in many fruits, vegetables, and herbs. Quercetin targets apoptosis, by upregulating Bax, caspase-3, and p21 while downregulating Akt, PLK-1, cyclin-B1, cyclin-A, CDC-2, CDK-2, and Bcl-2. Additionally, it has been reported to increase STAT3 protein degradation in liver cancer cells while decreasing STAT3 activation. Quercetin has a potential future in chemoprevention, based on substantial research on its anticancer effects. The current review discusses quercetin's mechanisms of action, nanodelivery strategies, and other potential cellular effects in liver cancer.

The critical role of the Hippo signaling pathway in kidney diseases

The Hippo signaling pathway is involved in cell growth, proliferation, and apoptosis, and it plays a key role in regulating organ size, tissue regeneration, and tumor development. The Hippo signaling pathway also participates in the occurrence and development of various human diseases. Recently, many studies have shown that the Hippo pathway is closely related to renal diseases, including renal cancer, cystic kidney disease, diabetic nephropathy, and renal fibrosis, and it promotes the transformation of acute kidney disease to chronic kidney disease (CKD). The present paper summarizes and analyzes the research status of the Hippo signaling pathway in different kidney diseases, and it also summarizes the expression of Hippo signaling pathway components in pathological tissues of kidney diseases. In addition, the present paper discusses the positive therapeutic significance of traditional Chinese medicine (TCM) in regulating the Hippo signaling pathway for treating kidney diseases. This article introduces new targets and ideas for drug development, clinical diagnosis, and treatment of kidney diseases.

Effects of Sorafenib and Quercetin Alone or in Combination in Treating Hepatocellular Carcinoma: In Vitro and In Vivo Approaches

Sorafenib is the first drug approved to treat advanced hepatocellular carcinoma (HCC) and continues as the gold-standard therapy against HCC. However, acquired drug resistance represents a main concern about sorafenib therapy. The flavanol quercetin found in plants has shown great anti-cancer and anti-inflammatory properties. In this work, quercetin was used as a therapeutic agent alone or in combination with a sorafenib chemotherapy drug to improve the routine HCC treatment with sorafenib. The in vitro and in vivo results presented here confirm that quercetin alone or in combination with sorafenib significantly inhibited HCC growth, induced cell cycle arrest and induced apoptosis and necrosis. Further molecular data shown in this report demonstrate that quercetin alone or combined with sorafenib downregulated key inflammatory, proliferative and angiogenesis-related genes (TNF-α, VEGF, P53 and NF-κB). Combined quercetin/sorafenib treatment markedly improved the morphology of the induced liver damage and showed significant antioxidant and anti-tumor effects. The advantage of combined treatment efficacy reported here can be attributed to quercetin's prominent effects in modulating cell cycle arrest, apoptosis, oxidative stress and inflammation.

A Comprehensive Analysis and Anti-Cancer Activities of Quercetin in ROS-Mediated Cancer and Cancer Stem Cells

Reactive oxygen species (ROS) induce carcinogenesis by causing genetic mutations, activating oncogenes, and increasing oxidative stress, all of which affect cell proliferation, survival, and apoptosis. When compared to normal cells, cancer cells have higher levels of ROS, and they are responsible for the maintenance of the cancer phenotype; this unique feature in cancer cells may, therefore, be exploited for targeted therapy. Quercetin (QC), a plant-derived bioflavonoid, is known for its ROS scavenging properties and was recently discovered to have various antitumor properties in a variety of solid tumors. Adaptive stress responses may be induced by persistent ROS stress, allowing cancer cells to survive with high levels of ROS while maintaining cellular viability. However, large amounts of ROS make cancer cells extremely susceptible to quercetin, one of the most available dietary flavonoids. Because of the molecular and metabolic distinctions between malignant and normal cells, targeting ROS metabolism might help overcome medication resistance and achieve therapeutic selectivity while having little or no effect on normal cells. The powerful bioactivity and modulatory role of quercetin has prompted extensive research into the chemical, which has identified a number of pathways that potentially work together to prevent cancer, alongside, QC has a great number of evidences to use as a therapeutic agent in cancer stem cells. This current study has broadly demonstrated the function-mechanistic relationship of quercetin and how it regulates ROS generation to kill cancer and cancer stem cells. Here, we have revealed the regulation and production of ROS in normal cells and cancer cells with a certain signaling mechanism. We demonstrated the specific molecular mechanisms of quercetin including MAPK/ERK1/2, p53, JAK/STAT and TRAIL, AMPKα1/ASK1/p38, RAGE/PI3K/AKT/mTOR axis, HMGB1 and NF-κB, Nrf2-induced signaling pathways and certain cell cycle arrest in cancer cell death, and how they regulate the specific cancer signaling pathways as long-searched cancer therapeutics.

Sulfonated, oxidized pectin-based double crosslinked bioprosthetic valve leaflets for synergistically enhancing hemocompatibility and cytocompatibility and reducing calcification

Clinically frequently-used glutaraldehyde (GA)-crosslinked bioprosthetic valve leaflets (BVLs) are still curbed by acute thrombosis, malignant immunoreaction, calcification, and poor durability. In this study, an anticoagulant heparin-like biomacromolecule, sulfonated, oxidized pectin (SAP) with a dialdehyde structure was first obtained by modifying citrus pectin with sulfonation of 3-amino-1-propane sulfonic acid and then oxidating with periodate. Notably, a novel crosslinking approach was established by doubly crosslinking BVLs with SAP and the nature-derived crosslinking agent quercetin (Que), which play a synergistic role in both crosslinking and bioactivity. The double crosslinked BVLs also presented enhanced mechanical properties and enzymatic degradation resistance owing to the double crosslinking networks formed via CN bonds and hydrogen bonds, respectively, and good HUVEC-cytocompatibility. The in vitro and ex vivo assay manifested that the double-crosslinked BVLs had excellent anticoagulant and antithrombotic properties, owing to the introduction of SAP. The subcutaneous implantation also demonstrated that the obtained BVLs showed a reduced inflammatory response and great resistance to calcification, which is attributed to quercetin with multiple physiological activities and depletion of aldehyde groups by hydroxyl aldehyde reaction. With excellent stability, hemocompatibility, anti-inflammatory, anti-calcification, and pro-endothelialization properties, the obtained double-crosslinked BVLs, SAP + Que-PP, would have great potential to substitute the current clinical GA-crosslinked BVLs.

Impact of Phytochemicals on PPAR Receptors: Implications for Disease Treatments

Peroxisome proliferator-activated receptors (PPARs) are members of the ligand-dependent nuclear receptor family. PPARs have attracted wide attention as pharmacologic mediators to manage multiple diseases and their underlying signaling targets. They mediate a broad range of specific biological activities and multiple organ toxicity, including cellular differentiation, metabolic syndrome, cancer, atherosclerosis, neurodegeneration, cardiovascular diseases, and inflammation related to their up/downstream signaling pathways. Consequently, several types of selective PPAR ligands, such as fibrates and thiazolidinediones (TZDs), have been approved as their pharmacological agonists. Despite these advances, the use of PPAR agonists is known to cause adverse effects in various systems. Conversely, some naturally occurring PPAR agonists, including polyunsaturated fatty acids and natural endogenous PPAR agonists curcumin and resveratrol, have been introduced as safe agonists as a result of their clinical evidence or preclinical experiments. This review focuses on research on plant-derived active ingredients (natural phytochemicals) as potential safe and promising PPAR agonists. Moreover, it provides a comprehensive review and critique of the role of phytochemicals in PPARs-related diseases and provides an understanding of phytochemical-mediated PPAR-dependent and -independent cascades. The findings of this research will help to define the functions of phytochemicals as potent PPAR pharmacological agonists in underlying disease mechanisms and their related complications.

Peroxisome Proliferator-Activated Receptors and the Hallmarks of Cancer

Peroxisome proliferator-activated receptors (PPARs) function as nuclear transcription factors upon the binding of physiological or pharmacological ligands and heterodimerization with retinoic X receptors. Physiological ligands include fatty acids and fatty-acid-derived compounds with low specificity for the different PPAR subtypes (alpha, beta/delta, and gamma). For each of the PPAR subtypes, specific pharmacological agonists and antagonists, as well as pan-agonists, are available. In agreement with their natural ligands, PPARs are mainly focused on as targets for the treatment of metabolic syndrome and its associated complications. Nevertheless, many publications are available that implicate PPARs in malignancies. In several instances, they are controversial for very similar models. Thus, to better predict the potential use of PPAR modulators for personalized medicine in therapies against malignancies, it seems necessary and timely to review the three PPARs in relation to the didactic concept of cancer hallmark capabilities. We previously described the functions of PPAR beta/delta with respect to the cancer hallmarks and reviewed the implications of all PPARs in angiogenesis. Thus, the current review updates our knowledge on PPAR beta and the hallmarks of cancer and extends the concept to PPAR alpha and PPAR gamma.

Peroxisome proliferator-activated receptor gamma as a therapeutic target for hepatocellular carcinoma: Experimental and clinical scenarios

Hepatocellular carcinoma (HCC) is the most common type of liver cancer worldwide. Viral hepatitis is a significant risk factor for HCC, although metabolic syndrome and diabetes are more frequently associated with the HCC. With increasing prevalence, there is expected to be > 1 million cases annually by 2025. Therefore, there is an urgent need to establish potential therapeutic targets to cure this disease. Peroxisome-proliferator-activated receptor gamma (PPARγ) is a ligand-activated transcription factor that plays a crucial role in the patho-physiology of HCC. Many synthetic agonists of PPARγ suppress HCC in experimental studies and clinical trials. These synthetic agonists have shown promising results by inducing cell cycle arrest and apoptosis in HCC cells and preventing the invasion and metastasis of HCC. However, some synthetic agonists also pose severe side effects in addition to their therapeutic efficacy. Thus natural PPARγ agonists can be an alternative to exploit this potential target for HCC treatment. In this review, the regulatory role of PPARγ in the pathogenesis of HCC is elucidated. Furthermore, the experimental and clinical scenario of both synthetic and natural PPARγ agonists against HCC is discussed. Most of the available literature advocates PPARγ as a potential therapeutic target for the treatment of HCC.

Quercetin as a JAK-STAT inhibitor: a potential role in solid tumors and neurodegenerative diseases

The Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway is involved in many immunological processes, including cell growth, proliferation, differentiation, apoptosis, and inflammatory responses. Some of these processes can contribute to cancer progression and neurodegeneration. Owing to the complexity of this pathway and its potential crosstalk with alternative pathways, monotherapy as targeted therapy has usually limited long-term efficacy. Currently, the majority of JAK-STAT-targeting drugs are still at preclinical stages. Meanwhile, a variety of plant polyphenols, especially quercetin, exert their inhibitory effects on the JAK-STAT pathway through known and unknown mechanisms. Quercetin has shown prominent inhibitory effects on the JAK-STAT pathway in terms of anti-inflammatory and antitumor activity, as well as control of neurodegenerative diseases. This review discusses the pharmacological effects of quercetin on the JAK-STAT signaling pathway in solid tumors and neurodegenerative diseases.

Selenium nanoparticles and quercetin suppress thioacetamide-induced hepatocellular carcinoma in rats: Attenuation of inflammation involvement

The current study investigates the anti-inflammatory and hepatoprotective effects of selenium (Se) formulated as nanoparticles (SeNPs) and in combination with quercetin (QCT) against thioacetamide (TAA)-induced hepatocellular carcinoma (HCC) in rats. ​​​​​​Seventy-two male Sprague-Dawley rats were divided into six groups (n = 12). Three control groups; normal, SeNPs; group received SeNPs only and HCC; group received TAA. In addition, three preventive groups; SeNPs + TAA, QCT + TAA, and QCT + SeNPs + TAA. Induction of HCC was detected histopathologically and by the raise of the serum level of alpha-fetoprotein (AFP). Oxidative stress was evaluated by the hepatic levels of reduced glutathione (GSH), glutathione peroxidase (GPx), and malondialdehyde (MDA) spectrophotometrically. The oncogenic pathway of p53/β-catenin/cyclin D1 was assessed by immunohistochemistry. The inflammatory markers; interleukin-33 (IL-33), IL-6, and IL-1β were assessed by enzyme-linked immune sorbent assay. SeNPs prevented the elevation of serum AFP and hepatic IL-33, IL-1β, and IL-6 in comparison to HCC or QCT + TAA groups. SeNPs + TAA exhibited a lower positive hepatic staining of p53, β-catenin, and cyclin D1 in comparison to HCC or QCT + TAA groups. Moreover, SeNPs improved the overall oxidative balance indicated by low hepatic MDA and enhanced GSH and GPx when compared to HCC or QCT + TAA groups. ​​SeNPs alone and in combination with QCT were found to suppress the progression of HCC in rats via the enhancement of the oxidative stress and then inflammatory status and the prevention of the deregulation of the oncogenic axis pathway of p53/β-catenin/cyclin D.

Quercetin Regulates Key Components of the Cellular Microenvironment during Early Hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is a health problem worldwide due to its high mortality rate, and the tumor microenvironment (TME) plays a key role in the HCC progression. The current ineffective therapies to fight the disease still warrant the development of preventive strategies. Quercetin has been shown to have different antitumor activities; however, its effect on TME components in preneoplastic lesions has not been fully investigated yet. Here, we aimed to evaluate the effect of quercetin (10 mg/kg) on TME components during the early stages of HCC progression induced in the rat. Histopathological and immunohistochemical analyses showed that quercetin decreases the size of preneoplastic lesions, glycogen and collagen accumulation, the expression of cancer stem cells and myofibroblasts markers, and that of the transporter ATP binding cassette subfamily C member 3 (ABCC3), a marker of HCC progression and multi-drug resistance. Our results strongly suggest that quercetin has the capability to reduce key components of TME, as well as the expression of ABCC3. Thus, quercetin can be an alternative treatment for inhibiting the growth of early HCC tumors.

Medicinal plants used against hepatic disorders in Bangladesh: A comprehensive review

ETHNOPHARMACOLOGICAL RELEVANCE

Liver disease is a major cause of illness and death worldwide which accounts for approximately 2 million deaths per year worldwide, 1 million due to complications of cirrhosis and 1 million due to viral hepatitis and hepatocellular carcinoma. That's why it is seeking the researchers' attention to find out the effective treatment strategies. Phytochemicals from natural resources are the main leads for the development of noble hepatoprotective drugs. The majority of the natural sources whose active compounds are currently employed actually have an ethnomedical use. Ethnopharmacological research is essential for the development of these bioactive compounds. These studies not only provide scientific evidence on medicinal plants utilized for particular therapeutic purposes, but they also ensure cultural heritage preservation. Plenty of experimental studies have been well-documented that the ethnomedicinal plants are of therapeutics' interest for the advanced pharmacological intervention in terms of hepatic disorders.

AIM OF THE STUDY

This study summarizes the processes of hepatotoxicity induced by various toxins and explores identified hepatoprotective plants and their phytoconstituents, which can guide the extraction of novel phytochemical constituents from plants to treat liver injury. This review aimed to summarize the hepatoprotective activity of Bangladeshi medicinal plants where the bioactive compounds may be leads for the drug discovery in future.

MATERIALS AND METHODS

Literature searches in electronic databases, such as Web of Science, Science Direct, SpringerLink, PubMed, Google Scholar, Semantic Scholar, Scopus, BanglaJOL, and so on, were performed using the keywords 'Bangladesh', 'ethnomedicinal plants', 'Hepatoprotective agents' as for primary searches, and secondary search terms were used as follows, either alone or in combination: traditional medicine, medicinal plants, folk medicine, liver, hepatitis, therapeutic uses, and anti-inflammatory. Besides, several books, including the book entitled "Medicinal plants of Bangladesh: chemical constituents and uses" authored by Abdul Ghani, were carefully considered, which contained pharmacological properties and phytoconstituents of many medicinal plants growing and traditionally available in Bangladesh. Among them, the most promising plant species with their latest therapeutic effects against hepatic disorders were deeply considered in this review.

RESULTS

The results of this study revealed that in most cases, therapy using plant extracts stabilized altered hepatic biochemical markers induced by hepatotoxins. Initially, we investigated 32 plant species for hepatoprotective activity, however after extensive literature searching; we observed that 20 plants offer good pharmacological evidence of hepatoprotective function. Consequently, most bioactive compounds derived from the herbs including berberine, thymoquinone, andrographolide, ursolic acid, luteolin, naringenin, genistein, quercetin, troxerutin, morin, epigallocatechin-3-gallate, chlorogenic acid, emodin, curcumin, resveratrol, capsaicin, ellagic acid, etc. are appeared to be effective against hepatic disorders.

CONCLUSIONS

Flavonoids, phenolic acids, monoterpenoids, diterpenoids, triterpenoids, alkaloids, chromenes, capsaicinoids, curcuminoids, and anthraquinones are among the phytoconstituents were appraised to have hepatoprotective activities. All the actions displayed by these ethnomedicinal plants could make them serve as leads in the formulation of drugs with higher efficacy to treat hepatic disorders.

Effect of extracts and isolated compounds derived from Retama monosperma (L.) Boiss. on anti-aging gene expression in human keratinocytes and antioxidant activity

ETHNOPHARMACOLOGICAL RELEVANCE

Moroccan folk medicine treats skin cicatrization with Retama monosperma (L.) Boiss. locally named "Rtem", but the mechanism involved is still not well known. Traditional healers use the plant in small doses as an anthelmintic, disinfectant and an effective abortive. In addition, the cladodes powder mixed with honey is employed as purgative and vermifuge. Equally, the SIRT1 and SIRT3 genes activation and sirtuin proteins expression, which delay cellular senescence, participate in wound healing and skin regeneration especially, SIRT1 the most studied gene, leads to fast skin restoration and cicatrization.

AIM OF THE STUDY

In this study, we evaluated the ability of the Retama monosperma (L.)Boiss. flowers and seeds extracts and the isolated compounds in augmenting the SIRT1 and SIRT3 gene expression in HaCaT cells and expressing the antioxidant activity.

MATERIALS AND METHODS

We examined for quantitative expression levels of SIRT1 and SIRT3 in HaCaT cell by qRT-PCR and the antioxidant activity by four tests (conjugated diene, TBARS assay, DPPH scavenging activity and H₂O₂ radical scavenging assay) of diethyl ether extract of flowers (DEF extract) and ethyl acetate extract of seeds (EAS extract) of R. monosperma(L.) Boiss. and the isolated compounds (quercetin, 6-methoxykaempferol, kaempferol and genistein).

RESULTS

The screening system by EGFP fluorescence revealed that all samples and resveratrol significantly increase SIRT1 and SIRT3 promoters activities in HaCaT cells with p< 0.05. Furthermore, EAS, quercetin, 6-methoxykaempferol and kaempferol increase significantly (p< 0.05) SIRT1 (3.43, 1.18, 2.62, and 1.72 expression quantity, respectively) and SIRT3 (16.27, 5.01, 3.01, and 6.18 expression quantity, respectively) in HaCaT cells. On the other hand, genistein has a moderate activity on SIRT1 and SIRT3 with 1.43 and 2.04 expression levels. For the antioxidant activity, the EAS and the pure compounds exhibited stronger antioxidant activity than BHT. While DEF and genistein have a moderate antioxidant activity when compared with BHT.

CONCLUSIONS

In this study, the expression levels of SIRT1 and SIRT3 in HaCaT cells increase in the presence of extracts of R. monosperma (L.) Boiss. and the pure compounds.

Inhibition of Cell Proliferation and Metastasis by Scutellarein Regulating PI3K/Akt/NF-κB Signaling through PTEN Activation in Hepatocellular Carcinoma

Scutellarein (SCU) is a well-known flavone with a broad range of biological activities against several cancers. Human hepatocellular carcinoma (HCC) is major cancer type due to its poor prognosis even after treatment with chemotherapeutic drugs, which causes a variety of side effects in patients. Therefore, efforts have been made to develop effective biomarkers in the treatment of HCC in order to improve therapeutic outcomes using natural based agents. The current study used SCU as a treatment approach against HCC using the HepG2 cell line. Based on the cell viability assessment up to a 200 μM concentration of SCU, three low-toxic concentrations of (25, 50, and 100) μM were adopted for further investigation. SCU induced cell cycle arrest at the G2/M phase and inhibited cell migration and proliferation in HepG2 cells in a dose-dependent manner. Furthermore, increased PTEN expression by SCU led to the subsequent downregulation of PI3K/Akt/NF-κB signaling pathway related proteins. In addition, SCU regulated the metastasis with EMT and migration-related proteins in HepG2 cells. In summary, SCU inhibits cell proliferation and metastasis in HepG2 cells through PI3K/Akt/NF-κB signaling by upregulation of PTEN, suggesting that SCU might be used as a potential agent for HCC therapy.

Quercetin as a protective agent for liver diseases: A comprehensive descriptive review of the molecular mechanism

Quercetin is the major representative of the flavonoid subgroup of flavones, with good pharmacological activities for the treatment of liver diseases, including liver steatosis, fatty hepatitis, liver fibrosis, and liver cancer. It can significantly influence the development of liver diseases via multiple targets and multiple pathways via antifat accumulation, anti-inflammatory, and antioxidant activity, as well as the inhibition of cellular apoptosis and proliferation. Despite extensive research on understanding the mechanism of quercetin in the treatment of liver diseases, there are still no targeted therapies available. Thus, we have comprehensively searched and summarized the different targets of quercetin in different stages of liver diseases and concluded that quercetin inhibited inflammation of the liver mainly through NF-κB/TLR/NLRP3, reduced PI3K/Nrf2-mediated oxidative stress, mTOR activation in autophagy, and inhibited the expression of apoptotic factors associated with the development of liver diseases. In addition, quercetin showed different mechanisms of action at different stages of liver diseases, including the regulation of PPAR, UCP, and PLIN2-related factors via brown fat activation in liver steatosis. The compound inhibited stromal ECM deposition at the liver fibrosis stage, affecting TGF1β, endoplasmic reticulum stress (ERs), and apoptosis. While at the final liver cancer stage, inhibiting cancer cell proliferation and spread via the hTERT, MEK1/ERK1/2, Notch, and Wnt/β-catenin-related signaling pathways. In conclusion, quercetin is an effective liver protectant. We hope to explore the pathogenesis of quercetin in different stages of liver diseases through the review, so as to provide more accurate targets and theoretical basis for further research of quercetin in the treatment of liver diseases.

Potential Therapeutic Targets of Quercetin, a Plant Flavonol, and Its Role in the Therapy of Various Types of Cancer through the Modulation of Various Cell Signaling Pathways

Polyphenolic flavonoids are considered natural, non-toxic chemopreventers, which are most commonly derived from plants, fruits, and vegetables. Most of these polyphenolics exhibit remarkable antioxidant, anti-inflammatory, and anticancer properties. Quercetin (Qu) is a chief representative of these polyphenolic compounds, which exhibits excellent antioxidant and anticancer potential, and has attracted the attention of researchers working in the area of cancer biology. Qu can regulate numerous tumor-related activities, such as oxidative stress, angiogenesis, cell cycle, tumor necrosis factor, proliferation, apoptosis, and metastasis. The anticancer properties of Qu mainly occur through the modulation of vascular endothelial growth factor (VEGF), apoptosis, phosphatidyl inositol-3-kinase (P13K)/Akt (proteinase-kinase B)/mTOR (mammalian target of rapamycin), MAPK (mitogen activated protein kinase)/ERK1/2 (extracellular signal-regulated kinase 1/2), and Wnt/β-catenin signaling pathways. The anticancer potential of Qu is documented in numerous in vivo and in vitro studies, involving several animal models and cell lines. Remarkably, this phytochemical possesses toxic activities against cancerous cells only, with limited toxic effects on normal cells. In this review, we present extensive research investigations aimed to discuss the therapeutic potential of Qu in the management of different types of cancers. The anticancer potential of Qu is specifically discussed by focusing its ability to target specific molecular signaling, such as p53, epidermal growth factor receptor (EGFR), VEGF, signal transducer and activator of transcription (STAT), PI3K/Akt, and nuclear factor kappa B (NF-κB) pathways. The anticancer potential of Qu has gained remarkable interest, but the exact mechanism of its action remains unclear. However, this natural compound has great pharmacological potential; it is now believed to be a complementary—or alternative—medicine for the prevention and treatment of different cancers.

A systems-based analysis to explore the multiple mechanisms of Shan Zha for treating human diseases

Shan Zha has garnered increasing attention in the field of functional foods and medicines due to its widely reported healing effects. However, the potential mechanisms of Shan Zha for human health benefits have not been fully interpreted. Therefore, in the current study, a systems-based method that integrates ADME evaluation, target fishing, gene ontology enrichment analysis, network pharmacology, and pathway analysis is proposed to clarify the underlying pharmacological mechanisms of Shan Zha. As a result, 45 active components of Shan Zha that interacted with 161 protein targets were screened and identified. Moreover, gene ontology enrichment, network and pathway analysis indicated that Shan Zha is beneficial for the treatment of cardiovascular system diseases, digestive system diseases, immune system diseases, inflammatory diseases, cancer, and other diseases through multiple mechanisms. Our study not only proposed an integrated method to comprehensively elucidate the complicated mechanisms of Shan Zha for the treatment of various disorders at the system level, but also provided a reference approach for the mechanistic research of other functional foods.

Multiple-endpoint in vitro carcinogenicity test in human cell line TK6 distinguishes carcinogens from non-carcinogens and highlights mechanisms of action

Current in vitro genotoxicity tests can produce misleading positive results, indicating an inability to effectively predict a compound's subsequent carcinogenic potential in vivo. Such oversensitivity can incur unnecessary in vivo tests to further investigate positive in vitro results, supporting the need to improve in vitro tests to better inform risk assessment. It is increasingly acknowledged that more informative in vitro tests using multiple endpoints may support the correct identification of carcinogenic potential. The present study, therefore, employed a holistic, multiple-endpoint approach using low doses of selected carcinogens and non-carcinogens (0.001-770 µM) to assess whether these chemicals caused perturbations in molecular and cellular endpoints relating to the Hallmarks of Cancer. Endpoints included micronucleus induction, alterations in gene expression, cell cycle dynamics, cell morphology and bioenergetics in the human lymphoblastoid cell line TK6. Carcinogens ochratoxin A and oestradiol produced greater Integrated Signature of Carcinogenicity scores for the combined endpoints than the "misleading" in vitro positive compounds, quercetin, 2,4-dichlorophenol and quinacrine dihydrochloride and toxic non-carcinogens, caffeine, cycloheximide and phenformin HCl. This study provides compelling evidence that carcinogens can successfully be distinguished from non-carcinogens using a holistic in vitro test system. Avoidance of misleading in vitro outcomes could lead to the reduction and replacement of animals in carcinogenicity testing.

IFN-α-2b induces apoptosis by decreasing cellular cholesterol levels in rat preneoplastic hepatocytes

IFN-α administration to patients has been long discouraged and pushed back by new and apparently better drugs; however the adverse secondary effect, the high costs and the lack of specific action, make these new drugs hard to be used and put IFN-α again in the eye of the researchers. IFN-α-2b was demonstrated to induce apoptosis and modulation of lipid metabolism and the mechanisms are still unknown. Here, we sought to find the link between these features using a model of early stage cancer development. Using in vitro and in vivo approaches, we evaluated apoptosis and lipid metabolism. IFN-α-2b induced changes in hepatic cholesterol mass due to decreased synthesis and increased secretion. Interestingly, the drop in cellular cholesterol levels was necessary for IFN-α-2b to induce apoptosis. Results presented in this paper show the complexity of the action of IFN-α-2b on the early stages of liver cancer development. We show for the first time an interrelationship between cholesterol, apoptosis and IFN-α-2b. This makes clear the need for a reevaluation of IFN-α-2b action in order to develop softer, safer and more bearable derivatives. In this regard, knowing the molecular mechanisms by which IFN-α exerts its cellular actions is of crucial importance, and it is the main condition for therapy success for classical and new malignancies.

Effects of quercetin on Aroclor 1254-induced expression of CYP450 and cytokines in pregnant rats

The present study aimed to investigate the protective effect of quercetin on polychlorinated biphenyls (PCB)-induced liver and embryo damage in pregnant Sprague-Dawley rats. Pregnant rats were divided into five groups, and then were orally gavaged daily with peanut oil (vehicle) or a commercial PCB mixture (Aroclor 1254) - with or without co-treatment with 75, 150, or 300 mg/kg quercetin - on gestation days (GD) 4-7. At GD 9, all rats were euthanized, and their blood, liver, and uterus were collected. Expressions of CYP₄₅₀ mRNA and protein in liver, cytokines (IFNγ, IL-2, IL-4, and IL-6) and IFNγ/IL-4 ratios in liver and sera, liver morphology, and the status of implanted embryos were analyzed. The results showed Aroclor 1254 treatment alone caused hepatic cord damage (i.e. cell disorganization, swelling, decreased cytoplasm, vacuolization), and that quercetin co-treatment appeared to mitigate this damage. Similarly, levels of CYP1A1 and CYP2B1 mRNA in livers of Aroclor 1254-only-treated rats were significantly higher than those in rats co-treated with quercetin. Hepatic and sera levels of IFNγ, IL-2, IL-6, and IFNγ/IL-4 ratios, and the ratio of delayed-development embryos, all increased in Aroclor 1254-treated rats, but were relatively decreased as a result of quercetin co-treatments. IL-4 levels were decreased by Aroclor 1254 and tended to increase back to normal when quercetin was used. The results indicated that quercetin imparted a protective effect against Aroclor 1254-induced toxicity in pregnant rats, in part, by modulating levels of important pro-inflammatory cytokines and reducing induced CYP1A1 and CYP2B1 expression.

Quercetin inhibits human microvascular endothelial cells viability, migration and tube-formation in vitro through restraining microRNA-216a

Background: Quercetin belongs to the flavonoids family, which has been proven to have extensive pharmacological effects. Nevertheless, the function of quercetin in peripheral arterial disease (PAD) has not yet been reported. In the research, we purposed to disclose the effectiveness of quercetin in the pathogenesis of PAD.Methods: HMEC-1 cells were cultivated in Matrigel for 24 h to observe the tube-formation. Detections of cell viability, migration and apoptosis were through implementing CCK-8, Transwell and flow cytometry methods. Western blot was utilised for measuring angiogenesis-, migration- and apoptosis-correlative factors. MiR-216a expression was examined via qRT-PCR, and its functions in HMEC-1 cells were uncovered after miR-216a mimic transfection. Assessment of JAK2/STAT3 and PI3K/AKT pathways was via implementing western blot.Results: HMEC-1 cells were spontaneously vascularised under Matrigel condition. Quercetin predominantly repressed cell viability, migration, VEGF expression and facilitated apoptosis in HMEC-1 cells. Additionally, suppression of miR-216a was discovered in HMEC-1 cells after quercetin stimulation, meanwhile miR-216a overexpression annulled the functions of quercetin in HMEC-1 cells. Besides, quercetin deactivated PI3K/AKT and JAK/STAT pathways through adjusting miR-216a.Conclusion: The above-mentioned consequences exhibited that quercetin suppressed HMEC-1 cell viability, migration and tube-formation through hindering JAK2/STAT3 and PI3K/AKT pathway via declination of miR-216a.

Participation of 5-lipoxygenase and LTB4 in liver regeneration after partial hepatectomy

Regeneration is the unmatched liver ability for recovering its functional mass after tissue lost. Leukotrienes (LT) are a family of eicosanoids with the capacity of signaling to promote proliferation. We analyzed the impact of blocking LT synthesis during liver regeneration after partial hepatectomy (PH). Male Wistar rats were subjected to two-third PH and treated with zileuton, a specific inhibitor of 5-lipoxygenase (5-LOX). Our first find was a significant increment of intrahepatic LTB4 during the first hour after PH together with an increase in 5-LOX expression. Zileuton reduced hepatic LTB4 levels at the moment of hepatectomy and also inhibited the increase in hepatic LTB4. This inhibition produced a delay in liver proliferation as seen by decreased PCNA and cyclin D1 nuclear expression 24 h post-PH. Results also showed that hepatic LTB4 diminution by zileuton was associated with a decrease in NF-ĸB activity. Additionally, decreased hepatic LTB4 levels by zileuton affected the recruitment of neutrophils and macrophages. Non-parenchymal cells (NPCs) from zileuton-treated PH-rats displayed higher apoptosis than NPCs from PH control rats. In conclusion, the present work provides evidences that 5-LOX activation and its product LTB4 are involved in the initial signaling events for liver regeneration after PH and the pharmacological inhibition of this enzyme can delay the initial time course of the phenomenon.

Quercetin shows anti-tumor effect in hepatocellular carcinoma LM3 cells by abrogating JAK2/STAT3 signaling pathway

Objective

Hepatocellular carcinima is one of the most common tumors in clinic and also one of the leading causes of death from cancer worldwide. Quercetin shows significant effects on blocking the development of various cancers.

Methods

We used the human hepatocellular carcinoma LM3 and nude mice tumor model to assess the effects of quercetin in hepatocellular carcinoma and clarify its mechanism of action. We collected LM3 cell line treated with different doses of quercetin at different time periods and determined the vital indexes. The liver tissues of mice were collected and used for western boltting (WB), Hematoxylin and Eosin (H&E) and TUNEL staining.

Results

Results indicated that quercetin suppressed the Hepatocellular carcinoma (HCC) growth both in vivo and in vitro. Quercetin could disturb LM3 cells proliferation and cell cycle distribution, thus inducing apoptosis. At the same time, quercetin inhibited LM3 cells migration and invasion and promoted HCC autophagy. These effects at least partly depended on the down‐regulation of the activation of JAK2 and STAT3 by quercetin.

Conclusion

Quercetin inhibited hepatocellular carcinoma progression by modulating cell apoptosis, migration, invasion, and autophagy; and its effects were at least partly related with the JAK2/STAT3 signaling pathway.

Quercetin inhibited mesangial cell proliferation of early diabetic nephropathy through the Hippo pathway

Diabetic nephropathy (DN) is one of the most common microvascular complications of diabetes and the leading cause of end-stage renal disease. The proliferation of glomerular mesangial cells (MCs) is a common and prominent pathological change of DN, which takes place at the early stage. Quercetin, a bioflavonoid compound, possesses therapeutic efficacy in cardiovascular and kidney diseases via anti-tumour, anti-oxidation, anti-virus, and anti-proliferation effects. However, the mechanism of quercetin in the proliferation of glomerular MCs in early DN has not been reported. In the present study, we investigated the effect of quercetin on the proliferation of glomerular MCs in high glucose-induced mouse glomerular MCs and in db/db mice. On this basis, we tried to clarify the specific mechanisms underlying these effects. The in vitro results showed that the proliferation of glomerular MCs was induced by high glucose, and the Hippo pathway was highly inactivated in high glucose-cultured MCs. Decreased phosphorylation of MST1 and Lats1 promoted expression and nuclear translocation of Yes-associated protein (YAP) and subsequently increased the combination of YAP and TEA/ATS domain (TEAD), which promoted the expression of the downstream target gene such as cyclinE. Quercetin effectively inhibited the high glucose-induced MC proliferation and reactivated the Hippo pathway. In vivo, the proliferation of glomerular MCs was increased, renal function was decreased, and blood fasting glucose was elevated in db/db mice. Furthermore, the Hippo pathway was inactivated in the renal cortex of db/db mice. Eight-week treatment of quercetin retarded MC proliferation, alleviated the renal function, and reactivated Hippo pathway in the renal cortex of db/db mice at 16 weeks. Our previous study clarified that the Hippo pathway was involved in MC proliferation of DN. The results revealed that quercetin inhibited MC proliferation in high glucose-treated mouse glomerular MCs and in DN via reactivation of the Hippo pathway.

Quercetin delays postovulatory aging of mouse oocytes by regulating SIRT expression and MPF activity

If no fertilization occurs at an appropriate time after ovulation, oocyte quality deteriorates rapidly as a process called postovulatory aging. Because the postovulatory aging of oocytes has detrimental effects on embryo development and offspring, many efforts have been made to prevent oocyte aging. Here we showed that quercetin prevented the decline in oocyte quality during postovulatory aging of oocytes. Quercetin treatment reduced aging-induced morphological changes and reactive oxygen species accumulation. Moreover, quercetin attenuated the aging-associated abnormalities in spindle organization and mitochondrial distribution, preventing decrease of SIRT expression and histone methylation. Quercetin also ameliorated the decrease in maturation-promoting factor activity and the onset of apoptosis during postovulatory aging. Furthermore, quercetin treatment during postovulatory aging improves early embryo development. Our results demonstrate that quercetin relieves deterioration in oocyte quality and improves subsequent embryo development.

Diethylnitrosamine Increases Proliferation in Early Stages of Hepatic Carcinogenesis in Insulin-Treated Type 1 Diabetic Mice

Diethylnitrosamine (DEN) induces hepatocarcinogenesis, increasing mitotic hepatocytes and leading to chronic inflammation. In addition, type 1 diabetes mellitus (T1DM) is also characterized by a proinflammatory state and by requiring insulin exogenous treatment. Given the association of diabetes, insulin treatment, and cell proliferation, our specific goal was to determine whether the liver in the diabetic state presents a greater response to DEN-induced cell cycle alteration, which is essential for the malignant transformation. Male C57BL/6 mice (four-week-old) were divided into 4 groups: C, C + DEN, T1DM, and T1DM + DEN. Mice were euthanized ten weeks after DEN injection. DEN per se produced an increase in liver lipid peroxidation levels. Besides, in T1DM + DEN, we found a greater increase in the proliferation index, in comparison with C + DEN. These results are in agreement with the increased expression observed in cell cycle progression markers: cyclin D1 and E1. In addition, a proapoptotic factor, such as activated caspase-3, evidenced a decrease in T1DM + DEN, while the Vascular Endothelial Growth Factor (VEGF) and the protooncogene p53 showed a higher increase with respect to C + DEN. Overall, the results allow us to highlight a major DEN response in T1DM, which may explain in part the greater predisposition to the development of hepatocarcinoma (HCC) during the diabetic state.

Quercetin ameliorates Aβ toxicity in Drosophila AD model by modulating cell cycle-related protein expression

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder characterized by β amyloid (Aβ) deposition and neurofibril tangles. It has been reported that a bioflavonoid, quercetin, could ameliorate AD phenotypes in C. elegans and mice. However, the mechanism underlying the ameliorative effect of quercetin is not fully understood yet. Drosophila models could recapitulate AD-like phenotypes, such as shortened lifespan, impaired locomotive ability as well as defects in learning and memory. So in this study, we investigated the effects of quercetin on AD in Drosophila model and explored the underlying mechanisms. We found quercetin could effectively intervene in AD pathogenesis in vivo. Mechanism study showed quercetin could restore the expression of genes perturbed by Aβ accumulation, such as those involved in cell cycle and DNA replication. Cyclin B, an important cell cycle protein, was chosen to test whether it participated in the AD ameliorative effects of quercetin. We found that cyclin B RNAi in the brain could alleviate AD phenotypes. Taken together, the current study suggested that the neuroprotective effects of quercetin were mediated at least partially by targeting cell cycle-related proteins.

Quercetin metabolism by fecal microbiota from healthy elderly human subjects

Quercetin is a polyphenol found in food that has numerous health benefits. This study investigated the relationship between quercetin metabolism, gut microbiota composition, and dietary intake in elderly Japanese subjects. A food frequency questionnaire was used to assess dietary intake during the week prior to stool sample collection. Fecal suspensions from 56 subjects were anaerobically incubated with quercetin and fecal microbiota composition was analyzed by next-generation sequencing. Inter-individual variations in quercetin concentration and fecal microbiota composition at family level suggested differences in microbial quercetin metabolism. The abundance of Sutterellaceae (r = -0.292) and Oscillospiraceae (r = -0.334) was negatively correlated whereas that of Fusobacteriaceae (r = 0.361) and Enterobacteriaceae (r = 0.321) was positively correlated with quercetin concentration. Niacin (r = -0.313), vitamin B6 (r = -0.297), vitamin B12 (r = -0.266), vitamin D (r = -0.301), and ratio of animal protein to total protein (r = -0.27) were also negatively correlated with quercetin concentration. Bacterial abundance was positively or negatively related to intake of food components. This is the first report describing the relationship between fecal quercetin metabolism, human microbiota, and dietary intake in the elderly.

Dietary quercetin potentiates the antiproliferative effect of interferon-α in hepatocellular carcinoma cells through activation of JAK/STAT pathway signaling by inhibition of SHP2 phosphatase

Type I interferons (IFN-α/β) have broad and potent immunoregulatory and antiproliferative activities, which are negatively regulated by Src homology domain 2 containing tyrosine phosphatase-2 (SHP-2). Inhibition of SHP2 by small molecules may be a new strategy to enhance the effcacy of type I IFNs. Using an in vitro screening assay for new inhibitors of SHP2 phosphatase, we found that quercetin was a potent inhibitor of SHP2. Computational modeling showed that quercetin exhibited an orientation favorable to nucleophilic attack in the phosphatase domain of SHP2. Quercetin enhanced the phosphorylation of signal transducer and activator of transcription proteins 1 (STAT1) and promoted endogenous IFN-α-regulated gene expression. Furthermore, quercetin also sensitized the antiproliferative effect of IFN-α on hepatocellular carcinoma HepG2 and Huh7 cells. The overexpression of SHP2 attenuated the effect of quercetin on IFN-α-stimulated STAT1 phosphorylation and antiproliferative effect, whereas the inhibition of SHP2 promoted the effect of quercetin on IFN-α-induced STAT1 phosphorylation and antiproliferative effect. The results suggested that quercetin potentiated the inhibitory effect of IFN-α on cancer cell proliferation through activation of JAK/STAT pathway signaling by inhibiting SHP2. Quercetin warrants further investigation as a novel therapeutic method to enhance the efficacy of IFN-α/β.

Hepatic preneoplasia induction in male Wistar rats: histological studies up to five months post treatment

BACKGROUND

Liver preneoplasia development in rats can be mimicked by an initiation-promotion model that induces the appearance of altered hepatocyte foc (FAH).

AIMS

We compare two initiation-promotion models to evaluate the presence of FAH or additional hepatic pathologies in which other organs were affected up to five month post treatment.

MATERIAL AND METHODS

FAH were induced in male adult Wistar rats with two doses of dietylnitrosamine (DEN, 150 mg/kg bw) followed by 4 doses per week (3 weeks) of 2-acetylaminofluorene (2-AAF, 20 mg/kg bw) or with one dose of DEN (200 mg/kg bw) followed by 2 doses per week (3 weeks) of 2-AAF. DEN 150, DEN 200 and control mice (received the vehicle of the drugs) groups were compared. Rats were euthanized immediately after the last dose of 2-AAF, at 3, 4 and 5 months (n = 3 euthanasia times per group). Samples of livers, lungs, kidneys, pancreatic tissue and small bowel were processed for histological and immunohistochemical analysis.

RESULTS

FAH persisted for 5 months in all livers of the DEN groups. Three months after withdrawal of 2-AAF, one rat from the DEN 150 group developed fibrosis and 5 months after 2-AAF removal another rat from the same group presented a microscopic hyperplastic nodule. Only the lungs had damage compatible with lesions induced by gavage-related reflux in DEN groups.

CONCLUSION

We concluded that up to five month post treatments, FAH persisted in all the livers from the DEN groups; livers from the DEN 200 group showed no other hepatic lesions besides FAH, and only the lungs suffered pathological alterations in both treated groups.

Attenuation of liver cancer development by oral glycerol supplementation in the rat

PURPOSE

Glycerol usage is increasing in food industry for human and animal nutrition. This study analyzed the impact of glycerol metabolism when orally supplemented during the early stage of rat liver carcinogenesis.

METHODS

Wistar rats were subjected to a 2-phase model of hepatocarcinogenesis (initiated-promoted, IP group). IP animals also received glycerol by gavage (200 mg/kg body weight, IPGly group).

RESULTS

Glycerol treatment reduced the volume of preneoplastic lesions by decreasing the proliferative status of liver foci, increasing the expression of p53 and p21 proteins and reducing the expression of cyclin D1 and cyclin-dependent kinase 1. Besides, apoptosis was enhanced in IPGly animals, given by an increment of Bax/Bcl-2 ratio, Bad and PUMA mitochondrial expression, a concomitant increase in cytochrome c release and caspase-3 activation. Furthermore, hepatic levels of glycerol phosphate and markers of oxidative stress were increased in IPGly rats. Oxidative stress intermediates act as intracellular messengers, inducing p53 activation and changes in JNK and Erk signaling pathways, with JNK activation and Erk inhibition.

CONCLUSION

The present work provides novel data concerning the preventive actions of glycerol during the development of liver cancer and represents an economically feasible intervention to treat high-risk individuals.

Hepatic carboxylesterase 3 (Ces3/Tgh) is downregulated in the early stages of liver cancer development in the rat

It is accepted that cancer development is associated with metabolic changes. Previously, we established a model of hepatic preneoplasia in which adult rats were subjected to a 2-phase model of hepatocarcinogenesis (initiated-promoted, IP) for 6weeks until they develop altered hepatic foci (AHF). Here, we found that a whole metabolic shift occurs in order to favor cancer development. IP animals presented with increased plasma lipids due to increased VLDL secretion as well as increased liver lipid accretion due to stimulated transacetylase activity rather than lipogenesis, compared to control rats. We found that carboxylesterase 3/triacylglycerol hydrolase (Ces3/Tgh) presented with a perilobular distribution surrounding lipid droplets in normal livers. However, it is downregulated both at the protein and mRNA level in liver homogenates and is almost undetectable inside the AHF with no changes in the surrounding tissue. Ces3/Tgh expression is regulated by ω-3 fatty acids, thus, supplementation of diet with fish oil, allowed the restoration of Ces3/Tgh expression inside the foci and, more interestingly, led to the decrease in number and volume of the AHF. These studies show a preventive role of Ces3/Tgh in liver cancer development.

Molecular mechanisms of action of quercetin in cancer: recent advances

In the last few decades, the scientific community has discovered an immense potential of natural compounds in the treatment of dreadful diseases such as cancer. Besides the availability of a variety of natural bioactive molecules, efficacious cancer therapy still needs to be developed. So, to design an efficacious cancer treatment strategy, it is essential to understand the interactions of natural molecules with their respective cellular targets. Quercetin (Quer) is a naturally occurring flavonol present in many commonly consumed food items. It governs numerous intracellular targets, including the proteins involved in apoptosis, cell cycle, detoxification, antioxidant replication, and angiogenesis. The weight of available synergistic studies vigorously fortifies the utilization of Quer as a chemoprevention drug. This extensive review covers various therapeutic interactions of Quer with their recognized cellular targets involved in cancer treatment.

Anti-Breast Cancer Potential of Quercetin via the Akt/AMPK/Mammalian Target of Rapamycin (mTOR) Signaling Cascade

The Akt/adenosine monophosphate protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway has emerged as a critical signaling nexus for regulating cellular metabolism, energy homeostasis, and cell growth. Thus, dysregulation of this pathway contributes to the development of metabolic disorders such as obesity, type 2diabetes, and cancer. We previously reported that a combination of grape polyphenols (resveratrol, quercetin and catechin: RQC), at equimolar concentrations, reduces breast cancer (BC) growth and metastasis in nude mice, and inhibits Akt and mTOR activities and activates AMPK, an endogenous inhibitor of mTOR, in metastatic BC cells. The objective of the present study was to determine the contribution of individual polyphenols to the effect of combined RQC on mTOR signaling. Metastatic BC cells were treated with RQC individually or in combination, at various concentrations, and the activities (phosphorylation) of AMPK, Akt, and the mTOR downstream effectors, p70S6 kinase (p70S6K) and 4E binding protein (4EBP1), were determined by Western blot. Results show that quercetin was the most effective compound for Akt/mTOR inhibition. Treatment with quercetin at 15μM had a similar effect as the RQC combination in the inhibition of BC cell proliferation, apoptosis, and migration. However, cell cycle analysis showed that the RQC treatment arrested BC cells in the G1 phase, while quercetin arrested the cell cycle in G2/M. In vivo experiments, using SCID mice with implanted tumors from metastatic BC cells, demonstrated that administration of quercetin at 15mg/kg body weight resulted in a ~70% reduction in tumor growth. In conclusion, quercetin appears to be a viable grape polyphenol for future development as an anti BC therapeutic.

Quercetin-induced apoptosis prevents EBV infection

Epstein-Barr virus (EBV) is a human gamma-1 herpesvirus that establishes a lifelong latency in over 90% of the world's population. During latency, virus exists predominantly as a chromatin-associated, multicopy episome in the nuclei of a variety of tumor cells derived from B cells, T cells, natural killer (NK) cells, and epithelial cells. Licorice is the root of Glycyrrhiza uralensis or G. glabra that has traditionally cultivated in eastern part of Asia. Licorice was reported to have anti-viral, anti-inflammatory, anti-atopic, hepatoprotective, anti-neurodegenerative, anti-tumor, anti-diabetic effects and so forth. Quercetin and isoliquiritigenin are produced from licorice and highly similar in molecular structure. They have diverse bioactive effects such as antiviral activity, anti-asthmatic activity, anti-cancer activity, anti-inflammation activity, monoamine-oxidase inhibitor, and etc. To determine anti-EBV and anti-EBVaGC (Epstein-Barr virus associated gastric carcinoma) effects of licorice, we investigated antitumor and antiviral effects of quercetin and isoliquiritigenin against EBVaGC. Although both quercetin and isoliquiritigenin are cytotoxic to SNU719 cells, quercetin induced more apoptosis in SNU719 cells than isoliquiritigenin, more completely eliminated DNMT1 and DNMT3A expressions than isoliquiritigenin, and more strongly affects the cell cycle progression of SNU719 than isoliquiritigenin. Both quercetin and isoliquiritigenin induce signal transductions to stimulate apoptosis, and induce EBV gene transcription. Quercetin enhances frequency of F promoter use, whereas isoliquiritigenin enhances frequency of Q promoter use. Quercetin reduces EBV latency, whereas isoliquiritigenin increases the latency. Quercetin increases more the EBV progeny production, and inhibits more EBV infection than isoliquiritigenin. These results indicate that quercetin could be a promising candidate for antiviral and antitumor agents against EBV and human gastric carcinoma.

Sophoraflavanone G Induces Apoptosis in Human Leukemia Cells and Blocks MAPK Activation

Sophoraflavanone G (SG) was isolated from Sophora flavescens. Previously, we have found that SG is able to suppress the inflammatory response in lipopolysaccharide-stimulated RAW 264.7 macrophages. This study aimed to evaluate the effects of SG on apoptosis, and explore its molecular mechanism in human leukemia HL-60 cells. HL-60 cells were treated with various concentrations of SG (3–30 [Formula: see text]M). The viability of the HL-60 cells was assessed using the MTT method, and the nuclear condensation indicative of apoptosis was observed by DAPI fluorescence staining. In addition, apoptotic signal proteins were examined using Western blotting. The results showed that apoptosis, including DNA fragmentation and nuclear condensation, increased significantly in SG-treated HL-60 cells. SG activated caspase-3 and caspase-9, and downregulated Bcl-2 and Bcl-xL. SG also upregulated Bax and released cytochrome c from the mitochondria into the cytoplasm, enabling apoptosis via the mitochondrially-mediated “intrinsic” pathway. Additionally, SG was able to cleave poly (ADP-ribose) polymerase 1 and activate mitogen-activated protein kinase (MAPK) pathways. These results suggest that SG might increase the effect of apoptosis on HL-60 cells through caspase-3 activation, mitochondrial-mediated pathways, and the MAPK pathway.

Selenium-containing chrysin and quercetin derivatives: attractive scaffolds for cancer therapy

Selenium-containing chrysin (SeChry) and 3,7,3',4'-tetramethylquercetin (SePQue) derivatives were synthesized by a microwave-based methodology. In addition to their improvement in terms of DPPH scavenging and potential GPx-like activities, when tested in a panel of cancer cell lines both selenium-derivatives revealed consistently to be more cytotoxic when compared with their oxo and thio-analogues, evidencing the key role of selenocabonyl moiety for these activities. In particular, SeChry elicited a noteworthy cytotoxic activity with mean IC50 values 18- and 3-fold lower than those observed for chrysin and cisplatin, respectively. Additionally, these seleno-derivatives evidenced an ability to overcome cisplatin and multidrug resistance. Notably, a differential behavior toward malignant and nonmalignant cells was observed for SeChry and SePQue, exhibiting higher selectivity indexes when compared with the chalcogen-derivatives and cisplatin. Our preliminary investigation on the mechanism of cytotoxicity of SeChry and SePQue in MCF-7 human mammary cancer cells demonstrated their capacity to efficiently suppress the clonal expansion along with their ability to hamper TrxR activity leading to apoptotic cell death.

The roles of endoplasmic reticulum overload response induced by HCV and NS4B protein in human hepatocyte viability and virus replication

Hepatitis C virus (HCV) replication is associated with endoplasmic reticulum (ER) and its infection triggers ER stress. In response to ER stress, ER overload response (EOR) can be activated, which involves the release of Ca²⁺ from ER, production of reactive oxygen species (ROS) and activation of nuclear factor κB (NF-κB). We have previously reported that HCV NS4B expression activates NF-κB via EOR-Ca²⁺-ROS pathway. Here, we showed that NS4B expression and HCV infection activated cancer-related NF-κB signaling pathway and induced the expression of cancer-related NF-κB target genes via EOR-Ca²⁺-ROS pathway. Moreover, we found that HCV-activated EOR-Ca²⁺-ROS pathway had profound effects on host cell viability and HCV replication. HCV infection induced human hepatocyte death by EOR-Ca²⁺-ROS pathway, whereas activation of EOR-Ca²⁺-ROS-NF-κB pathway increased the cell viability. Meanwhile, EOR-Ca²⁺-ROS-NF-κB pathway inhibited acute HCV replication, which could alleviate the detrimental effect of HCV on cell viability and enhance chronic HCV infection. Together, our findings provide new insights into the functions of EOR-Ca²⁺-ROS-NF-κB pathway in natural HCV replication and pathogenesis.