Inhibition of cell proliferation and migration by oxidative stress from ascorbate-driven juglone redox cycling in human bladder-derived T24 cells

Juglone-ascorbate treatment enhances reactive oxygen species mediated mitochondrial apoptosis in pancreatic cancer

BACKGROUND

Treatment of Pancreatic Cancer (PC) is challenging due to its aggressiveness and acquired resistance to conventional chemotherapy and radiotherapy. Therefore, the discovery of new therapeutic agents and strategies is essential. Juglone, a naphthoquinone, is a secondary metabolite produced naturally in walnut-type trees having allelopathic features in its native environment. Juglone was shown to prevent cell proliferation and induce ROS-mediated mitochondrial apoptosis. Ascorbate with both antioxidant and oxidant features, shows selective cytotoxicity in cancer cells.

METHODS AND RESULTS

In this study, we evaluated the anticancer effects of Juglone in combination with ascorbate in PANC-1 and BxPC-3 PC cells. The MTT assay was used to determine the IC50 dose of Juglone with 1 mM NaAscorbate (Jug-NaAsc). Subsequently, the cells were treated with 5, 10, 15 and 20 µM Jug-NaAsc for 24 h. Apoptotic effects were evaluated by analyzing the following genes using qPCR; proapoptotic Bax, antiapoptotic Bcl-2 related to the mitochondrial apoptotic pathway and apoptosis inhibitor Birc5 (Survivin). Immunofluorescence analysis was performed using Annexin V-FITC in PC cells. As an antioxidant enzyme, Trx2 protein levels were determined by a commercial ELISA test kit. Jug-NaAsc treatment decreased the expressions of antiapoptotic genes Bcl-2 and Birc5 while the apoptotic gene Bax expression increased at all doses. Additionally, a dose-dependently increase of apoptosis according to immunofluorescence analysis and the decreases of Trx2 enzyme levels at all treatments in both cell lines supported gene expression results.

CONCLUSION

Our results suggest that Juglone is a potential anticancer agent especially when combined with ascorbate.

8-Methoxy-α-lapachone and lawsone: antiproliferative effects on bladder tumour cells

Quinones are chemical compounds produced from the oxidation of phenols. Among the quinones, naphthoquinones stand out as potential antitumor agents. Bladder tumour is the tenth most diagnosed in the world. Based on this, using a urothelial carcinoma cell line (T24), two naphthoquinones had their cytotoxicity tested by the MTT colorimetric method and were submitted to assays of clonogenic survival, morphology, cell cycle, cell migration and species reactive oxygen. The results showed 8-methoxy-α-lapachone and lausone presented selectivity indexes (19.5 and 28.0, respectively) for T24 cells. Moreover, the two naphthoquinones reduced the cell viability, interfered with the process of cell migration, changed the cell cycle kinectics and induced the production of species reactive oxygen (ROS). Additionaly, 8-methoxy-α-lapachone altered the morphology of the cells. In conclusion, the studied naphthoquinones showed potential antiproliferative effects in bladder cancer cells, interfering in cellular processes, possibly through oxidative stress.

Proline Isomerization: From the Chemistry and Biology to Therapeutic Opportunities

Proline isomerization, the process of interconversion between the cis- and trans-forms of proline, is an important and unique post-translational modification that can affect protein folding and conformations, and ultimately regulate protein functions and biological pathways. Although impactful, the importance and prevalence of proline isomerization as a regulation mechanism in biological systems have not been fully understood or recognized. Aiming to fill gaps and bring new awareness, we attempt to provide a wholistic review on proline isomerization that firstly covers what proline isomerization is and the basic chemistry behind it. In this section, we vividly show that the cause of the unique ability of proline to adopt both cis- and trans-conformations in significant abundance is rooted from the steric hindrance of these two forms being similar, which is different from that in linear residues. We then discuss how proline isomerization was discovered historically followed by an introduction to all three types of proline isomerases and how proline isomerization plays a role in various cellular responses, such as cell cycle regulation, DNA damage repair, T-cell activation, and ion channel gating. We then explore various human diseases that have been linked to the dysregulation of proline isomerization. Finally, we wrap up with the current stage of various inhibitors developed to target proline isomerases as a strategy for therapeutic development.

Molecular biological mechanism of action in cancer therapies: Juglone and its derivatives, the future of development

Juglone (5 - hydroxy - 1, 4 - naphthalene diketone) is a kind of natural naphthoquinone, present in the roots, leaves, nut-hulls, bark and wood of walnut trees. Recent studies have found that Juglone has special significance in the treatment of cancer, which plays a significant role in the resistance of cancer cell proliferation, induction of cancer cell apoptosis, induction of autophagy, anti-angiogenesis and inhibition of cancer cell migration and invasion, etc. Additionally, its derivatives also play a tumor suppressive effect. In conclusion, Juglone and its derivatives have been identified as effective anticancer drugs. This paper reviews action mechanisms of Juglone and its derivatives in cancer treatment.

Synthesis, characterization and antiproliferative effects of naphtho [2,3-b] thiophen-4,9-quinone on bladder tumor cells

Naphthoquinones are natural plants products or synthesized compounds. They have α, β-cyclic aromatic dienones structure with a naphthalene skeleton. Little is known about naphthoquinone and nothing about naphtho [2,3-b] thiophen-4,9-quinone effects on bladder cancer. In this study, a naphthoquinone containing a hetero sulfur atom was synthesized using classical synthetic method. The molecular structure was elucidated by NMR techniques and the antitumor effects were evaluated on bladder tumor cell lines with different TP53 status using tripan blue and MTT cytotoxic method, quantification of reactive oxygen species (ROS), wound healing, cell morphology and cell cycle progression assays. The results showed selective cytotoxicity, colonies reduction, morphological change, inhibition of the cell migration process, induction of ROS production and cell cycle arrest. Naphtho [2,3-b] thiophen-4,9-quinone presents antiproliferative activity regardless TP53 status and may be a promising agent in the treatment of bladder cancer, as they have an oxidizing effect and interfere with cell cycle.

Antiproliferative, antimigratory, and prooxidative potential of novel platinum(IV) complexes and resveratrol on breast cancer (MDA-MB-231) and choriocarcinoma (JEG-3) cell lines

Platinum(IV) complexes offer the potential to overcome cisplatin resistance of cancer cells, with possible improved selectivity. Resveratrol, a natural polyphenol with anticancer and antioxidant capacity, could limit the possible side effects of chemotherapeutics on healthy cells. This study investigates the effects of platinum(IV) complexes containing some esters of the ethylenediamine-N,N'-di-S,S-(2,2'-dibenzyl)acetate acid (H₂ -S,S-eddba), and resveratrol on proliferation, migration, and redox balance of breast cancer (MDA-MB-231), choriocarcinoma (JEG-3), and human lung fibroblast (MRC-5) cell line. According to IC₅₀ values, all complexes exhibited a significantly stronger antiproliferative effect on tested cell lines compared to cisplatin. Due to reduced adverse effects on MRC-5 cells, the complex containing ethyl-substituent (10 μM) was selected for further examination with resveratrol (25 μM) cotreatment. Resveratrol enhanced the survival of MRC-5 cells while diminished the viability of both used cancer cell lines when applied combined with selected complex. Furthermore, cotreatment of these two compounds decreased the migratory potential of tested cancer cell lines. The examined platinum(IV) complex was able to induce oxidative stress in all tested cell lines. Resveratrol proved to be efficient in protecting MRC-5 cells from complex-induced oxidative damage, while it significantly amplified antiproliferative, antimigratory, and prooxidative effects of platinum(IV) complex on both examined cancer cell lines. These findings may be valuable in elucidating the mechanism of action of platinum(IV) drugs, which should be further investigated.

Oxoisoaporphines and Aporphines: Versatile Molecules with Anticancer Effects

Cancer is a disease that involves impaired genome stability with a high mortality index globally. Since its discovery, many have searched for effective treatment, assessing different molecules for their anticancer activity. One of the most studied sources for anticancer therapy is natural compounds and their derivates, like alkaloids, which are organic molecules containing nitrogen atoms in their structure. Among them, oxoisoaporphine and sampangine compounds are receiving increased attention due to their potential anticancer effects. Boldine has also been tested as an anticancer molecule. Boldine is the primary alkaloid extract from boldo, an endemic tree in Chile. These compounds and their derivatives have unique structural properties that potentially have an anticancer mechanism. Different studies showed that this molecule can target cancer cells through several mechanisms, including reactive oxygen species generation, DNA binding, and telomerase enzyme inhibition. In this review, we summarize the state-of-art research related to oxoisoaporphine, sampangine, and boldine, with emphasis on their structural characteristics and the relationship between structure, activity, methods of extraction or synthesis, and anticancer mechanism. With an effective cancer therapy still lacking, these three compounds are good candidates for new anticancer research.

Juglone eliminates MDSCs accumulation and enhances antitumor immunity

Myeloid-derived suppressor cells (MDSCs) contribute to immune activity suppression and promote the tumor progression. Elimination of MDSCs is a promising cancer therapeutic strategy, and some chemotherapeutic agents have been reported to hamper tumor progression by suppressing MDSCs. Juglone has been showed to exert a direct cytotoxic effect on tumor cells. However, the effect of juglone on MDSCs and anti-tumor immune statue has remained unexplored. In our study, we observed that juglone suppressed tumor growth and metastasis markedly, and the tumor growth suppression in immunocompetent mice was more drastic than that in immunodeficient mice. Juglone reduced the accumulation of MDSCs and increased IFN-γ production by CD8⁺ T cells. Consistently, juglone affected myeloid cells differentiation and maturation, impairing the immunosuppressive functions of MDSCs. Moreover, juglone down-regulated the level of IL-1β which was mediating accumulation of MDSCs. In addition, juglone inhibited 5FU-induced liver injury in a colorectal carcinoma-bearing mice model. Thus, our work suggests that the anti-tumor effect of juglone is mediated, at least in part, by eliminating accumulation of MDSCs.

Juglone in Oxidative Stress and Cell Signaling

Juglone (5-hydroxyl-1,4-naphthoquinone) is a phenolic compound found in walnuts. Because of the antioxidant capacities of phenolic compounds, juglone may serve to combat oxidative stress, thereby protecting against the development of various diseases and aging processes. However, being a quinone molecule, juglone could also act as a redox cycling agent and produce reactive oxygen species. Such prooxidant properties of juglone may confer health effects, such as by killing cancer cells. Further, recent studies revealed that juglone influences cell signaling. Notably, juglone is an inhibitor of Pin1 (peptidyl-prolyl cis/trans isomerase) that could regulate phosphorylation of Tau, implicating potential effects of juglone in Alzheimer’s disease. Juglone also activates mitogen-activated protein kinases that could promote cell survival, thereby protecting against conditions such as cardiac injury. This review describes recent advances in the understanding of the effects and roles of juglone in oxidative stress and cell signaling.

Natural Products to Fight Cancer: A Focus on Juglans regia

Even if cancer represents a burden for human society, an exhaustive cure has not been discovered yet. Low therapeutic index and resistance to pharmacotherapy are two of the major limits of antitumour treatments. Natural products represent an excellent library of bioactive molecules. Thus, tapping into the natural world may prove useful in identifying new therapeutic options with favourable pharmaco-toxicological profiles. Juglans regia, or common walnut, is a very resilient tree that has inhabited our planet for thousands of years. Many studies correlate walnut consumption to beneficial effects towards several chronic diseases, such as cancer, mainly due to the bioactive molecules stored in different parts of the plant. Among others, polyphenols, quinones, proteins, and essential fatty acids contribute to its pharmacologic activity. The present review aims to offer a comprehensive perspective about the antitumour potential of the most promising compounds stored in this plant, such as juglanin, juglone, and the ellagitannin-metabolites urolithins or deriving from walnut dietary intake. All molecules and a chronic intake of the fruit provide tangible anticancer effects. However, the scarcity of studies on humans does not allow results to be conclusive.

Sampangine (a Copyrine Alkaloid) Exerts Biological Activities through Cellular Redox Cycling of Its Quinone and Semiquinone Intermediates

The cananga tree alkaloid sampangine (1) has been extensively investigated for its antimicrobial and antitumor potential. Mechanistic studies have linked its biological activities to the reduction of cellular oxygen, the induction of reactive oxygen species (ROS), and alterations in heme biosynthesis. Based on the yeast gene deletion library screening results that indicated mitochondrial gene deletions enhanced the sensitivity to 1, the effects of 1 on cellular respiration were examined. Sampangine increased oxygen consumption rates in both yeast and human tumor cells. Mechanistic investigation indicated that 1 may have a modest uncoupling effect, but predominately acts by increasing oxygen consumption independent of mitochondrial complex IV. Sampangine thus appears to undergo redox cycling that may involve respiratory chain-dependent reduction to a semi-iminoquinone followed by oxidation and consequent superoxide production. Relatively high concentrations of 1 showed significant neurotoxicity in studies conducted with rat cerebellar granule neurons, indicating that sampangine use may be associated with potential neurotoxicity.

Augmentation of oxidative stress-induced apoptosis in MCF7 cells by ascorbate-tamoxifen and/or ascorbate-juglone treatments

Since reactive oxygen species (ROS) play diverse roles in cancer, modulating the redox status of cancerous cells seems to be a promising therapeutic approach. Oxidant-targeted therapy appears logical for intervention with the acquired adaptive response to oxidative stress in cancer. In this study, we investigated the cytotoxic effects of juglone (J) and tamoxifen (T) and also the combination of each with ascorbate (A): tamoxifen/ascorbate (TA) and/or juglone/ascorbate (JA) on MCF7 cancerous cells. The results revealed that the growth inhibitory effects of juglone and tamoxifen were each associated with enhanced levels of ROS production and lipid peroxidation. These effects were markedly intensified in tamoxifen/ascorbate and juglone/ascorbate co-treatments. On the other hand, the intracellular anti-oxidant components such as reduced glutathione (GSH), catalase, superoxide dismutase (SOD), and glutathione peroxidase significantly declined in cells subjected to combination treatments compared to that in cells exposed solely to tamoxifen, juglone, and the untreated control cells. In addition, ascorbate association induced more apoptotic and necrotic or necrotic-like cell death than cells treated with each drug alone. These results were further confirmed by comparing the Bax/Bcl2 ratio in combination-treated cells. Additionally, ascorbate was able to potentiate the cytotoxic effects of combination therapy via activation of ROS-responsive factors including Foxo family members.

DNA damage and inhibition of akt pathway in mcf-7 cells and ehrlich tumor in mice treated with 1,4-naphthoquinones in combination with ascorbate

The aim of this study was to enhance the understanding of the antitumor mechanism of 1,4-naphthoquinones and ascorbate. Juglone, phenylaminonaphthoquinone-7, and 9 (Q7/Q9) were evaluated for effects on CT-DNA and DNA of cancer cells. Evaluations in MCF-7 cells are DNA damage, ROS levels, viability, and proliferation. Proteins from MCF-7 lysates were immunoblotted for verifying PARP integrity, γH2AX, and pAkt. Antitumor activity was measured in Ehrlich ascites carcinoma-bearing mice. The same markers of molecular toxicity were assessed in vivo. The naphthoquinones intercalate into CT-DNA and caused oxidative cleavage, which is increased in the presence of ascorbate. Treatments caused DNA damage and reduced viability and proliferation of MCF-7 cells. Effects were potentiated by ascorbate. No PARP cleavage was observed. Naphthoquinones, combined with ascorbate, caused phosphorylation of H2AX and inhibited pAkt. ROS were enhanced in MCF-7 cells, particularly by the juglone and Q7 plus ascorbate. Ehrlich carcinoma was inhibited by juglone, Q7, or Q9, but the potentiating effect of ascorbate was reproduced in vivo only in the cases of juglone and Q7, which caused up to 60% inhibition of tumor and the largest extension of survival. Juglone and Q7 plus ascorbate caused enhanced ROS and DNA damage and inhibited pAkt also in Ehrlich carcinoma cells.

Identification of signaling pathways modulated by RHBDD2 in breast cancer cells: a link to the unfolded protein response

Rhomboid domain containing 2 (RHBDD2) was previously observed overexpressed and amplified in breast cancer samples. In order to identify biological pathways modulated by RHBDD2, gene expression profiles of RHBDD2 silenced breast cancer cells were analyzed using whole genome human microarray. Among the statistically significant overrepresented biological processes, we found protein metabolism—with the associated ontological terms folding , ubiquitination, and proteosomal degradation—cell death, cell cycle, and oxidative phosphorylation. In addition, we performed an in silico analysis searching for RHBDD2 co-expressed genes in several human tissues. Interestingly, the functional analysis of these genes showed similar results to those obtained with the microarray data, with negative regulation of protein metabolism and oxidative phosphorylation as the most enriched gene ontology terms. These data led us to hypothesize that RHBDD2 might be involved in endoplasmic reticulum (ER) stress response. Thus, we specifically analyzed the unfolding protein response (UPR) of the ER stress process. We used a lentivirus-based approach for stable silencing of RHBDD2 mRNA in the T47D breast cancer cell line, and we examined the transcriptional consequences on UPR genes as well as the phenotypic effects on migration and proliferation processes. By employing dithiothreitol as an UPR inducer, we observed that cells with silenced RHBDD2 showed increased expression of ATF6, IRE1, PERK, CRT, BiP, ATF4, and CHOP (p <0.01). We also observed that RHBDD2 silencing inhibited colony formation and decreased cell migration. Based on these studies, we hypothesize that RHBDD2 overexpression in breast cancer could represent an adaptive phenotype to the stressful tumor microenvironment by modulating the ER stress response.

Substituted 3‑acyl‑2‑phenylamino‑1,4‑naphthoquinones intercalate into DNA and cause genotoxicity through the increased generation of reactive oxygen species culminating in cell death

Naphthoquinones interact with biological systems by generating reactive oxygen species (ROS) that can damage cancer cells. The cytotoxicity and the antitumor activity of 3‑acyl‑2‑phenylamino‑1,4‑naphthoquinones (DPB1‑DPB9) were evaluated in the MCF7 human breast cancer cell line and in male Ehrlich tumor‑bearing Balb/c mice. DPB4 was the most cytotoxic derivative against MCF7 cells (EC50 15 µM) and DPB6 was the least cytotoxic one (EC50 56 µM). The 1,4‑naphthoquinone derivatives were able to cause DNA damage and promote DNA fragmentation as shown by the plasmid DNA cleavage assay (FII form). In addition, 1,4‑naphthoquinone derivatives possibly interacted with DNA as intercalating agents, which was demonstrated by the changes caused in the fluorescence of the DNA‑ethidium bromide complexes. Cell death of MCF7 cells induced by 3‑acyl‑2‑phenylamino‑1,4‑naphthoquinones was mostly due to apoptosis. The DNA fragmentation and subsequent apoptosis may be correlated to the redox potential of the 1,4‑naphthoquinone derivatives that, once present in the cell nucleus, led to the increased generation of ROS. Finally, certain 1,4‑naphthoquinone derivatives and particularly DPB4 significantly inhibited the growth of Ehrlich ascites tumors in mice (73%).

Information processing through a bio-based redox capacitor: signatures for redox-cycling

Redox-cycling compounds can significantly impact biological systems and can be responsible for activities that range from pathogen virulence and contaminant toxicities, to therapeutic drug mechanisms. Current methods to identify redox-cycling activities rely on the generation of reactive oxygen species (ROS), and employ enzymatic or chemical methods to detect ROS. Here, we couple the speed and sensitivity of electrochemistry with the molecular-electronic properties of a bio-based redox-capacitor to generate signatures of redox-cycling. The redox capacitor film is electrochemically-fabricated at the electrode surface and is composed of a polysaccharide hydrogel with grafted catechol moieties. This capacitor film is redox-active but non-conducting and can engage diffusible compounds in either oxidative or reductive redox-cycling. Using standard electrochemical mediators ferrocene dimethanol (Fc) and Ru(NH3)6Cl3 (Ru(3+)) as model redox-cyclers, we observed signal amplifications and rectifications that serve as signatures of redox-cycling. Three bio-relevant compounds were then probed for these signatures: (i) ascorbate, a redox-active compound that does not redox-cycle; (ii) pyocyanin, a virulence factor well-known for its reductive redox-cycling; and (iii) acetaminophen, an analgesic that oxidatively redox-cycles but also undergoes conjugation reactions. These studies demonstrate that the redox-capacitor can enlist the capabilities of electrochemistry to generate rapid and sensitive signatures of biologically-relevant chemical activities (i.e., redox-cycling).

Eco-friendly synthesis and antiproliferative evaluation of some oxygen substituted diaryl ketones

A broad variety of oxygen-substituted diaryl ketones has been synthesized by solar energy-induced Friedel Crafts acylations of 1,4-benzo- and 1,4-naphthoquinones with benzaldehydes. The in vitro antiproliferative properties of the photoproducts were assessed on prostate (DU-145), bladder (T24) and breast (MCF7) human-derived tumor cell lines and compared to non-tumor mouse fibroblasts (Balb/3T3). Among the tested compounds, it was found that those containing a 3,4,5-trimethoxyphenyl A-ring, such as 12 and 22 are more active on DU-145, with EC₅₀ values of 1.2 and 5.9 μM, respectively. By comparing their effects on the three cancer cell lines, the analogue 22 has the best mean selective index (2.4).