Potent inhibition of gastric cancer cells by a natural compound via inhibiting TrxR1 activity and activating ROS-mediated p38 MAPK pathway

Quantitative redox proteomics links thioredoxin to heavy ion resistance in Deinococcus radiodurans

Heavy ion radiotherapy is an effective treatment for tumors, but its therapeutic efficacy is limited in cancer cells with radiation resistance. Deinococcus radiodurans, well known for its extremely resisting various stresses, was used to explore radioresistant mechanism. We used quantitative redox proteomics to track the dynamic changes in the global redox state after 12C6+ irradiation. The redox-relevant metabolic signaling pathway was significantly changed, where thioredoxin 2 (DrTrx2) was found to shift towards more reduced status than other redox proteins, promoting great interest to explore the role of DrTrx2 redox in radioresistance. Both the reduction ratio and expression level of DrTrx2 were shown to affect the radioresistant phenotype under varying doses of 60Co irradiation. Additionally, the reduction at the active site was confirmed to provide the radioresistance to DrTrx2, further revealing the universality of DrTrx2 in radiation protection. Furthermore, we used radiation-sensitive Escherichia coli strain as host cells to analyze change of DrTrx2 interactome after UV radiation. Compared with the control, UV radiation induction altered the interaction of DrTrx2 with substrate proteins. The significantly altered proteins were enriched in DNA repair, base analogs metabolism, mitochondrial metabolism, RNA metabolism, transcription, translation, antioxidation, and so on. Therefore, DrTrx2 improved radioresistance by changing interaction with substrate proteins and their reduced states. Overall, this study provides a landscape of the radiation-induced dynamic change of redox state and the protein interaction, which provides novel insights for better understanding radioresistant mechanism and improving therapeutic efficiency of heavy ion irradiation for cancers.

Mining of antioxidant sesquiterpene lactones from the aerial parts of Saussurea involucrata with feature-based molecular network strategy

Sesquiterpene lactones (SLs) are a class of natural products with diverse structural scaffoldings and biological activities, making them intriguing objects in the fields of pharmaceutical industry, drug development, and pharmacology. Herein, fifteen SLs, including eleven undescribed SLs compounds sauruintones A-K (1-8 and 13-15), were isolated and identified from the aerial parts of Saussurea involucrata. Their structures were characterized by using mass spectrometry, spectroscopic methods, computational calculations, and single crystal X-ray diffraction. The Feature-Based Molecular Network (FBMN) strategy was utilized for the annotation of SLs with their MS/MS fragmentation patterns. Most of the SLs exerted their protective effects against oxidative stress by enhancing the levels of antioxidant enzyme (CAT) and reducing the malondialdehyde (MDA) levels. Among them, compound 12 exhibited potent reactive oxygen species (ROS) inhibitory activities and enhanced the activities of CAT, superoxide dismutase (SOD), and glutathione peroxidase (GSH), and decreased the content of MDA at concentrations of 10-25 μM. Further RT-qPCR assays and western blot analysis revealed it reduced the level of ROS by activating the nuclear factor erythroid 2-related factor 2 (Nrf-2) signaling pathway.

Targeting regulated cell death (RCD) with naturally derived sesquiterpene lactones in cancer therapy

Regulated cell death (RCD) is a type of cell death modulated by specific signal transduction pathways. Currently, known RCD types include apoptosis, autophagy, ferroptosis, necroptosis, cuproptosis, pyroptosis, and NETosis. Mutations in cancer cells may prevent the RCD pathway; therefore, targeting RCD in tumors has become a promising therapeutic approach. Sesquiterpene lactones represent a diverse and extensive class of plant-derived phytochemicals that serve as potential sources for developing various drugs. Recent studies have shown that sesquiterpene lactones have promising potential in cancer treatment. This review systematically summarizes recent progress in the study of sesquiterpene lactones as antitumor agents, highlighting their role in targeting various RCD pathways, including those involved in apoptosis, autophagy, ferroptosis, necroptosis, and cuproptosis. The primary purpose of the present review is to provide a clear picture of the regulation of RCD by sesquiterpene lactones against different targets in various cancers, which will facilitate the development of new strategies for cancer therapy.

Synthetic and Pharmacological Activities of Alantolactone and Its Derivatives

Alantolactone, a sesquiterpene lactone, is isolated from the traditional Chinese medicinal herb Inula helenium L. (Asteraceae). Alantolactone is known as its wide spectrum of biological effects, including antimicrobial, antifungal, antiviral, and anthelmintic activities; anti-inflammatory activities; and antiproliferative effects on several cancer cell lines. Thus, it has received extensive attention, causing in-depth research in medicinal chemistry, and numerous undescribed alantolactone derivatives have been synthesized through different strategies. Herein, recent advances in diverse bioactivities and mechanism of alantolactone, including its derivatives, were summarized.

Recent advances in lycopene and germacrene a biosynthesis and their role as antineoplastic drugs

Sesquiterpenes and tetraterpenes are classes of plant-derived natural products with antineoplastic effects. While plant extraction of the sesquiterpene, germacrene A, and the tetraterpene, lycopene suffers supply chain deficits and poor yields, chemical synthesis has difficulties in separating stereoisomers. This review highlights cutting-edge developments in producing germacrene A and lycopene from microbial cell factories. We then summarize the antineoplastic properties of β-elemene (a thermal product from germacrene A), sesquiterpene lactones (metabolic products from germacrene A), and lycopene. We also elaborate on strategies to optimize microbial-based germacrene A and lycopene production.

Sesquiterpene Lactones Containing an α-Methylene-γ-Lactone Moiety Selectively Down-Regulate the Expression of Tumor Necrosis Factor Receptor 1 by Promoting Its Ectodomain Shedding in Human Lung Adenocarcinoma A549 Cells

Alantolactone is a eudesmane-type sesquiterpene lactone containing an α-methylene-γ-lactone moiety. Previous studies showed that alantolactone inhibits the nuclear factor κB (NF-κB) signaling pathway by targeting the inhibitor of NF-κB (IκB) kinase. However, in the present study, we demonstrated that alantolactone selectively down-regulated the expression of tumor necrosis factor (TNF) receptor 1 (TNF-R1) in human lung adenocarcinoma A549 cells. Alantolactone did not affect the expression of three adaptor proteins recruited to TNF-R1. The down-regulation of TNF-R1 expression by alantolactone was suppressed by an inhibitor of TNF-α-converting enzyme. Alantolactone increased the soluble forms of TNF-R1 that were released into the culture medium as an ectodomain. The structure-activity relationship of eight eudesmane derivatives revealed that an α-methylene-γ-lactone moiety was needed to promote TNF-R1 ectodomain shedding. In addition, parthenolide and costunolide, two sesquiterpene lactones with an α-methylene-γ-lactone moiety, increased the amount of soluble TNF-R1. Therefore, the present results demonstrate that sesquiterpene lactones with an α-methylene-γ-lactone moiety can down-regulate the expression of TNF-R1 by promoting its ectodomain shedding in A549 cells.

Babao Dan Inhibits Gastric Cancer Progression in vivo through Multiple Signaling Pathways

Objective:

The aim of this study was to explore the effects of Babao dan (BBD), a traditional Chinese medicine, on gastric cancer (GC) progressionin vivo.

Materials and Methods:

A subcutaneous xenograft mouse model of GC was established using MGC80-3 cells. The terminal deoxynucleotidyl transferase-mediated dUTP: 2’-deoxyuridine 5’-triphosphate -biotin nick-end labeling method was adopted to detect cell apoptosisin vivo. The expression levels of proteins associated with proliferation, apoptosis, and angiogenesis were measured by immunohistochemical staining or western blotting (WB). The activation and protein levels of p-c-Jun N-terminal kinase (JNK), p-p38, p-extracellular-regulated kinase 1/2, p-nuclear factor-κB (NF-κB), and p-STAT3 were examined by Bio-plex and WB.

Results:

BBD significantly inhibited tumor growth in GC mouse models with no adverse effect on body weight or organ function. It was also found that BBD significantly suppressed the proliferation of GC tumor cells, induced the apoptosis of tumor cells, and inhibited angiogenesis through inactivating with mitogen-activated protein kinase, NF-κB, and STAT3 pathways.

Conclusions:

BBD exerts suppressive effects on GC tumor growth by regulating multiple pathwaysin vivo, which may provide a novel treatment option for GC therapy.

Research progress on antitumor mechanisms and molecular targets of Inula sesquiterpene lactones

The pharmacological effects of natural product therapy have received sigificant attention, among which terpenoids such as sesquiterpene lactones stand out due to their biological activity and pharmacological potential as anti-tumor drugs. Inula sesquiterpene lactones are a kind of sesquiterpene lactones extracted from Inula species. They have many pharmacological activities such as anti-inflammation, anti-asthma, anti-tumor, neuroprotective and anti-allergic. In recent years, more and more studies have proved that they are important candidate drugs for the treatment of a variety of cancers because of its good anti-tumor activity. In this paper, the structure, structure-activity relationship, antitumor activities, mechanisms and targets of Inula sesquiterpene lactones reported in recent years were reviewed in order to provide clues for the development of novel anticancer drugs.

Alantolactone induces platelet apoptosis by activating the Akt pathway

Alantolactone (ALT), a sesquiterpene lactone compound isolated from Inula helenium L., has recently attracted much attention for its anti-tumor properties. ALT reportedly functions by regulating the Akt pathway, which has been shown to be involved in programmed platelet death (apoptosis) and platelet activation. However, the precise effect of ALT on platelets remains unclear. In this study, washed platelets were treated with ALT in vitro, and apoptotic events and platelet activation were detected. In vivo, platelet transfusion experiments were employed to detect the effect of ALT on platelet clearance. Platelet counts were examined after intravenous injection of ALT. We found that ALT treatment induced Akt activation and Akt-mediated apoptosis in platelets. ALT-activated Akt elicited platelet apoptosis by activating phosphodiesterase (PDE3A) and PDE3A-mediated protein kinase A (PKA) inhibition. Pharmacological inhibition of the PI3K/Akt/PDE3A signaling pathway or PKA activation was found to protect platelets from apoptosis induced by ALT. Moreover, ALT-induced apoptotic platelets were removed faster in vivo, and ALT injection resulted in the platelet count decline. Either PI3K/Akt/PDE3A inhibitors or a PKA activator could protect platelets from clearance, ultimately ameliorating the ALT-induced decline in platelet count in the animal model. These results reveal the effects of ALT on platelets and their related mechanisms, suggesting potential therapeutic targets for the prevention and alleviation of possible side effects resulting from ALT treatments.

Antitumoral Activity of Leptocarpha rivularis Flower Extracts against Gastric Cancer Cells

Leptocarpha rivularis is a native South American plant used ancestrally by Mapuche people to treat gastrointestinal ailments. L. rivularis flower extracts are rich in molecules with therapeutic potential, including the sesquiterpene lactone leptocarpin, which displays cytotoxic effects against various cancer types in vitro. However, the combination of active molecules in these extracts could offer a hitherto unexplored potential for targeting cancer. In this study, we investigated the effect of L. rivularis flower extracts on the proliferation, survival, and spread parameters of gastric cancer cells in vitro. Gastric cancer (AGS and MKN-45) and normal immortalized (GES-1) cell lines were treated with different concentrations of L. rivularis flower extracts (DCM, Hex, EtOAc, and EtOH) and we determined the changes in proliferation (MTS assay, cell cycle analysis), cell viability/cytotoxicity (trypan blue exclusion assay, DEVDase activity, mitochondrial membrane potential MMP, and clonogenic ability), senescence (β-galactosidase activity) and spread potential (invasion and migration assays using the Boyden chamber approach) in all these cells. The results showed that the DCM, EtOAc, and Hex extracts display a selective antitumoral effect in gastric cancer cells by affecting all the cancer parameters tested. These findings reveal an attractive antitumoral potential of L. rivularis flower extracts by targeting several acquired capabilities of cancer cells.

Anti-inflammatory effects of extracellular vesicles from Morchella on LPS-stimulated RAW264.7 cells via the ROS-mediated p38 MAPK signaling pathway

Morchella is a kind of important edible and medicinal fungi, which is rich in polysaccharides, enzymes, fatty acids, amino acids and other active components. Extracellular vesicles (EVs) have a typical membrane structure, and the vesicles contain some specific lipids, miRNAs and proteins, and their can deliver the contents to different cells to change their functions. The present study investigated whether Morchella produce extracellular vesicles and its anti-inflammatory effect on lipopolysaccharide (LPS)-induced RAW246.7 macrophages. The experimental results showed that Morchella produced extracellular vesicles and significantly reduced the production of nitric oxide (NO) and reactive oxygen species (ROS) in a model of LPS-induced inflammation. In addition, the expression of inflammatory factor-related genes such as inducible nitric oxide synthase (iNOS), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and cyclooxygenase-2 (COX-2) showed dose-dependent inhibition. Morchella extracellular vesicles also can inhibit the inflammatory response induced by LPS by inhibiting the production of ROS and reducing the phosphorylation levels of the p38 MAPK signaling pathway. These results indicate that the Morchella extracellular vesicles can be used as a potential anti-inflammatory substance in the treatment of inflammatory diseases.

Lessons learned from the discovery and development of the sesquiterpene lactones in cancer therapy and prevention

INTRODUCTION

Sesquiterpene lactones (SLs) are one of the most diverse bioactive secondary metabolites found in plants and exhibit a broad range of therapeutic properties . SLs have been showing promising potential in cancer clinical trials, and the molecular mechanisms underlying their anticancer potential are being uncovered. Recent evidence also points to a potential utility of SLs in cancer prevention.

AREAS COVERED

This work evaluates SLs with promising anticancer potential based on cell, animal, and clinical models: Artemisinin, micheliolide, thapsigargin dehydrocostuslactone, arglabin, parthenolide, costunolide, deoxyelephantopin, alantolactone, isoalantolactone, atractylenolide 1, and xanthatin as well as their synthetic derivatives. We highlight actionable molecular targets and biological mechanisms underlying the anticancer therapeutic properties of SLs. This is complemented by a unique assessment of SL mechanisms of action that can be exploited in cancer prevention. We also provide insights into structure-activity and pharmacokinetic properties of SLs and their potential use in combination therapies.

EXPERT OPINION

We extract seven major lessons learned and present evidence-based solutions that can circumvent some scientific limitations or logistic impediments in SL anticancer research. SLs continue to be at the forefront of cancer drug discovery and are worth a joint interdisciplinary effort in order to leverage their potential in cancer therapy and prevention.

Alantolactone-Loaded Pegylated Prodrug Nanocarriers for Synergistic Treatment of Cisplatin-Resistant Ovarian Cancer via Reactivating Mitochondrial Apoptotic Pathway

Ovarian cancer (OV) seriously damages women's health because of refractory OV and the development of platinum (Pt) resistance. New treatment strategies are urgently needed to deal with the treatment of cisplatin-resistant OV. Here, a reduction-sensitive pegylated Pt(IV) prodrug was synthesized by amidation of methoxy polyethylene glycol amine (PEG₇₅₀-NH₂) with monocarboxylic Pt(IV) prodrug (Pt(IV)-COOH). Then alantolactone (AL) loaded PEG-Pt(IV) nanocarriers (NP(Pt)@AL) were prepared. In the cisplatin-resistant model of OV, cancer cells actively ingest NP(Pt)@AL through endocytosis, and AL and Pt(II) were disintegrated and released under high intracellular reductant condition. The activity of thioredoxin reductase 1 (TrxR1) inhibited by AL and the adducts of Pt(II) with mitochondrial DNA (mDNA) can costimulate reactive oxygen species (ROS) and reactivate the mitochondrial pathway of apoptosis. Meanwhile, Pt(II) binds with nuclear DNA (nDNA) to jointly promote cell apoptosis. Both in vitro and in vivo results demonstrated that NP(Pt)@AL could effectively reverse the drug resistance and displayed excellent synergistic therapeutic efficacy on platinum-resistant OV with high safety. Therefore, reactivation of the mitochondrial pathway of apoptosis would be a potential strategy to improve the therapeutic effect of Pt-based chemotherapy and even reverse drug resistance.

From Monographs to Chromatograms: The Antimicrobial Potential of Inula Helenium L. (Elecampane) Naturalised in Ireland

With antimicrobial resistance rising globally, the exploration of alternative sources of candidate molecules is critical to safeguard effective chemotherapeutics worldwide. Plant natural products are accessible, structurally diverse compounds with antimicrobial potential. The pharmacological applications of plants in medicine can be guided by the attestation of traditional use, as demonstrated in this study. In Irish ethnomedical literature, Inula helenium L. (elecampane) is often indicated for respiratory and dermal ailments. This is the first assessment of antimicrobial sesquiterpene lactones from the roots of elecampane, naturalised in Ireland. Traditional hydro-ethanolic extracts were prepared from multi-origin elecampane roots. A novel clean-up strategy facilitated the bioactivity-guided fractionation of a subset of anti-staphylococcal fractions (the compositions of which were investigated using HPLC-DAD, supported by ¹H NMR). The natural products attributing to the antimicrobial activity, observed in vitro, were identified as alantolactone (1), isoalantolactone (2), igalan (3), and an unseparated mixture of dugesialactone (4) and alloalantolactone (5), as major compounds. The findings suggest that the geographical origin of the plant does not influence the anti-bacterial potency nor the chemical composition of traditional elecampane root. Considering the prevalence of staphylococci-associated infections and associated broad spectrum resistance in Irish hospitals, currently, further research is warranted into the usage of the identified compounds as potential candidates in the control of staphylococcal carriage and infection.

Alantolactone: A Natural Plant Extract as a Potential Therapeutic Agent for Cancer

Alantolactone (ALT) is a natural compound extracted from Chinese traditional medicine Inula helenium L. with therapeutic potential in the treatment of various diseases. Recently, in vitro and in vivo studies have indicated cytotoxic effects of ALT on various cancers, including liver cancer, colorectal cancer, breast cancer, etc. The inhibitory effects of ALT depend on several cancer-associated signaling pathways and abnormal regulatory factors in cancer cells. Moreover, emerging studies have reported several promising strategies to enhance the oral bioavailability of ALT, such as combining ALT with other herbs and using ALT-entrapped nanostructured carriers. In this review, studies on the anti-tumor roles of ALT are mainly summarized, and the underlying molecular mechanisms of ALT exerting anticancer effects on cells investigated in animal-based studies are also discussed.

Back to the Roots-An Overview of the Chemical Composition and Bioactivity of Selected Root-Essential Oils

Since ancient times, plant roots have been widely used in traditional medicine for treating various ailments and diseases due to their beneficial effects. A large number of studies have demonstrated that-besides their aromatic properties-their biological activity can often be attributed to volatile constituents. This review provides a comprehensive overview of investigations into the chemical composition of essential oils and volatile components obtained from selected aromatic roots, including Angelica archangelica, Armoracia rusticana, Carlina sp., Chrysopogon zizanioides, Coleus forskohlii, Inula helenium, Sassafras albidum, Saussurea costus, and Valeriana officinalis. Additionally, their most important associated biological impacts are reported, such as anticarcinogenic, antimicrobial, antioxidant, pesticidal, and other miscellaneous properties. Various literature and electronic databases-including PubMed, ScienceDirect, Springer, Scopus, Google Scholar, and Wiley-were screened and data was obtained accordingly. The results indicate the promising properties of root-essential oils and their potential as a source for natural biologically active products for flavor, pharmaceutical, agricultural, and fragrance industries. However, more research is required to further establish the mechanism of action mediating these bioactivities as well as essential oil standardization because the chemical composition often strongly varies depending on external factors.

Thioredoxin reductase inhibitors: updated patent review (2017-present)

Introduction: Thioredoxin reductase (TrxR) is a selenocysteine-containing enzyme which is responsible - as a part of the thioredoxin system - for maintaining redox homeostasis in cells. It is upregulated in cancerous state as a defense against oxidative stress. TrxR has been mostly considered an anticancer drug target although it has applications in other therapeutic areas such as neurodegeneration, inflammation, microbial infections, and neonatal hyperoxic lung injury.Areas covered: The present review covers the patent literature that appeared in the period 2017-2020, i.e. since the publication of the previous expert opinion patent review on TrxR inhibitors. The recent additions to the following traditional classes of inhibitors are discussed: metal complexes, Michael acceptors as well as arsenic and selenium compounds. At the same time, a novel group of nitro (hetero)aromatic compounds have emerged which likely acts via covalent inhibition mechanism. Several miscellaneous chemotypes are grouped under Miscellaneous subsection.Expert opinion: While specificity over glutathione reductase is achieved easily, TrxR is still moving toward the later stages of development at a very slow rate. Michael acceptors, particularly based on TRXR substrate-mimicking scaffolds, are gaining impetus and so are dual and hybrid compounds. The development prospects of the emerging nitro (hetero)aromatic chemotypes remain uncertain.

Grape Seed Proanthocyanidins play the roles of radioprotection on Normal Lung and radiosensitization on Lung Cancer via differential regulation of the MAPK Signaling Pathway

Radiation-induced lung injury (RILI) is a common serious complication and dose-limiting factor caused by radiotherapy for lung cancer. This study was to investigate radioprotective effects of grape seed proanthocyanidins (GSP) on normal lung as well as radiosensitizing effects on lung cancer. In vitro, we demonstrated radioprotective effects of GSP on normal alveolar epithelial cells (MLE-12 and BEAS/2B) and radiosensitizing effects on lung cancer cells (LLC and A549). In vivo, we confirmed these two-way effects in tumor-bearing mice. The results showed that GSP inhibited tumor growth, and played a synergistic killing effect with radiotherapy on lung cancer. Meanwhile, GSP reduced radiation damage to normal lung tissues. The two-way effects related to the differential regulation of the MAPK signaling pathway by GSP on normal lung and lung cancer. Moreover, GSP regulated secretion of cytokines IL-6 and IFN-γ and expression of p53 and Ki67 on normal lung and lung cancer. Our findings suggest that GSP is expected to be an ideal radioprotective drug for lung cancer patients who are treated with radiotherapy.

Redox Regulation of the Actin Cytoskeleton in Cell Migration and Adhesion: On the Way to a Spatiotemporal View

The actin cytoskeleton of eukaryotic cells is a dynamic, fibrous network that is regulated by the concerted action of actin-binding proteins (ABPs). In particular, rapid polarization of cells in response to internal and external stimuli is fundamental to cell migration and invasion. Various isoforms of ABPs in different tissues equip cells with variable degrees of migratory and adhesive capacities. In addition, regulation of ABPs by posttranslational modifications (PTM) is pivotal to the rapid responsiveness of cells. In this context, phosphorylation of ABPs and its functional consequences have been studied extensively. However, the study of reduction/oxidation (redox) modifications of oxidation-sensitive cysteine and methionine residues of actin, ABPs, adhesion molecules, and signaling proteins regulating actin cytoskeletal dynamics has only recently emerged as a field. The relevance of such protein oxidations to cellular physiology and pathophysiology has remained largely elusive. Importantly, studying protein oxidation spatiotemporally can provide novel insights into localized redox regulation of cellular functions. In this review, we focus on the redox regulation of the actin cytoskeleton, its challenges, and recently developed tools to study its physiological and pathophysiological consequences.

A comprehensive review of anticancer mechanisms of action of Alantolactone

Cancer is considered as the main challenge of human communities, and it annually imposes a significant economic burden on society. Natural products have been used for treatment of many diseases including inflammation, infections, neurological disorders, atherosclerosis, asthma and cancer for many years. Sesquiterpene lactones (STLs) refers to a group of natural products with different biological activities. A type of STL that has recently attracted much attention is Alantolactone (ALT). In recent years, many studies have investigated the molecular mechanism of this compound affecting cancer cells and results suggest that this compound exerts its anticancer effects by providing free radicals and inhibiting some of the signaling pathways that are effective in progression of cancer cells. The present study is aimed to introduce the latest molecular mechanisms of ALT proposed by researchers in recent years.

Isodeoxyelephantopin Inactivates Thioredoxin Reductase 1 and Activates ROS-Mediated JNK Signaling Pathway to Exacerbate Cisplatin Effectiveness in Human Colon Cancer Cells

Colon cancer is one of the leading causes of cancer-related death in the world. The development of new drugs and therapeutic strategies for patients with colon cancer are urgently needed. Isodeoxyelephantopin (ESI), a sesquiterpene lactone isolated from the medicinal plant Elephantopus scaber L., has been reported to exert antitumor effects on several cancer cells. However, the molecular mechanisms underlying the action of ESI is still elusive. In the present study, we found that ESI potently suppressed cell proliferation in human colon cancer cells. Furthermore, our results showed that ESI treatment markedly increased cellular reactive oxygen species (ROS) levels by inhibiting thioredoxin reductase 1 (TrxR1) activity, which leads to activation of the JNK signaling pathway and eventually cell death in HCT116 and RKO cells. Importantly, we found that ESI markedly enhanced cisplatin-induced cytotoxicity in HCT116 and RKO cells. Combination of ESI and cisplatin significantly increased the production of ROS, resulting in activation of the JNK signaling pathway in HCT116 and RKO cells. In vivo, we found that ESI combined with cisplatin significantly suppressed tumor growth in HCT116 xenograft models. Together, our study provide a preclinical proof-of-concept for ESI as a potential strategy for colon cancer treatment.

Applications of Sesquiterpene Lactones: A Review of Some Potential Success Cases

Sesquiterpene lactones, a vast range of terpenoids isolated from Asteraceae species, exhibit a broad spectrum of biological effects and several of them are already commercially available, such as artemisinin. Here the most recent and impactful results of in vivo, preclinical and clinical studies involving a selection of ten sesquiterpene lactones (alantolactone, arglabin, costunolide, cynaropicrin, helenalin, inuviscolide, lactucin, parthenolide, thapsigargin and tomentosin) are presented and discussed, along with some of their derivatives. In the authors’ opinion, these compounds have been neglected compared to others, although they could be of great use in developing important new pharmaceutical products. The selected sesquiterpenes show promising anticancer and anti-inflammatory effects, acting on various targets. Moreover, they exhibit antifungal, anxiolytic, analgesic, and antitrypanosomal activities. Several studies discussed here clearly show the potential that some of them have in combination therapy, as sensitizing agents to facilitate and enhance the action of drugs in clinical use. The derivatives show greater pharmacological value since they have better pharmacokinetics, stability, potency, and/or selectivity. All these natural terpenoids and their derivatives exhibit properties that invite further research by the scientific community.

Synergistic lethality between PARP-trapping and alantolactone-induced oxidative DNA damage in homologous recombination-proficient cancer cells

PARP1 and PARP2 play critical roles in regulating DNA repair and PARP inhibitors have been approved for the treatment of BRCA1/2-mutated ovarian and breast cancers. It has long been known that PARP inhibition sensitizes cancer cells to DNA-damaging cytotoxic agents independent of BRCA status, however, clinical use of PARP inhibitors in combination with DNA-damaging chemotherapy is limited by the more-than-additive cytotoxicity. The natural compound alantolactone (ATL) inhibits the thioredoxin reductase to induce ROS accumulation and oxidative DNA damage selectively in cancer cells. Here, we showed that nontoxic doses of ATL markedly synergized with the PARP inhibitor olaparib to result in synthetic lethality irrespective of homologous recombination status. Synergistic cytotoxicity was seen in cancer but not noncancerous cells and was reduced by the ROS inhibitor NAC or knockdown of OGG1, demonstrating that the cytotoxicity resulted from the repair of ATL-induced oxidative DNA damage. PARP1 knockdown suppressed the synergistic lethality and olaparib was much more toxic than veliparib when combined with ATL, suggesting PARP-trapping as the primary inducer of cytotoxicity. Consistently, combined use of ATL and olaparib caused intense signs of replication stress and formation of double strand DNA breaks, leading to S and G₂ arrest followed by apoptosis. In vivo, the combination effectively induced regression of tumor xenografts, while either agent alone had no effect. Hence, PARP trapping combined with specific pro-oxidative agents may provide safe and effective ways to broaden the therapeutic potential of PARP inhibitors.