NF-κB p65 repression by the sesquiterpene lactone, Helenalin, contributes to the induction of autophagy cell death

Telomerase: a nexus between cancer nanotherapy and circadian rhythm

Cancer represents a complex disease category defined by the unregulated proliferation and dissemination of anomalous cells within the human body. According to the GLOBOCAN 2020 report, the year 2020 witnessed the diagnosis of approximately 19.3 million new cases of cancer and 10.0 million individuals succumbed to the disease. A typical cell eventually becomes cancerous because of a long-term buildup of genetic instability and replicative immortality. Telomerase is a crucial regulator of cancer progression as it induces replicative immortality. In cancer cells, telomerase inhibits apoptosis by elongating the length of the telomeric region, which usually protects the genome from shortening. Many nanoparticles are documented as being available for detecting the presence of telomerase, and many were used as delivery systems to transport drugs. Furthermore, telomere homeostasis is regulated by the circadian time-keeping machinery, leading to 24-hour rhythms in telomerase activity and TERT mRNA expression in mammals. This review provides a comprehensive discussion of various kinds of nanoparticles used in telomerase detection, inhibition, and multiple drug-related pathways, as well as enlightens an imperative association between circadian rhythm and telomerase activity from the perspective of nanoparticle-based anticancer therapeutics.

Enhancing Ocular Surface in Dry Eye Disease Patients: A Clinical Evaluation of a Topical Formulation Containing Sesquiterpene Lactone Helenalin

The aim of this work was to assess the tolerability, safety, and efficacy of an ophthalmic topical formulation containing helenalin from Arnica montana and hyaluronic acid 0.4% (HA) in patients with mild-to-moderate Dry Eye Disease (DED) exhibiting positive Matrix Metalloproteinase 9 (MMP-9) test results. Tolerability and safety were evaluated in 24 healthy subjects. Participants were instructed to apply one drop of the formulation three times a day in the study eye, for 2 weeks, followed by a clinical follow-up of 21 days. Efficacy was studied in 48 DED patients randomized into Study (Group 1/receiving the studied formulation) or Control (Group 2/Receiving HA 0.4% eye lubricant) groups for 1 month. Assessments included an MMP-9 positivity test, conjunctival impression cytology (CIC), Ocular Surface Disease Index (OSDI), non-invasive film tear breakup time (NIBUT), non-invasive average breakup time (NIAvg-BUT), ocular surface staining, Schirmer's test, and meibomiography. A crossover design with an additional 1-month follow-up was applied to both groups. Healthy subjects receiving the studied formulation exhibited good tolerability and no adverse events. Regarding the efficacy study, Group 1 exhibited a statistically significant reduction in the MMP-9 positivity rate compared to Group 2 (p < 0.001). Both Group 1 and Group 2 exhibited substantial improvements in OSDI and NIBUT scores (p < 0.001). However, Group 1 demonstrated a significant improvement in NI-Avg-BUT and Schirmer's test scores (p < 0.001), whereas Group 2 did not (p > 0.05). Finally, after the crossover, the proportion of MMP-9-positive subjects in Group 1 increased from 25% to 91.6%, while Group 2 showed a significant decrease from 87.5% to 20.8%. Overall, the topical formulation containing sesquiterpene helenalin from Arnica montana and hyaluronic acid was well tolerated and exhibited a favorable safety profile. Our formulation reduces DED symptomatology and modulates the ocular surface inflammatory process; this is evidenced by the enhancement of CIC, the improvement of DED-related tear film status, and the reduction of the MMP-9 positivity rate.

New Visions on Natural Products and Cancer Therapy: Autophagy and Related Regulatory Pathways

Macroautophagy (autophagy) has been a highly conserved process throughout evolution and allows cells to degrade aggregated/misfolded proteins, dysfunctional or superfluous organelles and damaged macromolecules, in order to recycle them for biosynthetic and/or energetic purposes to preserve cellular homeostasis and health. Changes in autophagy are indeed correlated with several pathological disorders such as neurodegenerative and cardiovascular diseases, infections, cancer and inflammatory diseases. Conversely, autophagy controls both apoptosis and the unfolded protein response (UPR) in the cells. Therefore, any changes in the autophagy pathway will affect both the UPR and apoptosis. Recent evidence has shown that several natural products can modulate (induce or inhibit) the autophagy pathway. Natural products may target different regulatory components of the autophagy pathway, including specific kinases or phosphatases. In this review, we evaluated ~100 natural compounds and plant species and their impact on different types of cancers via the autophagy pathway. We also discuss the impact of these compounds on the UPR and apoptosis via the autophagy pathway. A multitude of preclinical findings have shown the function of botanicals in regulating cell autophagy and its potential impact on cancer therapy; however, the number of related clinical trials to date remains low. In this regard, further pre-clinical and clinical studies are warranted to better clarify the utility of natural compounds and their modulatory effects on autophagy, as fine-tuning of autophagy could be translated into therapeutic applications for several cancers.

Sesquiterpenoid lactones as potential anti-cancer agents: an update on molecular mechanisms and recent studies

Plants-based natural compounds are well-identified and recognized chemoprotective agents that can be used for primary and secondary cancer prevention, as they have proven efficacy and fewer side effects. In today's scenario, when cancer cases rapidly increase in developed and developing countries, the anti-cancerous plant-based compounds become highly imperative. Among others, the Asteraceae (Compositae) family's plants are rich in sesquiterpenoid lactones, a subclass of terpenoids with wide structural diversity, and offer unique anti-cancerous effects. These plants are utilized in folk medicine against numerous diseases worldwide. However, these plants are now a part of the modern medical system, with their sesquiterpenoid lactones researched extensively to find more effective and efficient cancer drug regimens. Given the evolving importance of sesquiterpenoid lactones for cancer research, this review comprehensively covers different domains in a spectrum of sesquiterpenoid lactones viz (i) Guaianolides (ii) Pseudoguaianolide (iii) Eudesmanolide (iv) Melampodinin A and (v) Germacrene, from important plants such as Cynara scolymus (globe artichoke), Arnica montana (wolf weeds), Spilanthes acmella, Taraxacum officinale, Melampodium, Solidago spp. The review, therefore, envisages being a helpful resource for the growth of plant-based anti-cancerous drug development.

Glutathione-Mediated Conjugation of Anticancer Drugs: An Overview of Reaction Mechanisms and Biological Significance for Drug Detoxification and Bioactivation

The effectiveness of many anticancer drugs depends on the creation of specific metabolites that may alter their therapeutic or toxic properties. One significant route of biotransformation is a conjugation of electrophilic compounds with reduced glutathione, which can be non-enzymatic and/or catalyzed by glutathione-dependent enzymes. Glutathione usually combines with anticancer drugs and/or their metabolites to form more polar and water-soluble glutathione S-conjugates, readily excreted outside the body. In this regard, glutathione plays a role in detoxification, decreasing the likelihood that a xenobiotic will react with cellular targets. However, some drugs once transformed into thioethers are more active or toxic than the parent compound. Thus, glutathione conjugation may also lead to pharmacological or toxicological effects through bioactivation reactions. My purpose here is to provide a broad overview of the mechanisms of glutathione-mediated conjugation of anticancer drugs. Additionally, I discuss the biological importance of glutathione conjugation to anticancer drug detoxification and bioactivation pathways. I also consider the potential role of glutathione in the metabolism of unsymmetrical bisacridines, a novel prosperous class of anticancer compounds developed in our laboratory. The knowledge on glutathione-mediated conjugation of anticancer drugs presented in this review may be noteworthy for improving cancer therapy and preventing drug resistance in cancers.

Domain fusion TLR2-4 enhances the autophagy-dependent clearance of Staphylococcus aureus in the genetic engineering goat

Staphylococcus aureus infections pose a potential threat to livestock production and public health. A novel strategy is needed to control S. aureus infections due to its adaptive evolution to antibiotics. Autophagy plays a key role in degrading bacteria for innate immune cells. In order to promote S. aureus clearance via Toll-like receptor (TLR)-induced autophagy pathway, the domain fusion TLR2-4 with the extracellular domain of TLR2, specific recognizing S. aureus, and transmembrane and intracellular domains of TLR4 is assembled, then the goat expressing TLR2-4 is generated. TLR2-4 substantially augments the removal of S. aureus within macrophages by elevating autophagy level. Phosphorylated JNK and ERK1/2 promote LC3-puncta in TLR2-4 macrophages during S. aureus-induced autophagy via MyD88 mediated the TAK1 signaling cascade. Meantime, the TRIF-dependent TBK1-TFEB-OPTN signaling is involved in TLR2-4-triggered autophagy after S. aureus challenge. Moreover, the transcript of ATG5 and ATG12 is significantly increased via cAMP-PKA-NF-κB signaling, which facilitates S. aureus-induced autophagy in TLR2-4 macrophages. Overall, the novel receptor TLR2-4 enhances the autophagy-dependent clearance of S. aureus in macrophages via TAK1/TBK1-JNK/ERK, TBK1-TFEB-OPTN, and cAMP-PKA-NF-κB-ATGs signaling pathways, which provide an alternative approach for resistant against S. aureus infection.

Arnica Montana L. Supercritical Extraction Optimization for Antibiotic and Anticancer Activity

Arnica montana L. flower heads are known for their antioxidant, antimicrobial, and anticancer activity. The aim of this work was to optimize the process of supercritical CO₂ extraction, to achieve high extraction yield and high content of biologically active components, and to confirm the antimicrobial and anticancer activity of the extract. The influence of pressure and temperature on the total phenolic content, antioxidant activity, and proanthocyanidin content was evaluated. The pressure and temperature were found to be interdependent. A temperature of 60°C and a pressure of 30 MPa resulted in a high extraction yield, antioxidant activity and phenolic content. The content of proanthocyanidins was highest at a pressure between 18 and 24 MPa. The extracts inhibited three different microorganisms successfully; Staphylococcus aureus, Escherichia coli and Candida albicans, at concentrations ranging from 0.1 to 5.16 mg/ml and showed anticancer activity decrease up to 85% at a concentration of 0.5 mg/ml.

Perindopril/Ambrosin Combination Mitigates Dextran Sulfate Sodium-Induced Colitis in Mice: Crosstalk between Toll-like Receptor 4, the Pro-Inflammatory Pathways, and SIRT1/PPAR-γ Signaling

Colitis is one of the inflammatory states that affect the intestinal wall and may even predispose to malignancy due to chronic irritation. Although the etiology of colitis is not yet fully explored, a combination of genetic and environmental factors is strongly incriminated. Perindopril is an angiotensin-converting enzyme inhibitor that is used for the management of a wide range of cardiovascular diseases. Ambrosin is a sesquiterpene lactone that was proven to have beneficial effects in disorders characterized by inflammatory nature. The objective of this study is to make a comparison between the effects of perindopril or ambrosin on dextran sulfate sodium (DSS)-induced colitis in mice and to explore the effect of their combination. The present findings indicate that each ambrosin or perindopril alone or in combination is able to ameliorate oxidative stress and suppress the proinflammatory pathways in the colonic tissues of DSS-treated mice via mechanisms related to toll-like receptor 4/nuclear factor kappa B signaling and modulation of peroxisome proliferator-activated receptor gamma/sirtuin-1 levels. In addition, each ambrosin or perindopril alone or in combination inhibits apoptosis and augments the mediators of autophagy in DSS-treated mice. These effects are reflected in the amelioration of the histopathological and electron microscopic changes in the colonic tissues. Interestingly, the most remarkable effects are those encountered with the perindopril/ambrosin combination compared to the groups treated with each of these agents alone. In conclusion, the perindopril/ambrosin combination might represent an effective modality for mitigation of the pathogenic events and the clinical sequelae of colitis.

Therapeutic Potential of Certain Terpenoids as Anticancer Agents: A Scoping Review

Cancer is a life-threatening disease and is considered to be among the leading causes of death worldwide. Chemoresistance, severe toxicity, relapse and metastasis are the major obstacles in cancer therapy. Therefore, introducing new therapeutic agents for cancer remains a priority to increase the range of effective treatments. Terpenoids, a large group of secondary metabolites, are derived from plant sources and are composed of several isoprene units. The high diversity of terpenoids has drawn attention to their potential anticancer and pharmacological activities. Some terpenoids exhibit an anticancer effect by triggering various stages of cancer progression, for example, suppressing the early stage of tumorigenesis via induction of cell cycle arrest, inhibiting cancer cell differentiation and activating apoptosis. At the late stage of cancer development, certain terpenoids are able to inhibit angiogenesis and metastasis via modulation of different intracellular signaling pathways. Significant progress in the identification of the mechanism of action and signaling pathways through which terpenoids exert their anticancer effects has been highlighted. Hence, in this review, the anticancer activities of twenty-five terpenoids are discussed in detail. In addition, this review provides insights on the current clinical trials and future directions towards the development of certain terpenoids as potential anticancer agents.

In vitro metabolism of helenalin and its inhibitory effect on human cytochrome P450 activity

Sesquiterpene lactone helenalin is used as an antiphlogistic in European and Chinese folk medicine. The pharmacological activities of helenalin have been extensively investigated, yet insufficient information exists about its metabolic properties. The objectives of the present study were (1) to investigate the in vitro NADPH-dependent metabolism of helenalin (5 and 100 µM) using human and rat liver microsomes and liver cytosol, (2) to elucidate the role of human cytochrome P450 (CYP) enzymes in its oxidative metabolism, and (3) to study the inhibition of human CYPs by helenalin. Five oxidative metabolites were detected in NADPH-dependent human and rat liver microsomal incubations, while two reduced metabolites were detected only in NADPH-dependent human microsomal and cytosolic incubations. In human liver microsomes, the main oxidative metabolite was 14-hydroxyhelenalin, and in rat liver microsomes 9-hydroxyhelenalin. The overall oxidation of helenalin was several times more efficient in rat than in human liver microsomes. In humans, CYP3A4 and CYP3A5 followed by CYP2B6 were the main enzymes responsible for the hepatic metabolism of helenalin. The extrahepatic CYP2A13 oxidized helenalin most efficiently among CYP enzymes, possessing the K_m value of 0.6 µM. Helenalin inhibited CYP3A4 (IC₅₀ = 18.7 µM) and CYP3A5 (IC₅₀ = 62.6 µM), and acted as a mechanism-based inhibitor of CYP2A13 (IC₅₀ = 1.1 µM, K_I = 6.7 µM, and k_inact = 0.58 ln(%)/min). It may be concluded that the metabolism of helenalin differs between rats and humans, in the latter its oxidation is catalyzed by hepatic CYP2B6, CYP3A4, CYP3A5, and CYP3A7, and extrahepatic CYP2A13.

Intervention of NF-Κb Signaling Pathway and Preventing Post-Operative Cognitive Dysfunction as Well as Neuronal Apoptosis

Background:

The Postoperative cognitive dysfunction (POCD) model was constructed by resection of the left hepatic lobe in aged mice to determine the behavioral effects of the POCD model in aged mice and the relationship between NF-κB and POCD in apoptosis and autophagy. Provide a theoretical basis for POCD prevention and treatment.

Methods:

This study was carried out in Ningbo No. 6 Hospital, Zhejiang, China, from Jun 2019 to Dec 2020. The POCD model was constructed after resection of the left extrahepatic lobe in aged mice and randomly divided into 6 groups: sham operation group, operation group (normal saline control group, solvent group, YC-1 group, PDTC group and 3-MA group). Related indicators of behavioral changes, neuronal inflammatory responses, apoptosis, and autophagy were examined.

Results:

The escape latency of the aged mice in the surgical group was significantly prolonged at three time points compared with the control group, and the number of insertions decreased significantly. Microglia are activated and the inflammatory response is increased, whereas PDTC has an inhibitory effect. It was demonstrated that apoptosis and necrosis of neurons can be induced by the NF-κb pathway, and autophagy can be promoted, whereas autophagy occurs before apoptosis.

Conclusion:

Activation of NF-κb pathway in neurons after POCD causes neuronal apoptosis and autophagy, and cognitive impairment occurs. PDTC, a NF-κb pathway inhibitor, can effectively reduce neuronal apoptosis induced by secondary brain injury after POCD. Necrosis, to protect the brain tissue.

Mechanism of Action of the Sesquiterpene Compound Helenalin in Rhabdomyosarcoma Cells

Rhabdomyosarcoma (RMS) is the most frequent soft tissue sarcoma in paediatric patients. Relapsed or refractory RMS shows very low 5-year survival rates, which urgently necessitates new chemotherapy agents. Herein, the sesquiterpene lactone, helenalin, was investigated as a new potential therapeutic agent against the embryonal RMS (eRMS) and alveolar RMS (aRMS) cells. We have evaluated in vitro antiproliferative efficacy of helenalin on RMS cells by the MTT and wound healing assay, and estimated several cell death pathways by flow cytometry, confocal microscopy and immunoblotting. It was shown that helenalin was able to increase reactive oxygen species levels, decrease mitochondrial membrane potential, trigger endoplasmic reticulum stress and deactivate the NF-κB pathway. Confirmation was obtained through the use of antagonistic compounds which alleviated the effects of helenalin in the corresponding pathways. Our findings demonstrate that oxidative stress is the pivotal mechanism of action of helenalin in promoting RMS cell death in vitro.

Sesquiterpene Lactones: Promising Natural Compounds to Fight Inflammation

Inflammation is a crucial and complex process that reestablishes the physiological state after a noxious stimulus. In pathological conditions the inflammatory state may persist, leading to chronic inflammation and causing tissue damage. Sesquiterpene lactones (SLs) are composed of a large and diverse group of highly bioactive plant secondary metabolites, characterized by a 15-carbon backbone structure. In recent years, the interest in SLs has risen due to their vast array of biological activities beneficial for human health. The anti-inflammatory potential of these compounds results from their ability to target and inhibit various key pro-inflammatory molecules enrolled in diverse inflammatory pathways, and prevent or reduce the inflammatory damage on tissues. Research on the anti-inflammatory mechanisms of SLs has thrived over the last years, and numerous compounds from diverse plants have been studied, using in silico, in vitro, and in vivo assays. Besides their anti-inflammatory potential, their cytotoxicity, structure–activity relationships, and pharmacokinetics have been investigated. This review aims to gather the most relevant results and insights concerning the anti-inflammatory potential of SL-rich extracts and pure SLs, focusing on their effects in different inflammatory pathways and on different molecular players.

Function-Oriented and Modular (+/-)-cis-Pseudoguaianolide Synthesis: Discovery of New Nrf2 Activators and NF-κB Inhibitors

Described herein is a function-oriented synthesis route and biological evaluation of pseudoguaianolide analogues. The 10-step synthetic route developed retains the topological complexity of the natural product, installs functional handles for late-stage diversification, and forges the key bioactive Michael acceptors early in the synthesis. The analogues were found to be low-micromolar Nrf2 activators and micromolar NF-κB inhibitors and dependent on the local environment of the Michael acceptor moieties.

Natural Sesquiterpene Lactones in the Prevention and Treatment of Inflammatory Disorders and cancer: A Systematic Study of this Emerging Therapeutic Approach based on Chemical and Pharmacological Aspect

Background and Introduction:

Sesquiterpene lactones are a class of secondary metabolite that contains sesquiterpenoids and lactone ring as pharmacophore moiety. A large group of bioactive secondary metabolites such as phytopharmaceuticals belong to this category. From the Asteraceae family-based medicinal plants, more than 5,000 sesquiterpene lactones have been reported so far. Sesquiterpene lactone-based pharmacophore moieties hold promise for broad-spectrum biological activities against cancer, inflammation, parasitic, bacterial, fungal, viral infection and other functional disorders. Moreover, these moiety based phytocompounds have been highlighted with a new dimension in the natural drug discovery program worldwide after the 2015 Medicine Nobel Prize achieved by the Artemisinin researchers.

Objective:

These bitter substances often contain an α, β-unsaturated-γ-lactone as a major structural backbone, which in recent studies has been explored to be associated with anti-tumor, cytotoxic, and anti-inflammatory action. Recently, the use of sesquiterpene lactones as phytomedicine has been increased. This study will review the prospect of sesquiterpene lactones against inflammation and cancer.

Methods:

Hence, we emphasized on the different features of this moiety by incorporating its structural diversity on biological activities to explore structure-activity relationships (SAR) against inflammation and cancer.

Results:

How the dual mode of action such as anti-inflammatory and anti-cancer has been exhibitedby these phytopharmaceuticals will be forecasted in this study. Furthermore, the correlation of anti-inflammatory and anti-cancer activity executed by the sesquiterpene lactones for fruitful phytotherapy will also be revealed in the present review in the milieu of pharmacophore activity relation and pharmacodynamics study as well.

Conclusion:

So, these metabolites are paramount in phytopharmacological aspects. The present discussion on the future prospect of this moiety based on the reported literature could be a guide for anti-inflammatory and anti-cancer drug discovery programs for the upcoming researchers.

Recent Advances in Characterizing Natural Products that Regulate Autophagy

Autophagy, an intricate response to nutrient deprivation, pathogen infection, Endoplasmic Reticulum (ER)-stress and drugs, is crucial for the homeostatic maintenance in living cells. This highly regulated, multistep process has been involved in several diseases including cardiovascular and neurodegenerative diseases, especially in cancer. It can function as either a promoter or a suppressor in cancer, which underlines the potential utility as a therapeutic target. In recent years, increasing evidence has suggested that many natural products could modulate autophagy through diverse signaling pathways, either inducing or inhibiting. In this review, we briefly introduce autophagy and systematically describe several classes of natural products that implicated autophagy modulation. These compounds are of great interest for their potential activity against many types of cancer, such as ovarian, breast, cervical, pancreatic, and so on, hoping to provide valuable information for the development of cancer treatments based on autophagy.

Terpenoids as Potential Geroprotectors

Terpenes and terpenoids are the largest groups of plant secondary metabolites. However, unlike polyphenols, they are rarely associated with geroprotective properties. Here we evaluated the conformity of the biological effects of terpenoids with the criteria of geroprotectors, including primary criteria (lifespan-extending effects in model organisms, improvement of aging biomarkers, low toxicity, minimal adverse effects, improvement of the quality of life) and secondary criteria (evolutionarily conserved mechanisms of action, reproducibility of the effects on different models, prevention of age-associated diseases, increasing of stress-resistance). The number of substances that demonstrate the greatest compliance with both primary and secondary criteria of geroprotectors were found among different classes of terpenoids. Thus, terpenoids are an underestimated source of potential geroprotectors that can effectively influence the mechanisms of aging and age-related diseases.

Protein methylation functions as the posttranslational modification switch to regulate autophagy

Studies over the past decades have elucidated the critical role of autophagy in human health and diseases. Although the processes of autophagy in the cytoplasm have been well studied, the posttranscriptional and epigenetic regulation mechanisms of autophagy are still poorly understood. Protein methylation, including histone methylation and non-histone protein methylation, is the most important type of posttranscriptional and epigenetic modification. Recent studies have shown that protein methylation is associated with effects on autophagosome formation, autophagy-related protein expression, and signaling pathway activation, but the details are still unclear. Thus, it is important to summarize the current status and discuss the future directions of research on protein methylation in the context of autophagy.

Costunolide Inhibits the Growth of OAW42-A Multidrug-Resistant Human Ovarian Cancer Cells by Activating Apoptotic and Autophagic Pathways, Production of Reactive Oxygen Species (ROS), Cleaved Caspase-3 and Cleaved Caspase-9

Background

Worldwide, ovarian cancer has a high mortality rate due to the difficulty in diagnosing early-stage disease and resistance to chemotherapy agents. Costunolide is a plant-derived sesquiterpene lactone with anti-oxidant properties. This study aimed to investigate the effects of costunolide on cell growth, apoptosis, autophagy, the production of reactive oxygen species (ROS), cleaved caspase-3, and cleaved caspase-9 on the multidrug-resistant ovarian cancer cell line, OAW42-A.

Material/Methods

The MTT assay determined the proliferation rate of OAW42-A multidrug-resistant ovarian cancer cells and the apoptosis rate was determined using propidium iodide (PI) staining. Autophagy was detected by measuring the expression of LC3 II. Fluorescence flow cytometry was used to measure the levels of reactive oxygen species (ROS) and the mitochondrial membrane potential. Protein expression of LC3 II, beclin 1, cleaved caspase-3, and cleaved caspase-9 were measured by Western blot.

Results

Costunolide treatment inhibited the growth of OAW42-A cells with an IC₅₀ of 25 μM, resulted in apoptotic cell death, increased the expression of Bax, and decreased the expression of Bcl-2. Confocal electron microscopy showed that costunolide induced autophagy in the OAW42-A cells. Western blot showed that costunolide treatment of OAW42-A cells increased the expression of the LC3 II, beclin 1, cleaved caspase-3, and cleaved caspase-9. Costunolide treatment significantly increased the levels of ROS and reduced the OAW42-A cell mitochondrial membrane potential.

Conclusions

Costunolide inhibited growth, apoptosis, ROS generation, and was associated with loss of mitochondrial membrane potential of OAW42-A multidrug-resistant ovarian cancer cells.

Anthecotulide Sesquiterpene Lactone Exhibits Selective Anticancer Effects in Human Malignant Melanoma Cells by Activating Apoptotic and Autophagic Pathways, S-Phase Cell Cycle Arrest, Caspase Activation, and Inhibition of NF-κB Signalling Pathway

BACKGROUND We examined the anticancer potential of anthecotulide against SK-MEL-24 malignant melanoma cells. The apoptotic and autophagic effects of anthecotulide were also investigated. MATERIAL AND METHODS The cell viability of SK-MEL-24 human malignant melanoma cells was evaluated by WST-1 assay. Fluorescence microscopy using acridine orange and ethidium bromide staining, as well as Western blot analysis, were used to study apoptotic effects induced by anthecotulide. Autophagy was assessed by Western blot analysis and fluorescence microscopy. Effects of anthecotulide on cell cycle progression were analyzed by flow cytometry. RESULTS The results revealed that anthecotulide exerts significant growth-inhibitory effects on SK-MEL-24 cells. The IC₅₀ of anthecotulide against the SK-MEL-24 cells was found to be 10 µM. However, the anticancer effects against the normal cells were minimal (IC50; 100 µM). Investigation of the underlying mechanism revealed that anthecotulide prompts apoptotic cell death of the SK-MEL-24 cells, which was linked with increased expression of Bax and decreased expression of Bcl-2. It also triggered concentration-dependent activation of caspase 3 and 9. Anthecotulide induced autophagy in the SK-MEL-24 cells, which was associated with upregulation of LC3 II and Beclin-1 expression. Anthecotulide also halted the SK-MEL-24 cells at S-phase of the cell cycle and downregulated the expression of Cyclin B1. However, the expression of p27 was upregulated. CONCLUSIONS These results indicate anthecotulide is a potent lead molecule for the treatment of melanoma. In vivo and other related experiments are warranted to further assess this promising drug candidate.

Pikuni-Blackfeet traditional medicine: Neuroprotective activities of medicinal plants used to treat Parkinson's disease-related symptoms

ETHNOPHARMACOLOGICAL RELEVANCE

Parkinson's disease (PD) is a multifactorial neurodegenerative disorder affecting 5% of the population over the age of 85 years. Current treatments primarily involve dopamine replacement therapy, which leads to temporary relief of motor symptoms but fails to slow the underlying neurodegeneration. Thus, there is a need for safe PD therapies with neuroprotective activity. In this study, we analyzed contemporary herbal medicinal practices used by members of the Pikuni-Blackfeet tribe from Western Montana to treat PD-related symptoms, in an effort to identify medicinal plants that are affordable to traditional communities and accessible to larger populations.

AIM OF THE STUDY

The aims of this study were to (i) identify medicinal plants used by the Pikuni-Blackfeet tribe to treat individuals with symptoms related to PD or other CNS disorders, and (ii) characterize a subset of the identified plants in terms of antioxidant and neuroprotective activities in cellular models of PD.

MATERIALS AND METHODS

Interviews of healers and local people were carried out on the Blackfeet Indian reservation. Plant samples were collected, and water extracts were produced for subsequent analysis. A subset of botanical extracts was tested for the ability to induce activation of the Nrf2-mediated transcriptional response and to protect against neurotoxicity elicited by the PD-related toxins rotenone and paraquat.

RESULTS

The ethnopharmacological interviews resulted in the documentation of 26 medicinal plants used to treat various ailments and diseases, including symptoms related to PD. Seven botanical extracts (out of a total of 10 extracts tested) showed activation of Nrf2-mediated transcriptional activity in primary cortical astrocytes. Extracts prepared from Allium sativum cloves, Trifolium pratense flowers, and Amelanchier arborea berries exhibited neuroprotective activity against toxicity elicited by rotenone, whereas only the extracts prepared from Allium sativum and Amelanchier arborea alleviated PQ-induced dopaminergic cell death.

CONCLUSIONS

Our findings highlight the potential clinical utility of plants used for medicinal purposes over generations by the Pikuni-Blackfeet people, and they shed light on mechanisms by which the plant extracts could slow neurodegeneration in PD.

Natural Compounds from Herbs that can Potentially Execute as Autophagy Inducers for Cancer Therapy

Accumulated evidence indicates that autophagy is a response of cancer cells to various anti-cancer therapies. Autophagy is designated as programmed cell death type II, and is characterized by the formation of autophagic vacuoles in the cytoplasm. Numerous herbs, including Chinese herbs, have been applied to cancer treatments as complementary and alternative medicines, supplements, or nutraceuticals to dampen the side or adverse effects of chemotherapy drugs. Moreover, the tumor suppressive actions of herbs and natural products induced autophagy that may lead to cell senescence, increase apoptosis-independent cell death or complement apoptotic processes. Hereby, the underlying mechanisms of natural autophagy inducers are cautiously reviewed in this article. Additionally, three natural compounds—curcumin, 16-hydroxycleroda-3,13-dien-15,16-olide, and prodigiosin—are presented as candidates for autophagy inducers that can trigger cell death in a supplement or alternative medicine for cancer therapy. Despite recent advancements in therapeutic drugs or agents of natural products in several cancers, it warrants further investigation in preclinical and clinical studies.

EM23, a natural sesquiterpene lactone, targets thioredoxin reductase to activate JNK and cell death pathways in human cervical cancer cells

Sesquiterpene lactones (SLs) are the active constituents of a variety of medicinal plants and found to have potential anticancer activities. However, the intracellular molecular targets of SLs and the underlying molecular mechanisms have not been well elucidated. In this study, we observed that EM23, a natural SL, exhibited anti-cancer activity in human cervical cancer cell lines by inducing apoptosis as indicated by caspase 3 activation, XIAP downregulation and mitochondrial dysfunction. Mechanistic studies indicated that EM23-induced apoptosis was mediated by reactive oxygen species (ROS) and the knockdown of thioredoxin (Trx) or thioredoxin reductase (TrxR) resulted in a reduction in apoptosis. EM23 attenuated TrxR activity by alkylation of C-terminal redox-active site Sec498 of TrxR and inhibited the expression levels of Trx/TrxR to facilitate ROS accumulation. Furthermore, inhibition of Trx/TrxR system resulted in the dissociation of ASK1 from Trx and the downstream activation of JNK. Pretreatment with ASK1/JNK inhibitors partially rescued cells from EM23-induced apoptosis. Additionally, EM23 inhibited Akt/mTOR pathway and induced autophagy, which was observed to be proapoptotic and mediated by ROS. Together, these results reveal a potential molecular mechanism for the apoptotic induction observed with SL compound EM23, and emphasize its putative role as a therapeutic agent for human cervical cancer.

Autophagy modulators from traditional Chinese medicine: Mechanisms and therapeutic potentials for cancer and neurodegenerative diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine (TCM), an ancient yet still alive medicinal system widely used in East Asia, has played an essential role in health maintenance and diseases control, for a wide range of human chronic diseases like cancers and neurodegenerative diseases. TCM-derived compounds and extracts attract wide attention for their potential application as therapeutic agents against above mentioned diseases.

AIM OF REVIEW

Recent years the enthusiasm in searching for autophagy regulators for human diseases has yielded many positive hits. TCM-derived compounds as important sources for drug discovery have been widely tested in different models for autophagy modulation. Here we summarize the current progress in the discovery of natural autophagy regulators from TCM for the therapeutic application in cancer and neurodegenerative disease models, aiming to provide the direct link from traditional use to new pharmacological application.

METHODS

The present review collected the literature published during the recent 10 years which studied the effect of TCM-derived compounds or extracts on autophagy regulation from PubMed, Web of Science, Google Scholar and Science Direct. The names of chemical compounds studied in this article are corresponding to the information in journal plant list.

RESULTS

In this review, we give a brief introduction about the autophagy and its roles in cancer and neurodegenerative disease models and describe the molecular mechanisms of autophagy modulation. We also make comprehensive lists to summarize the effects and underlying mechanisms of TCM-derived autophagy regulators in cancer and neurodegenerative disease models. In the end of the review, we discuss the current strategies, problems and future direction for TCM-derived autophagy regulators in the treatment of human diseases.

CONCLUSIONS

A number of data from in vivo and in vitro models indicated TCM derived compounds and extracts hold great potential for the treatment of human diseases including cancers and neurodegenerative diseases. Autophagy, as a novel and promising drug target involved in a wide range of human diseases, can be modulated by many TCM derived agents, indicating autophagy modulation may be an important mechanism underlying the therapeutic effect of TCM in treating diseases. Furthermore, we look forward to seeing the discovery of ideal autophagy modulators from TCM with considerably higher selectivity for the treatment of human diseases.

Tumor Protein (TP)-p53 Members as Regulators of Autophagy in Tumor Cells upon Marine Drug Exposure

Targeting autophagic pathways might play a critical role in designing novel chemotherapeutic approaches in the treatment of human cancers, and the prevention of tumor-derived chemoresistance. Marine compounds were found to decrease tumor cell growth in vitro and in vivo. Some of them were shown to induce autophagic flux in tumor cells. In this study, we observed that the selected marine life-derived compounds (Chromomycin A2, Psammaplin A, and Ilimaquinone) induce expression of several autophagic signaling intermediates in human squamous cell carcinoma, glioblastoma, and colorectal carcinoma cells in vitro through a transcriptional regulation by tumor protein (TP)-p53 family members. These conclusions were supported by specific qPCR expression analysis, luciferase reporter promoter assay, and chromatin immunoprecipitation of promoter sequences bound to the TP53 family proteins, and silencing of the TP53 members in tumor cells.

Parthenolide induces autophagy via the depletion of 4E-BP1

Parthenolide (PTL) is a sesquiterpene lactone isolated from feverfew and exhibits potent antitumor activity against various cancers. Many studies indicate that PTL treatment leads to apoptosis, however, the mechanism has not been defined. Here, we observed that cells underwent autophagy shortly after PTL treatment. Inhibition of autophagy by knocking out autophagy associated gene atg5 blocked PTL-induced apoptosis. Surprisingly, PTL decreased the level of translation initiation factor eIF4E binding protein 1 (4E-BP1) in correlation with autophagy. Ectopic expression or shRNA knockdown of 4E-BP1 further verified the effect of 4E-BP1 on PTL-induced autophagy. Meanwhile, PTL elevated the cellular reactive oxygen species (ROS) which located upstream of the depletion of 4E-BP1, and contributed to the consequent autophagy. This study revealed 4E-BP1 as a trigger for PTL-induced autophagy and may lead to therapeutic strategy to enhance the efficacy of anticancer drugs.

Tumor necrosis factor-α promotes the lymphangiogenesis of gallbladder carcinoma through nuclear factor-κB-mediated upregulation of vascular endothelial growth factor-C

Vascular endothelial growth factor (VEGF)-C is an important lymphangiogenic factor involved in the lymphangiogenesis of gallbladder carcinoma (GBC) and the lymph node metastasis of the tumor. Tumor necrosis factor (TNF)-α, a key inflammatory cytokine responding to chronic inflammation of GBC, has been reported to stimulate the expression of VEGF-C in some nonneoplastic cells. But whether TNF-α promotes the expression of VEGF-C in GBC has yet to be determined. Therefore, in the present study, the concentration of TNF-α and VEGF-C and the lymphatic vessel density (LVD) in the clinical GBC specimens were analyzed, and a linear correlation was found between the concentration of TNF-α and that of VEGF-C, the lymphatic vessel density (LVD); The transcription and protein level of VEGF-C in NOZ cell line were detected by real-time polymerase chain reaction (PCR) and enzyme linked immunosorbent assay (ELISA), and TNF-α enhanced the expression of VEGF-C in NOZ cell lines in a dose and time-dependent manner. Lymphatic tube formation in vitro was observed in a three-dimensional coculture system consisting of HDLECs and NOZ cell lines, and lymphatic vessels of GBC in nude mice model was detected by immunohistochemistry. TNF-α promoted the tube formation of lymphatic endothelial cells in vitro and the lymphangiogenesis of GBC in nude mice; The nuclear factor (NF)-κB binding site on the VEGF-C promoter was identified using Site-directed mutagenesis, electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation assay (ChIP). Taken together, TNF-α can upregulate the expression of VEGF-C and promote the lymphangiogenesis of GBC via NF-κB combining with the promoter of VEGF-C.

Natural sesquiterpene lactones induce programmed cell death in Trypanosoma cruzi: a new therapeutic target?

BACKGROUND

Chagas disease or American Trypanosomiasis is caused by the flagellated protozoan parasite Trypanosoma cruzi (T. cruzi) and is recognized by the WHO as one of the world's 17 neglected tropical diseases. Only two drugs (Benznidazol, Bz and Nifurtimox, Nx) are currently accepted for treatment, however they cause severe adverse effects and their efficacy is still controversial. It is then important to explore for new drugs.

PURPOSE

Programmed cell death (PCD) in parasites offers interesting new therapeutic targets. The aim of this work was to evaluate the induction of PCD in T. cruzi by two natural sesquiterpene lactones (STLs), dehydroleucodine (DhL) and helenalin (Hln) as compared with the two conventional drugs, Bz and Nx.

MATERIAL AND METHODS

Hln and DhL were isolated from aerial parts of Gaillardia megapotamica and Artemisia douglassiana Besser, respectively. Purity of compounds (greater than 95%) was confirmed by (13)C-nuclear magnetic resonance, melting point analysis, and optical rotation. Induction of PCD in T. cruzi epimastigotes and trypomastigotes by DhL, Hln, Bz and Nx was assayed by phosphatidylserine exposure at the parasite surface and by detection of DNA fragmentation using the TUNEL assay. Trypanocidal activity of natural and synthetic compounds was assayed by measuring parasite viability using the MTT method.

RESULTS

The two natural STLs, DhL and Hln, induce programmed cell death in both, the replicative epimastigote form and the infective trypomastigote form of T. cruzi. Interestingly, the two conventional antichagasic drugs (Bz and Nx) do not induce programmed cell death. A combination of DhL and either Bz or Nx showed an increased effect of natural compounds and synthetic drugs on the decrease of parasite viability.

CONCLUSION

DhL and Hln induce programmed cell death in T. cruzi replicative epimastigote and infective trypomastigote forms, which is a different mechanism of action than the conventional drugs to kill the parasite. Therefore DhL and Hln may offer an interesting option for the treatment of Chagas disease, alone or in combination with conventional drugs.

A curated census of autophagy-modulating proteins and small molecules: candidate targets for cancer therapy

Autophagy, a programmed process in which cell contents are delivered to lysosomes for degradation, appears to have both tumor-suppressive and tumor-promoting functions; both stimulation and inhibition of autophagy have been reported to induce cancer cell death, and particular genes and proteins have been associated both positively and negatively with autophagy. To provide a basis for incisive analysis of those complexities and ambiguities and to guide development of new autophagy-targeted treatments for cancer, we have compiled a comprehensive, curated inventory of autophagy modulators by integrating information from published siRNA screens, multiple pathway analysis algorithms, and extensive, manually curated text-mining of the literature. The resulting inventory includes 739 proteins and 385 chemicals (including drugs, small molecules, and metabolites). Because autophagy is still at an early stage of investigation, we provide extensive analysis of our sources of information and their complex relationships with each other. We conclude with a discussion of novel strategies that could potentially be used to target autophagy for cancer therapy.

High-throughput screen of natural product libraries for hsp90 inhibitors

Hsp90 has become the target of intensive investigation, as inhibition of its function has the ability to simultaneously incapacitate proteins that function in pathways that represent the six hallmarks of cancer. While a number of Hsp90 inhibitors have made it into clinical trials, a number of short-comings have been noted, such that the search continues for novel Hsp90 inhibitors with superior pharmacological properties. To identify new potential Hsp90 inhibitors, we have utilized a high-throughput assay based on measuring Hsp90-dependent refolding of thermally denatured luciferase to screen natural compound libraries. Over 4,000 compounds were screen with over 100 hits. Data mining of the literature indicated that 51 compounds had physiological effects that Hsp90 inhibitors also exhibit, and/or the ability to downregulate the expression levels of Hsp90-dependent proteins. Of these 51 compounds, seven were previously characterized as Hsp90 inhibitors. Four compounds, anthothecol, garcinol, piplartine, and rottlerin, were further characterized, and the ability of these compounds to inhibit the refolding of luciferase, and reduce the rate of growth of MCF7 breast cancer cells, correlated with their ability to suppress the Hsp90-dependent maturation of the heme-regulated eIF2α kinase, and deplete cultured cells of Hsp90-dependent client proteins. Thus, this screen has identified an additional 44 compounds with known beneficial pharmacological properties, but with unknown mechanisms of action as possible new inhibitors of the Hsp90 chaperone machine.