Exploring the molecular targets of dietary flavonoid fisetin in cancer

NUF2 activated by YY1 promotes prostate cancer malignancy via p38/MAPK signaling axis and serves as a therapeutic target

Prostate cancer (PCa) is one of the most prevalent malignancies in the male urogenital system. Despite extensive research into its mechanisms of initiation and progression, the full scope of its pathophysiology remains insufficiently understood. This study demonstrated that NUF2 was significantly overexpressed in PCa, with its elevated levels correlating with poor patient survival outcomes. Silencing NUF2 notably impaired PCa cell proliferation and metastasis in both in vitro and in vivo models, whereas its overexpression promoted these processes. Additionally, YY1 was identified as a direct transcriptional activator of NUF2, binding to its promoter and enhancing its oncogenic effects through activation of downstream targets. Moreover, NUF2 promoted PCa progression by recruiting p38, accelerating its phosphorylation, and activating the p38/MAPK signaling pathway. Through the PubChem database, fisetin was identified as a small molecule inhibitor of NUF2. Fisetin effectively inhibited PCa cell proliferation, and NUF2 overexpression reversed this inhibitory effect. In conclusion, our results suggest that NUF2 overexpression accelerated PCa progression via the p38/MAPK pathway, regulated by YY1. The identification of fisetin as a NUF2 inhibitor offers a promising therapeutic strategy for targeting NUF2 to impede PCa growth. NUF2 may thus serve as a valuable prognostic biomarker and a potential therapeutic target for PCa.

The context-dependent effect of cellular senescence: From embryogenesis and wound healing to aging

Aging is characterized by a steady loss of physiological integrity, leading to impaired function and increased vulnerability to death. Cell senescence is a biological process that progresses with aging and is believed to be a key driver of age-related diseases. Senescence, a hallmark of aging, also demonstrates its beneficial physiological aspects as an anti-cancer, pro-regenerative, homeostatic, and developmental mechanism. A transitory response in which the senescent cells are quickly formed and cleared may promote tissue regeneration and organismal fitness. At the same time, senescence-related secretory phenotypes associated with extended senescence can have devastating effects. The fact that the interaction between senescent cells and their surroundings is very context-dependent may also help to explain this seemingly opposing pleiotropic function. Further, mitochondrial dysfunction is an often-unappreciated hallmark of cellular senescence and figures prominently in multiple feedback loops that induce and maintain the senescent phenotype. This review summarizes the mechanism of cellular senescence and the significance of acute senescence. We concisely introduced the context-dependent role of senescent cells and SASP, aspects of mitochondrial biology altered in the senescent cells, and their impact on the senescent phenotype. Finally, we conclude with recent therapeutic advancements targeting cellular senescence, focusing on acute injuries and age-associated diseases. Collectively, these insights provide a future roadmap for the role of senescence in organismal fitness and life span extension.

Fisetin as a chemoprotective and chemotherapeutic agent: mechanistic insights and future directions in cancer therapy

Cancer remains a leading cause of mortality globally, characterized by the uncontrolled proliferation of abnormal cells, invasion of healthy tissues, and potential metastasis. Natural compounds have become a focus in cancer research due to their potential therapeutic roles. Among these, fisetin, a dietary flavonoid, demonstrates notable anti-cancer properties through various molecular mechanisms. This review evaluates the chemoprotective and chemotherapeutic potential of fisetin, focusing on its mechanisms of action against cancer and its capacity to enhance cancer treatment. A systematic literature search was conducted across PubMed, Web of Science, and Scopus databases using keywords related to fisetin and cancer. The review synthesizes findings from in vitro and in vivo studies examining fisetin's effects on signaling pathways, apoptosis induction, oxidative stress modulation, and synergistic potential with chemotherapeutic agents. Fisetin has shown the ability to suppress tumor growth and metastasis by modulating critical signaling pathways, including PI3K/Akt/mTOR, NF-κB, and MAPK. It induces apoptosis in cancer cells through mitochondrial and endoplasmic reticulum stress responses and demonstrates antioxidative properties by reducing reactive oxygen species. Additionally, fisetin enhances the efficacy of conventional chemotherapies, indicating its role as a potential adjuvant in cancer treatment. Fisetin presents a promising natural compound with diverse anti-cancer effects, impacting cell cycle arrest, apoptosis, and oxidative stress pathways. Further clinical studies are warranted to fully elucidate its therapeutic potential and to optimize its delivery for improved bioavailability in cancer patients.

Exploring the therapeutic promise of fisetin: molecular mechanisms and clinical aspects in lung cancer

Fisetin, a flavonol belonging to the flavonoid subclass, is a ubiquitous dietary flavonoid present in fruits and vegetables, including fruit peels, and has proven potential for anticancer activity, especially for lung cancer - a leading cause of cancer-related deaths globally. The current paper provides the most detailed and elaborate list of the various roles of fisetin in experimentally induced lung cancer cells, and these roles include the promotion of apoptosis, inhibition of cell proliferation, migration, and invasion, as well as the regulation of autophagy. Among the molecular targets, some identified pathways, such as PI3K/Akt, MAPK, and NF-κB, that fisetin affects are crucial for tumor formation, so it can be considered a potential chemopreventive agent. Moreover, fisetin improves the effectiveness of conventional treatments as a chemo- and radiosensitizer and minimizes side effects. However, the overall utility of fisetin for clinical use is now somewhat restricted by its poor solubility and short half-life. It is predicted that the future development of nanotechnologies for drug delivery, such as nanoparticle encapsulation, might help solve these difficulties. Further Preclinical and clinical investigations are required to uniformly determine the safety, efficacy, and standard dosage of fisetin for consumption in lung cancer therapy.

Rhoifolin Suppresses Cell Proliferation and Induces Apoptosis in Hepatocellular Carcinoma Cells In Vitro and In Vivo

Background: Hepatocellular carcinoma (HCC) is the most prevalent malignant tumor, ranking fifth in terms of fatality with poor prognosis and a low survival rate. Rhoifolin (ROF), a flavonoid constituent, has previously been shown to suppress the proliferation of breast and pancreatic cancer cells. However, its inhibitory effect on HCC has remained unexplored. Objectives: Exploring the potent inhibitory activities and underlying mechanisms of ROF on HCC cells. Methods: The suppressive effect of ROF on HCC cells were assessed via CCK8 assay, apoptosis assay, cell cycle analysis and xenograft tumor mouse model. Furthermore, quantitative real-time PCR and western blot were applied to analyze the underlying mechanisms of ROF on HCC cells. Results: Firstly, the IC50 values of ROF in HepG2 and HuH7 cells were 373.9 and 288.7 µg/mL at 24 h and 208.9 and 218.0 µg/mL at 48 h, respectively. Moreover, the apoptosis rates of HepG2 and HuH7 cells increased from 6.63% and 6.59% to 17.61% and 21.83% at 24 h and increased from 6.63% and 6.59% to 30.04% and 37.90% at 48 h, respectively. Additionally, ROF induced cell cycle arrest at the S phase in HCC cells. Furthermore, ROF suppressed the tumor growth of HCC cells in vivo without obvious toxicity. Mechanically, ROF facilitated apoptosis by upregulating the expression of PIDD1, CASP8, CASP9, BID, BAX, BIM, and BAK1 in HCC cells. Conclusions: ROF significantly restrains the growth of HCC cells in vitro and in vivo, which could be an effective supplement for HCC therapy.

A comprehensive view on the fisetin impact on colorectal cancer in animal models: Focusing on cellular and molecular mechanisms

Flavonoids, including fisetin, have been linked to a reduced risk of colorectal cancer (CRC) and have potential therapeutic applications for the condition. Fisetin, a natural flavonoid found in various fruits and vegetables, has shown promise in managing CRC due to its diverse biological activities. It has been found to influence key cell signaling pathways related to inflammation, angiogenesis, apoptosis, and transcription factors. The results of this study demonstrate that fisetin induces colon cancer cell apoptosis through multiple mechanisms. It impacts the p53 pathway, leading to increased levels of p53 and decreased levels of murine double minute 2, contributing to apoptosis induction. Fisetin also triggers the release of important components in the apoptotic process, such as second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI and cytochrome c. Furthermore, fisetin inhibits the cyclooxygenase-2 and wingless-related integration site (Wnt)/epidermal growth factor receptor/nuclear factor kappa B signaling pathways, reducing Wnt target gene expression and hindering colony formation. It achieves this by regulating the activities of cyclin-dependent kinase 2 and cyclin-dependent kinase 4, reducing retinoblastoma protein phosphorylation, decreasing cyclin E levels, and increasing p21 levels, ultimately influencing E2 promoter binding factor 1 and cell division cycle 2 (CDC2) protein levels. Additionally, fisetin exhibits various effects on CRC cells, including inhibiting the phosphorylation of Y-box binding protein 1 and ribosomal S6 kinase, promoting the phosphorylation of extracellular signal-regulated kinase 1/2, and disrupting the repair process of DNA double-strand breaks. Moreover, fisetin serves as an adjunct therapy for the prevention and treatment of phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit α (PIK3CA)-mutant CRC, resulting in a reduction in phosphatidylinositol-3 kinase (PI3K) expression, Ak strain transforming phosphorylation, mTOR activity, and downstream target proteins in CRC cells with a PIK3CA mutation. These findings highlight the multifaceted potential of fisetin in managing CRC and position it as a promising candidate for future therapy development.

The development of nanocarriers for natural products

Natural bioactive compounds from plants exhibit substantial pharmacological potency and therapeutic value. However, the development of most plant bioactive compounds is hindered by low solubility and instability. Conventional pharmaceutical forms, such as tablets and capsules, only partially overcome these limitations, restricting their efficacy. With the recent development of nanotechnology, nanocarriers can enhance the bioavailability, stability, and precise intracellular transport of plant bioactive compounds. Researchers are increasingly integrating nanocarrier-based drug delivery systems (NDDS) into the development of natural plant compounds with significant success. Moreover, natural products benefit from nanotechnological enhancement and contribute to the innovation and optimization of nanocarriers via self-assembly, grafting modifications, and biomimetic designs. This review aims to elucidate the collaborative and reciprocal advancement achieved by integrating nanocarriers with botanical products, such as bioactive compounds, polysaccharides, proteins, and extracellular vesicles. This review underscores the salient challenges in nanomedicine, encompassing long-term safety evaluations of nanomedicine formulations, precise targeting mechanisms, biodistribution complexities, and hurdles in clinical translation. Further, this study provides new perspectives to leverage nanotechnology in promoting the development and optimization of natural plant products for nanomedical applications and guiding the progression of NDDS toward enhanced efficiency, precision, and safety. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Fisetin nanoparticles based on cells cycle and apoptosis intervention for the treatment of lymphoma and leukemia

Lymphoma and leukemia are both hematological system tumors with complex etiology, and mainly treated with chemotherapeutic drugs. However, therapeutic drugs can interrupt curative effect due to different side effects. Therefore, it is worthwhile to develop a novel therapeutic for providing insights for clinical tumor treatment. In this study, we developed a fisetin nanoparticles (Fisetin NPs) through a self-assembled method, and investigated the activity and potential mechanism of Fisetin NPs against lymphoma and leukemia. The spherical and uniformly distributed Fisetin NPs effectively inhibited both tumor cells proliferation, arrested EL4 cells G0/G1 phase and K562 cells G2/M phase, and induced apoptosis in vitro. In vivo, Fisetin NPs exhibited excellent tumor growth inhibition, effective inhibition of cell proliferation and angiogenesis, significant induction of apoptosis and ideal safety. Mechanically, fisetin upregulated genes (Fas, Pidd, Puma, Apaf1, and p21) in the p53 signaling pathway and bound to N-acetyltransferase 10 (NAT10), ribosomal protein L34 (RPL34) and GTP binding protein 4 (GTPBP4). Collectively, Fisetin NPs have promising therapeutic effects on lymphoma and leukemia, which are of great significant for clinical implications.

Fisetin orchestrates neuroinflammation resolution and facilitates spinal cord injury recovery through enhanced autophagy in pro-inflammatory glial cells

BACKGROUND

Neuroinflammation, a critical component of the secondary injury cascade post-spinal cord injury, involves the activation of pro-inflammatory cells and release of inflammatory mediators. Resolution of neuroinflammation is closely linked to cellular autophagy. This study investigates the potential of Fisetin, a natural anti-inflammatory compound, to ameliorate neuroinflammation and confer spinal cord injury protection through the regulation of autophagy in pro-inflammatory cells.

METHODS

Utilizing a rat T10 spinal cord injury model with distinct treatment groups (Sham, Fisetin-treated, and Fisetin combined with autophagy inhibitor), alongside in vitro models involving lipopolysaccharide (LPS)-stimulated microglial cell activation and co-culture with neurons, we employed techniques such as transcriptomic sequencing, histological assessments (immunofluorescence staining, etc.), molecular analyses (PCR, WB, ELISA, etc.), and behavioral evaluations to discern differences in neuroinflammation, autophagy, neuronal apoptosis, and neurological function recovery.

RESULTS

Fisetin significantly augmented autophagic activity in injured spinal cord tissue, crucially contributing to neurological function recovery in spinal cord-injured rats. Fisetin's autophagy-dependent effects were associated with a reduction in neuronal apoptosis at the injury site. The treatment reduced the population of CD68+ and iNOS+ cells, coupled with decreased pro-inflammatory cytokines IL-6 and TNF-α levels, through autophagy-dependent pathways. Fisetin pre-treatment attenuated LPS-induced pro-inflammatory polarization of microglial cells, with this protective effect partially blocked by autophagy inhibition. Fisetin-induced autophagy in the injured spinal cord and pro-inflammatory microglial cells was associated with significant activation of AMPK and inhibition of mTOR.

CONCLUSION

Fisetin orchestrates enhanced autophagy in pro-inflammatory microglial cells through the AMPK-mTOR signaling pathway, thereby mitigating neuroinflammation and reducing the apoptotic effects of neuroinflammation on neurons. This mechanistic insight significantly contributes to the protection and recovery of neurological function following spinal cord injury, underscoring the vital nature of Fisetin as a potential therapeutic agent.

Novel PEGylated cholephytosomes for targeting fisetin to breast cancer: in vitro appraisal and in vivo antitumoral studies

Fisetin (FIS) is a multifunctional bioactive flavanol that has been recently exploited as anticancer drug against various cancers including breast cancer. However, its poor aqueous solubility has constrained its clinical application. In the current work, fisetin is complexed for the first time with soy phosphatidylcholine in the presence of cholesterol to form a novel biocompatible phytosomal system entitled "cholephytosomes." To improve fisetin antitumor activity against breast cancer, stearylamine bearing cationic cholephytosomes (mPHY) were prepared and furtherly modified with hyaluronic acid (HPHY) to allow their orientation to cancer cells through their surface exposed phosphatidylserine and CD-44 receptors, respectively. In vitro characterization studies revealed promising physicochemical properties of both modified vesicles (mPHY and HPHY) including excellent FIS complexation efficiency (˷100%), improved octanol/water solubility along with a sustained drug release over 24 h. In vitro cell line studies against MDA-MB-231 cell line showed about 10- and 3.5-fold inhibition in IC50 of modified vesicles compared with free drug and conventional drug-phospholipid complex, respectively. Preclinical studies revealed that both modified cholephytosomes (mPHY and HPHY) had comparable cytotoxicity that is significantly surpassing free drug cytotoxicity. TGF-β1and its non-canonical related signaling pathway; ERK1/2, NF-κB, and MMP-9 were involved in halting tumorigenesis. Thus, tailoring novel phytosomal nanosystems for FIS could open opportunity for its clinical utility against cancer.

Effects and Mechanisms of Fisetin against Ischemia-reperfusion Injuries: A Systematic Review

BACKGROUND

Ischemia-reperfusion injury (IRI) is a well-known ailment that can disturb organ function.

OBJECTIVES

This systematic review study investigated fisetin's effects and possible mechanisms in attenuating myocardial, cerebral, renal, and hepatic IRIs.

METHODS

This systematic review included studies earlier than Sep 2023 by following the PRISMA statement 2020. After determining inclusion and exclusion criteria and related keywords, bibliographic databases, such as Cochrane Library, PubMed, Web of Science, Embase, and Scopus databases, were used to search the relevant studies. Studies were imported in End- Note X8, and the primary information was recorded in Excel.

RESULTS

Fisetin reduced reactive oxygen species (ROS) generation and upregulated antioxidant enzymes, such as superoxide dismutase (SOD), glutathione (GSH), catalase (CAT), and glutathione peroxidase (GPx), in ischemic tissues. Moreover, fisetin can attenuate oxidative stress by activating phosphoinositide-3-kinase-protein kinase B/Akt (PI3K/Akt) and nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathways. Fisetin has been indicated to prevent the activation of several pro-inflammatory signaling pathways, including NF-κB (Nuclear factor kappa-light-chain-enhancer of activated B cells) and MAPKs (Mitogen-activated protein kinases). It also inhibits the production of pro-inflammatory cytokines and enzymes like tumor necrosis factor-a (TNF-α), inducible-NO synthase (iNOS), cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), interleukin-1β (IL-1β), IL-1, and IL-6. Fisetin attenuates IRI by improving mitochondrial function, anti-apoptotic effects, promoting autophagy, and preserving tissues from histological changes induced by IRIs.

CONCLUSION

Fisetin, by antioxidant, anti-inflammatory, mitochondrial protection, promoting autophagy, and anti-apoptotic properties, can reduce cell injury due to myocardial, cerebral renal, and hepatic IRIs without any significant side effects.

Post-translational modification of CDK1-STAT3 signaling by fisetin suppresses pancreatic cancer stem cell properties

BACKGROUND

Pancreatic cancer stem cells (CSCs) promote pancreatic ductal adenocarcinoma (PDAC) tumorigenesis and chemoresistance. Cyclin-dependent kinase 1 (CDK1) plays an important role in tumor initiation in other tumors, but the function of CDK1 in PDAC remains unclear. Fisetin is a bioactive flavonoid with anti-tumor properties in multiple tumors, while its function in CSCs remains elusive.

RESULTS

In this study, we demonstrated that CDK1 was correlated with prognosis and was highly expressed in pancreatic cancer tissue and gemcitabine-resistant cells. Silencing CDK1 impaired tumor stemness and reduced a subset of CSCs. We found that fisetin blocked the kinase pocket domain of CDK1 and inhibited pancreatic CSC characteristics. Using acetylation proteomics analysis and phosphorylation array assay, we confirmed that fisetin reduced CDK1 expression and increased CDK1 acetylation at lysine 33 (K33), which resulted in the suppression of CDK1 phosphorylation. Silencing CDK1 or STAT3 suppressed tumor stemness properties, while overexpressing CDK1 or STAT3 showed the opposite effect. Mutation or acetylation of CDK1 at K33 weakened STAT3 phosphorylation at Y705, impairing the expression of stem-related genes and pancreatic cancer stemness. In addition, lack of histone deacetylase 3 (HDAC3), which deacetylates CDK1, contributed to weakening STAT3 phosphorylation by regulating the post-translational modification of CDK1, thereby decreasing the stemness of PDAC. Moreover, our results revealed that fisetin enhanced the effect of gemcitabine through eliminating a subpopulation of pancreatic CSCs by inhibiting the CDK1-STAT3 axis in vitro and in vivo.

CONCLUSION

Our findings highlight the role of post-translational modifications of CDK1-STAT3 signaling in maintaining cancer stemness of PDAC, and indicated that targeting the CDK1-STAT3 axis with inhibitors such as fisetin is a potential therapeutic strategy to diminish drug resistance and eliminate PDAC.

Fisetin induces apoptosis in human skin cancer cells through downregulating MTH1

Fisetin, a natural flavonoid molecule, has been shown to have anticancer properties against various malignancies. In this investigation, we discovered that Fisetin decreased cell viability of both the treated skin cancer cell lines A375 and A431 in a dose and time-dependent manner. The IC50 values ranging from 57.60 µM ± 6.59 to 41.70 µM ± 1.25 in A375 and 48.70 µM ± 5.49 to 33.67 µM ± 1.03 for A431 at the observed time ranging between 24 h to 72 h of treatment remained quite enthusiastic when compared with the normal HEK 293 cells. Fisetin significantly decreased colony formation and migratory ability of the cancer cells. Flow cytometry analysis revealed that Fisetin significantly restricted the progression of skin cancer cells in the G0/G1 phase of the cell cycle and induced cells to undergo apoptosis by increasing reactive oxygen species, decreasing mitochondrial membrane potential, and elevating the count of early and late apoptotic cells. Our in silico studies of molecular docking followed by molecular dynamics simulation found that the interactions and stability of MTH1 protein with Fisetin further showed a considerable binding affinity for MTH1 (-11.4 kcal/mol) and developed stable complexes maintained throughout 100 ns trajectories. Our western blot analysis endorsed this. We found that Fisetin downregulated the expression levels of MTH1 also in addition, it played a crucial role in regulation of apoptotic events in cancer cells. We therefore, conclude that Fisetin anticancer properties against skin cancer cells are mediated through MTH1 inhibition followed by ATM and P53 upregulation.Communicated by Ramaswamy H. Sarma.

Self-assembled fisetin-phospholipid complex: Fisetin-integrated phytosomes for effective delivery to breast cancer

Nowadays, fisetin (FIS) is extensively studied as potent anticancer surrogate with a multitarget actions against various types of cancers including breast cancer. However, its poor aqueous solubility handicapped its clinical utility. The current work endeavored, for the first time, to develop FIS phytosomes (FIS-PHY) for improving its physicochemical properties and subsequently its anticancer activity. Optimization of FIS- phytosomes involved different preparation techniques (Thin film hydration and ethanol injection) and different FIS: phospholipid molar ratios (1:1, 1:2, and 1:3). Complex formation was confirmed by complexation efficiency, infrared spectroscopy (IR), solubility studies and transmission electron microscope. The optimized FIS-PHY of 1:1 M ratio (PHY1) exhibited a nanometric particle size of 233.01 ± 9.46 nm with homogenous distribution (PDI = 0.27), negative zeta potential of - 29.41 mV, 100% complexation efficiency and controlled drug release over 24 h. In-vitro cytotoxicity study showed 2.5-fold decrease in IC50 of PHY1 compared with free FIS. Also, pharmacodynamic studies confirmed the promoted cytotoxicity of PHY1 against breast cancer through modulating TGF-β1/MMP-9 molecular pathways of tumorigenesis. Overall, overcoming FIS drawbacks were successfully achieved through development of innovative biocompatible phytosomal system.

Senolytic and senomorphic interventions to defy senescence-associated mitochondrial dysfunction

The accumulation of senescent cells in the aging individual is associated with an increase in the occurrence of age-associated pathologies that contribute to poor health, frailty, and mortality. The number and type of senescent cells is viewed as a contributor to the body's senescence burden. Cellular models of senescence are based on induction of senescence in cultured cells in the laboratory. One type of senescence is triggered by mitochondrial dysfunction. There are several indications that mitochondria defects contribute to body aging. Senotherapeutics, targeting senescent cells, have been shown to induce their lysis by means of senolytics, or repress expression of their secretome, by means of senomorphics, senostatics or gerosuppressors. An outline of the mechanism of action of various senotherapeutics targeting mitochondria and senescence-associated mitochondria dysfunction will be here addressed. The combination of geroprotective interventions together with senotherapeutics will help to strengthen mitochondrial energy metabolism, biogenesis and turnover, and lengthen the mitochondria healthspan, minimizing one of several molecular pathways contributing to the aging phenotype.

Senolytic Flavonoids Enhance Type-I and Type-II Cell Death in Human Radioresistant Colon Cancer Cells through AMPK/MAPK Pathway

Resistance to cancer therapies remains a clinical challenge and an unsolved problem. In a previous study, we characterized a new colon cancer cell line, namely HT500, derived from human HT29 cells and resistant to clinically relevant levels of ionizing radiation (IR). Here, we explored the effects of two natural flavonoids, quercetin (Q) and fisetin (F), well-known senolytic agents that inhibit genotoxic stress by selectively removing senescent cells. We hypothesized that the biochemical mechanisms responsible for the radiosensitising effects of these natural senolytics could intercept multiple biochemical pathways of signal transduction correlated to cell death resistance. Radioresistant HT500 cells modulate autophagic flux differently than HT29 cells and secrete pro-inflammatory cytokines (IL-8), commonly associated with senescence-related secretory phenotypes (SASP). Q and F inhibit PI₃K/AKT and ERK pathways, which promote p16^INK4 stability and resistance to apoptosis, but they also activate AMPK and ULK kinases in response to autophagic stress at an early stage. In summary, the combination of natural senolytics and IR activates two forms of cell death: apoptosis correlated to the inhibition of ERKs and lethal autophagy dependent on AMPK kinase. Our study confirms that senescence and autophagy partially overlap, share common modulatory pathways, and reveal how senolytic flavonoids can play an important role in these processes.

Targeting cellular senescence with senotherapeutics: senolytics and senomorphics

The concept of geroscience is that since ageing is the greatest risk factor for many diseases and conditions, targeting the ageing process itself will have the greatest impact on human health. Of the hallmarks of ageing, cellular senescence has emerged as a druggable therapeutic target for extending healthspan in model organisms. Cellular senescence is a cell state of irreversible proliferative arrest driven by different types of stress, including oncogene-induced stress. Many senescent cells (SnCs) develop a senescent-associated secretory phenotype (SASP) comprising pro-inflammatory cytokines, chemokines, proteases, bioactive lipids, inhibitory molecules, extracellular vesicles, metabolites, lipids and other factors, able to promote chronic inflammation and tissue dysfunction. SnCs up-regulate senescent cell anti-apoptotic pathways (SCAPs) that prevent them from dying despite the accumulation of damage to DNA and other organelles. These SCAPs and other pathways altered in SnCs represent therapeutic targets for the development of senotherapeutic drugs that induce selective cell death of SnCs, specifically termed senolytics or suppress markers of senescence, in particular the SASP, termed senomorphics. Here, we review the current state of the development of senolytics and senomorphics for the treatment of age-related diseases and disorders and extension of healthy longevity. In addition, the challenges of documenting senolytic and senomorphic activity in pre-clinical models and the current state of the clinical application of the different senotherapeutics will be discussed.

In Vitro and In Vivo Evaluation of the Effectiveness and Safety of Amygdalin as a Cancer Therapy

Cancer is one of the most important causes of death worldwide. Several studies have shown the efficacy of apricot kernel seed as a cancer therapy due to the presence of amygdalin. These studies have demonstrated amygdalin's cytotoxicity, antioxidant activity, and apoptosis in vitro using human cancer cell lines. However, no studies have demonstrated their cancer activity in vivo. The aim of this study is to develop an amygdalin-loaded niosomes (ALN) gel formulation as a drug delivery system in order to investigate the selectivity, efficacy, and toxicity of amygdalin as a cancer therapy in vivo using the 7,12-dimethylbenz (a) anthracene (DMBA) carcinoma rat model. Based on pre-formulation studies, the ALN formulation composed of Tween 60: cholesterol: dihexadecyl phosphate in a molar ratio of 1:2:0.1 was chosen as an optimum formulation because it has a percent of EE of 66.52% with a particle size of 269.3 nm and a reflux of 3.54 µg.cm^-2.h^-1. The ALN gel formulation was integrated into carbopol gel to be evaluated in vivo. Compared to DMBA control, treatment with ALN gel showed a reduction in the carcinoma volume and in the hyperplasia of the epidermis with no signs of edema. In conclusion, the ALN gel formulation could be an efficient cancer therapy.

The neuroprotective effects of fisetin, a natural flavonoid in neurodegenerative diseases: Focus on the role of oxidative stress

Oxidative stress (OS) disrupts the chemical integrity of macromolecules and increases the risk of neurodegenerative diseases. Fisetin is a flavonoid that exhibits potent antioxidant properties and protects the cells against OS. We have viewed the NCBI database, PubMed, Science Direct (Elsevier), Springer-Nature, ResearchGate, and Google Scholar databases to search and collect relevant articles during the preparation of this review. The search keywords are OS, neurodegenerative diseases, fisetin, etc. High level of ROS in the brain tissue decreases ATP levels, and mitochondrial membrane potential and induces lipid peroxidation, chronic inflammation, DNA damage, and apoptosis. The subsequent results are various neuronal diseases. Fisetin is a polyphenolic compound, commonly present in dietary ingredients. The antioxidant properties of this flavonoid diminish oxidative stress, ROS production, neurotoxicity, neuro-inflammation, and neurological disorders. Moreover, it maintains the redox profiles, and mitochondrial functions and inhibits NO production. At the molecular level, fisetin regulates the activity of PI3K/Akt, Nrf2, NF-κB, protein kinase C, and MAPK pathways to prevent OS, inflammatory response, and cytotoxicity. The antioxidant properties of fisetin protect the neural cells from inflammation and apoptotic degeneration. Thus, it can be used in the prevention of neurodegenerative disorders.

Long non-coding RNAs regulated NF-κB signaling in cancer metastasis: Micromanaging by not so small non-coding RNAs

Cancer metastasis is a major reason for the cancer-associated deaths and a role of long non-coding RNAs (lncRNAs) in cancer metastasis is increasingly being realized. Among the many oncogenic pathways, NF-κB signalling's involvement in cancer metastasis as a key inflammation-regulatory transcription factor has been a subject of interest for long time. Accumulating data from in vitro as well as in vivo studies along with analysis of clinical cancer tissues points to regulation of NF-κB signalling by lncRNAs with implications toward the onset of cancer metastasis. LncRNAs FOXD2-AS1, KRT19P3 and the NF-κB interacting lncRNA (NKILA) associate with lymph node metastasis and poor prognosis of individual cancers. The role of epithelial-mesenchymal transition (EMT) in cancer metastasis is well known. EMT is regulated by NF-κB and regulation of NF-κB/EMT-induced metastasis by lncRNAs remains a hot topic of research with indications for such roles of lncRNAs MALAT1, SNHG15, CRNDE and AC007271.3. Among the many lncRNAs, NKILA stands out as the most investigated lncRNA for its regulation of NF-κB. This tumor suppressive lncRNA has been reported downregulated in clinical samples representing different human cancers. Mechanistically, NKILA has been consistently shown to inhibit NF-κB activation via inhibition of IκBα phosphorylation and the resulting suppression of EMT. NKILA is also a target of natural anticancer compounds. Given the importance of NF-κB as a master regulatory transcription factor, lncRNAs, as the modulators of NF-κB signaling, can provide alternate targets for metastatic cancers with constitutively active NF-κB.

Flavonoids regulate tumor-associated macrophages - From structure-activity relationship to clinical potential (Review)

In recent years, the strategy for tumor therapy has changed from focusing on the direct killing effect of different types of therapeutic agents on cancer cells to the new mainstream of multi-mode and -pathway combined interventions in the microenvironment of the developing tumor. Flavonoids, with unique tricyclic structures, have diverse and extensive immunomodulatory and anti-cancer activities in the tumor microenvironment (TME). Tumor-associated macrophages (TAMs) are the most abundant immunosuppressive cells in the TME. The regulation of macrophages to fight cancer is a promising immunotherapeutic strategy. This study covers the most comprehensive cognition of flavonoids in regulating TAMs so far. Far more than a simple list of studies, we try to dig out evidence of crosstalk at the molecular level between flavonoids and TAMs from literature, in order to discuss the most relevant chemical structure and its possible relationship with the multimodal pharmacological activity, as well as systematically build a structure-activity relationship between flavonoids and TAMs. Additionally, we point out the advantages of the macro-control of flavonoids in the TME and discuss the potential clinical implications as well as areas for future research of flavonoids in regulating TAMs. These results will provide hopeful directions for the research of antitumor drugs, while providing new ideas for the pharmaceutical industry to develop more effective forms of flavonoids.

New Trends in Aging Drug Discovery

Aging is considered the main risk factor for many chronic diseases that frequently appear at advanced ages. However, the inevitability of this process is being questioned by recent research that suggests that senescent cells have specific features that differentiate them from younger cells and that removal of these cells ameliorates senescent phenotype and associated diseases. This opens the door to the design of tailored therapeutic interventions aimed at reducing and delaying the impact of senescence in life, that is, extending healthspan and treating aging as another chronic disease. Although these ideas are still far from reaching the bedside, it is conceivable that they will revolutionize the way we understand aging in the next decades. In this review, we analyze the main and well-validated cellular pathways and targets related to senescence as well as their implication in aging-associated diseases. In addition, the most relevant small molecules with senotherapeutic potential, with a special emphasis on their mechanism of action, ongoing clinical trials, and potential limitations, are discussed. Finally, a brief overview of alternative strategies that go beyond the small molecule field, together with our perspectives for the future of the field, is provided.

Isolation and Identification of Fisetin: An Antioxidative Compound Obtained from Rhus verniciflua Seeds

The goal of this study was to provide basic data for the development of functional food and health materials for Rhus verniciflua (R. verniciflua) seeds. We investigated an antioxidative compound obtained from these seeds. Solvent fractionation was carried out on a 50%-ethanol extract of the seeds. The DPPH and ABTS radical-scavenging activity and superoxide dismutase (SOD) activity were measured, and high antioxidant activity was seen in the ethyl acetate fraction. The antioxidant compounds in the ethyl acetate fraction were isolated using silica-gel column chromatography by adjusting the solvent between chloroform and methanol. Fraction numbers 2–7 showed activity of more than 50%. Next, primary column chromatography was used to mix and concentrate the fractions that demonstrated antioxidant activity. The fractions were then subjected to secondary column chromatography to obtain subfraction 4, which showed high antioxidant activity. The separation of subfraction 4 was then performed using high-performance liquid chromatography (HPLC). Three peaks were identified and peak number 2 was judged to be the primary antioxidative compound, which was then isolated by pure separation. Finally, the purified subfraction peak number 2 was identified as a fisetin compound by liquid chromatography–mass spectrometry (LC–MS), nuclear magnetic resonance (NMR), and HPLC.

Identification and characterization of two Isatis indigotica O-methyltransferases methylating C-glycosylflavonoids

Isatis indigotica accumulates several active substances, including C-glycosylflavonoids, which have important pharmacological activities and health benefits. However, enzymes catalyzing the methylation step of C-glycosylflavonoids in I. indigotica remain unknown. In this study, three O-methyltransferases (OMTs) were identified from I. indigotica that have the capacity for O-methylation of the C-glycosylflavonoid isoorientin. The Type II OMTs IiOMT1 and IiOMT2 efficiently catalyze isoorientin to form isoscoparin, and decorate one of the aromatic vicinal hydroxyl groups on flavones and methylate the C6, C8, and 3'-hydroxyl positions to form oroxylin A, wogonin, and chrysoeriol, respectively. However, the Type I OMT IiOMT3 exhibited broader substrate promiscuity and methylated the C7 and 3'-hydroxyl positions of flavonoids. Further site-directed mutagenesis studies demonstrated that five amino acids of IiOMT1/IiOMT2 (D121/D100, D173/D149, A174/A150R, N200/N176, and D248/D233) were critical residues for their catalytic activity. Additionally, only transient overexpression of Type II OMTs IiOMT1 and IiOMT2 in Nicotiana benthamiana significantly increased isoscoparin accumulation, indicating that the Type II OMTs IiOMT1 and IiOMT2 could catalyze the methylation step of C-glycosylflavonoid, isoorientin at the 3'-hydroxyl position. This study provides insights into the biosynthesis of methylated C-glycosylflavonoids, and IiOMTs could be promising catalysts in the synthesis of bioactive compounds.

The Role of m6A RNA Methylation in Cancer: Implication for Nature Products Anti-Cancer Research

N6-methyladenosine (m6A) RNA methylation is identified as the most common, abundant and reversible RNA epigenetic modification in messenger RNA (mRNA) and non-coding RNA, especially within eukaryotic messenger RNAs (mRNAs), which post-transcriptionally directs many important processes of RNA. It has also been demonstrated that m6A modification plays a pivotal role in the occurrence and development of tumors by regulating RNA splicing, localization, translation, stabilization and decay. Growing number of studies have indicated that natural products have outstanding anti-cancer effects of their unique advantages of high efficiency and minimal side effects. However, at present, there are very few research articles to study and explore the relationship between natural products and m6A RNA modification in tumorigenesis. m6A is dynamically deposited, removed, and recognized by m6A methyltransferases (METTL3/14, METTL16, WTAP, RBM15/15B, VIRMA, CBLL1, and ZC3H13, called as “writers”), demethylases (FTO and ALKBH5, called as “erasers”), and m6A-specific binding proteins (YTHDF1/2/3, YTHDC1/2, IGH2BP1/2/3, hnRNPs, eIF3, and FMR1, called as “readers”), respectively. In this review, we summarize the biological function of m6A modification, the role of m6A and the related signaling pathway in cancer, such as AKT, NF-kB, MAPK, ERK, Wnt/β-catenin, STAT, p53, Notch signaling pathway, and so on. Furthermore, we reviewed the current research on nature products in anti-tumor, and further to get a better understanding of the anti-tumor mechanism, thus provide an implication for nature products with anti-cancer research by regulating m6A modification in the future.

ZC3H13-mediated N6-methyladenosine modification of PHF10 is impaired by fisetin which inhibits the DNA damage response in pancreatic cancer

DNA damage repair is a major barrier for chemotherapy efficacy of pancreatic ductal adenocarcinoma (PDAC), including the efficacy of platinum-based and gemcitabine/nab-paclitaxel treatments. N6-methyladenosine modifications (m6A) have recently been reported to play a role in homologous recombination (HR) repair of DNA double strand breaks (DSBs); however, the mechanism of action remains unknown. Our previous work indicated that fisetin may be a promising anti-tumour agent that induces DNA damage. In this study, we reported that fisetin induced DSBs and suppressed HR repair through m6A modification in PDAC cells. The m6A writer ZC3H13 and PHF10, which is a subunit of the PBAF chromatin remodelling complex, were identified as the main molecules affected by fisetin treatment. To our knowledge, it's the first time that PHF10 was found and involved in the DNA damage response. PHF10 loss-of-function resulted in elevated recruitment of γH2AX, RAD51, and 53BP1 to DSB sites and decreased HR repair efficiency. Moreover, ZC3H13 knockdown downregulated the m6A methylation of PHF10 and decreased PHF10 translation in a YTHDF1-dependent manner. In conclusion, our study demonstrates that fisetin enhanced DSBs via ZC3Hl3-mediated m6A modification of PHF10, which may provide insight into novel therapeutic approaches for PDAC.

Fisetin promotes osteoblast differentiation and osteogenesis through GSK-3β phosphorylation at Ser9 and consequent β-catenin activation, inhibiting osteoporosis

Fisetin is a bioactive flavonol that inhibits osteoclastogenesis and promotes osteoblastogenesis. However, the osteogenic activity of fisetin needs to be comprehensively elucidated. In the present study, we observed that fisetin significantly increased alkaline phosphatase (ALP) activity and bone mineralization in MC3T3-E1 preosteoblasts, accompanied by a significant increase in runt-related transcription factor 2 (RUNX2), ALP, collagen type Ⅰ alpha 1 (Col1α1), osterix (OSX), osteocalcin (OCN), and bone morphogenetic protein 4 (BMP4) expression. Furthermore, fisetin promoted vertebral formation in zebrafish larvae, with the highest fisetin concentration comparable with that observed in β-glycerophosphate treatment. Fisetin also inhibited prednisolone (PDS)-induced anti-osteoblastic genes, including nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), tartrate-resistant acid phosphatase-6 (ACP6), dendritic cell-specific transmembrane protein (DC-STAMP), and cathepsin K (CTSK). Fisetin potently mitigated the PDS-induced inhibition of ALP activity and bone mineralization, as well as vertebral resorption in zebrafish larvae. Moreover, we confirmed that fisetin-induced osteogenic effect was activated through phosphorylation of glycogen synthase kinase-3β (GSK-3β) at Ser9, consequently releasing β-catenin from the destructive complex to promote its nuclear translocation. β-Catenin inhibition by FH535 and the stabilization of GSK-3β by DOI hydrochloride remarkably inhibited fisetin-induced osteogenic activities, indicating that the GSK-3β/β-catenin signaling pathway plays a vital role in fisetin-induced osteogenesis. Collectively, our findings suggest that fisetin stimulates osteogenic activity and could be used as an effective strategy to prevent bone resorption.

Urolithins: The Gut Based Polyphenol Metabolites of Ellagitannins in Cancer Prevention, a Review

Cancer as a disease continues to ravage the world population without regard to sex, age, and race. Due to the growing number of cases worldwide, cancer exerts a significant negative impact on global health and the economy. Interestingly, chemotherapy has been used over the years as a therapeutic intervention against cancer. However, high cost, resistance, and toxic by-effects to treatment have overshadowed some of its benefits. In recent times, efforts have been ongoing in searching for anticancer therapeutics of plant origin, focusing on polyphenols. Urolithins are secondary polyphenol metabolites derived from the gut microbial action on ellagitannins and ellagic acid-rich foods such as pomegranate, berries, and nuts. Urolithins are emerging as a new class of anticancer compounds that can mediate their cancer-preventive activities through cell cycle arrest, aromatase inhibition, induction of apoptosis, tumor suppression, promotion of autophagy, and senescence, transcriptional regulation of oncogenes, and growth factor receptors. In this review, we discussed the growing shreds of evidence supporting these secondary phenolic metabolites' anticancer properties. Furthermore, we have pointed out some of the future directions needed to establish urolithins as anticancer agents.

Fisetin Alleviates Neointimal Hyperplasia via PPARγ/PON2 Antioxidative Pathway in SHR Rat Artery Injury Model

The phenotypic transformation of proliferation and migration in vascular smooth muscle cells (VSMCs) from media to intima is the basic pathology of neointimal hyperplasia after angioplasty in hypertensive patients. Angiotensin II (AngII) stimulates oxidative stress in VSMC, inducing VSMC proliferation and migration, which is a critical factor in both developments of hypertension and angioplasty-induced arterial restenosis. Fisetin, a plant flavonoid polyphenol, has been reported to be antioxidative and potent senolytic. It is unknown whether fisetin would inhibit neointimal hyperplasia. Therefore, we investigated the role of fisetin in neointimal formation in vitro and in vivo. The rat thoracic aortic smooth muscle cells (A10 cells) stimulated by AngII were used as the in vitro neointimal hyperplasia model, where AngII significantly induced the proliferation and migration in A10 cells. We found that fisetin could dose-dependently inhibit the effect of AngII via inducing the expression of an antioxidant, paraoxonase-2 (PON2), whose overexpression could inhibit the proliferation and migration of A10 cells and downexpression by siRNA had the opposite effect. Furthermore, we found the mechanism of fisetin's inducing PON2 expression involved PPARγ. Rosiglitazone, a PPARγ agonist, could increase PON2 expression in A10 cells, while the PPARγ inhibitor prevented the effect of fisetin on PON2. The in vivo neointimal hyperplasia model was established 2 weeks after the carotid artery balloon injury in SHR rats. Administration of fisetin (ip 3 mg/kg daily for 2 weeks) right after the injury significantly increased PON2 expression in the artery, inhibiting ROS production, and efficiently reduced carotid neointimal hyperplasia. These results indicate that fisetin increases the expression of antioxidant PON2 via activation of PPARγ, reducing oxidative stress, inhibiting VSMC proliferation and migration, and alleviates neointimal hyperplasia after intimal injury. PON2 may be a potential therapeutic target to reduce arterial remodeling after angioplasty in hypertensive patients.

The Interaction of the Flavonoid Fisetin with Human Glutathione Transferase A1-1

Glutathione transferases (GSTs) are a family of Phase II detoxification enzymes that are involved in the development of the multidrug resistance (MDR) mechanism in cancer cells and therefore affect the clinical outcome of cancer chemotherapy. The discovery of nontoxic natural compounds as inhibitors for GSTs is a promising approach for chemosensitizing and reversing MDR. Fisetin (7,3′,4′-flavon-3-ol) is a plant flavonol present in many plants and fruits. In the present work, the interaction of fisetin with human glutathione transferase A1-1 (hGSTA1-1) was investigated. Kinetic analysis revealed that fisetin is a reversible inhibitor for hGSTA1-1 with IC₅₀ 1.2 ± 0.1 μΜ. It functions as a mixed-type inhibitor toward glutathione (GSH) and as a noncompetitive inhibitor toward the electrophile substrate 1-chloro-2,4-dinitrobenzene (CDNB). In silico molecular modeling and docking predicted that fisetin binds at a distinct location, in the solvent channel of the enzyme, and occupies the entrance of the substrate-binding sites. Treatment of proliferating human epithelial colorectal adenocarcinoma cells (CaCo-2) with fisetin causes a reduction in the expression of hGSTA1-1 at the mRNA and protein levels. In addition, fisetin inhibits GST activity in CaCo-2 cell crude extract with an IC₅₀ (2.5 ± 0.1 μΜ), comparable to that measured using purified recombinant hGSTA1-1. These actions of fisetin can provide a synergistic role toward the suppression and chemosensitization of cancer cells. The results of the present study provide insights into the development of safe and effective GST-targeted cancer chemosensitizers.

Synthesis, inverse docking-assisted identification and in vitro biological characterization of Flavonol-based analogs of fisetin as c-Kit, CDK2 and mTOR inhibitors against melanoma and non-melanoma skin cancers

Due to hurdles, including resistance, adverse effects, and poor bioavailability, among others linked with existing therapies, there is an urgent unmet need to devise new, safe, and more effective treatment modalities for skin cancers. Herein, a series of flavonol-based derivatives of fisetin, a plant-based flavonoid identified as an anti-tumorigenic agent targeting the mammalian targets of rapamycin (mTOR)-regulated pathways, were synthesized and fully characterized. New potential inhibitors of receptor tyrosine kinases (c-KITs), cyclin-dependent kinase-2 (CDK2), and mTOR, representing attractive therapeutic targets for melanoma and non-melanoma skin cancers (NMSCs) treatment, were identified using inverse-docking, in vitro kinase activity and various cell-based anticancer screening assays. Eleven compounds exhibited significant inhibitory activities greater than the parent molecule against four human skin cancer cell lines, including melanoma (A375 and SK-Mel-28) and NMSCs (A431 and UWBCC1), with IC50 values ranging from 0.12 to < 15 μM. Seven compounds were identified as potentially potent single, dual or multi-kinase c-KITs, CDK2, and mTOR kinase inhibitors after inverse-docking and screening against twelve known cancer targets, followed by kinase activity profiling. Moreover, the potent compound F20, and the multi-kinase F9 and F17 targeted compounds, markedly decreased scratch wound closure, colony formation, and heightened expression levels of key cancer-promoting pathway molecular targets c-Kit, CDK2, and mTOR. In addition, these compounds downregulated Bcl-2 levels and upregulated Bax and cleaved caspase-3/7/8 and PARP levels, thus inducing apoptosis of A375 and A431 cells in a dose-dependent manner. Overall, compounds F20, F9 and F17, were identified as promising c-Kit, CDK2 and mTOR inhibitors, worthy of further investigation as therapeutics, or as adjuvants to standard therapies for the control of melanoma and NMSCs.

Antiangiogenic Activity of Flavonoids: A Systematic Review and Meta-Analysis

Abstract: An imbalance of angiogenesis contributes to many pathologies such as cancer, arthritis and retinopathy, hence molecules that can modulate angiogenesis are of considerable therapeutic importance. Despite many reports on the promising antiangiogenic properties of naturally occurring flavonoids, no flavonoids have progressed to the clinic for this application. This systematic review and meta-analysis therefore evaluates the antiangiogenic activities of a wide range of flavonoids and is presented in two sections. The first part of the study (Systematic overview) included 402 articles identified by searching articles published before May 2020 using ScienceDirect, PubMed and Web of Science databases. From this initial search, different classes of flavonoids with antiangiogenic activities, related pathologies and use of in vitro and/or in/ex vivo angiogenesis assays were identified. In the second part (Meta-analysis), 25 studies concerning the antiangiogenic evaluation of flavonoids using the in vivo chick chorioallantoic membrane (CAM) assay were included, following a targeted search on articles published prior to June 2020. Meta-analysis of 15 out of the 25 eligible studies showed concentration dependent antiangiogenic activity of six compared subclasses of flavonoids with isoflavones, flavonols and flavones being the most active (64 to 80% reduction of blood vessels at 100 µM). Furthermore, the key structural features required for the antiangiogenic activity of flavonoids were derived from the pooled data in a structure activity relationship (SAR) study. All in all, flavonoids are promising candidates for the development of antiangiogenic agents, however further investigations are needed to determine the key structural features responsible for their activity.

Implications of flavonoids as potential modulators of cancer neovascularity

PURPOSE

The formation of new blood vessels from previous ones, angiogenesis, is critical in tissue repair, expansion or remodeling in physiological processes and in various pathologies including cancer. Despite that, the development of anti-angiogenic drugs has great potential as the treatment of cancer faces many problems such as development of the resistance to treatment or an improperly selected therapy approach. An evaluation of predictive markers in personalized medicine could significantly improve treatment outcomes in many patients.

METHODS

This comprehensive review emphasizes the anticancer potential of flavonoids mediated by their anti-angiogenic efficacy evaluated in current preclinical and clinical cancer research.

RESULTS AND CONCLUSION

Flavonoids are important groups of phytochemicals present in common diet. Flavonoids show significant anticancer effects. The anti-angiogenic effects of flavonoids are currently a widely discussed topic of preclinical cancer research. Flavonoids are able to regulate the process of tumor angiogenesis through modulation of signaling molecules such as VEGF, MMPs, ILs, HIF or others. However, the evaluation of the anti-angiogenic potential of flavonoids within the clinical studies is not frequently discussed and is still of significant scientific interest.

YB-1: The key to personalised prostate cancer management?

Y-box-binding protein 1 (YB-1) is a DNA/RNA binding protein increasingly implicated in the regulation of cancer cell biology. Normally located in the cytoplasm, nuclear localisation in prostate cancer is associated with more aggressive, potentially treatment-resistant disease. This is attributed to the ability of YB-1 to act as a transcription factor for various target genes associated with androgen receptor signalling, survival, DNA repair, proliferation, invasion, differentiation, angiogenesis and hypoxia. This review aims to examine the clinical potential of YB-1 in the detection and therapeutic management of prostate cancer.

Protective effect of fisetin against subchronic chlorpyrifos-induced toxicity on oxidative stress biomarkers and neurobehavioral parameters in adult male albino mice

Chlorpyrifos (CPF), a chlorinated organophosphate insecticide that is widely used in agriculture and public health, has neurotoxic effects in animals. In addition to acetylcholinesterase inhibition, CPF has been shown to induce alterations such as oxidative stress and lipid peroxidation. Fisetin is a dietary flavonol that protects the brain tissue against oxidative stress by modulating the activity of antioxidant enzymes. This study was designed to investigate the protective role of fisetin against brain oxidative damages and neurobehavioral parameters induced by subchronic oral exposure to CPF in albino mice. Adult albino mice (males, n = 32, weighing 20 ~ 25 g) were assigned randomly into 4 groups and treated accordingly for 7 weeks as follows: Group 1(S/OIL): served as the control group and were given 2 ml/kg of soya oil; Group 2 (CPF): received CPF (6.6 mg/kg; 1/5th of the LD₅₀); Group 3 (FIS): fisetin (15 mg/kg) and Group 4 (FIS + CPF): received fisetin at 15 mg/kg, followed by CPF (6.6 mg/kg) 30 min later. Co-treatment with FIS + CPF mitigated the increase in brain malondialdehyde concentration (0.28 ± 0.02 nmol/mg) and orchestrated the increase in the activities of catalase (81.35 ± 7.26 µ/mg), superoxide dismutase (93.03 ± 6.63 IU/mL), glutathione peroxidase (68.76 ± 3.554 nmol/mL) and acetylcholinesterase (11.59 ± 0.72 nmol/min/mL) when compared to the CPF group. The result showed that deficits in motor strength and excitability scores induced by subchronic CPF were mitigated by fisetin administration. It was concluded that fisetin has a protective potential in mitigating against oxidative stress and damages in the brain tissues, induced by subchronic exposure to CPF in adult male albino mice.

Roles of Histone Deacetylases and Inhibitors in Anticancer Therapy

Histones are the main structural proteins of eukaryotic chromatin. Histone acetylation/ deacetylation are the epigenetic mechanisms of the regulation of gene expression and are catalyzed by histone acetyltransferases (HAT) and histone deacetylases (HDAC). These epigenetic alterations of DNA structure influence the action of transcription factors which can induce or repress gene transcription. The HATs catalyze acetylation and the events related to gene transcription and are also responsible for transporting newly synthesized histones from the cytoplasm to the nucleus. The activity of HDACs is mainly involved in silencing gene expression and according to their specialized functions are divided into classes I, II, III and IV. The disturbance of the expression and mutations of HDAC genes causes the aberrant transcription of key genes regulating important cancer pathways such as cell proliferation, cell-cycle regulation and apoptosis. In view of their role in cancer pathways, HDACs are considered promising therapeutic targets and the development of HDAC inhibitors is a hot topic in the search for new anticancer drugs. The present review will focus on HDACs I, II and IV, the best known inhibitors and potential alternative inhibitors derived from natural and synthetic products which can be used to influence HDAC activity and the development of new cancer therapies.

RNA-seq data analysis of stimulated hepatocellular carcinoma cells treated with epigallocatechin gallate and fisetin reveals target genes and action mechanisms

Hepatocellular carcinoma (HCC) is an essentially incurable inflammation-related cancer. We have previously shown by network analysis of proteomic data that the flavonoids epigallocatechin gallate (EGCG) and fisetin (FIS) efficiently downregulated pro-tumor cytokines released by HCC through inhibition of Akt/mTOR/RPS6 phospho-signaling. However, their mode of action at the global transcriptome level remains unclear. Herein, we endeavor to compare gene expression alterations mediated by these compounds through a comprehensive transcriptome analysis based on RNA-seq in HEP3B, a responsive HCC cell line, upon perturbation with a mixture of prototypical stimuli mimicking conditions of tumor microenvironment or under constitutive state.

Analysis of RNA-seq data revealed extended changes on HEP3B transcriptome imposed by test nutraceuticals. Under stimulated conditions, EGCG and FIS significantly modified, compared to the corresponding control, the expression of 922 and 973 genes, respectively, the large majority of which (695 genes), was affected by both compounds. Hierarchical clustering based on the expression data of shared genes demonstrated an almost identical profile in nutraceutical-treated stimulated cells which was virtually opposite in cells exposed to stimuli alone. Downstream enrichment analyses of the co-modified genes uncovered significant associations with cancer-related transcription factors as well as terms of Gene Ontology/Reactome Pathways and highlighted ECM dynamics as a nodal modulation point by nutraceuticals along with angiogenesis, inflammation, cell motility and growth. RNA-seq data for selected genes were independently confirmed by RT-qPCR.

Overall, the present systems approach provides novel evidence stepping up the mechanistic understanding of test nutraceuticals, thus rationalizing their clinical exploitation in new preventive/therapeutic modalities against HCC.

Preferential targeting cancer-related i-motif DNAs by the plant flavonol fisetin for theranostics applications

The relationship of i-motif DNAs with cancer has prompted the development of specific ligands to detect and regulate their formation. Some plant flavonols show unique fluorescence and anti-cancer properties, which suggest the utility of the theranostics approach to cancer therapy related to i-motif DNA. We investigated the effect of the plant flavonol, fisetin (Fis), on the physicochemical property of i-motif DNAs. Binding of Fis to the i-motif from the promoter region of the human vascular endothelial growth factor (VEGF) gene dramatically induced the excited state intramolecular proton transfer (ESIPT) reaction that significantly enhanced the intensity of the tautomer emission band of Fis. This unique response was due to the coincidence of the structural change from i-motif to the hairpin-like structure which is stabilized via putative Watson-Crick base pairs between some guanines within the loop region of the i-motif and cytosines in the structure. As a result, the VEGF i-motif did not act as a replication block in the presence of Fis, which indicates the applicability of Fis for the regulation of gene expression of VEGF. The fluorescence and biological properties of Fis may be utilised for theranostics applications for cancers related to a specific cancer-related gene, such as VEGF.

Cellular and molecular alterations induced by low‑dose fisetin in human chronic myeloid leukemia cells

The present study aimed to evaluate the cellular and molecular effects of low concentrations of the flavonoid, fisetin, on K562 human chronic myeloid leukemia cells, in the context of both potential anti-proliferative and anti-metastatic effects. Thiazolyl blue tetrazolium bromide assay, Trypan blue exclusion assay, Annexin V/propidium iodide test, cell cycle analysis, Transwell migration and invasion assays, the fluorescence staining of β-catenin and F-actin as well as reverse transcription-quantitative polymerase chain reaction were performed to achieve the research goal. Furthermore, the nature of the interaction between fisetin and arsenic trioxide in the K562 cells was analyzed according to the Chou-Talalay median-effect method. We found that low concentrations of fisetin had not only a negligible effect on the viability and apoptosis of the K562 cells, but also modulated the mRNA levels of selected metastatic-related markers, accompanied by an increase in the migratory and invasive properties of these cancer cells. Although some markers of cell death were significantly elevated in response to fisetin treatment, these were counterbalanced through anti-apoptotic and pro-survival signals. With decreasing concentrations of fisetin and arsenic trioxide, the antagonistic interactions between the 2 agents increased. On the whole, the findings of this study suggest that careful consideration should be taken when advising cancer patients to take fisetin as a dietary supplement and when considering fisetin as a potential candidate for the treatment of chronic myeloid leukemia. Further more detailed studies are required to confirm our findings.

Fisetin, a 3,7,3',4'-Tetrahydroxyflavone Inhibits the PI3K/Akt/mTOR and MAPK Pathways and Ameliorates Psoriasis Pathology in 2D and 3D Organotypic Human Inflammatory Skin Models

Psoriasis is a chronic immune-mediated skin disease that involves the interaction of immune and skin cells, and is characterized by cytokine-driven epidermal hyperplasia, deviant differentiation, inflammation, and angiogenesis. Because the available treatments for psoriasis have significant limitations, dietary products are potential natural sources of therapeutic molecules, which can repair the molecular defects associated with psoriasis and could possibly be developed for its management. Fisetin (3,7,3',4'-tetrahydroxyflavone), a phytochemical naturally found in pigmented fruits and vegetables, has demonstrated proapoptotic and antioxidant effects in several malignancies. This study utilized biochemical, cellular, pharmacological, and tissue engineering tools to characterize the effects of fisetin on normal human epidermal keratinocytes (NHEKs), peripheral blood mononuclear cells (PBMC), and CD4+ T lymphocytes in 2D and 3D psoriasis-like disease models. Fisetin treatment of NHEKs dose- and time-dependently induced differentiation and inhibited interleukin-22-induced proliferation, as well as activation of the PI3K/Akt/mTOR pathway. Fisetin treatment of TNF-α stimulated NHEKs also significantly inhibited the activation of p38 and JNK, but had enhanced effect on ERK1/2 (MAPK). In addition, fisetin treatment significantly decreased the secretion of Th1/Th-17 pro-inflammatory cytokines, particularly IFN-γ and IL-17A by 12-O-tetradecanolylphorbol 13-acetate (TPA)-stimulated NHEKs and anti-CD3/CD28-activated human PBMCs. Furthermore, we established the in vivo relevance of fisetin functions, using a 3D full-thickness human skin model of psoriasis (FTRHSP) that closely mimics in vivo human psoriatic skin lesions. Herein, fisetin significantly ameliorated psoriasis-like disease features, and decreased the production of IL-17 by CD4+ T lymphocytes co-cultured with FTRHSP. Collectively, our data identify the prodifferentiative, antiproliferative, and anti-inflammatory effects of fisetin, via modulation of the PI3K-Akt-mTOR and p38/JNK pathways and the production of cytokines in 2D and 3D human skin models of psoriasis. These results suggest that fisetin has a great potential to be developed as an effective and inexpensive agent for the treatment of psoriasis and other related inflammatory skin disorders.

Identification of a UDP-Glucosyltransferase favouring substrate- and regio-specific biosynthesis of flavonoid glucosides in Cyclocarya paliurus

Cyclocarya paliurus (Batalin) Iljinsk is a medicinal plant belonging to the Juglandaceae family, and its leaves are used for a traditional sweet herbal tea with bioactivity against obesity and hyperglycaemia in China. It contains various bioactive specialised metabolites, such as flavonoids, triterpenes and their glucosides, while no glycosyltransferases (GTs) have been reported in C. paliurus to date. Herein, we identified and cloned the first glucosyltransferase C. paliurus GT1. The expression profiles of C. paliurus GT1 showed very high expression in young leaves, callus and branches, but relatively low expression in old leaves and bark and no expression in root. The recombinant C. paliurus GT1 protein was heterologously expressed in Escherichia coli and exhibited catalytic activity towards multiple flavonoids favouring substrate- and regio-specific biosynthesis. Further enzyme assays indicated a preference for certain hydroxyl group glucosylation by C. paliurus GT1. C. paliurus GT1 actively catalysed the glucosylation of flavones and flavonols, but it was less active towards isoflavones, flavanones or triterpenes. C. paliurus GT1 was also able to catalyse the attachment of sugars to the thiol (S-) or amine (N-) sites on aromatic compounds but not on aliphatic compounds. Molecular docking and site-directed mutagenesis analyses indicated that A43F, V84P, and M201Y dramatically altered the regio-selectivity and activity, and the W283M mutation and deletion of the V309-D320 region enhanced the activity and the formation of disaccharides. Herein, we present the identification and characterization of the first multi-functional glucosyltransferase in C. paliurus and provide a basis for understanding the biosynthesis of flavonoid glucosides. C. paliurus GT1 could be utilized as a synthetic biology tool for the synthesis of O-, N-, or S-glucosylated natural/unnatural products.

Fisetin and 5-fluorouracil: Effective combination for PIK3CA-mutant colorectal cancer

The normal colon epithelium is transformed into its neoplastic counterpart through a series of genetic alterations in driver genes including activating mutations in PIK3CA. Treatment often involves surgery followed by 5-fluorouracil (5-FU) based therapy, which has limited efficiency and serious side effects. We sought to determine whether fisetin, a dietary flavonoid, alone or in combination with 5-FU affected tumorigenesis in the mammalian intestine. We first determined the effect of fisetin, 5-FU or their combination on PIK3CA-mutant and PIK3CA wild-type colon cancer cells by assessing cell viability, colony formation, apoptosis and effects on PI3K/AKT/mTOR signaling. Treatment of PIK3CA-mutant cells with fisetin and 5-FU reduced the expression of PI3K, phosphorylation of AKT, mTOR, its target proteins, constituents of mTOR signaling complex and this treatment increased the phosphorylation of AMPKα. We then determined whether fisetin and 5-FU together or singly affected tumorigenesis in Apc^Min/+ mice that also express constitutively active PI3K in the distal small intestine and colon. Tumor incidence was markedly lower in fisetin-treated FC¹ 3K¹ Apc^Min/+ mice that also express constitutively active PI3K in distal small intestine and colon, as compared to control animals, indicating that fisetin is a strong preventive agent. In addition, the combination of fisetin and 5-FU also reduced the total number of intestinal tumors. Fisetin could be used as a preventive agent plus an adjuvant with 5-FU for the treatment of PIK3CA-mutant colorectal cancer.

Epithelial-mesenchymal transition as a target for botanicals in cancer metastasis

BACKGROUND

The plant kingdom represents an unlimited source of phytotherapeutics with promising perspectives in the field of anticancer drug discovery.

PURPOSE

In this view, epithelial-mesenchymal transition (EMT) represents a novel and major target in anticancer therapy. Therefore, this narrative review aims to provide an updated overview on the bioactive phytochemicals with anti-EMT activity.

CONCLUSION

Among the plant products reviewed, phenylpropanoids were the most investigated at preclinical phase, thus exhibiting a promising potential as anticancer drugs, though an evidence-based clinical efficacy is still lacking.

Synthesis, Spectroscopic Study and Radical Scavenging Activity of Kaempferol Derivatives: Enhanced Water Solubility and Antioxidant Activity

Kaempferol (Kae) is a natural flavonoid with potent antioxidant activity, but its therapeutic use is limited by its low aqueous solubility. Here, a series of Kae derivatives were synthesized to improve Kae dissolution property in water and antioxidant activity. These compounds included sulfonated Kae (Kae-SO₃), gallium (Ga) complexes with Kae (Kae-Ga) and Kae-SO₃ (Kae-SO₃-Ga). The compound structures were characterized by high-resolution mass spectrometry (HRMS), nuclear magnetic resonance (NMR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and thermal methods (TG/DSC). The results showed that a sulfonic group (-SO₃) was successfully tethered on the C3' of Kae to form Kae-SO₃. And in the metal complexation, 4-CO and 3-OH of the ligand participated in the coordination with Ga(III). The metal-to-ligand ratio 1:2 was suggested for both complexes. Interestingly, Kae-SO₃-Ga was obviously superior to other compounds in terms of overcoming the poor water-solubility of free Kae, and the solubility of Kae-SO₃-Ga was about 300-fold higher than that of Kae-Ga. Furthermore, the evaluation of antioxidant activities in vitro was carried out for Kae derivatives by using α,α-diphenyl-β-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS) free radical scavenging. The results showed that Kae-SO₃-Ga was also optimal for scavenging free radicals in a dose-dependent manner. These data demonstrate that sulfonate kaempferol-gallium complex has a promising future as a potential antioxidant and as a potential therapeutic agent for further biomedical studies.

Fisetin targets YB-1/RSK axis independent of its effect on ERK signaling: insights from in vitro and in vivo melanoma models

The anti-proliferative activity of dietary flavonoid fisetin has been validated in various cancer models. Establishing its precise mechanism of action has proved somewhat challenging given the multiplicity of its targets. We demonstrated that YB-1 promotes epithelial-to-mesenchymal transition and its inhibition suppressed tumor cell proliferation and invasion. The p90 ribosomal S6 kinase (RSK), an important ERK effector, activates YB-1 to drive melanoma growth. We found that fisetin treatment of monolayer/3-D melanoma cultures resulted in YB-1 dephosphorylation and reduced transcript levels. In parallel, fisetin suppressed mesenchymal markers and matrix-metalloproteinases in melanoma cells. Data from cell-free/cell-based systems indicated that fisetin inhibited RSK activity through binding to the kinase. Affinity studies for RSK isoforms evaluated stronger interaction for RSK2 than RSK1. Competition assays performed to monitor binding responses revealed that YB-1 and RSK2 do not compete, rather binding of fisetin to RSK2 promotes its binding to YB-1. Fisetin suppressed YB-1/RSK signaling independent of its effect on ERK, and reduced MDR1 levels. Comparable efficacy of fisetin and vemurafenib for inhibiting melanoma growth was noted albeit through divergent modulation of ERK. Our studies provide insight into additional modes of regulation through which fisetin interferes with melanoma growth underscoring its potential therapeutic efficacy in disease progression.

Flavonoids as Putative Epi-Modulators: Insight into Their Binding Mode with BRD4 Bromodomains Using Molecular Docking and Dynamics

Flavonoids are widely recognized as natural polydrugs, given their anti-inflammatory, antioxidant, sedative, and antineoplastic activities. Recently, different studies showed that flavonoids have the potential to inhibit bromodomain and extraterminal (BET) bromodomains. Previous reports suggested that flavonoids bind between the Z and A loops of the bromodomain (ZA channel) due to their orientation and interactions with P86, V87, L92, L94, and N140. Herein, a comprehensive characterization of the binding modes of fisetin and the biflavonoid, amentoflavone, is discussed. To this end, both compounds were docked with BET bromodomain 4 (BRD4) using four docking programs. The results were post-processed with protein–ligand interaction fingerprints. To gain further insight into the binding mode of the two natural products, the docking results were further analyzed with molecular dynamics simulations. The results showed that amentoflavone makes numerous contacts in the ZA channel, as previously described for flavonoids and kinase inhibitors. It was also found that amentoflavone can potentially make contacts with non-canonical residues for BET inhibition. Most of these contacts were not observed with fisetin. Based on these results, amentoflavone was experimentally tested for BRD4 inhibition, showing activity in the micromolar range. This work may serve as the basis for scaffold optimization and the further characterization of flavonoids as BET inhibitors.