Small molecules regulating reactive oxygen species homeostasis for cancer therapy

Addressing the gaps in homeostatic mechanisms of copper and copper dithiocarbamate complexes in cancer therapy: a shift from classical platinum-drug mechanisms

The platinum drug, cisplatin, is considered as among the most successful medications in cancer treatment. However, due to its inherent toxicity and resistance limitations, research into other metal-based non-platinum anticancer medications with diverse mechanisms of action remains an active field. In this regard, copper complexes feature among non-platinum compounds which have shown promising potential as effective anticancer drugs. Moreover, the interesting discovery that cancer cells can alter their copper homeostatic processes to develop resistance to platinum-based treatments leads to suggestions that some copper compounds can indeed re-sensitize cancer cells to these drugs. In this work, we review copper and copper complexes bearing dithiocarbamate ligands which have shown promising results as anticancer agents. Dithiocarbamate ligands act as effective ionophores to convey the complexes of interest into cells thereby influencing the metal homeostatic balance and inducing apoptosis through various mechanisms. We focus on copper homeostasis in mammalian cells and on our current understanding of copper dysregulation in cancer and recent therapeutic breakthroughs using copper coordination complexes as anticancer drugs. We also discuss the molecular foundation of the mechanisms underlying their anticancer action. The opportunities that exist in research for these compounds and their potential as anticancer agents, especially when coupled with ligands such as dithiocarbamates, are also reviewed.

In Response to Precision Medicine: Current Subcellular Targeting Strategies for Cancer Therapy

Emerging as a potent anticancer treatment, subcellular targeted cancer therapy has drawn increasing attention, bringing great opportunities for clinical application. Here, two targeting strategies for four main subcellular organelles (mitochondria, lysosome, endoplasmic reticulum, and nucleus), including molecule- and nanomaterial (inorganic nanoparticles, micelles, organic polymers, and others)-based targeted delivery or therapeutic strategies, are summarized. Phototherapy, chemotherapy, radiotherapy, immunotherapy, and "all-in-one" combination therapy are among the strategies covered in detail. Such materials are constructed based on the specific properties and relevant mechanisms of organelles, enabling the elimination of tumors by inducing dysfunction in the corresponding organelles or destroying specific structures. The challenges faced by organelle-targeting cancer therapies are also summarized. Looking forward, a paradigm for organelle-targeting therapy with enhanced therapeutic efficacy compared to current clinical approaches is envisioned.

Ferroptosis-modulating small molecules for targeting drug-resistant cancer: Challenges and opportunities in manipulating redox signaling

Ferroptosis is an iron-dependent cell death program that is characterized by excessive lipid peroxidation. Triggering ferroptosis has been proposed as a promising strategy to fight cancer and overcome drug resistance in antitumor therapy. Understanding the molecular interactions and structural features of ferroptosis-inducing compounds might therefore open the door to efficient pharmacological strategies against aggressive, metastatic, and therapy-resistant cancer. We here summarize the molecular mechanisms and structural requirements of ferroptosis-inducing small molecules that target central players in ferroptosis. Focus is placed on (i) glutathione peroxidase (GPX) 4, the only GPX isoenzyme that detoxifies complex membrane-bound lipid hydroperoxides, (ii) the cystine/glutamate antiporter system Xc - that is central for glutathione regeneration, (iii) the redox-protective transcription factor nuclear factor erythroid 2-related factor (NRF2), and (iv) GPX4 repression in combination with induced heme degradation via heme oxygenase-1. We deduce common features for efficient ferroptotic activity and highlight challenges in drug development. Moreover, we critically discuss the potential of natural products as ferroptosis-inducing lead structures and provide a comprehensive overview of structurally diverse biogenic and bioinspired small molecules that trigger ferroptosis via iron oxidation, inhibition of the thioredoxin/thioredoxin reductase system or less defined modes of action.

Tumor killing by a dietary curcumin mono-carbonyl analog that works as a selective ROS generator via TrxR inhibition

In comparison with normal cells, cancer cells feature intrinsic oxidative stress, thereby being more vulnerable to further production of reactive oxygen species (ROS) by pro-oxidative anticancer agents (PAAs). However, PAAs also inevitably generate ROS in normal cells, resulting in their narrow therapeutic window and toxic side effects that greatly limit their clinical application. To develop PAAs that generate ROS selectively in cancer cells over in normal cells, we rationally designed three series of 21 dietary curcumin 5-carbon mono-carbonyl analogs differentiated by either placement of the cyclohexanone, piperidone, and methylpiperidone linkers, or introduction of electron-withdrawing trifluoromethyl and electron-donating methoxyl groups on its two aromatic rings in the ortho, meta, or para position to the linkers. From the designed molecules, 2c, characterized of the presence of the meta-CF₃-substituted mode and the piperidone linker, was identified as a potent selective ROS-generating agent, allowing its ability to kill selectively human non-small cell lung cancer NCI-H460 (IC₅₀ = 0.44 μM) over human normal lung MRC-5 cells with a selectivity index of 32.0. Additionally, it was more potent and selective than the conventional chemotherapeutic agents (5-fluorouracil and camptothecin) did. Mechanistical investigation reveals that by means of its Michael acceptor unit and structure characteristics as described above, 2c could covalently modify the Sec-498 residue of intracellular thioredoxin reductase (TrxR) to generate ROS selectively, resulting in ROS-dependent apoptosis and ferroptosis of NCI-H460 cells. Noticeably, 2c inhibited significantly the growth of NCI-H460 cell xenograft tumor in nude mice without obvious toxicity to liver and kidney. Together, this work highlights a practical strategy of targeting TrxR overexpressed in cancer cells to develop PAAs capable of generating ROS selectively, as evidenced by the example of 2c.

Protective effects of pentoxifylline against chlorine-induced acute lung injury in rats

OBJECTIVE

Chlorine is a chemical threat agent that can be harmful to humans. Inhalation of high levels of chlorine can lead to acute lung injury (ALI). Currently, there is no satisfactory treatment, and effective antidote is urgently needed. Pentoxifylline (PTX), a methylxanthine derivative and nonspecific phosphodiesterase inhibitor, is widely used for the treatment of vascular disorders. The present study was aimed to investigate the inhibitory effects of PTX on chlorine-induced ALI in rats.

METHODS

Adult male Sprague-Dawley rats were exposed to 400 ppm Cl₂ for 5 min. The histopathological examination was carried out and intracellular reactive oxygen species (ROS) levels were measured by the confocal laser scanning system. Subsequently, to evaluate the effect of PTX, a dose of 100 mg/kg was administered. The activities of superoxide dismutase (SOD) and the contents of malondialdehyde (MDA), glutathione (GSH), oxidized glutathione (GSSG) and lactate dehydrogenase (LDH) were determined by using commercial kits according to the manufacturer's instructions. Western blot assay was used to detect the protein expressions of SOD1, SOD2, catalase (CAT), hypoxia-inducible factor (HIF)-1α, vascular endothelial growth factor (VEGF), occludin, E-cadherin, bcl-xl, LC 3, Beclin 1, PTEN-induced putative kinase 1 (PINK 1) and Parkin.

RESULTS

The histopathological examination demonstrated that chlorine could destroy the lung structure with hemorrhage, alveolar collapse, and inflammatory infiltration. ROS accumulation was significantly higher in the lungs of rats suffering from inhaling chlorine (P<0.05). PTX markedly reduced concentrations of MAD and GSSG, while increased GSH (P<0.05). The protein expression levels of SOD1 and CAT also decreased (P<0.05). Furthermore, the activity of LDH in rats treated with PTX was significantly decreased compared to those of non-treated group (P<0.05). Additionally, the results also showed that PTX exerted an inhibition effect on protein expressions of HIF-1α, VEGF and occludin, and increased the level of E-cadherin (P<0.05). While the up-regulation of Beclin 1, LC 3II/I, Bcl-xl, and Parkin both in the lung tissues and mitochondria, were found in PTX treated rats (P<0.05). The other protein levels were decreased when treated with PTX (P<0.05).

CONCLUSION

PTX could ameliorate chlorine-induced lung injury via inhibition effects on oxidative stress, hypoxia and autophagy, thus suggesting that PTX could serve as a potential therapeutic approach for ALI.

Metastasis prevention: How to catch metastatic seeds

Despite considerable advances in the evolution of anticancer therapies, metastasis still remains the main cause of cancer mortality. Therefore, current strategies for cancer cure should be redirected towards prevention of metastasis. Targeting metastatic pathways represents a promising therapeutic opportunity aimed at obstructing tumor cell dissemination and metastatic colonization. In this review, we focus on preclinical studies and clinical trials over the last five years that showed high efficacy in suppressing metastasis through targeting lymph node dissemination, tumor cell extravasation, reactive oxygen species, pre-metastatic niche, exosome machinery, and dormancy.

Characterization of Chlorogenic Acid as a Two-Photon Fluorogenic Probe that Regulates Glycolysis in Tumor Cells under Hypoxia

High levels of steady-state mitochondrial reactive oxygen species (ROS) and glycolysis are hallmarks of cancer. An improved understanding of interactions between tumor energetics and mitochondrial ROS modulation is useful for the development of new anticancer strategies. Here, we show that the natural product chlorogenic acid (CGA) specifically scavenged abnormally elevated mitochondrial O₂^•- and exhibited a two-photon fluorescence turn-on response to tumor cells under hypoxia and tumor tissues in vivo. Furthermore, we illustrated that CGA treatment reduced O₂^•- levels in cells, hampered activation of AMP-activated protein kinase (AMPK), and shifted metabolism from glycolysis to oxidative phosphorylation (OXPHOS), resulting in inhibition of tumor growth under hypoxia. This study demonstrates an efficient two-photon fluorescent tool for real-time assessment of mitochondrial O₂^•- and a clear link between reducing intracellular ROS levels by CGA treatments and regulating metabolism, as well as undeniably helpful insights for the development of new anticancer strategies.

Synthesis and discovery of Baylis-Hillman adducts as potent and selective thioredoxin reductase inhibitors for cancer treatment

The selenoprotein thioredoxin reductase (TrxR) is of paramount importance in maintaining cellular redox homeostasis, and aberrant upregulation of TrxR is frequently observed in various cancers due to their elevated oxidative stress in cells. Thus, it seems promising and feasible to target the ablation of intracellular TrxR for the treatment of cancers. We report herein the design and synthesis of a series of Baylis-Hillman adducts, and identified a typical adduct that possesses the superior cytotoxicity against HepG2 cells over other types of cancer cells. The biological investigation shows the selected typical adduct selectively targets TrxR in HepG2 cells, which thereafter results in the collapse of intracellular redox homeostasis. Further mechanistic studies reveal that the selected typical adduct arrests the cell cycle in G1/G0 phase. Importantly, the malignant metastasis of HepG2 cells is significantly restrained by the selected typical adduct. With well-defined molecular target and mechanism of action, the selected typical adduct, even other Baylis-Hillman skeleton-bearing compounds, merits further development as candidate or ancillary agent for the treatment of various cancers.

Thioredoxin Signaling Pathways in Cancer

Significance: Thioredoxin (Trx) is a powerful antioxidant that reduces protein disulfides to maintain redox stability in cells and is involved in regulating multiple redox-dependent signaling pathways. Recent Advance: The current accumulation of findings suggests that Trx participates in signaling pathways that interact with various proteins to manipulate their dynamic regulation of structure and function. These network pathways are critical for cancer pathogenesis and therapy. Promising clinical advances have been presented by most anticancer agents targeting such signaling pathways. Critical Issues: We herein link the signaling pathways regulated by the Trx system to potential cancer therapeutic opportunities, focusing on the coordination and strengths of the Trx signaling pathways in apoptosis, ferroptosis, immunomodulation, and drug resistance. We also provide a mechanistic network for the exploitation of therapeutic small molecules targeting the Trx signaling pathways. Future Directions: As research data accumulate, future complex networks of Trx-related signaling pathways will gain in detail. In-depth exploration and establishment of these signaling pathways, including Trx upstream and downstream regulatory proteins, will be critical to advancing novel cancer therapeutics. Antioxid. Redox Signal. 38, 403-424.

Upgrade of chrysomycin A as a novel topoisomerase II inhibitor to curb KRAS-mutant lung adenocarcinoma progression

A primary strategy employed in cancer therapy is the inhibition of topoisomerase II (Topo II), implicated in cell survival. However, side effects and adverse reactions restrict the utilization of Topo II inhibitors. Thus, investigations focus on the discovery of novel compounds that are capable of inhibiting the Topo II enzyme and feature safer toxicological profiles. Herein, we upgrade an old antibiotic chrysomycin A from Streptomyces sp. 891 as a compelling Topo II enzyme inhibitor. Our results show that chrysomycin A is a new chemical entity. Notably, chrysomycin A targets the DNA-unwinding enzyme Topo II with an efficient binding potency and a significant inhibition of intracellular enzyme levels. Intriguingly, chrysomycin A kills KRAS-mutant lung adenocarcinoma cells and is negligible cytotoxic to normal cells at the cellular level, thus indicating a capability of potential treatment. Furthermore, mechanism studies demonstrate that chrysomycin A inhibits the Topo II enzyme and stimulates the accumulation of reactive oxygen species, thereby inducing DNA damage-mediated cancer cell apoptosis. Importantly, chrysomycin A exhibits excellent control of cancer progression and excellent safety in tumor-bearing models. Our results provide a chemical scaffold for the synthesis of new types of Topo II inhibitors and reveal a novel target for chrysomycin A to meet its further application.

Shikonin triggers GSDME-mediated pyroptosis in tumours by regulating autophagy via the ROS-MAPK14/p38α axis

BACKGROUND

Shikonin (SK), a botanical drug extracted from Lithospermum erythrorhizon, has been shown to inhibit tumour growth through apoptosis and necrosis. However, whether SK induces pyroptosis in cancer cells is still unknown.

PURPOSE

This study aims to investigated the mechanisms of SK-induced pyroptosis in tumour cells and mice.

METHODS

In vivo and in vitro methods were used in this study. Cell deaths were analysed by LDH and CCK-8 assay and western blotting. To investigated the signalling pathway of SK-induced pyroptosis, various genes expressions were supressed by shRNA or inhibitors. High-sensitivity mass spectrometry assay was used to identified potential factors that regulate GSDME-mediated pyroptosis. Finally, a mouse model was used to investigate the effect of SK administration on tumour growth in vivo.

RESULTS

The activation of BAX/caspase-3 signalling was essential for GSDME-mediated pyroptosis by SK. Mechanistically, the intracellular reactive oxygen species (ROS) generation induced by SK treatment initiated GSDME-dependant pyroptosis. SK stimulation induced protective autophagy in a ROS-dependant manner, and repressed autophagy significantly enhanced SK-induced pyroptosis. Moreover, MAPK14/p38α, a ROS sensor, modulated SK-induced autophagy and ultimately affected GSDME-dependant pyroptosis.

CONCLUSION

Here, for the first time we demonstrated that SK treatment induced GSDME-dependant pyroptosis in tumour cells. Our results demonstrated that SK initiates ROS signalling to drive pyroptosis in cancer cells.

Nanoscopic evaluation on mitochondrial ultrastructures by regulating reactive oxygen species productivity within terpyridyl Zn(II) complexes with different alkyl chain lengths

Mitochondria targeting complexes are widely utilized as photosensitizers in photodynamic therapy. However, the mechanisms by which they regulate reactive oxygen species (ROS) production at the molecular level and their influence on intracellular mitochondrial signaling and ultrastructures remain rarely studied. Herein, we present two terpyridyl Zn(II) complexes with different side alkyl chain lengths (Zn-2C and Zn-6C) that lead to low and high ROS productivities in vitro, respectively. Both complexes could enter live cells effectively with minimal dark toxicity and accumulate preferably in the mitochondria. We also demonstrated that Zn-6C, with more efficient ROS productivity, could significantly downregulate the caspase signaling pathway but showed no evident influence on mitochondrial membrane proteins. We also highlighted and compared the mitochondrial ultrastructural variations during such a process by stimulated emission depletion (STED) super-resolution nanoscopy.

Alterperylenol as a Novel Thioredoxin Reductase Inhibitor Induces Liver Cancer Cell Apoptosis and Ferroptosis

Natural products are a rich resource for discovering innovational drugs. Herein, we isolated and characterized two compounds dihydroalterperylenol (DAP) and alterperylenol (AP) from Alternaria sp. MG1, an endophytic fungus isolated from Vitis quinquangularis, and investigated the underlying antitumor mechanism of AP. Mechanistically, AP inhibits the growth of HepG2 cells by targeting the selenoprotein thioredoxin reductase (TrxR) and ultimately induces cell apoptosis and ferroptosis. Compared to DAP, the α,β-unsaturated carbonyl structure of AP is an indispensable moiety for its antitumor activity and TrxR inhibition. Specifically, inhibition of TrxR causes the extensive reactive oxygen species and consequently results in DNA damage, G2/M cell cycle arrest, and mitochondrial fission. Furthermore, ferroptosis is driven via excess toxic lipid peroxidation and elevation of intracellular iron levels via regulating iron-related proteins. In vivo validation also shows that AP owns anticancer activity in xenograft mice. Collectively, our results disclose a novel natural TrxR inhibitor AP exerting the antitumor effect via inducing cell apoptosis and ferroptosis and evidence that AP is a promising candidate agent for liver carcinoma therapy. The link of TrxR inhibition to ferroptosis further highlights the physiological importance of TrxR in regulating ferroptosis.

The intricate interplay between HIFs, ROS, and the ubiquitin system in the tumor hypoxic microenvironment

Alterations in protein ubiquitination and hypoxia-inducible factor (HIF) signaling both contribute to tumorigenesis and tumor progression. Ubiquitination is a dynamic process that is coordinately regulated by E3 ligases and deubiquitinases (DUBs), which have emerged as attractive therapeutic targets. HIF expression and transcriptional activity are usually increased in tumors, leading to poor clinical outcomes. Reactive oxygen species (ROS) are upregulated in tumors and have multiple effects on HIF signaling and the ubiquitin system. A growing body of evidence has shown that multiple E3 ligases and UBDs function synergistically to control the expression and activity of HIF, thereby allowing cancer cells to cope with the hypoxic microenvironment. Conversely, several E3 ligases and DUBs are regulated by hypoxia and/or HIF signaling. Hypoxia also induces ROS production, which in turn modulates the stability or activity of HIF, E3 ligases, and DUBs. Understanding the complex networks between E3 ligase, DUBs, ROS, and HIF will provide insights into the fundamental mechanism of the cellular response to hypoxia and help identify novel molecular targets for cancer treatment. We review the current knowledge on the comprehensive relationship between E3 ligase, DUBs, ROS, and HIF signaling, with a particular focus on the use of E3 ligase or DUB inhibitors in cancer.

A Reversible Fluorescent Probe Based on a Redox-Switchable Excited-State Intramolecular Proton-Transfer Active Metal-Organic Framework for Detection and Imaging of Highly Reactive Oxygen Species in Live Cells

Detection and imaging of highly reactive oxygen species (hROS) in biological systems using fluorescent probes are critical for the study of physiological and pathological processes induced by hROS. Herein, we report a redox-active luminescent metal-organic framework (MOF), which incorporates a hydroquinone moiety that can undergo a reversible transformation from the hydroquinone to the quinone by hROS like •OH and ClO^-. Moreover, the intrinsic fluorescence originating from the excited-state intramolecular proton transfer (ESIPT) property of the organic linker can be finely regulated during this redox-switchable process. A reversible fluorescent probe for hROS is thus developed. The presented probe shows a sensitive, selective, and reversible response to hROS due to the integration of excellent structural characteristics and unique spectral properties of the MOF. The detection limits of •OH and ClO^- are 0.22 and 0.18 μM, respectively. Furthermore, with good photostability and super biocompatibility, this simple yet efficient fluorescent probe has been successfully applied to dynamic monitoring of endogenous and exogenous •OH and ClO^- in live cells.

Revealing PACMA 31 as a new chemical type TrxR inhibitor to promote cancer cell apoptosis

Thioredoxin reductase (TrxR) is a pivotal regulator of redox homeostasis, while dysregulation of redox homeostasis is a hallmark for cancer cells. Thus, there is considerable potential to inhibit the aberrantly upregulated TrxR in cancer cells to discover selective cancer therapeutic agents. Nevertheless, the structural types of TrxR inhibitors presented currently are still relatively limited. We herein report that PACMA 31, previously reported to inhibit protein disulfide isomerase (PDI), is a potent TrxR inhibitor. PACMA 31 possesses a pharmacophore scaffold that is structurally different from the announced TrxR inhibitors and exhibits effective cytotoxicity against cervical cancer cells. Our results reveal that PACMA 31 selectively inhibits TrxR over the related glutathione reductase (GR) and in the presence of reduced glutathione (GSH). Further studies with mutant enzyme and molecular docking suggest that the propynamide fragment of PACMA 31 interacts covalently with the selenocysteine residue of TrxR. Moreover, PACMA 31 effectively and selectively curbs TrxR activity in cells and further stimulates the production of reactive oxygen species (ROS) at low micromolar concentrations, which in turn triggers the accumulation of oxidized thioredoxin (Trx) and GSSG in cells. Follow-up studies demonstrate that PACMA 31 targets TrxR in cells to induce oxidative stress-mediated cancer cell apoptosis. Our results provide a new structural type of TrxR inhibitor that may serve as a useful probe for investigating the biology of TrxR-implicated pathways, and uncover a new target of PACMA 31 that contributes to it becoming a candidate for cancer treatment.

Two Important Anticancer Mechanisms of Natural and Synthetic Chalcones

ATP-binding cassette subfamily G and tubulin pharmacological mechanisms decrease the effectiveness of anticancer drugs by modulating drug absorption and by creating tubulin assembly through polymerization. A series of natural and synthetic chalcones have been reported to have very good anticancer activity, with a half-maximal inhibitory concentration lower than 1 µM. By modulation, it is observed in case of the first mechanism that methoxy substituents on the aromatic cycle of acetophenone residue and substitution of phenyl nucleus by a heterocycle and by methoxy or hydroxyl groups have a positive impact. To inhibit tubulin, compounds bind to colchicine binding site. Presence of methoxy groups, amino groups or heterocyclic substituents increase activity.

Multi-Target Mechanisms of Phytochemicals in Alzheimer’s Disease: Effects on Oxidative Stress, Neuroinflammation and Protein Aggregation

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by a tangle-shaped accumulation of beta-amyloid peptide fragments and Tau protein in brain neurons. The pathophysiological mechanism involves the presence of Aβ-amyloid peptide, Tau protein, oxidative stress, and an exacerbated neuro-inflammatory response. This review aims to offer an updated compendium of the most recent and promising advances in AD treatment through the administration of phytochemicals. The literature survey was carried out by electronic search in the following specialized databases PubMed/Medline, Embase, TRIP database, Google Scholar, Wiley, and Web of Science regarding published works that included molecular mechanisms and signaling pathways targeted by phytochemicals in various experimental models of Alzheimer’s disease in vitro and in vivo. The results of the studies showed that the use of phytochemicals against AD has gained relevance due to their antioxidant, anti-neuroinflammatory, anti-amyloid, and anti-hyperphosphorylation properties of Tau protein. Some bioactive compounds from plants have been shown to have the ability to prevent and stop the progression of Alzheimer’s.

Tri- and Pentacyclic Azaphenothiazine as Pro-Apoptotic Agents in Lung Carcinoma with a Protective Potential to Healthy Cell Lines

The phenothiazine derivatives, tricyclic 10H-3,6-diazaphenothiazine (DPT-1) and pentacyclic 7-(3′-dimethylaminopropyl)diquinothiazine (DPT-2), have recently been shown to exhibit promising anticancer activities in vitro. In this report, we demonstrated that DPT-1 and DPT-2 could be pro-apoptotic agents in lung carcinoma, the human lung carcinoma A549 and non-small lung carcinoma H1299, in the range of IC50 = 1.52–12.89 µM, with a protective potential to healthy cell lines BEAS-2B and NHDF. The compounds showed higher activity in the range of the tested concentrations and low cytotoxicity in relation to normal healthy cells than doxorubicin, used as the reference drug. The cytostatic potential of DPT-1 and DPT-2 was demonstrated with the use of MTT assay. Cell cycle analysis via flow cytometry using Annexin-V assay showed the pro-apoptotic and pro-necrotic role of the studied diazaphenothiazines in the cell cycle. DPT-1 and DPT-2 initiated a biological response in the investigated cancer models with a different mechanism and at a different rate. Based on these findings, it can be concluded that DPT-1 and DPT-2 have potential as chemotherapeutic agents.

The biological activities of quinolizidine alkaloids

Quinolizidine alkaloids isolated from various marine and terrestrial animals and plants are primarily composed of lupinine-, matrine-, and sparteine-type alkaloids. Matrine, phenanthroquinolizidines, bis-quinolizidines, and small molecules from amphibian skins are representative compounds of such alkaloids. Quinolizidine alkaloids harbor anticancer, antibacterial, antiinflammatory, antifibrosis, antiviral, and anti-arrhythmia. In this chapter, we comprehensively outline the biological activity and pharmacological action of quinolizidine alkaloids and discuss new avenues toward the discovery of novel and more efficient drugs based on these naturally occurring compounds. It is urgent for basic research and clinical practice to conduct more targeted comprehensive research based on the lead drugs of quinolizidine alkaloids with significant pharmacological activity.

Nrf2 Knockout Affected the Ferroptosis Signaling Pathway against Cisplatin-Induced Hair Cell-Like HEI-OC1 Cell Death

Cisplatin is a well-known and widely used anticancer drug with high therapeutic efficacy in solid tumors; however, side effects are common with its use. Because cisplatin can be retained in the cochlea, ototoxicity leading to hearing loss limits its clinical applications. Here, we report that Nrf2 knockout (KO) strongly increased cisplatin resistance in HEI-OC1 cells, which are immortalized cells from the murine organ of Corti. The underlying mechanism of this phenomenon was uncovered, and an important novel therapeutic target for combating cisplatin-induced hearing loss was identified. Preliminary investigations determined that Nrf2 KO markedly decreased TfR1 protein levels and increased GPX4 protein levels. Thus, ferroptosis may protect organisms from cisplatin-induced cell death. Furthermore, Nrf2 KO cells were resistant to the classical ferroptosis inducers RSL3 and erastin, providing solid evidence that Nrf2 KO inhibits ferroptosis and that knocking out Nrf2 may be a new clinical strategy to prevent cisplatin-induced hearing loss.

The Role of SLC7A11 in Cancer: Friend or Foe?

SLC7A11 controls the uptake of extracellular cystine in exchange for glutamate at a ratio of 1:1, and it is overexpressed in a variety of tumours. Accumulating evidence has shown that the expression of SLC7A11 is fine-tuned at multiple levels, and plays diverse functional and pharmacological roles in tumours, such as cellular redox homeostasis, cell growth and death, and cell metabolism. Many reports have suggested that the inhibition of SLC7A11 expression and activity is favourable for tumour therapy; thus, SLC7A11 is regarded as a potential therapeutic target. However, emerging evidence also suggests that on some occasions, the inhibition of SLC7A11 is beneficial to the survival of cancer cells, and confers the development of drug resistance. In this review, we first briefly introduce the biological properties of SLC7A11, including its structure and physiological functions, and further summarise its regulatory network and potential regulators. Then, focusing on its role in cancer, we describe the relationships of SLC7A11 with tumourigenesis, survival, proliferation, metastasis, and therapeutic resistance in more detail. Finally, since SLC7A11 has been linked to cancer through multiple approaches, we propose that its contribution and regulatory mechanism require further elucidation. Thus, more personalised therapeutic strategies should be adapted when targeting SLC7A11.

Michael acceptor-dependent pro-oxidative intervention against angiogenesis by [6]-dehydroshogaol, a pungent constituent of ginger

Accumulating evidence suggests that ginger and its pungent constituents harbor a wealth of biological activities including cancer chemopreventive activity. However, relatively few researches focus on [6]-dehydroshogaol (6-DHS) compared with other ginger pungent constituents such as [6]-shogaol (6S). In this work, we selected three ginger compounds, 6-DHS, 6S and [6]-paradol (6P) differentiated by the presence and number of the Michael acceptor units, to probe structural basis and mechanism of 6-DHS in inhibiting angiogenesis, a key step for tumor growth and metastasis. It was found that their antiangiogenic activity is significantly dependent on the presence and number of Michael acceptor units. Benefiting from its two Michael acceptor units, 6-DHS is the most potent inhibitor of thioredoxin reductase and depletor of glutathione, thereby being the most active generator of reactive oxygen species, which is responsible for its strongest ability to inhibit angiogenesis. This work highlights 6-DHS being a Michael acceptor-dependent pro-oxidative angiogenesis inhibitor.

Progress and perspective on hydrogen sulfide donors and their biomedical applications

Following the discovery of nitric oxide (NO) and carbon monoxide (CO), hydrogen sulfide (H₂ S) has been identified as the third gasotransmitter in humans. Increasing evidence have shown that H₂ S is of preventive or therapeutic effects on diverse pathological complications. As a consequence, it is of great significance to develop suitable approaches of H₂ S-based therapeutics for biomedical applications. H₂ S-releasing agents (H₂ S donors) play important roles in exploring and understanding the physiological functions of H₂ S. More importantly, accumulating studies have validated the theranostic potential of H₂ S donors in extensive repertoires of in vitro and in vivo disease models. Thus, it is imperative to summarize and update the literatures in this field. In this review, first, the background of H₂ S on its chemical and biological aspects is concisely introduced. Second, the studies regarding the H₂ S-releasing compounds are categorized and described, and accordingly, their H₂ S-donating mechanisms, biological applications, and therapeutic values are also comprehensively delineated and discussed. Necessary comparisons between related H₂ S donors are presented, and the drawbacks of many typical H₂ S donors are analyzed and revealed. Finally, several critical challenges encountered in the development of multifunctional H₂ S donors are discussed, and the direction of their future development as well as their biomedical applications is proposed. We expect that this review will reach extensive audiences across multiple disciplines and promote the innovation of H₂ S biomedicine.

Targeting thioredoxin reductase by micheliolide contributes to radiosensitizing and inducing apoptosis of HeLa cells

Inhibition of thioredoxin reductase (TrxR) is a crucial strategy for the discovery of antineoplastic drugs and radiosensitizers. As an anticancer candidate derived from Michelia, micheliolide (MCL) is converted readily from parthenolide (PTL), and has better stability and solubility than PTL. However, the anticancer mechanism of MCL has not been fully dissected. We present here for the first time that MCL-targeted inhibition of TrxR not only promotes oxidative stress-mediated HeLa cell apoptosis but also sensitizes ionizing radiation (IR) treatment. Further mechanistic studies demonstrate that MCL covalently binds to Sec at position 498 of TrxR to restrain the biological function of TrxR. It exhibits the inhibition of TrxR activity, enhancement of oxidized Trx, and sensitization of IR in the cellular environment, accompanied by the accumulation of reactive oxygen species (ROS) and the collapse of the intracellular redox balance. In addition, HeLa-shTrxR1 cells with knockdown of TrxR were more sensitive than the HeLa-shNT cells to either MCL-treated or IR-induced cytotoxicity, ROS, and apoptosis, suggesting that inhibition of TrxR by MCL is likely responsible for increased cytotoxicity and enhanced radiation response. These findings further establish the mechanistic understanding and preclinical data to support the further investigation of MCL's potential as a prospective radiosensitizer and cancer chemotherapeutic agent.

Piperlongumine Inhibits Thioredoxin Reductase 1 by Targeting Selenocysteine Residues and Sensitizes Cancer Cells to Erastin

Piperlongumine, a natural alkaloid substance extracted from the fruit of the long pepper (Piper longum Linn.), is known to inhibit the cytosolic thioredoxin reductase (TXNRD1 or TrxR1) and selectively kill cancer cells. However, the details and mechanism of the inhibition by piperlongumine against TXNRD1 remain unclear. In this study, based on the classical DTNB reducing assay, irreversible inhibition of recombinant TXNRD1 by piperlongumine was found and showed an apparent kinact value of 0.206 × 10−3 µM−1 min−1. Meanwhile, compared with the wild-type TXNRD1 (-GCUG), the UGA-truncated form (-GC) of TXNRD1 was resistant to piperlongumine, suggesting the preferential target of piperlongumine is the selenol (-SeH) at the C-terminal redox motif of the enzyme. Interestingly, the high concentration of piperlongumine-inhibited TXNRD1 showed that its Sec-dependent activity is decayed but its intrinsic NADPH oxidase activity is retained. Furthermore, piperlongumine did not induce ferroptosis in HCT116 cells at 10 µM, whereas significantly promoted erastin-induced lipid oxidation, which could be alleviated by supplying glutathione (GSH) or N-acetyl L-cysteine (NAC). However, restricting GSH synthesis by inhibiting glutaminase (GLS) using the small molecule inhibitor CB-839 only slightly enhanced erastin-induced cell death. Taken together, this study elucidates the molecular mechanism of the antitumor capacity of piperlongumine by targeting TXNRD1 and reveals the potential possibility of inhibiting TXNRD1 to strengthen cancer cells’ ferroptosis.

Effects of Green Tea (-)-Epigallocatechin-3-Gallate (EGCG) on Cardiac Function - A Review of the Therapeutic Mechanism and Potentials

Heart disease, the leading cause of death globally, refers to various illnesses that affect heart structure and function. Specific abnormalities affecting cardiac muscle contractility and remodeling and common factors including oxidative stress, inflammation, and apoptosis underlie the pathogenesis of heart diseases. Epidemiology studies have associated green tea consumption with lower morbidity and mortality of cardiovascular diseases, including heart and blood vessel dysfunction. Among the various compounds found in green tea, catechins are believed to play a significant role in producing benefits to cardiovascular health. Comprehensive literature reviews have been published to summarize the tea catechins' antioxidative, anti-inflammatory, and anti-apoptosis effects in the context of various diseases, such as cardiovascular diseases, cancers, and metabolic diseases. However, recent studies on tea catechins, especially the most abundant (-)-Epigallocatechin-3-Gallate (EGCG), revealed their capabilities in regulating cardiac muscle contraction by directly altering myofilament Ca2+ sensitivity on force development and Ca2+ ion handling in cardiomyocytes under both physiological and pathological conditions. In vitro and in vivo data also demonstrated that green tea extract or EGCG protected or rescued cardiac function, independent of their well-known effects against oxidative stress and inflammation. This minireview will focus on the specific effects of tea catechins on heart muscle contractility at the molecular and cellular level, revisit their effects on oxidative stress and inflammation in a variety of heart diseases, and discuss EGCG's potential as one of the lead compounds for new drug discovery for heart diseases.

Metabolic Profiling of Thymic Epithelial Tumors Hints to a Strong Warburg Effect, Glutaminolysis and Precarious Redox Homeostasis as Potential Therapeutic Targets

Simple Summary

Thymomas and thymic carcinomas (TCs) are malignant thymic epithelial tumors (TETs) with poor outcome, if non-resectable. Metabolic signatures of TETs have not yet been studied and may offer new therapeutic options. This is the first metabolomics investigation on thymic epithelial tumors employing nuclear magnetic resonance spectroscopy of tissue samples. We could detect and quantify up to 37 metabolites in the major tumor subtypes, including acetylcholine that was not previously detected in other non-endocrine cancers. A metabolite-based cluster analysis distinguished three clinically relevant tumor subgroups, namely indolent and aggressive thymomas, as well as TCs. A metabolite-based metabolic pathway analysis also gave hints to activated metabolic pathways shared between aggressive thymomas and TCs. This finding was largely backed by enrichment of these pathways at the transcriptomic level in a large, publicly available, independent TET dataset. Due to the differential expression of metabolites in thymic epithelial tumors versus normal thymus, pathways related to proline, cysteine, glutathione, lactate and glutamine appear as promising therapeutic targets. From these findings, inhibitors of glutaminolysis and of the downstream TCA cycle are anticipated to be rational therapeutic strategies. If our results can be confirmed in future, sufficiently powered studies, metabolic signatures may contribute to the identification of new therapeutic options for aggressive thymomas and TCs.

Abstract

Thymomas and thymic carcinomas (TC) are malignant thymic epithelial tumors (TETs) with poor outcome, if non-resectable. Metabolic signatures of TETs have not yet been studied and may offer new therapeutic options. Metabolic profiles of snap-frozen thymomas (WHO types A, AB, B1, B2, B3, n = 12) and TCs (n = 3) were determined by high resolution magic angle spinning 1H nuclear magnetic resonance (HRMAS 1H-NMR) spectroscopy. Metabolite-based prediction of active KEGG metabolic pathways was achieved with MetPA. In relation to metabolite-based metabolic pathways, gene expression signatures of TETs (n = 115) were investigated in the public “The Cancer Genome Atlas” (TCGA) dataset using gene set enrichment analysis. Overall, thirty-seven metabolites were quantified in TETs, including acetylcholine that was not previously detected in other non-endocrine cancers. Metabolite-based cluster analysis distinguished clinically indolent (A, AB, B1) and aggressive TETs (B2, B3, TCs). Using MetPA, six KEGG metabolic pathways were predicted to be activated, including proline/arginine, glycolysis and glutathione pathways. The activated pathways as predicted by metabolite-profiling were generally enriched transcriptionally in the independent TCGA dataset. Shared high lactic acid and glutamine levels, together with associated gene expression signatures suggested a strong “Warburg effect”, glutaminolysis and redox homeostasis as potential vulnerabilities that need validation in a large, independent cohort of aggressive TETs. If confirmed, targeting metabolic pathways may eventually prove as adjunct therapeutic options in TETs, since the metabolic features identified here are known to confer resistance to cisplatin-based chemotherapy, kinase inhibitors and immune checkpoint blockers, i.e., currently used therapies for non-resectable TETs.

On the origin of chaotrope-modulated electrocatalytic activity of cytochrome c at electrified aqueous|organic interfaces

Electrochemical, spectroscopic and computational methods are used to demonstrate that electrified aqueous|organic interfaces are a suitable bio-mimetic platform to study and contrast the accelerated electrocatalytic activity of cytochrome c towards the production of reactive oxygen species (ROS) in the presence of denaturing agents such as guanidinium chloride and urea.

Rheumatoid arthritis drug sinomenine induces apoptosis of cervical tumor cells by targeting thioredoxin reductase in vitro and in vivo

Overexpression of thioredoxin reductase (TrxR) has been linked to tumorigenesis and phenotypic maintenance of malignant tumors. Thus, targeting TrxR with natural molecules is a promising strategy for developing anticancer drugs. Sinomenine is a naturally occurring alkaloid isolated from Sinomenium acutum. The drug, Zhengqing Fengtongning made from sinomenine, has been universally applied in rheumatoid arthritis treatment in China as well as other Asian countries for decades. Recently, increasing evidence indicates that sinomenine appears to be a promising therapeutic agent against various cancer cells. However, the exact mechanism underlying the anticancer activity of sinomenine remains unclear. In this study, we identified sinomenine as a kind of new inhibitor for TrxR. Pharmacological inhibition of TrxR by sinomenine results in the decrease of thiols content, increases the levels of reactive oxygen species, and finally facilitates oxidative stress-mediated cancer cell apoptosis. It is vital that knockdown in TrxR1 by shRNA can increase cell sensitivity to sinomenine. Treatment with sinomenine in vivo leads to a decrease in TrxR activity and tumor growth, and an increase in apoptosis. Our findings provide a novel action mechanism related to sinomenine and presents an insight on how to develop sinomenine as a chemotherapeutic agent for cancer therapy.

Novel strategies for targeting the thioredoxin system for cancer therapy

INTRODUCTION

: The thioredoxin system is increasingly recognized as an important executor for maintaining cell redox homeostasis and regulating multiple cell signaling pathways. Targeting this system for cancer treatment has therefore attracted much attention.

AREAS COVERED

: The authors focus on providing coverage and emphasizing the strategy of targeting the thioredoxin system to develop anticancer therapeutics in the past five years, especially from the perspective of discovering novel protein functions or new downstream regulatory pathways, and designing new therapeutic reagents. The authors also provide the readers with their expert perspectives for future development.

EXPERT OPINION

: The limited pharmacophore of inhibitors and the slow progress of clinical research partially restrict the development of anticancer drugs targeting the thioredoxin system, necessitating thus novel strategies to accelerate the system for treating cancer. Nevertheless, the synergistic targeting of thioredoxin system for cancer therapy is a promising strategy, particularly with regards to chemotherapy resistance and/or sensitization immunotherapy.

Thioredoxin reductase 1 inhibitor shikonin promotes cell necroptosis via SecTRAPs generation and oxygen-coupled redox cycling

Shikonin, a naturally occurring naphthoquinone with potent anti-tumor activity, has been reported to induce cancer cell death via targeting selenoenzyme thioredoxin reductase 1 (TrxR1; TXNRD1). However, the interaction between shikonin and TrxR1 remains unclear, and the roles of the cellular antioxidant system in shikonin induced cell death are obscure. Here, we found that shikonin modified the Sec⁴⁹⁸ residue of TrxR1 to fully inhibit its antioxidant activity, however, the shikonin-modified TrxR1 still remained intrinsic NADPH oxidase activity, which promotes superoxide anions production. Besides, TrxR1 efficiently reduced shikonin in both selenocysteine dependent and selenocysteine independent manners, and the oxygen-coupled redox cycling of shikonin also generates excessive superoxide anions. The inhibitory effects and the redox cycling of shikonin towards TrxR1 caused cancer cell ROS-dependent necroptosis. Interestingly, as we evaluated, some cancer cell lines were insensitive to shikonin, especially kelch-like ECH associated protein 1 (KEAP1)-mutant non-small cell lung cancer (NSCLC) cells, which harbor constitutive activation of the nuclear factor-erythroid 2-related factor 2 (NRF2). NADPH bankruptcy caused by glucose starvation or glucose limitation (inhibiting glucose transporter 1 by BAY-876) could efficiently overcome the resistance of KEAP1-mutant NSCLC cells to shikonin. Glucose-6-phosphate dehydrogenase (G6PD), was known as a rate-limiting enzyme in the pentose phosphate pathway, however, the pharmacological inhibition of G6PD by 6-aminonicotinamide (6-AN), enhanced the shikonin-induced cytotoxicity but has no selectivity on KEAP1-mutant NSCLC cells. This study will be helpful in applying shikonin for potential chemotherapy, and in combinational treatment of KEAP1-mutant NSCLC.

Inhibition of thioredoxin reductase by natural anticancer candidate β-lapachone accounts for triggering redox activation-mediated HL-60 cell apoptosis

β-Lapachone as a natural novel anticancer candidate is under clinical trials. Previous studies suggested that β-lapachone works by redox activation to ablate cancer cells. However, it is still unclear whether thioredoxin reductase (TrxR), one of the key redox catalytic enzymes in cells, plays a role in the pharmacological effects of β-lapachone. Herein, we present that β-lapachone kills human promyelocytic leukemia HL-60 cells with preference over other cancer cells and normal cells. The follow-up studies demonstrate that β-lapachone induces the HL-60 cell apoptosis through inhibition of TrxR and further elevation of oxidative stress. Overexpression of the TrxR alleviates the efficiency of β-lapachone while knockdown of the enzyme increases the β-lapachone cytotoxicity, scientifically underpinning the correlation of the observed biological behaviors of β-lapachone to TrxR inhibition. The disclosure of the novel action mechanism of β-lapachone sheds light on understanding its capacity in interfering with cellular redox signaling and supports β-lapachone as an anticancer drug candidate.

Regulation of reactive oxygen species by phytochemicals for the management of cancer and diabetes

Cancer and diabetes mellitus are served as typical life-threatening diseases with common risk factors. Developing therapeutic measures in cancers and diabetes have aroused attention for a long time. However, the problems with conventional treatments are in challenge, including side effects, economic burdens, and patient compliance. It is essential to secure safe and efficient therapeutic methods to overcome these issues. As an alternative method, antioxidant and pro-oxidant properties of phytochemicals from edible plants have come to the fore. Phytochemicals are naturally occurring compounds, considered promising agent applicable in treatment of various diseases with beneficial effects. Either antioxidative or pro-oxidative activity of various phytochemicals were found to contribute to regulation of cell proliferation, differentiation, cell cycle arrest, and apoptosis, which can exert preventive and therapeutic effects against cancer and diabetes. In this article, the antioxidant or pro-oxidant effects and underlying mechanisms of flavonoids, alkaloids, and saponins in cancer or diabetic models demonstrated by the recent studies are summarized.

Integration of a Diselenide Unit Generates Fluorogenic Camptothecin Prodrugs with Improved Cytotoxicity to Cancer Cells

A diselenide/disulfide unit was introduced into camptothecin (CPT), and two selenoprodrugs (e.g., CPT-Se3 and CPT-Se4) were identified to show improved potency in killing cancer cells and inhibiting tumor growth in vivo. Interestingly, the intrinsic fluorescence of CPT was severely quenched by the diselenide bond. Both the selenoprodrugs were activated by glutathione with a nearly complete recovery of CPT's fluorescence. The activation of prodrugs was accompanied by the production of selenol intermediates, which catalyzed the constant conversion of glutathione and oxygen to oxidized glutathione and superoxides. The diselenide unit is widely employed in constructing thiol-responsive materials. However, the selenol intermediates were largely ignored in the activation process prior to this study. Our work verified that integration of the diselenide unit may further enhance the parent drug's efficacy. Also, the discovery of the fluorescence quenching property of the diselenide/disulfide bond further shed light on constructing novel theranostic agents.

Onopordopicrin from the new genus Shangwua as a novel thioredoxin reductase inhibitor to induce oxidative stress-mediated tumor cell apoptosis

Isolation and identification of natural products from plants is an essential approach for discovering drug candidates. Herein we report the characterization of three sesquiterpene lactones from a new genus Shangwua, e.g. onopordopicrin (ONP), C2, and C3, and evaluation of their pharmacological functions in interfering cellular redox signaling. Compared to C2 and C3, ONP shows the most potency in killing cancer cells. Further experiments demonstrate that ONP robustly inhibits thioredoxin reductase (TrxR), which leads to perturbation of cellular redox homeostasis with the favor of oxidative stress. Knockdown of the TrxR sensitizes cells to the ONP treatment while overexpression of the enzyme reduces the potency of ONP, underpinning the correlation of TrxR inhibition to the cytotoxicity of ONP. The discovery of ONP expands the library of the natural TrxR inhibitors, and the disclosure of the action mechanism of ONP provides a foundation for the further development of ONP as an anticancer agent.

Assay of selenol species in biological samples by the fluorescent probe Sel-green

Selenium (Se) is an essential trace element for diverse cellular functions. The biological significance of Se is predominantly dependent on its incorporation into the selenocysteine (Sec) for synthesis of selenoproteins (SePs), such as thioredoxin reductase family enzymes and glutathione peroxidase family enzymes. In general, the hyperactivity of the selenol group in Sec confers the Sec residue critical for functions of SePs. The Sec is much less abundant than its sulfur analog cysteine (Cys), and it remains a high challenge to detect Sec, especially in complex biological samples. We recently reported a selective fluorescent probe Sel-green for selenols and summarized the principles for design of selenol (and thiophenol) probes. Sel-green discriminates selenols from other biological species, especially thiols, under physiological conditions, and has been applied to detect both endogenous and exogenous selenol species in live cells. In this chapter, we describe a protocol and guideline for the selective detection of Sec by applying the Sel-green. This protocol is also suitable for detection of other selenol species. This practical and convenient assay would assist scientists to better understand the pivotal roles of Sec as well as SePs.

Structural Modification of Aminophenylarsenoxides Generates Candidates for Leukemia Treatment via Thioredoxin Reductase Inhibition

Upregulation of the selenoprotein thioredoxin reductase (TrxR) is of pathological significance in maintaining tumor phenotypes. Thus, TrxR inhibitors are promising cancer therapeutic agents. We prepared different amino-substituted phenylarsine oxides and evaluated their cytotoxicity and inhibition of TrxR. Compared with our reported p-substituted molecule (8), the o-substituted molecule (10) shows improved efficacy (nearly a fourfold increase) to kill leukemia HL-60 cells. Although the compounds 8 and 10 display similar potency to inhibit the purified TrxR, the o-substitution 10 exhibits higher potency than the p-substitution 8 to inhibit the cellular TrxR activity. Molecular docking results demonstrate the favorable weak interactions of the o-amino group with the TrxR C-terminal active site. Efficient inhibition of TrxR consequently induces the oxidative stress-mediated apoptosis of cancer cells. Silence of the TrxR expression sensitizes the cells to the arsenic compound treatment, further supporting the critical involvement of TrxR in the cellular actions of compound 10.

One-Pot Surface Modification of β-Cu2O NPs for Biocatalytic Performance against A-549 Lung Carcinoma Cell Lines through Docking Analysis

The physicochemical approaches and biological principles in bio-nanotechnology favor specially functionalized nanosized particles. Cuprous oxide nanoparticles (β-Cu₂O NPs) of cuprite phase with a little tenorite (CuO) may be very effective in the development of novel therapeutic approaches against several fatalities including A-549 lung carcinoma cell lines. Consequently, the synthesis of β-Cu₂O NPs for the improvement in the therapeutic index and drug delivery application is becoming an effective strategy in conventional anticarcinoma treatment. Hence, surface-enhanced nanosized spherical cuprous oxide nanoparticles (β-Cu₂O NPs) of cuprite phase were successfully prepared using poly(ethylene glycol) (PEG) as an amphiphilic nonionic surfactant and l-ascorbic acid (K₃[Cu(Cl₅)]@LAA-PEG) reduced to cuprites β-Cu₂O NPs via the sonochemical route. Less improved toxicity and better solubility of β-Cu₂O NPs compared with Axitinib were a major reason for producing β-Cu₂O NPs from K₃[Cu(Cl₅)]@LAA-PEG (LAA, l-ascorbic acid, PEG, poly(ethylene glycol) (PEG)). These nanoparticle syntheses have been suggested to influence their cytotoxicity, free-radical scavenging analysis, and reactive oxygen species (ROS) using poly(ethylene glycol) (PEG) and l-ascorbic acid (LAA) as coated and grafted materials due to their dose-dependent nature and IC₅₀ calculations. The surface morphology of the formed β-Cu₂O NPs has been examined via UV-vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy with energy diffraction scattering spectroscopy (SEM@EDS), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) analysis. X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) surface analysis results confirm the presence of pure cuprite with a very little amount of tenorite (CuO) phase, Dynamic light scattering (DLS) confirms the negative ζ-value with stable nature. Docking was performed using PDB of lung carcinomas and others, as rigid receptors, whereas the β-Cu₂O NP cluster was treated as a flexible ligand.

XHL11, a novel selective EGFR inhibitor, overcomes EGFRT790M-mediated resistance in non-small cell lung cancer

The first-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), gefitinib and erlotinib significantly improved the therapeutic effect in non-small cell lung cancer (NSCLC) patients with EGFR mutation. However, the EGFRT790M mutation occurs and results in acquired resistance. Consequently, mutant selective third-generation EGFR TKIs represented by AZD9291 (Osimertinib) have been developed to offer more effective therapeutic treatment, but the clinical application is limited by the acquired resistance and the high costs. A series of 5-chloropyrimidine-2,4-diamine derivatives were synthesized and screened for in vitro antitumor activity on H1975 and A431 cells. XHL11 showed the strongest antineoplastic activity. Compared to AZD9291, XHL11 suppressed cellular proliferation and colony formation and induced apoptosis in H1975 cells with EGFRL858R/T790M mutation. In addition, XHL11 caused expression changes in EGFR and apoptosis-related pathways. Moreover, oral administration of XHL11 suppressed tumor progression in vivo in a H1975 subcutaneous xenograft model. These data demonstrated that XHL11 might be developed as a promising EGFR TKI for the therapeutic use of NSCLC patients.