The microtubule depolymerizing agent naphthazarin induces both apoptosis and autophagy in A549 lung cancer cells

Energy metabolism as the hub of advanced non-small cell lung cancer management: a comprehensive view in the framework of predictive, preventive, and personalized medicine

Energy metabolism is a hub of governing all processes at cellular and organismal levels such as, on one hand, reparable vs. irreparable cell damage, cell fate (proliferation, survival, apoptosis, malignant transformation etc.), and, on the other hand, carcinogenesis, tumor development, progression and metastazing versus anti-cancer protection and cure. The orchestrator is the mitochondria who produce, store and invest energy, conduct intracellular and systemically relevant signals decisive for internal and environmental stress adaptation, and coordinate corresponding processes at cellular and organismal levels. Consequently, the quality of mitochondrial health and homeostasis is a reliable target for health risk assessment at the stage of reversible damage to the health followed by cost-effective personalized protection against health-to-disease transition as well as for targeted protection against the disease progression (secondary care of cancer patients against growing primary tumors and metastatic disease). The energy reprogramming of non-small cell lung cancer (NSCLC) attracts particular attention as clinically relevant and instrumental for the paradigm change from reactive medical services to predictive, preventive and personalized medicine (3PM). This article provides a detailed overview towards mechanisms and biological pathways involving metabolic reprogramming (MR) with respect to inhibiting the synthesis of biomolecules and blocking common NSCLC metabolic pathways as anti-NSCLC therapeutic strategies. For instance, mitophagy recycles macromolecules to yield mitochondrial substrates for energy homeostasis and nucleotide synthesis. Histone modification and DNA methylation can predict the onset of diseases, and plasma C7 analysis is an efficient medical service potentially resulting in an optimized healthcare economy in corresponding areas. The MEMP scoring provides the guidance for immunotherapy, prognostic assessment, and anti-cancer drug development. Metabolite sensing mechanisms of nutrients and their derivatives are potential MR-related therapy in NSCLC. Moreover, miR-495-3p reprogramming of sphingolipid rheostat by targeting Sphk1, 22/FOXM1 axis regulation, and A2 receptor antagonist are highly promising therapy strategies. TFEB as a biomarker in predicting immune checkpoint blockade and redox-related lncRNA prognostic signature (redox-LPS) are considered reliable predictive approaches. Finally, exemplified in this article metabolic phenotyping is instrumental for innovative population screening, health risk assessment, predictive multi-level diagnostics, targeted prevention, and treatment algorithms tailored to personalized patient profiles-all are essential pillars in the paradigm change from reactive medical services to 3PM approach in overall management of lung cancers. This article highlights the 3PM relevant innovation focused on energy metabolism as the hub to advance NSCLC management benefiting vulnerable subpopulations, affected patients, and healthcare at large.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-024-00357-5.

Heavy water (D2O) induces autophagy-dependent apoptotic cell death in non-small cell lung cancer A549 cells by generating reactive oxygen species (ROS) upon microtubule disruption

OBJECTIVE

Deuterium oxide (D2O) or heavy water is known to have diverse biological activities and have a few therapeutic applications due to its limited toxicity to human subjects. In the present study, we investigated the mechanism of D2O-induced cytotoxicity in non-small cell lung cancer A549 cells.

RESULTS

We found that D2O-treatment resulted in cytotoxicity, cell cycle arrest, and apoptosis in A549 cells in a dose-dependent fashion. In contrast, limited cytotoxicity was observed in lung fibroblasts WI38 cells. Moreover, D2O-treatment resulted in the disruption of the cellular microtubule network, accompanied by the generation of ROS. On further investigation, we observed that the intracellular ROS triggered autophagic responses in D2O-treated cells, leading to apoptosis by inhibiting the oncogenic PI3K/ Akt/ mTOR signaling. D2O-treatment was also found to enhance the efficacy of paclitaxel in A549 cells.

SIGNIFICANCE

D2O induces autophagy-dependent apoptosis in A549 cells via ROS generation upon microtubule depolymerization and inhibition of PI3K/ Akt/ mTOR signaling. It augments the efficacy of other microtubule-targeting anticancer drug taxol, which indicates the potential therapeutic importance of D2O as an anticancer agent either alone or in combination with other chemotherapeutic drugs.

Fe(III)-Naphthazarin Metal-Phenolic Networks for Glutathione-Depleting Enhanced Ferroptosis-Apoptosis Combined Cancer Therapy

Nowadays, Fenton chemistry-based chemodynamic therapy (CDT) is an emerging approach to killing tumor cells by converting endogenous H₂ O₂ into cytotoxic hydroxyl radicals (·OH). However, the elimination of ·OH by intracellular overexpressed glutathione (GSH) results in unsatisfactory antitumor efficiency. In addition, the single mode of consuming GSH and undesirable drug loading efficiency cannot guarantee the efficient cancer cells killing effect. Herein, a simple one-step strategy for the construction of Fe³⁺ -naphthazarin metal-phenolic networks (FNP MPNs) with ultrahigh loading capacity, followed by the modification of NH₂ -PEG-NH₂ , is developed. The carrier-free FNP MPNs can be triggered by acid and GSH, and rapidly release naphthazarin and Fe³⁺ , which is further reduced to Fe²⁺ that exerts Fenton catalytic activity to produce abundant ·OH. Meanwhile, the Michael addition between naphthazarin and GSH can lead to GSH depletion and thus achieve tumor microenvironment (TME)-triggered enhanced CDT, followed by activating ferroptosis and apoptosis. In addition, the reduced Fe²⁺ as a T₁ -weighted contrast agent endows the FNP MPNs with magnetic resonance imaging (MRI) functionality. Overall, this work is the debut of naphthazarin as ligands to fabricate functional MPNs for effectively depleting GSH, disrupting intracellular redox homeostasis, and enhancing CDT effects, which opens new perspectives on multifunctional MPNs for tumor synergistic therapy.

Novel Indole-Chalcone Derivative-Ligated Platinum(IV) Prodrugs Attenuate Cisplatin Resistance in Lung Cancer through ROS/ER Stress and Mitochondrial Dysfunction

Developing multifunctional platinum(IV) prodrugs via integrating bioactive pharmacophores into one entity is an attractive strategy to ameliorate the defects of platinum(II) drugs. Herein, a series of indole-chalcone derivative-ligated platinum(IV) complexes were synthesized and evaluated for their anticancer activities. Among them, optimal complex 17a exerted superior activity compared to that of cisplatin (CDDP) against the tested cells but showed lower cytotoxicity toward human normal lung cells. Detailed mechanisms demonstrated that 17a significantly enhanced intracellular accumulation, induced DNA damage, and inhibited migration in A549/CDDP cells. Furthermore, 17a efficiently disturbed the tubulin-microtubule system, initiated reactive oxygen species (ROS)-mediated endoplasmic reticulum stress, and activated a mitochondrion-dependent apoptosis signaling pathway. Besides, 17a was superior to free drugs or their combination in inhibiting cancer growth in A549/CDDP xenografts without inducing obvious side effects. The physical mixture of 16a and CDDP was almost identical to 17a but showed apparent systematic side effects. In summary, our studies may provide an efficient treatment regimen for CDDP resistance.

Glucose and mannose analogs inhibit KSHV replication by blocking N-glycosylation and inducing the unfolded protein response

Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiological agent for Kaposi's sarcoma (KS), an HIV/AIDS-associated malignancy. Effective treatments against KS remain to be developed. The sugar analog 2-deoxy- d-glucose (2-DG) is an anticancer agent that is well-tolerated and safe in patients and was recently demonstrated to be a potent antiviral, including KSHV and severe acute respiratory syndrome coronavirus 2. Because 2-DG inhibits glycolysis and N-glycosylation, identifying its molecular targets is challenging. Here we compare the antiviral effect of 2-DG with 2-fluoro-deoxy- d-glucose, a glycolysis inhibitor, and 2-deoxy-fluoro- d-mannose (2-DFM), a specific N-glycosylation inhibitor. At doses similar to those clinically achievable with 2-DG, the three drugs impair KSHV replication and virion production in iSLK.219 cells via downregulation of viral structural glycoprotein expression (K8.1 and gB), being 2-DFM the most potent KSHV inhibitor. Consistently with the higher potency of 2-DFM, we found that d-mannose rescues KSHV glycoprotein synthesis and virus production, indicating that inhibition of N-glycosylation is the main antiviral target using d-mannose competition experiments. Suppression of N-glycosylation by the sugar drugs triggers ER stress. It activates the host unfolded protein response (UPR), counteracting KSHV-induced inhibition of the protein kinase R-like endoplasmic reticulum kinase branch, particularly activating transcription factor 4 and C/EBP homologous protein expression. Finally, we demonstrate that sugar analogs induce autophagy (a prosurvival mechanism) and, thus, inhibit viral replication playing a protective role against KSHV-induced cell death, further supporting their direct antiviral effect and potential therapeutic use. Our work identifies inhibition of N-glycosylation leading to ER stress and UPR as an antienveloped virus target and sugar analogs such as 2-DG and the newly identified 2-DFM as antiviral drugs.

Identification and Characterization of Natural and Semisynthetic Quinones as Aurora Kinase Inhibitors

Aurora kinases (Aurora A, B, and C) are a family of serine/threonine kinases that play critical roles during mitotic initiation and progression. Aurora A and B kinases are ubiquitously expressed, and their overexpression and/or amplification in many cancers have been associated with poor prognosis. Several inhibitors that target Aurora kinases A, B, or both have been developed during the past decade with efficacy in different in vitro and in vivo models for a variety of cancers. Recent studies have also identified Aurora A as a synthetic lethal target for different tumor suppressors, including RB1, SMARCA4, and ARID1A, which signifies the need for Aurora-A-selective inhibitors. Here, we report the screening of a small library of quinones (nine naphthoquinones, one orthoquinone, and one anthraquinone) in a biochemical assay for Aurora A kinase that resulted in the identification of several quinones as inhibitors. IC₅₀ determination against Aurora A and B kinases revealed the inhibition of both kinases with selectivity toward Aurora A. Two of the compounds, natural quinone naphthazarin (1) and a pseudo anthraquinone, 2-(chloromethyl)quinizarin (11), potently inhibited the proliferation of various cancer cell lines with IC₅₀ values ranging from 0.16 ± 0.15 to 1.7 ± 0.06 and 0.15 ± 0.04 to 6.3 ± 1.8 μM, respectively. Treatment of cancer cells with these compounds for 24 h resulted in abrogated mitosis and apoptotic cell death. Direct binding of both the compounds with Aurora A kinase was also confirmed through STD NMR analysis. Docking studies predicted the binding of both compounds to the ATP binding pocket of Aurora A kinase. We have, therefore, identified quinones as Aurora kinase inhibitors that can serve as a lead for future drug discovery endeavors.

Pathogenic Mechanisms of Secondary Organic Aerosols

Air pollution represents a major health problem and an economic burden. In recent years, advances in air pollution research has allowed particle fractionation and identification of secondary organic aerosol (SOA). SOA is formed from either biogenic or anthropogenic emissions, through a mass transfer from the gaseous mass to the particulate phase in the atmosphere. They can have deleterious impact on health and the mortality of individuals with chronic inflammatory diseases. The pleiotropic effects of SOA could involve different and interconnected pathogenic mechanisms ranging from oxidative stress, inflammation, and immune system dysfunction. The purpose of this review is to present recent findings about SOA pathogenic roles and potential underlying mechanisms focusing on the lungs; the latter being the primary exposed organ to atmospheric pollutants.

Carrier free photodynamic oxidizer for enhanced tumor therapy by redox homeostasis disruption

Abnormal tumor microenvironments play important roles in cancer progression. In general, tumor cells are capable of upregulating glutathione (GSH) levels to keep aberrant redox homeostasis and cause a resistance to...

Antiparasitic Effect of Stilbene and Terphenyl Compounds against Trypanosoma cruzi Parasites

Background: Chagas disease, also known as American trypanosomiasis, is a potentially life-threatening illness caused by the protozoan parasite Trypanosoma cruzi. No progress in the treatment of this pathology has been made since Nifurtimox was introduced more than fifty years ago, and this drug is considered very aggressive and may cause several adverse effects. This drug currently has severe limitations, including a high frequency of undesirable side effects and limited efficacy and availability, so research to discover new drugs for the treatment of Chagas disease is imperative. Many drugs available on the market are natural products as found in nature or compounds designed based on the structure and activity of these natural products. Methods: This study evaluated the in vitro antiparasitic activity of a series of previously synthesized stilbene and terphenyl compounds in T. cruzi epimastigotes and intracellular amastigotes. The action of the most selective compounds was investigated by flow cytometric analysis to evaluate the mechanism of cell death. The ability to induce apoptosis or caspase-1 inflammasomes was assayed in macrophages infected with T. cruzi after treatment, comparing it with that of Nifurtimox. Results: The stilbene ST18 was the most potent compound of the series. It was slightly less active than Nifurtimox in epimastigotes but most active in intracellular amastigotes. Compared to Nifurtimox, it was markedly less cytotoxic when tested in vitro on normal cells. ST18 was able to induce a marked increase in parasites positive for Annexin V and monodansylcadaverine. Moreover, ST18 induced the activation, in infected macrophages, of caspase-1, a conserved enzyme that plays a major role in controlling parasitemia, host survival and the onset of the adaptive immune response in Trypanosoma infection. Conclusions: The antiparasitic activity of ST18 together with its ability to activate caspase-1 in infected macrophages and its low toxicity toward normal cells makes this compound interesting for further clinical investigation.

Synthesis, Cytotoxic Activity Evaluation and Quantitative Structure-Activity Analysis of Substituted 5,8-Dihydroxy-1,4-Naphthoquinones and their O- and S-Glycoside Derivatives Tested Against Neuro-2a Cancer Cells

Based on 6,7-substituted 2,5,8-trihydroxy-1,4-naphtoquinones (1,4-NQs) derived from sea urchins, five new acetyl-O-glucosides of NQs were prepared. A new method of conjugation of per-O-acetylated 1-mercaptosaccharides with 2-hydroxy-1,4-NQs through a methylene spacer was developed. Methylation of 2-hydroxy group of quinone core of acetylthiomethylglycosides by diazomethane and deacetylation of sugar moiety led to 28 new thiomethylglycosidesof 2-hydroxy- and 2-methoxy-1,4-NQs. The cytotoxic activity of starting 1,4-NQs (13 compounds) and their O- and S-glycoside derivatives (37 compounds) was determined by the MTT method against Neuro-2a mouse neuroblastoma cells. Cytotoxic compounds with EC50 = 2.7-87.0 μM and nontoxic compounds with EC50 > 100 μM were found. Acetylated O- and S-glycosides 1,4-NQs were the most potent, with EC50 = 2.7-16.4 μM. Methylation of the 2-OH group innaphthoquinone core led to a sharp increase in the cytotoxic activity of acetylated thioglycosidesof NQs, which was partially retained for their deacetylated derivatives. Thiomethylglycosides of 2-hydroxy-1,4-NQs with OH and MeO groups in quinone core at positions 6 and 7, resprectively formed a nontoxic set of compounds with EC50 > 100 μM. A quantitative structure-activity relationship (QSAR) model of cytotoxic activity of 22 1,4-NQ derivatives was constructed and tested. Descriptors related to the cytotoxic activity of new 1,4-NQ derivatives were determined. The QSAR model is good at predicting the activity of 1,4-NQ derivatives which are unused for QSAR models and nontoxic derivatives.

Molecular Insights into the Multifunctional Role of Natural Compounds: Autophagy Modulation and Cancer Prevention

Autophagy is a vacuolar, lysosomal degradation pathway for injured and damaged protein molecules and organelles in eukaryotic cells, which is controlled by nutrients and stress responses. Dysregulation of cellular autophagy may lead to various diseases such as neurodegenerative disease, obesity, cardiovascular disease, diabetes, and malignancies. Recently, natural compounds have come to attention for being able to modulate the autophagy pathway in cancer prevention, although the prospective role of autophagy in cancer treatment is very complex and not yet clearly elucidated. Numerous synthetic chemicals have been identified that modulate autophagy and are favorable candidates for cancer treatment, but they have adverse side effects. Therefore, different phytochemicals, which include natural compounds and their derivatives, have attracted significant attention for use as autophagy modulators in cancer treatment with minimal side effects. In the current review, we discuss the promising role of natural compounds in modulating the autophagy pathway to control and prevent cancer, and provide possible therapeutic options.

Synthesis and biological evaluation of substituted N-(2-(1H-benzo[d]imidazol-2-yl)phenyl)cinnamides as tubulin polymerization inhibitors

A new series of N-(2-(1H-benzo[d]imidazol-2-yl)phenyl) cinnamides was prepared and evaluated for their in vitro cytotoxic activity using various cancer cell lines viz. A549 (human non-small cell lung cancer), MDA-MB-231 (human triple negative breast cancer), B16-F10 (mouse melanoma), BT-474 (human breast cancer), and 4 T1 (mouse triple negative breast cancer). In the series of tested compounds, 12h showed potent cytotoxic activity against non-small cell lung cancer cell line with IC₅₀ value of 0.29 ± 0.02 µM. The cytoxicity of most potent compound 12h was also tested on NRK-52E (normal rat kidney epithelial cell line) and showed less cytotoxicity compared to cancer cells. Tubulin polymerization assay indicated that the compound 12h was able to impede the cell division by inhibiting tubulin polymerization. Moreover, molecular docking study also suggested the binding of 12h at the colchicine-binding site of the tubulin protein. Cell cycle analysis revealed that the compound 12h arrests G2/M phase. In addition, 12h induced apoptosis in A549 cell lines was evaluated by various staining studies like acridine orange, DAPI, analysis of mitochondrial membrane potential, annexin V-FITC, and DCFDA assays.

NMK-BH2, a novel microtubule-depolymerising bis (indolyl)-hydrazide-hydrazone, induces apoptotic and autophagic cell death in cervical cancer cells by binding to tubulin at colchicine - site

BACKGROUND

Microtubules, the key components of the eukaryotic cytoskeleton and mitotic spindle, are one of the most sought-after targets for cancer chemotherapy, especially due to their indispensible role in mitosis. Cervical cancer is a prevalent malignancy among women of developing countries including India. In spite of the remarkable therapeutic advancement, the non-specificity of chemotherapeutic drugs adversely affect the patients' survival and well-being, thus, necessitating the quest for novel indole-based anti-microtubule agent against cervical cancer, with high degree of potency and selectivity.

METHODS

For in vitro studies, we used MTT assay, confocal microscopy, fluorescence microscopy, flow cytometry and Western blot analysis. Study in cell free system was accomplished by spectrophotometry, fluorescence spectroscopy and TEM and computational analysis was done by AutodockTools 1.5.6.

RESULTS

NMK-BH2 exhibited significant and selective anti-proliferative activity against cervical cancer HeLa cells (IC₅₀ = 1.5 μM) over normal cells. It perturbed the cytoskeletal and spindle microtubules of HeLa cells leading to mitotic block and cell death by apoptosis and autophagy. Furthermore, NMK-BH2 targeted the tubulin-microtubule system through fast and strong binding to the αβ-tubulin heterodimers at colchicine-site.

CONCLUSION

This study identifies and characterises NMK-BH2 as a novel anti-microtubule agent and provides insights into its key anti-cancer mechanism through two different cell death pathways: apoptosis and autophagy, which are mutually independent.

GENERAL SIGNIFICANCE

It navigates the potential of the novel bis (indolyl)-hydrazide-hydrazone, NMK-BH2, to serve as lead for development of new generation microtubule-disrupting chemotherapeutic with improved efficacy and remarkable selectivity towards better cure of cervical cancer.

A hydrogen peroxide-activated Cu(II) pro-ionophore strategy for modifying naphthazarin as a promising anticancer agent with high selectivity for generating ROS in HepG2 cells over in L02 cells

Targeting redox vulnerability of cancer cells by pro-oxidants capable of generating reactive oxygen species (ROS) has surfaced as an important anticancer strategy. Due to the intrinsic narrow therapeutic window and other dangerous side effects of ROS generation, it is highly needed and challenging to develop pro-oxidative anticancer agents (PAAs) with high selectivity for generating ROS in cancer cells. Herein we report a hydrogen peroxide (H₂O₂)-activated Cu(II) pro-ionophore strategy to develop naphthazarin (Nap) as such type of PAAs based on the H₂O₂-mediated conversion of boronate to free phenol. The boronate-protected Nap (PNap) can exploit increased levels of H₂O₂ in HepG2 cells to in situ release Nap followed by its efflux via conjugation with reduced glutathione (GSH), allowing that the Nap-GSH adduct works as a Cu(II) ionophore to induce continuously GSH depletion via a reduction-dependent releasing of Cu(I) by GSH. This strategy endows PNap with the unprecedented ability to hit multi-redox characteristics (increased levels of H₂O₂, GSH and copper) of HepG2 cells, leading to ROS generation preferentially in HepG2 cells along with their selective death.

A Novel Benzofuran Derivative Moracin N Induces Autophagy and Apoptosis Through ROS Generation in Lung Cancer

Introduction

The leaves of Morus alba L is a traditional Chinese medicine widely applied in lung diseases. Moracin N (MAN), a secondary metabolite extracted form the leaves of Morus alba L, is a potent anticancer agent. But its molecular mechanism remains unveiled.

Objective

In this study, we aimed to examine the effect of MAN on human lung cancer and reveal the underlying molecular mechanism.

Methods

MTT assay was conducted to measure cell viability. Annexin V-FITC/PI staining was used to detect cell apoptosis. Confocal microscope was performed to determine the formation of autophagosomes and autolysosomes. Flow cytometry was performed to quantify cell death. Western blotting was used to determine the related-signaling pathway.

Results

In the present study, we demonstrated for the first time that MAN inhibitd cell proliferation and induced cell apoptosis in human non-small-cell lung carcinoma (NSCLC) cells. We found that MAN treatment dysregulated mitochondrial function and led to mitochondrial apoptosis in A549 and PC9 cells. Meanwhile, MAN enhanced autophagy flux by the increase of autophagosome formation, the fusion of autophagsomes and lysosomes and lysosomal function. Moreover, mTOR signaling pathway, a classical pathway regualting autophagy, was inhibited by MAN in a time- and dose-dependent mannner, resulting in autophagy induction. Interestingly, autophagy inhibition by CQ or Atg5 knockdown attenuated cell apoptosis by MAN, indicating that autophagy serves as cell death. Furthermore, autophagy-mediated cell death by MAN can be blocked by reactive oxygen species (ROS) scavenger NAC, indicating that ROS accumulation is the inducing factor of apoptosis and autophagy. In summary, we revealed the molecular mechanism of MAN against lung cancer through apoptosis and autophagy, suggesting that MAN might be a novel therapeutic agent for NSCLC treatment.

Inspired by Sea Urchins: Warburg Effect Mediated Selectivity of Novel Synthetic Non-Glycoside 1,4-Naphthoquinone-6S-Glucose Conjugates in Prostate Cancer

The phenomenon of high sugar consumption by tumor cells is known as Warburg effect. It results from a high glycolysis rate, used by tumors as preferred metabolic pathway even in aerobic conditions. Targeting the Warburg effect to specifically deliver sugar conjugated cytotoxic compounds into tumor cells is a promising approach to create new selective drugs. We designed, synthesized, and analyzed a library of novel 6-S-(1,4-naphthoquinone-2-yl)-d-glucose chimera molecules (SABs)—novel sugar conjugates of 1,4-naphthoquinone analogs of the sea urchin pigments spinochromes, which have previously shown anticancer properties. A sulfur linker (thioether bond) was used to prevent potential hydrolysis by human glycoside-unspecific enzymes. The synthesized compounds exhibited a Warburg effect mediated selectivity to human prostate cancer cells (including highly drug-resistant cell lines). Mitochondria were identified as a primary cellular target of SABs. The mechanism of action included mitochondria membrane permeabilization, followed by ROS upregulation and release of cytotoxic mitochondrial proteins (AIF and cytochrome C) to the cytoplasm, which led to the consequent caspase-9 and -3 activation, PARP cleavage, and apoptosis-like cell death. These results enable us to further clinically develop these compounds for effective Warburg effect targeting.

1,2,3-Triazole tethered 2-mercaptobenzimidazole derivatives: design, synthesis and molecular assessment toward C6 glioma cell line

Aim: Glioblastoma multiforme (GBM) is an aggressive cancer with very limited clinical therapies. Herein, we have designed novel mercaptobenzimidazole derivatives (1-7) as multitarget antineoplastic drugs and assessed their antiproliferative profiles on an experimental model for GBM, the C6 glioma line. Results: The target compounds were synthesized in few steps with reasonable yields (33-90%). Compounds 1 (∼18 μM) and 4 (∼20 μM) showed dose-dependent antiproliferative effects on C6 glioma and significantly increased early apoptosis, but only 4 disrupted the cell cycle progression and did not induce autophagy. Docking simulations suggested these compounds as dual kinase and colchicine binding site inhibitors. Conclusion: In spite of the limited selective toxicity, 4 hold the potential to be further optimized for the treatment of GBM.

ROS -mediated p53 activation by juglone enhances apoptosis and autophagy in vivo and in vitro

Juglone (JG) exhibits a broad-spectrum of cytotoxicity against some cancer cells. However, its molecular mechanisms have not been investigated well. Here, the present results showed that JG significantly inhibited tumor growth in vivo. CCK-8 assays, flow cytometric analysis, western blotting and immunohistochemistry revealed that JG effectively inhibited cell proliferation and induced apoptosis through extrinsic pathways. We also observed that JG treatment induced autophagy flux via activiting the AMPK-mTOR signaling pathway. In addition, we found that JG enhanced p53 activation by increasing down-regulation of ubiquitin-mediated degradation. Inhibition of p53 by siRNA attenuated JG-induced cell death and autophagy. Moreover, JG enhanced the generation of hydrogen peroxide (H₂O₂) and superoxide anion radical (O₂^{• -}). Further experiments proved that H₂O₂ was a major factor since the H₂O₂ scavenger catalase (CAT) reduced both autophagy and cell death to a greater extent than the O₂^{• -} scavenger SOD. Overall, our results illustrated that JG caused apoptosis and autophagy via activating the ROS-mediated p53 pathway in human liver cancer cells in vitro and in vivo, which provided basic scientific evidence that JG serves as a potential anti-cancer agent.

Autophagy dysfunctions associated with cancer cells and their therapeutic implications

Genomic analysis of human cancers indicates that the loss or mutation of core autophagy related genes, (ATG) is uncommon, whereas oncogenic events that activate autophagy and lysosomal biogenesis have been identified. Several studies have demonstrated that autophagy plays a wide variety of physiological and pathophysiological roles in cells: a cellular process that maintains the homeostasis of the normal cell, while self-defects can lead to a lawsuit to accelerate tumorigenesis and developing diseases, such as cancer. Depending on different contexts, autophagy dysfunctions may play a role: neutral, tumor-suppressive, or tumor-promoting. The process of autophagy may function in tumor suppression by mitigating metabolic stress and, in concert with apoptosis, by preventing tumor cell death by necrosis. In this case, optimal combination of autophagy inhibition (CQ, HCQ) with other conventional therapies - chemo or radiotherapy in a variety of tumor types in different phases can be successful approaches for improve the effect of anticancer therapies. This review examines recent insights of the molecular mechanism of autophagy and the potential roles of autophagy in cell death, cancer development, overview of the most recent therapeutic strategies involving autophagy modulators in cancer prevention and therapeutic opportunities.

Effects of Naphthazarin (DHNQ) Combined with Lawsone (NQ-2-OH) or 1,4-Naphthoquinone (NQ) on the Auxin-Induced Growth of Zea mays L. Coleoptile Segments

Naphthoquinones, plants secondary metabolites are known for their antibacterial, antifungal, anti-inflammatory, anti-cancer and anti-parasitic properties. The biological activity of naphthoquinones is connected with their ability to generate reactive oxygen species and to modify biological molecules at their nucleophilic sites. In our research, the effect of naphthazarin (DHNQ) combined with 2-hydroxy-1,4-naphthoquinone (NQ-2-OH) or 1,4-naphthoquinone (1,4-NQ) on the elongation growth, pH changes of the incubation medium, oxidative stress and redox activity of maize coleoptile cells were investigated. This paper describes experiments performed with maize (Zea mays L.) coleoptile segments, which is a classical model system to study plant cell elongation growth. The data presented clearly demonstrate that lawsone and 1,4-naphthoquinone combined with naphthazarin, at low concentrations (1 and 10 nM), reduced the endogenous and IAA-induced (Indole-3-Acetic Acid) elongation growth of maize coleoptile segments. Those changes in growth correlated with the proton concentration in the incubation medium, which suggests that the changes in the growth of maize coleoptile segments observed in the presence of naphthoquinones are mediated through the activity of PM H⁺-ATPase. The presence of naphthoquinones induced oxidative stress in the maize coleoptile tissue by producing hydrogen peroxide and causing changes in the redox activity. Moreover, the incubation of maize segments with both naphthoquinones combined with naphthazarin resulted in lipid peroxidation and membrane damage. The regulation of PM H⁺-ATPase activity, especially its inhibition, may result from two major types of reaction: first, a direct interaction between an enzyme and naphthoquinone, which leads to the covalent modification of the protein thiols and the generation of thioethers, which have been found to alter the activity of the PM H⁺-ATPases; second, naphthoquinones induce reactive oxygen species (ROS) production, which inhibits PM H⁺-ATPases by increasing cytosolic Ca2+. This harmful effect was stronger when naphthazarin and 1,4-naphthoquinone were added together. Taking these results into account, it can be suggested that by combining naphthoquinones in small quantities, an alternative to synthetic pesticides could be developed.

Novel naphthalene-enoates: Design and anticancer activity through regulation cell autophagy

Eleven dihydroxy-2-(1-hydroxy-4-methylpent-3-enyl)naphthalene derivatives as anticancer agents through regulating cell autophagy were designed and synthesized. The anticancer activity results indicated that most compounds manifested obvious un-toxic effect on GES-1 and L-02 with IC₅₀ from 0.58 to 1.41 mM. Among them, (S,Z)-1-(5,8-dihydroxy-1,4-dioxo-1,4-dihydronaphthalen-2-yl)-4-methylpent-3-enyl 4-(3,4- dihydroisoquinolin-2(1 H)-yl)-4-oxobut-2-enoate (compound 4i) could induce cancer cells apoptosis. Further experiments showed that autophagy played an important role in the pro-apoptotic effect of this compound. Preliminary mechanism indicated that this compound could inhibit phosphoinositide 3-kinase/protein kinase B and the mammalian target of rapamycin (PI3K/AKT/mTOR) pathway by mediating apoptosis in an autophagy-dependent manner.

The Effect of Naphthazarin on the Growth, Electrogenicity, Oxidative Stress, and Microtubule Array in Z. mays Coleoptile Cells Treated With IAA

Naphthazarin (5,8-dihydroxy-1,4-naphthoquinone, DHNQ) is a naturally occurring 1,4-naphthoquinone derivative. In this study, we focused on elucidating the toxic effect of this secondary metabolite on the growth of plant cells. The dose-response curves that were obtained for the effects of DHNQ on endogenous and IAA-induced growth in maize coleoptile segments differ in shape; in the first case, it is linear, while in the presence of auxin it is bell-shaped with the maximum at 1 μM. It was found that DHNQ at almost all concentrations studied, when added to the incubation medium inhibited endogenous growth (excluding naphthazarin at 0.001 μM) as well as growth in the presence of IAA. Simultaneous measurements of the growth and external medium pH of coleoptile segments indicated that DHNQ diminished or eliminated proton extrusion at all of the concentrations that were used. Interestingly, the oxidative stress in maize coleoptile cells, which was measured as hydrogen peroxide (H2O2) production, catalase activity, redox activity and malondialdehyde (MDA) content, increased at the lower concentrations of DHNQ (<1 μM), thus suggesting a specific character of its action. It was also found that naphthazarin at concentration higher than 0.1 μM caused the depolarization of the membrane potential (E m). An analysis of the organization and anisotropy of the cortical microtubules showed that naphthazarin at all of the concentrations that were studied changed the IAA-induced transverse microtubule reorientation to an oblique reorientation. Our results indicate that naphthazarin diminished the growth of maize coleoptile cells by a broad spectrum of its toxic effects, thereby suggesting that naphthazarin might be a hypothetical component of new bioherbicides and biopesticides.

Structure-activity relationships, biological evaluation and structural studies of novel pyrrolonaphthoxazepines as antitumor agents

Microtubule-targeting agents (MTAs) are a class of clinically successful anti-cancer drugs. The emergence of multidrug resistance to MTAs imposes the need for developing new MTAs endowed with diverse mechanistic properties. Benzoxazepines were recently identified as a novel class of MTAs. These anticancer agents were thoroughly characterized for their antitumor activity, although, their exact mechanism of action remained elusive. Combining chemical, biochemical, cellular, bioinformatics and structural efforts we developed improved pyrrolonaphthoxazepines antitumor agents and their mode of action at the molecular level was elucidated. Compound 6j, one of the most potent analogues, was confirmed by X-ray as a colchicine-site MTA. A comprehensive structural investigation was performed for a complete elucidation of the structure-activity relationships. Selected pyrrolonaphthoxazepines were evaluated for their effects on cell cycle, apoptosis and differentiation in a variety of cancer cells, including multidrug resistant cell lines. Our results define compound 6j as a potentially useful optimized hit for the development of effective compounds for treating drug-resistant tumors.

Maintenance and pharmacologic targeting of ROR1 protein levels via UHRF1 in t(1;19) pre-B-ALL

Expression of the transmembrane pseudokinase ROR1 is required for survival of t(1;19)-pre-B-cell acute lymphoblastic leukemia (t(1;19) pre-B-ALL), chronic lymphocytic leukemia, and many solid tumors. However, targeting ROR1 with small-molecules has been challenging due to the absence of ROR1 kinase activity. To identify genes that regulate ROR1 expression and may, therefore, serve as surrogate drug targets, we employed an siRNA screening approach and determined that the epigenetic regulator and E3 ubiquitin ligase, UHRF1, is required for t(1;19) pre-B-ALL cell viability in a ROR1-dependent manner. Upon UHRF1 silencing, ROR1 protein is reduced without altering ROR1 mRNA, and ectopically expressed UHRF1 is sufficient to increase ROR1 levels. Additionally, proteasome inhibition rescues loss of ROR1 protein after UHRF1 silencing, suggesting a role for the proteasome in the UHRF1-ROR1 axis. Finally, we show that ROR1-positive cells are twice as sensitive to the UHRF1-targeting drug, naphthazarin, and undergo increased apoptosis compared to ROR1-negative cells. Naphthazarin elicits reduced expression of UHRF1 and ROR1, and combination of naphthazarin with inhibitors of pre-B cell receptor signaling results in further reduction of cell survival compared with either inhibitor alone. Therefore, our work reveals a mechanism by which UHRF1 stabilizes ROR1, suggesting a potential targeting strategy to inhibit ROR1 in t(1;19) pre-B-ALL and other malignancies.

Naphthoquinones: A continuing source for discovery of therapeutic antineoplastic agents

Naturally occurring naphthoquinones, usually in forms of botanical extracts, have been implicated with human life since ancient time, far earlier than their isolation and identification in modern era. The long use history of naphthoquinones has witnessed their functional shift from the original purposes as dyes and ornaments toward medicinal benefits. Hitherto, numerous studies have been carried out to elucidate the pharmacological profile of both natural and artificial naphthoquinones. A number of entities have been identified with promising therapeutic potential. Apart from the traditional effects of wound healing, anti-inflammatory, hemostatic, antifertility, insecticidal and antimicrobial, etc., the anticancer potential of naphthoquinones either in combination with other treatment approaches or on their own is being more and more realized. The molecular mechanisms of naphthoquinones in cells mainly fall into two categories as inducing oxidant stress by ROS (reactive oxygen species) generation and directly interacting with traditional therapeutic targets in a non-oxidant mechanism. Based on this knowledge, optimized agents with naphthoquinones scaffold have been acquired and further tested. Hereby, we summarize the explored biological mechanisms of naphthoquinones in cells and review the application perspective of promising naphthoquinones in cancer therapies.

Synthesis of naphthazarin derivatives and identification of novel thioredoxin reductase inhibitor as potential anticancer agent

Mammalian thioredoxin reductase (TrxR) enzymes play a crucial role in regulating multiple redox-based signaling pathways and have attracted increasing attention as promising anticancer drug targets. We report here the synthesis of a panel of naphthazarin derivatives and discovery of 2-methyl-5,8-dihydroxy-1,4-naphthoquinone (3, 2-methylnaphthazarin) as a potent cytotoxic agent with a submicromolar half maximal inhibitory concentration to the human promyelocytic leukemia HL-60 cells. Mechanism studies reveal that the compound selectively inhibits TrxR to induce oxidative stress-mediated apoptosis of HL-60 cells. Knockdown of TrxR sensitizes the cells to 3 insults, while overexpression of the functional enzyme confers resistance to the compound treatment, underpinning the physiological significance of targeting TrxR by 3. Clarification of the interaction of compound 3 with TrxR unveils a mechanism underlying the cellular action of the compound, and sheds light in considering development of the compound as a potential cancer chemotherapeutic agent.

Synthesis and Comparative Evaluation of Polymethoxy Substituted 1,4-Naphthoquinones and their Acetyl-O-glucosides as Cytotoxic Agents

Twenty five hydroxy-, chloro- and methoxy derivatives of natural and synthetic naphthazarins and their acetylated O-glycosides were synthesized. Targeted compounds were screened as cytotoxic agents on mouse Ehrlich ascites carcinoma cells using MTT test. Chloro- and methoxy-substituted naphthoquinones as well as naphthoquinone O-acetylglucosides were the most potent with IC50 in low micromolar concentration range. Glucosidation of hydroxynaphthoquinones was shown to enhance cytotoxicity, whereas methoxylation yielded both more active and less active derivatives depending on the number and position of methoxy groups. Evaluation using a phenotypic sea urchin embryo assay suggested that naphthazarins exerted their cytotoxic effects through tubulin-unrelated mechanism.

Paclitaxel resistance development is associated with biphasic changes in reactive oxygen species, mitochondrial membrane potential and autophagy with elevated energy production capacity in lung cancer cells: A chronological study

Paclitaxel (Tx) is one of the first-line chemotherapeutic drugs used against lung cancer, but acquired resistance to this drug is a major challenge against successful chemotherapy. In this work, we have focused on the chronological changes of various cellular parameters and associated effect on Tx (10 nM) resistance development in A549 cell line. It was observed, at initial stage, the cell death percentage due to drug treatment had increased up to 20 days, and thereafter, it started declining and became completely resistant by 40 days. Expressions of βIII tubulin and drug efflux pumps also increased over the period of resistance development. Changes in cellular autophagy and reactive oxygen species generation showed a biphasic pattern and increased gradually over the course of upto 20 days, thereafter declined gradually; however, their levels remained higher than untreated cells when resistance was acquired. Increase in extracellular acidification rates and oxygen consumption rates was found to be directly correlated with acquisition of resistance. The depolarisation of mitochondrial membrane potential was also biphasic; first, it increased with increase of cell death up to 20 days, thereafter, it gradually decreased to normal level along with resistance development. Increase in activity of catalase, glutathione peroxidase and glutathione content over these periods may attribute in bringing down the reactive oxygen species levels and normalisation of mitochondrial membrane potential in spite of comparatively higher reactive oxygen species production by the Tx-resistant cells.

Naphthazarin suppresses cell proliferation and induces apoptosis in human colorectal cancer cells via the B-cell lymphoma 2/B-cell associated X protein signaling pathway

Colorectal cancer is the most common gastrointestinal cancer in the USA. Naphthazarin, one of the naturally available 1,4-naphthoquinone derivatives, is a natural bioactive molecule that exhibits an antitumor effect. To the best of our knowledge, this is the first study to investigate the anticancer effect of naphthazarin on cell proliferation and apoptosis in human SW480 colorectal cancer cells. In the present study, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assays were performed to assess the effect of napthazarin on cell proliferation and cytotoxicity of SW430 cells, respectively. In addition, an Annexin V-fluorescein isothiocyanate/propidium iodide apoptosis assay and 4',6-diamidino-2-phenylindole staining were used to analyze cell and nuclei apoptosis of SW480 cells, respectively, following treatment with naphthazarin. Poly (ADP-ribose) polymerase (PARP), B-cell lymphoma 2 (Bcl-2) and B-cell associated X protein (Bax) protein expression was analyzed by western blot. Furthermore, caspase-3 activation was analyzed using a commercial kit. The results revealed that naphthazarin exhibited cell growth inhibition, an increase in cytotoxicity and apoptosis induction in SW480 cells, which was associated with activation of the Bax/Bcl-2 signaling pathway and cleaved caspase-3 activation. However, no significant differences in PARP expression were identified following treatment with naphthazarin in SW480 cells. Taken together, these results suggest that naphthazarin decreased cell viability and induced apoptosis of SW480 cells, indicating that naphthazarin may present a potential therapeutic agent for human colorectal cancer treatment.

A potent anticancer agent of shikonin derivative targeting tubulin

In this study, a shikonin ester derivative, compound , was selected to evaluate its anticancer activities and we found that compound exhibited better antitubulin activities against the human HepG2 cell line with an IC50 value of 1.097 μM. Furthermore, the inhibition of tubulin polymerization results indicated that compound demonstrated the most potent antitubulin activity (IC50  = 13.88), which was compared with shikonin and colchicine as positive controls (IC50  = 25.28 μM and 22.56 μM), respectively. Compound was simulated to have good binding site with tubulin and arrested the cell cycle at G2/M phase, which also induces apoptosis in HepG2 cells, in which P53 and members of Bcl-2 protein family were both involved in the progress of apoptosis revealed by western blot. Confocal microscopy observations revealed compound targeted tubulin and altered its polymerization by interfering with microtubule organization. Based on these results, compound functions as a potent anticancer agent targeting tubulin.

Naphthazarin enhances ionizing radiation-induced cell cycle arrest and apoptosis in human breast cancer cells

Naphthazarin (Naph, DHNQ, 5,8-dihydroxy-l,4-naphthoquinone) is one of the naturally available 1,4-naphthoquinone derivatives that are well-known for their anti-inflammatory, antioxidant, antibacterial and antitumor cytotoxic effects in cancer cells. Herein, we investigated whether Naph has effects on cell cycle arrest and apoptosis in MCF-7 human breast cancer cells exposed to ionizing radiation (IR). Naph reduced the MCF-7 cell viability in a dose-dependent manner. We also found that Naph and/or IR increased the p53-dependent p21 (CIP/WAF1) promoter activity. Noteworthy, our ChIP assay results showed that Naph and IR combined treatment activated the p21 promoter via inhibition of binding of multi-domain proteins, DNMT1, UHRF1 and HDAC1. Apoptosis and cell cycle analyses demonstrated that Naph and IR combined treatment induced cell cycle arrest and apoptosis in MCF-7 cells. Herein, we showed that Naph treatment enhances IR-induced cell cycle arrest and death in MCF-7 human breast cancer cells through the p53-dependent p21 activation mechanism. These results suggest that Naph might sensitize breast cancer cells to radiotherapy by enhancing the p53-p21 mechanism activity.

Design, synthesis and mechanism of novel shikonin derivatives as potent anticancer agents

Novel shikonin derivatives were synthesised and probed as anticancer agents. Compound 40 showed the best anticancer activity with an IC₅₀ of 1.26 μM, could induce apoptosis and cause cell cycle arrest at the G2/M phase via the P21 p-CDC2 (Tyr15) pathway independent of P53.

Inhibition of autophagy by chloroquine potentiates synergistically anti-cancer property of artemisinin by promoting ROS dependent apoptosis

Artemisinin (ART) is a well-known anti-malarial drug, and recently it is shown prospective to selectively kill cancer cells. But low potency makes it inappropriate for use as an anticancer drug. In this study, we modulated the ART-induced autophagy to increase Potency of ART as an anticancer agent. ART reduced the cell viability and colony forming ability of non-small lung carcinoma (A549) cells and it was non-toxic against normal lung (WI38) cells. ART induced autophagy at the early stage of treatment. Pre-treatment with chloroquine (CQ) and followed by ART treatment had synergistic combination index (CI) for cell death. Inhibition of autophagy by CQ pre-treatment led to accumulation of acidic vacuoles (AVOs) which acquainted with unprocessed damage mitochondria that subsequently promoted ROS generation, and resulted releases of Cyt C in cytosol that caused caspase-3 dependent apoptosis cell death in ART-treated A549 cells. Scavenging of ROS by antioxidant N-acetyl-cysteine (NAC) inhibited caspase-3 activity and rescued the cells from apoptosis. Similar effects were observed in other cancer cells SCC25 and MDA-MB-231. The appropriate manipulation of autophagy by using CQ provides a powerful strategy to increase the Potency of selective anticancer property of ART.

Natural small-molecule enhancers of autophagy induce autophagic cell death in apoptosis-defective cells

Resistance of cancer cells to chemotherapy is a significant problem in oncology, and the development of sensitising agents or small-molecules with new mechanisms of action to kill these cells is needed. Autophagy is a cellular process responsible for the turnover of misfolded proteins or damaged organelles, and it also recycles nutrients to maintain energy levels for cell survival. In some apoptosis-resistant cancer cells, autophagy can also enhance the efficacy of anti-cancer drugs through autophagy-mediated mechanisms of cell death. Because the modulation of autophagic processes can be therapeutically useful to circumvent chemoresistance and enhance the effects of cancer treatment, the identification of novel autophagic enhancers for use in oncology is highly desirable. Many novel anti-cancer compounds have been isolated from natural products; therefore, we worked to discover natural, anti-cancer small-molecule enhancers of autophagy. Here, we have identified a group of natural alkaloid small-molecules that function as novel autophagic enhancers. These alkaloids, including liensinine, isoliensinine, dauricine and cepharanthine, stimulated AMPK-mTOR dependent induction of autophagy and autophagic cell death in a panel of apoptosis-resistant cells. Taken together, our work provides novel insights into the biological functions, mechanisms and potential therapeutic values of alkaloids for the induction of autophagy.

Microtubules and their role in cellular stress in cancer

Microtubules are highly dynamic structures, which consist of α- and β-tubulin heterodimers, and are involved in cell movement, intracellular trafficking, and mitosis. In the context of cancer, the tubulin family of proteins is recognized as the target of the tubulin-binding chemotherapeutics, which suppress the dynamics of the mitotic spindle to cause mitotic arrest and cell death. Importantly, changes in microtubule stability and the expression of different tubulin isotypes as well as altered post-translational modifications have been reported for a range of cancers. These changes have been correlated with poor prognosis and chemotherapy resistance in solid and hematological cancers. However, the mechanisms underlying these observations have remained poorly understood. Emerging evidence suggests that tubulins and microtubule-associated proteins may play a role in a range of cellular stress responses, thus conferring survival advantage to cancer cells. This review will focus on the importance of the microtubule-protein network in regulating critical cellular processes in response to stress. Understanding the role of microtubules in this context may offer novel therapeutic approaches for the treatment of cancer.

A synthetic curcumin derivative hydrazinobenzoylcurcumin induces autophagy in A549 lung cancer cells

CONTEXT

Curcumin exhibits growth-suppressive activity against a variety of cancer cells, but low bioavailability restricts its application in chemotherapeutic trials. Nowadays, a growing number of curcumin derivatives or analogs are known, hoping to replace curcumin and circumvent this problem. Hydrazinobenzoylcurcumin (HBC) has been synthesized and identified as a potent inhibitor of cell proliferation in previous reports.

OBJECTIVE

This study presents a novel mechanism of cell autophagy induced by HBC in the human non-small lung epithelial carcinoma (A549) cells.

MATERIALS AND METHODS

Cells were cultured and treated with HBC at different concentrations (10-80 μM) and at different time periods (1-24 h). Microscopic analysis was used to detect the morphology changes and autophagolysosomes of A549 cells. An acridine orange staining assay was conducted to evaluate the autophagolysosomes and autophagic vacuoles was analyzed by monodansylcadaverine (MDC) and GFP-LC3 transfection analysis. Western blotting was used to assess the conversion of microtubule-associated protein light chain 3 (LC3).

RESULTS

HBC could induce A549 cells autophagolysosomes formation in a dose and time-dependent manner and the inhibitory rate of HBC (80 μM) on the viability of A549 cells reached 76.68 ± 5.81% after 24 h of treatment. Autophagic vacuoles increased in a concentration-dependent manner in HBC-treated cell. Furthermore, conversion of LC3-I to LC3-II, accumulation of GFP-tagged LC3 positive intracellular vacuoles and increased fusion of autophagosomes with lysosomes suggested the occurrence of autophagy.

CONCLUSION

Our data indicate that HBC induced A549 cell autophagy, which is a novel cell death mechanism induced by curcumin derivatives.

Design, synthesis and biological evaluation of shikonin thio-glycoside derivatives: new anti-tubulin agents

Among the acetyl-β-d-thio-glycoside modified shikonin derivatives, IIb showed the best cancer cell proliferative inhibition effect via inhibiting tubulin polymerization.