Nitric oxide for cancer therapy

Recent advances on the development of NO-releasing molecules (NORMs) for biomedical applications

Nitric oxide (NO) is an important biological messenger as well as a signaling molecule that participates in a broad range of physiological events and therapeutic applications in biological systems. However, due to its very short half-life in physiological conditions, its therapeutic applications are restricted. Efforts have been made to develop an enormous number of NO-releasing molecules (NORMs) and motifs for NO delivery to the target tissues. These NORMs involve organic nitrate, nitrite, nitro compounds, transition metal nitrosyls, and several nanomaterials. The controlled release of NO from these NORMs to the specific site requires several external stimuli like light, sound, pH, heat, enzyme, etc. Herein, we have provided a comprehensive review of the biochemistry of nitric oxide, recent advancements in NO-releasing materials with the appropriate stimuli of NO release, and their biomedical applications in cancer and other disease control.

Development of novel quinoline-NO donor hybrids inducing human breast cancer cells apoptosis via inhibition of topoisomerase I

A number of NO-releasing quinoline derivatives have been designed and synthesized by introducing NO donor to quinoline carboxylic acid fragment. The anti-proliferation of all target compounds was evaluated against human cancer cell lines (HCT-116, MCF-7, and A549), MCF-7/ADR and normal cell (MCF-10A). Most compounds showed cytotoxic activity on cancer cells and drug-resistant cells with IC50 values in the range of 0.62-5.51 μM. Importantly, these compounds showed low toxicity to normal cells (4.21-34.08 μM). Further mechanism studies showed that the most potent compound 9 could release high concentration of NO and inhibit the activity of topoisomerase I. In addition, 9 regulated apoptosis-related proteins, generated ROS and blocked MCF-7 cells in G2/M phase to induce cell apoptosis. Furthermore, the P-gp-mediated transport was also influenced by 9. And 9 could significantly inhibit the growth of tumor in vivo without observable organ-related toxicities. Overall, as a novel NO-releasing quinoline derivative, 9 was worthy for further in-depth study.

Can Nitric Oxide-Based Therapy Be Improved for the Treatment of Cancers? A Perspective

Since the early observations that nitric oxide (•NO) at high concentrations is cytotoxic to cancer cells and that it may play an important role in the treatment of human cancers, a significant number of compounds (NO-donors) have been prepared to deliver •NO to tumors. •NO also sensitizes various clinically active anticancer drugs and has been shown to induce the reversal of multi-drug resistance in tumor cells expressing ATP-binding cassette-transporter proteins. For the successful treatment of cancers, •NO needs to be delivered precisely to tumors, and its adverse toxicity must be limited. Like other chemotherapeutics, the precise delivery of drugs has been a problem and various attempts have been made, such as the encapsulation of drugs in lipid polymers, to overcome this. This prospective study examines the use of various strategies for delivering •NO (using NO-donors) for the treatment of cancers. Finding and utilizing such a delivery system is an important step in delivering cytotoxic concentrations of •NO to tumors without adverse reactions, leading to a successful clinical outcome for patient management.

Repurposing of the Drug Tezosentan for Cancer Therapy

Tezosentan is a vasodilator drug that was originally developed to treat pulmonary arterial hypertension. It acts by inhibiting endothelin (ET) receptors, which are overexpressed in many types of cancer cells. Endothelin-1 (ET1) is a substance produced by the body that causes blood vessels to narrow. Tezosentan has affinity for both ET_A and ET_B receptors. By blocking the effects of ET1, tezosentan can help to dilate blood vessels, improve the blood flow, and reduce the workload on the heart. Tezosentan has been found to have anticancer properties due to its ability to target the ET receptors, which are involved in promoting cellular processes such as proliferation, survival, neovascularization, immune cell response, and drug resistance. This review intends to demonstrate the potential of this drug in the field of oncology. Drug repurposing can be an excellent way to improve the known profiles of first-line drugs and to solve several resistance problems of these same antineoplastic drugs.

Protein persulfidation: Rewiring the hydrogen sulfide signaling in cell stress response

The past few decades have witnessed significant progress in the discovery of hydrogen sulfide (H₂S) as a ubiquitous gaseous signaling molecule in mammalian physiology, akin to nitric oxide and carbon monoxide. As the third gasotransmitter, H₂S is now known to exert a wide range of physiological and cytoprotective functions in the biological systems. However, endogenous H₂S concentrations are usually low, and its potential biologic mechanisms responsible have not yet been fully clarified. Recently, a growing body of evidence has demonstrated that protein persulfidation, a posttranslational modification of cysteine residues (RSH) to persulfides (RSSH) elicited by H₂S, is a fundamental mechanism of H₂S-mediated signaling pathways. Persulfidation, as a biological switch for protein function, plays an important role in the maintenance of cell homeostasis in response to various internal and external stress stimuli and is also implicated in numerous diseases, such as cardiovascular and neurodegenerative diseases and cancer. In this review, the biological significance of protein persulfidation by H₂S in cell stress response is reviewed providing a framework for understanding the multifaceted roles of H₂S. A mechanism-guided perspective can help open novel avenues for the exploitation of therapeutics based on H₂S-induced persulfidation in the context of diseases.

Chemical Attachment of 5-Nitrosalicylaldimine Motif to Silatrane Resulting in an Organic-Inorganic Structure with High Medicinal Significance

Two chemical motifs of interest for medicinal chemistry, silatrane as 1-(3-aminopropyl) silatrane (SIL M), and nitro group attached in position 5 to salicylaldehyde, are coupled in a new structure, 1-(3-{[(2-hydroxy-5-nitrophenyl)methylidene]amino}propyl)silatrane (SIL-BS), through an azomethine moiety, also known as a versatile pharmacophore. The high purity isolated compound was structurally characterized by an elemental, spectral, and single crystal X-ray diffraction analysis. Given the structural premises for being a biologically active compound, different specific techniques and protocols have been used to evaluate their in vitro hydrolytic stability in simulated physiological conditions, the cytotoxicity on two cancer cell lines (HepG2 and MCF7), and protein binding ability-with a major role in drug ADME (Absorption, Distribution, Metabolism and Excretion), in parallel with those of the SIL M. While the latter had a good biocompatibility, the nitro-silatrane derivative, SIL-BS, exhibited a higher cytotoxic activity on HepG2 and MCF7 cell lines, performance assigned, among others, to the known capacity of the nitro group to promote a specific cytotoxicity by a "activation by reduction" mechanism. Both compounds exhibited increased bio- and muco-adhesiveness, which can favor an optimized therapeutic effect by increased drug permeation and residence time in tumor location. Additional benefits of these compounds have been demonstrated by their antimicrobial activity on several fungi and bacteria species. Molecular docking computations on Human Serum Albumin (HSA) and MPRO COVID-19 protease demonstrated their potential in the development of new drugs for combined therapy.

Gaseous nitric oxide tumor ablation induces an anti-tumor abscopal effect

BACKGROUND

In-situ tumor ablation provides the immune system with the appropriate antigens to induce anti-tumor immunity. Here, we present an innovative technique for generating anti-tumor immunity by delivering exogenous ultra-high concentration (> 10,000 ppm) gaseous nitric oxide (UHCgNO) intratumorally.

METHODS

The capability of UHCgNO to induce apoptosis was tested in vitro in mouse colon (CT26), breast (4T1) and Lewis lung carcinoma (LLC-1) cancer cell lines. In vivo, UHCgNO was studied by treating CT26 tumor-bearing mice in-situ and assessing the immune response using a Challenge assay.

RESULTS

Exposing CT26, 4T1 and LLC-1 cell lines to UHCgNO for 10 s-2.5 min induced cellular apoptosis 24 h after exposure. Treating CT26 tumors in-situ with UHCgNO followed by surgical resection 14 days later resulted in a significant secondary anti-tumor effect in vivo. 100% of tumor-bearing mice treated with 50,000 ppm UHCgNO and 64% of mice treated with 20,000 ppm UHCgNO rejected a second tumor inoculation, compared to 0% in the naive control for 70 days. Additionally, more dendrocytes infiltrated the tumor 14 days post UHCgNO treatment versus the nitrogen control. Moreover, T-cell penetration into the primary tumor was observed in a dose-dependent manner. Systemic increases in T- and B-cells were seen in UHCgNO-treated mice compared to nitrogen control. Furthermore, polymorphonuclear-myeloid-derived suppressor cells were downregulated in the spleen in the UHCgNO-treated groups.

CONCLUSIONS

Taken together, our data demonstrate that UHCgNO followed by the surgical removal of the primary tumor 14 days later induces a strong and potent anti-tumor response.

Recent progress in nitric oxide-generating nanomedicine for cancer therapy

Nitric oxide (NO) is an endogenous, multipotent biological signaling molecule that participates in several physiological processes. Recently, exogenous supplementation of tumor tissues with NO has emerged as a potential anticancer therapy. In particular, it induces synergistic effects with other conventional therapies (such as chemo-, radio-, and photodynamic therapies) by regulating the activity of P-glycoprotein, acting as a vascular relaxant to relieve tumor hypoxia, and participating in the metabolism of reactive oxygen species. However, NO is highly reactive, and its half-life is relatively short after generation. Meanwhile, NO-induced anticancer activity is dose-dependent. Therefore, the targeted delivery of NO to the tumor is required for better therapeutic effects. In the past decade, NO-generating nanomedicines (NONs), which enable sustained and specific NO release in tumor tissues, have been developed for enhanced cancer therapy. This review describes the recent efforts and preclinical achievements in the development of NON-based cancer therapies. The chemical structures employed in the fabrication of NONs are summarized, and the strategies involved in NON-based cancer therapies are elaborated.

Influence of nitric oxide signaling mechanisms in cancer

Nitric oxide (NO) is a molecule with multiple biological functions that is involved in various pathophysiological processes such as neurotransmission and blood vessel relaxation as well as the endocrine system, immune system, growth factors, and cancer. However, in the carcinogenesis process, it has a dual behavior; at low doses, NO regulates homeostatic functions, while at high concentrations, it promotes tissue damage or acts as an agent for immune defense against microorganisms. Thus, its participation in the carcinogenic process is controversial. Cancer is a multifactorial disease that presents complex behavior. A better understanding of the molecular mechanisms associated with the initiation, promotion, and progression of neoplastic processes is required. Some hypotheses have been proposed regarding the influence of NO in activating oncogenic pathways that trigger carcinogenic processes, because NO might regulate some signaling pathways thought to promote cancer development and more aggressive tumor growth. Additionally, NO inhibits apoptosis of tumor cells, together with the deregulation of proteins that are involved in tissue homeostasis, promoting spreading to other organs and initiating metastatic processes. This paper describes the signaling pathways that are associated with cancer, and how the concentration of NO can serve a beneficial or pathological function in the initiation and promotion of neoplastic events.

Exploring Nitric Oxide (NO)-Releasing Celecoxib Derivatives as Modulators of Radioresponse in Pheochromocytoma Cells

COX-2 can be considered as a clinically relevant molecular target for adjuvant, in particular radiosensitizing treatments. In this regard, using selective COX-2 inhibitors, e.g., in combination with radiotherapy or endoradiotherapy, represents an interesting treatment option. Based on our own findings that nitric oxide (NO)-releasing and celecoxib-derived COX-2 inhibitors (COXIBs) showed promising radiosensitizing effects in vitro, we herein present the development of a series of eight novel NO-COXIBs differing in the peripheral substitution pattern and their chemical and in vitro characterization. COX-1 and COX-2 inhibition potency was found to be comparable to the lead NO-COXIBs, and NO-releasing properties were demonstrated to be mainly influenced by the substituent in 4-position of the pyrazole (Cl vs. H). Introduction of the N-propionamide at the sulfamoyl residue as a potential prodrug strategy lowered lipophilicity markedly and abolished COX inhibition while NO-releasing properties were not markedly influenced. NO-COXIBs were tested in vitro for a combination with single-dose external X-ray irradiation as well as [¹⁷⁷Lu]LuCl₃ treatment in HIF2α-positive mouse pheochromocytoma (MPC-HIF2a) tumor spheroids. When applied directly before X-ray irradiation or ¹⁷⁷Lu treatment, NO-COXIBs showed radioprotective effects, as did celecoxib, which was used as a control. Radiosensitizing effects were observed when applied shortly after X-ray irradiation. Overall, the NO-COXIBs were found to be more radioprotective compared with celecoxib, which does not warrant further preclinical studies with the NO-COXIBs for the treatment of pheochromocytoma. However, evaluation as radioprotective agents for healthy tissues could be considered for the NO-COXIBs developed here, especially when used directly before irradiation.

Visible-light NO photolysis of ruthenium nitrosyl complexes with N2O2 ligands bearing π-extended rings and their photorelease dynamics

NO photorelease and its dynamics for two {RuNO}⁶ complexes, Ru(salophen)(NO)Cl (1) and Ru(naphophen)(NO)Cl (2), with salen-type ligands bearing π-extended systems (salophenH₂ = N,N'-(1,2-phenylene)-bis(salicylideneimine) and naphophenH₂ = N,N'-1,2-phenylene-bis(2-hydroxy-1-naphthylmethyleneimine)) were investigated. NO photolysis was performed under white room light and monitored by UV/Vis, EPR, and NMR spectroscopies. NO photolysis was also performed under 459 and 489 nm irradiation for 1 and 2, respectively. The photochemical quantum yields of the NO photolysis (Φ_NO) of both 1 and 2 were determined to be 9% at the irradiation wavelengths. The structural and spectroscopic characteristics of the complexes before and after the photolysis confirmed the conversion of diamagnetic Ru(II)(L)(Cl)-NO⁺ to paramagnetic S = ½ Ru(III)(L)(Cl)-solvent by photons (L = salophen^2- and naphophen^2-). The photoreleased NO radicals were detected by spin-trapping EPR. DFT and TDDFT calculations found that the photoactive bands are configured as mostly the ligand-to-ligand charge transfer (LLCT) of π(L) → π*(Ru-NO), suggesting that the NO photorelease was initiated by the LLCT. Dynamics of NO photorelease from the complexes in DMSO under 320 nm excitation were investigated by femtosecond (fs) time-resolved mid-IR spectroscopy. The primary photorelease of NO occurred for less than 0.32 ps after the excitation. The rate constants (k_-1) of the geminate rebinding of NO to the photolyzed 1 and 2 were determined to be (15 ps)^-1 and (13 ps)^-1, respectively. The photochemical quantum yields of NO photolysis (Φ_NO, λ = 320 nm) were estimated to be no higher than 14% for 1 and 11% for 2, based on the analysis of the fs time-resolved IR data. The results of fs time-resolved IR spectroscopy and theoretical calculations provided some insight into the overall kinetic reaction pathway, localized electron pathway or resonance pathway, of the NO photolysis of 1 and 2. Overall, our study found that the investigated {RuNO}⁶ complexes, 1 and 2, with planar N₂O₂ ligands bearing π-extended rings effectively released NO under visible light.

Buffer concentration dramatically affects the stability of S-nitrosothiols in aqueous solutions

S-nitrosothiols (RSNOs) are an important group of nitric oxide (NO)-donating compounds with low toxicity and wide biomedical applications. In this paper, we, for the first time, demonstrate that the concentration of buffer remarkably affects the stability of RSNOs including naturally occurring S-nitrosoglutathione (GSNO) and synthetic S-nitroso-N-acetylpenicillamine (SNAP). For a solution with a high concentration of GSNO (e.g., 50 mM) and an initial near-neutral pH, the optimal buffer concentration is close to the GSNO concentration under our experimental conditions. A lower buffer concentration does not have adequate buffer capacity to resist the pH drop caused by GSNO decomposition. The decreased solution pH further accelerates GSNO decomposition because GSNO is most stable at near-neutral pH according to our density functional theory (DFT) calculations. A higher-than-optimal buffer concentration also reduces the GSNO stability because buffer ingredients including phosphate, Tris base, and HEPES consume NO/N₂O₃. In contrast to GSNO, the highest SNAP stability is obtained when the starting solution at a neutral pH does not contain buffer species, and the stability decreases as the buffer concentration increases. This is because SNAP is more stable at mildly acidic pH and the SNAP decomposition-induced pH drop stabilizes the donor. When the RSNO concentration is low (e.g., 1 mM), the buffer concentration also matters because any excess buffer accelerates the donor decomposition. Since the effect of buffer concentration was previously overlooked and suboptimal buffer concentrations were often used, this paper will aid in the formulation of RSNO solutions to obtain the maximum stability for prolonged storage and sustained NO release.

Ruthenium-nitrosyl complexes as NO-releasing molecules and potential anticancer drugs

The synthesis of new types of mono- and polynuclear ruthenium nitrosyl complexes is driving progress in the field of NO generation for a variety of applications. Light-induced Ru-NO bond dissociation...

Glycyrrhizin as a Nitric Oxide Regulator in Cancer Chemotherapy

Simple Summary

Glycyrrhizin (GL) has anti-cancer, anti-inflammatory, anti-viral, and anti-oxidant activity. In particular, GL reduces multidrug resistance (MDR) in cancer cells, which is a major obstacle to chemotherapy. Nitric oxide (NO) also plays an important role in MDR, and GL affects NO concentration in the tumor microenvironment. However, the effects of GL and NO interaction on MDR have not been reviewed. Here, we review the role of GL as an NO regulator in cancer cells and its subsequent anti-MDR effect and posit that GL is a promising MDR inhibitor for cancer chemotherapy.

Abstract

Chemotherapy is used widely for cancer treatment; however, the evolution of multidrug resistance (MDR) in many patients limits the therapeutic benefits of chemotherapy. It is important to overcome MDR for enhanced chemotherapy. ATP-dependent efflux of drugs out of cells is the main mechanism of MDR. Recent studies have suggested that nitric oxide (NO) can be used to overcome MDR by inhibiting the ATPase function of ATP-dependent pumps. Several attempts have been made to deliver NO to the tumor microenvironment (TME), however there are limitations in delivery. Glycyrrhizin (GL), an active compound of licorice, has been reported to both reduce the MDR effect by inhibiting ATP-dependent pumps and function as a regulator of NO production in the TME. In this review, we describe the potential role of GL as an NO regulator and MDR inhibitor that efficiently reduces the MDR effect in cancer chemotherapy.

Synthesis and biological evaluation of N, N-dialkylcarboxy coumarin-NO donor conjugates as potential anticancer agents

A series of nitric oxide (NO) donor furoxan conjugates of N, N-dialkylcarboxy coumarins have been synthesized as potential anticancer agents. The synthesized compounds have been tested for their in vitro antiproliferative activities on various cancer and noncancerous cell lines. The candidate derivatives exhibit selectivity towards cancer cells with excellent activities in low nM to µM concentrations. In vitro mechanistic studies indicate that the candidate compounds generate substantial NO, inhibit colony formation, and cause apoptosis in cancer cells. A preliminary in vivo tolerance study of the lead candidate 10 in mice indicates that it is well-tolerated, evidenced by zero mortality and normal body weight gains in treated mice. Further translation of the lead derivative 10 using MDA-MB-231 based tumor xenograft model shows good tumor growth reduction.

Role of human glutathione transferases in biotransformation of the nitric oxide prodrug JS-K

Nitric oxide (NO) plays a prominent physiological role as a low-molecular-mass signal molecule involved in diverse biological functions. Great attention has been directed to pharmacologically modulating the release of NO for various therapeutic applications. We have focused on O2-(2,4-dinitrophenyl) 1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate (JS-K) as an example of diazeniumdiolate prodrugs with potential for cancer chemotherapy. JS-K is reportedly activated by glutathione conjugation by glutathione transferase (GST), but the scope of activities among the numerous members of the GSTome is unknown. We demonstrate that all human GSTs tested except GST T1-1 are active with JS-K as a substrate, but their specific activities are notably spanning a > 100-fold range. The most effective enzyme was the mu class member GST M2-2 with a specific activity of 273 ± 5 µmol min-1 mg-1 and the kinetic parameters Km 63 µM, kcat 353 s-1, kcat/Km 6 × 106 M-1 s-1. The abundance of the GSTs as an ensemble and their high catalytic efficiency indicate that release of NO occurs rapidly in normal tissues such that this influence must be considered in clarification of the tumor-killing effect of JS-K.

NO-HDAC dual inhibitors

HDAC inhibitors and NO donors have both demonstrated independently broad therapeutic potential in a variety of diseases. Borretto et al. presented the topic of NO-HDAC dual inhibitors for the first time in 2013 as an attractive new topic. Here we collected the general structure of all synthesized NO-HDAC dual inhibitors, lead compounds, synthesis methods and biological features of the most potent dual NO-HDAC inhibitor in each category with the intention of assisting in the synthesis and optimization of new drug-like compounds for diverse diseases. Based on studies done so far, NO-HDAC dual inhibitors have displayed satisfactory results against wound healing (3), heart hypertrophy (3), inflammatory, cardiovascular, neuromuscular illnesses (11a-11e) and cancer (6a-6o, 9a-9d, 10a-10d, 16 and 17). NO-HDAC dual inhibitors can have high therapeutic potential for various diseases due to their new properties, NO properties, HDAC inhibitor properties and also due to the effects of NO on HDAC enzymes.

A Density Matrix Renormalization Group Study of the Low-Lying Excited States of a Molybdenum Carbonyl-Nitrosyl Complex

A density matrix renormalization group-self consistent field (DMRG-SCF) study has been carried out to calculate the low-lying excited states of CpMo(CO)₂ NO, a molybdenum complex containing NO and CO ligands. In order to automatically select an appropriate active space, a novel procedure employing the maximum single-orbital entropy for several states has been introduced and shown to be efficient and easy-to-implement when several electronic states are simultaneously considered. The analysis of the resulting natural transition orbitals and charge-transfer numbers shows that the lowest five excited electronic states are excitation into metal-NO antibonding orbitals, which offer the possibility for nitric oxide (NO) photorelease after excitation with visible light. Higher excited states are metal-centered excitations with contributions of metal-CO antibonding orbitals, which may serve as a gateway for carbon monoxide (CO) delivery. Time-dependent density functional theory calculations done for comparison, show that the state characters agree remarkably well with those from DMRG-SCF, while excitation energies are 0.4-1.0 eV red-shifted with respect to the DMRG-SCF ones.

GC-MS Profiling and Antineoplastic Activity of Pelargonium Inquinans Ait Leaves on Acute Leukaemia Cell Lines U937 and Jurkat

We investigated the antineoplastic activities of extracts of Pelargonium inquinans leaves, a plant native to South Africa on acute leukemia cell lines, U937 and Jurkat and the inflammatory effect (nitric oxide and cyclo-oxygenase-2) on RAW 264.7 cells. The extracts of Pelargonium inquinans have significant cytotoxicity especially on U937 cells and pro-inflammatory release of nitric oxide on RAW 264.7 macrophages. The GC-MS study of the essential oil showed it had more than a hundred compounds. This study showed that Pelargonium inquinans have antineoplastic and anti-inflammatory activities which can be further explored in In Vivo studies.

Protein Phosphorylation in Cancer: Role of Nitric Oxide Signaling Pathway

Nitric oxide (NO), a free radical, plays a critical role in a wide range of physiological and pathological processes. Due to its pleiotropic function, it has been widely investigated in various types of cancers and is strongly associated with cancer development. Mounting pieces of evidence show that NO regulates various cancer-related events, which mainly depends on phosphorylating the key proteins in several signaling pathways. However, phosphorylation of proteins modulated by NO signaling pathway may lead to different effects in different types of cancer, which is complex and remains unclear. Therefore, in this review, we focus on the effect of protein phosphorylation modulated by NO signaling pathway in different types of cancers including breast cancer, lung cancer, prostate cancer, colon cancer, gastric cancer, pancreatic cancer, ovarian cancer, and neuroblastoma. Phosphorylation of key proteins, including p38 MAPK, ERK, PI3K, STAT3, and p53, modified by NO in various signaling pathways affects different cancer-related processes including cell apoptosis, proliferation, angiogenesis, metastasis, and several cancer therapies. Our review links the NO signaling pathway to protein phosphorylation in cancer development and provides new insight into potential targets and cancer therapy.

Biological activities of Pleurotus spp. polysaccharides: A review

Mushrooms are consumed for their nutrients and therapeutic bioactive compounds and are used medicinally in Chinese and Japanese medicine traditions since time immemorial. Members of the genus Pleurotus form a heterogeneous group of edible species with outstanding nutritional profiles rich in fiber, vitamins (thiamine, riboflavin, ascorbic acid, ergosterine, and niacin), micro and macro-elements (phosphorus and iron), and carbohydrates. Pleurotus is one of the most diversified medicinal and edible mushrooms related to the composition of chemical structures such as polysaccharides, glycoproteins, and secondary metabolites such as alkaloids and betalains. The cultivation of Pleurotus spp. on lignocellulosic wastes represents one of the most economically and cost-effective organic recycling processes, especially for the utilization of different feasible and cheap recyclable residues. Also, several Pleurotus spp. have the ability to remove phenolic compounds from wastewater with the action of phenoloxidase activity. Here, we have reviewed the chemistry of such polysaccharides and their reported biological activities, namely, anti-inflammatory, immunomodulatory, anti-diabetic, anti-tumor, antioxidant, etc. The mechanism of action and effects of novel polysaccharides extracted from various species of Pleurotus have been studied. The current study will be beneficial for guiding future research projects on the above concept and investigating more deeply the health of human beings. PRACTICAL APPLICATIONS: Mushrooms are one of the most delicious foods around the globe and have many medicinal properties for decades. Various Pleurotus species have been in focus in recent years because of their palatability and medicinal importance too. It contains many bioactive compounds among which polysaccharides are valued to a great extent. Many biological activities are exerted by polysaccharides derived from the Pleurotus spp., namely, anti-tumor, antioxidant, and many more. They are responsible for significant physiological responses in animals, animal-alternative in vitro models, and humans. Their important physicochemical characteristics benefit their use in the food industry as well. So, the biological activities of these Pleurotus spp. polysaccharides will provide an insight to develop Pleurotus spp. as functional foods, because of their nutritional value and presence of bioactive components.

Nitric Oxide in Hematological Cancers: Partner or Rival?

Significance: Hematological malignancies represent the fourth most diagnosed cancer. Relapse and acquired resistance to anticancer therapy constitute two actual issues that need to be overcome. Nitric oxide (NO) plays a pivotal role in regulating cancer progression. At present, many studies are attempting to uncover the potentials of modulating NO levels to improve the efficacy of currently available treatments against lymphoma, leukemia, and myeloma. Recent Advances: It is becoming progressively clear that NO modulation may help hematological cancer management, either by targeting directly tumor cells or by driving the immune system to eliminate cancer cells. Critical Issues: NO is a dual molecule that can have a tumor-protecting or stimulating effect, depending on its local concentration. Moreover, NO is able to target a wide range of molecules involved in both cancer genesis and evolution. In this review, an overview of the recent findings regarding the pivotal role played by NO and nitric oxide synthase in cancer progression and anticancer therapy is presented, with particular focus on hematological malignancies. Future Directions: It is critical to establish the cancer-specific function of NO and critically drive its modulation to improve cancer management toward a personalized approach. This has a special importance in hematological tumors, where the urgency of finding eradicative therapies is constant. Antioxid. Redox Signal. 34, 383-401.

Theranostic Activity of Nitric Oxide-Releasing Carbon Quantum Dots

The synthesis and anticancer cell activity of nitric oxide (NO)-releasing carbon quantum dots (CQDs) are described as potential theranostics. A series of secondary amine-modified CQDs were prepared using a hydrothermal method to modify β-cyclodextrin with hydroxyl and primary amine terminal functional groups. Subsequent reaction of the CQDs with NO gas under alkaline conditions yielded N-diazeniumdiolate NO donor-modified CQDs with adjustable NO payloads (0.2-1.1 μmol/mg) and release kinetics (half-lives from 29 to 79 min) depending on the level of secondary amines and surface functional groups. The anticancer activity of the NO-releasing CQDs against Pa14c, A549, and SW480 cancer cell lines proved to be dependent on both NO payloads and surface functionalizations. Primary amine-modified CQDs with NO payloads ∼1.11 μmol/mg exhibited the greatest anticancer action. A fluorescence microscopy study demonstrated the utility of these NO-releasing CQDs as dual NO-releasing and bioimaging probes.

Prognostic significance of DNMT3a gene expression and reactive nitrogen species in newly diagnosed Egyptian de novo adult acute myeloid leukemia patients

Background

DNA methyltransferase 3a (DNMT3a) gene is a frequently dysregulated epigenetic modifier gene involved in the process of carcinogenesis. Also, there is a dichotomous nature of nitric oxide action with the ability to both promote and repress cancers. There is a host of research work delineating the frequency of DNMT3a mutation in acute myeloid leukemia (AML), but little is known about its level of expression in AML patients or its probable relationship to nitrosative stress. This study aims at the assessment DNMT3a gene expression as well as nitric oxide levels in newly diagnosed adult patients with de novo AML. Moreover, it aims at relating these two variables to other disease features and prognostic indicators as well as treatment outcomes. The study included 45 adult de novo AML patients and 10 healthy control subjects. Measurement of DNMT3a messenger ribonucleic acid (mRNA) transcripts was done by real-time quantitative polymerase chain reaction (RQ-PCR) followed by Sanger sequencing to identify the presence or absence of DNMT3a arginine 882 (R882) mutation. This was followed by the assessment of serum nitrite level as a surrogate marker for nitric oxide radical (NO) using colorimetric methods.

Results

DNMT3a gene expression, as well as serum nitrite levels, were significantly higher among AML cases in relation to controls before chemotherapy with P values of < 0.001 and 0.035, respectively. Dividing patients into low and high expressors in relation to the hotspot mutation demonstrated no difference between the two groups in terms of demographic, clinical, and laboratory characteristics or treatment outcomes.

Conclusion

DNMT3a gene expression is increased among the AML population in relation to normal healthy controls. This may point out the need for the assessment of the influence of this gene expression on methylcytosine content of tumor samples with the subsequent implementation of hypomethylating agents as a line of therapy in cases exhibiting excessive hypermethylation.

Hybrids of Coumarin Derivatives as Potent and Multifunctional Bioactive Agents: A Review

BACKGROUND

Coumarins exhibit a plethora of biological activities, e.g. antiinflammatory and anti-tumor. Molecular hybridization technique has been implemented in the design of novel coumarin hybrids with several bioactive groups in order to obtain molecules with better pharmacological activity and improved pharmacokinetic profile.

OBJECTIVE

Therefore, we tried to gather as many as possible biologically active coumarin hybrids referred in the literature till now, to delineate the structural characteristics in relation to the activities and to have a survey that might help the medicinal chemists to design new coumarin hybrids with drug-likeness and varied bioactivities.

RESULTS

The biological activities of the hybrids in most of the cases were found to be different from the biological activities presented by the parent coumarins. The results showed that the hybrid molecules are more potent compared to the standard drugs used in the evaluation experiments.

CONCLUSION

Conjugation of coumarin with varied pharmacophore groups/druglike molecules responsible for different biological activities led to many novel hybrid molecules, with a multitarget behavior and improved pharmacokinetic properties.

Synthesis and Antiproliferative Activity of Nitric Oxide-Donor Largazole Prodrugs

The marine natural product Largazole is the most potent Class I HDAC inhibitor identified to date. Since its discovery, many research groups have been attracted by the structural complexity and the peculiar anticancer activity, due to its capability to discriminate between tumor cells and normal cells. Herein, we discuss the synthesis and the in vitro biological profile of hybrid analogues of Largazole, as dual HDAC inhibitor and nitric oxide (NO) donors, potentially useful as anticancer agents. In particular, the metabolic stability of the modified thioester moiety of Largazole, bearing the NO-donor function/s, the in vitro release of NO, and the antiproliferative activity in tumor cell lines are presented.

Real-time redox monitoring of a nitrosyl ruthenium complex acting as NO-donor agent in a single A549 cancer cell with multiplex Fourier-transform infrared microscopy

Multiplex Fourier-transform infrared microscopy (μFT-IR) helped to monitor trans-[Ru(NO) (NH₃)₄ (isn)]³⁺(I), uptake by A549 lung carcinoma cell, as well as the generation of its product, nitric oxide (NO), inside the cell. Chronoamperometry with NO-sensor and μFT-IR showed that exogenous NADH and the A549 cell induced the NO release redox mechanism. Chemical imaging confirmed that (I) was taken up by the cell, and that its localization coincided with its consumption in the cellular environment within 15 min of exposure. The Ru-NO absorption band in the IR spectrum shifted from 1932 cm^-1, when NO was coordinated to Ru as {Ru^II-NO⁺}³⁺, to 1876 cm^-1, due the formation of reduced species {Ru^II-NO⁰}²⁺, a precursor of NO release. Futhermore, the μFT-IR spectral profile demonstrated that, as a result of the NO action on the target, NO interacted with nucleic acids, which provided a biochemical response that is detectable in living cells.

Low-Temperature Trigger Nitric Oxide Nanogenerators for Enhanced Mild Photothermal Therapy

Surmounting the restriction issues of nitric oxide (NO) delivery to realize their precious on-demand release is highly beneficial for the widespread deployment of gas therapy for application in biomedicine. Herein, by employing core-shell structure Au@SiO₂ nanomaterials with high photothermal performance, a novel strategy was proposed by integrating photothermal conversion nanomaterials and heat-triggered NO donors (RSNO) into a nanoplatform, which achieved photothermal therapy (PTT)-enhanced NO gas therapy under near-infrared (NIR) radiation. Specifically, 2-phenylethynesulfonamide (PES), an inhibitor of heat shock protein 70 (HSP-70), was loaded into the NO nanogenerators to realize effective low-temperature (∼45 °C) PTT. The obtained results showed that the near-infrared radiation (NIR) mediated mild PTT and gas therapy by releasing NO showed a substantially improved synergistic effect based on in vitro and in vivo results in breast cancer (MCF-7) models. Our study points out a strategy to realize mild photothermal therapy by inhibiting the expression of HSP-70 and simultaneously providing an avenue to achieve controllable release of NO. More important, this research highlights the great potential of multifunctional therapeutic agents in the synergistic treatment of cancer.

Nitroxyl as a Potential Theranostic in the Cancer Arena

Significance: As one-electron reduced molecule of nitric oxide (NO), nitroxyl (HNO) has gained enormous attention because of its novel physiological or pharmacological properties, ranging from cardiovascular protective actions to antitumoricidal effects. Recent Advances: HNO is emerging as a new entity with therapeutic advantages over its redox sibling, NO. The interests in the chemical, pharmacological, and biological characteristics of HNO have broadened our current understanding of its role in physiology and pathophysiology. Critical Issues: In particular, the experimental evidence suggests the therapeutic potential of HNO in tumor pharmacology, such as neuroblastoma, gastrointestinal tumor, ovarian, lung, and breast cancers. Indeed, HNO donors have been demonstrated to attenuate tumor proliferation and angiogenesis. Future Directions: In this review, the generation and detection of HNO are outlined, and the roles of HNO in cancer progression are further discussed. We anticipate that the completion of this review might give novel insights into the roles of HNO in cancer pharmacology and open up a novel field of cancer therapy based on HNO.

Toxicity and Antitumor Activity of a Thiophene-Acridine Hybrid

The antitumor effects of thiophene and acridine compounds have been described; however, the clinical usefulness of these compounds is limited due to the risk of high toxicity and drug resistance. The strategy of molecular hybridization presents the opportunity to develop new drugs which may display better target affinity and less serious side effects. Herein, 2-((6-Chloro-2-methoxy-acridin-9-yl)amino)-5,6,7,8-tetrahydro-4H-cyclohepta[b]-thiophene-3-carbonitrile (ACS03), a hybrid thiophene–acridine compound with antileishmanial activity, was tested for toxicity and antitumor activity. The toxicity was evaluated in vitro (on HaCat and peripheral blood mononuclear cells) and in vivo (zebrafish embryos and acute toxicity in mice). Antitumor activity was also assessed in vitro in HCT-116 (human colon carcinoma cell line), K562 (chronic myeloid leukemic cell line), HL-60 (human promyelocytic leukemia cell line), HeLa (human cervical cancer cell line), and MCF-7 (breast cancer cell line) and in vivo (Ehrlich ascites carcinoma model). ACS03 exhibited selectivity toward HCT-116 cells (Half maximal inhibitory concentration, IC50 = 23.11 ± 1.03 µM). In zebrafish embryos, ACS03 induced an increase in lactate dehydrogenase, glutathione S-transferase, and acetylcholinesterase activities. The LD50 (lethal dose 50%) value in mice was estimated to be higher than 5000 mg/kg (intraperitoneally). In vivo, ACS03 (12.5 mg/kg) induced a significant reduction in tumor volume and cell viability. In vivo antitumor activity was associated with the nitric oxide cytotoxic effect. In conclusion, significant antitumor activity and weak toxicity were recorded for this hybrid compound, characterizing it as a potential anticancer compound.

S-nitrosothiols and H2S donors: Potential chemo-therapeutic agents in cancer

Nitric Oxide (NO) and Hydrogen Sulfide (H2S) are components of an "interactome", which is defined as a redox system involving the interactions of RSS, RNS and ROS. Chemical interaction by these species is common and is characterized by one and two electron oxidation, nitrosylation, nitration and sulfuration/polysulfidation reactions. NO and H2S are gases that penetrate cell membranes, are synthesized by specific enzymes, are ubiquitous, regulate protein activities through post-translational modifications and participate in cell signaling. The two molecules at high concentrations compared to physiological concentrations may result in cellular damage particularly through their interaction with other reactive species. NO and H2S can interact with each other and form a variety of molecular species which may have constructive or destructive behavior depending on the cell type, the cellular environment (ex. oxygen tension, pH, redox state), where the products are produced and in what concentrations. Cross talk exists between NO and H2S, whereby they can influence the generation and signaling behavior of each other. Given the above mentioned properties of NO and H2S and studies in cancer cells and animal models employing NO and H2S donors that generate higher than physiological concentrations of NO and H2S and are effective in killing cancer cells but not normal cells, lend credence to the possibility of the utility of these donors in an approach to the treatment of cancer.

Synergistic induction of apoptosis in a cell model of human leukemia K562 by nitroglycerine and valproic acid

Nitroglycerin (NG), a nitric oxide donor, and valproic acid (VPA), an inhibitor of histone deacetylases, have impressive effects on numerous cancer cell lines. This study intended to evaluate synergistic effects of NG and VPA on cell viability and apoptosis in K562 cells. K562 cells were cultured in RPMI-1640 supplemented with 10 % heat-inactivated FBS. They were treated with different doses of NG, VPA and cisplatin for 24, 48, and 72 h, and MTT assay was performed to analyze cell viability. Also, Peripheral blood mononuclear cells (PBMC) were cultured in RPMI-1640 media and incubated with NG (200 μM), VAP (100 μM), NG+VPA (150 μM) and cisplatin (8 μM) to evaluate cytotoxicity. IC₅₀ of the drugs, when they were applied separately and in combination, were calculated using the COMPUSYN software. DNA electrophoresis, TUNEL assay, and Hoechst staining were performed to investigate apoptosis induction. RT-PCR was used for the evaluation of apoptotic genes expression. The results of the MTT assay showed that cell viability decreased at all applied doses of NG and VPA. It was noticed that the cytotoxic effects of these drugs were dose- and time-dependent. Based on the COMPUSYN output, the combination of the drugs (VPA and NG) in a certain ratio concentration synergistically decreased cell viability. Cisplatin significantly decreased cell viability of PBMCs and K562 cells. Also, the combination drug had cytotoxic effect and significantly reduced viability of K562 cells compared with PBMCs and control cells. In the target cells treated with this combination, Bax and caspase-3 expression increased but Bcl-2 expression decreased. These results suggest that NG, VPA, and their combination decreased cell viability and induced apoptosis via the intrinsic apoptotic pathway. This study suggests that this combination therapy can be considered for further evaluation as an effective chemotherapeutic strategy for patients with chronic myeloid leukemia.

Insulin resistance in prostate cancer patients and predisposing them to acute ischemic heart disease

Lack of insulin or insulin resistance (IR) plays a central role in diabetes mellitus and makes diabetics prone to acute ischemic heart disease (AIHD). It has likewise been found that many cancer patients, including prostate cancer patients die of AIHD. Previously it has been delineated from our laboratory that dermcidin could induce anomalous platelet aggregation in AIHD and also impaired nitric oxide and insulin activity and furthermore dermcidin was also found in a few types of cancer patients. To determine the role of this protein in prostatic malignancy, a retrospective case-control study was conducted and blood was collected from prostate cancer patients and healthy normal volunteers. So, we measured the level of dermcidin protein and analyzed the IR by Homeostasis Model Assessment (HOMA) score calculation. Nitric oxide was measured by methemoglobin method. HDL, glycated hemoglobin (HbA1c), BMI, hs-cTroponin-T were measured for the validation of the patients' status in the presence of Dermcidin isoform-2 (DCN-2). Multiple logistic regression model adjusted for age and BMI identified that the HOMA score was significantly elevated in prostate cancer patients (OR = 7.19, P<0.001). Prostate cancer patients are associated with lower level of NO and higher level of both proteins dermcidin (OR = 1.12, P<0.001) and hs-TroponinT (OR = 1.76, P<0.001). From the results, it can be interpreted that IR plays a key role in the pathophysiology of prostate cancer where dermcidin was the cause of IR through NO inhibition leading to AIHD was also explained by high-sensitive fifth generation cTroponin-T (hs-cTroponinT) and HbA1c level which are associated with endothelial dysfunction.

Polyamines - A New Metabolic Switch: Crosstalk With Networks Involving Senescence, Crop Improvement, and Mammalian Cancer Therapy

Polyamines (PAs) are low molecular weight organic cations comprising biogenic amines that play multiple roles in plant growth and senescence. PA metabolism was found to play a central role in metabolic and genetic reprogramming during dark-induced barley leaf senescence (DILS). Robust PA catabolism can impact the rate of senescence progression in plants. We opine that deciphering senescence-dependent polyamine-mediated multidirectional metabolic crosstalks is important to understand regulation and involvement of PAs in plant death and re-mobilization of nutrients during senescence. This will involve optimizing the use of PA biosynthesis inhibitors, robust transgenic approaches to modulate PA biosynthetic and catabolic genes, and developing novel germplasm enriched in pro- and anti-senescence traits to ensure sustained crop productivity. PA-mediated delay of senescence can extend the photosynthesis capacity, thereby increasing grain starch content in malting grains such as barley. On the other hand, accelerating the onset of senescence can lead to increases in mineral and nitrogen content in grains for animal feed. Unraveling the "polyamine metabolic switch" and delineating the roles of PAs in senescence should further our knowledge about autophagy mechanisms involved in plant senescence as well as mammalian systems. It is noteworthy that inhibitors of PA biosynthesis block cell viability in animal model systems (cell tumor lines) to control some cancers, in this instance, proliferative cancer cells were led toward cell death. Likewise, PA conjugates work as signal carriers for slow release of regulatory molecule nitric oxide in the targeted cells. Taken together, these and other outcomes provide examples for developing novel therapeutics for human health wellness as well as developing plant resistance/tolerance to stress stimuli.

Antimicrobial Activity and Cytotoxicity to Tumor Cells of Nitric Oxide Donor and Silver Nanoparticles Containing PVA/PEG Films for Topical Applications

Because of their antibacterial activity, silver nanoparticles (AgNPs) have been explored in biomedical applications. Similarly, nitric oxide (NO) is an important endogenous free radical with an antimicrobial effect and toxicity toward cancer cells that plays pivotal roles in several processes. In this work, biogenic AgNPs were prepared using green tea extract and the principles of green chemistry, and the NO donor S-nitrosoglutathione (GSNO) was prepared by the nitrosation of glutathione. To enhance the potentialities of GSNO and AgNPs in biomedical applications, the NO donor and metallic nanoparticles were individually or simultaneously incorporated into polymeric solid films of poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG). The resulting solid nanocomposites were characterized by several techniques, and the diffusion profiles of GSNO and AgNPs were investigated. The results demonstrated the formation of homogeneous PVA/PEG solid films containing GSNO and nanoscale AgNPs that are distributed in the polymeric matrix. PVA/PEG films containing AgNPs demonstrated a potent antibacterial effect against Gram-positive and Gram-negative bacterial strains. GSNO-containing PVA/PEG films demonstrated toxicity toward human cervical carcinoma and human prostate cancer cell lines. Interestingly, the incorporation of AgNPs in PVA/PEG/GSNO films had a superior effect on the decrease of cell viability of both cancer cell lines, compared with cells treated with films containing GSNO or AgNPs individually. To our best knowledge, this is the first report to describe the preparation of PVA/PEG solid films containing GSNO and/or biogenically synthesized AgNPs. These polymeric films might find important biomedical applications as a solid material with antimicrobial and antitumorigenic properties.

Employment of enhanced permeability and retention effect (EPR): Nanoparticle-based precision tools for targeting of therapeutic and diagnostic agent in cancer

In tumorous tissues, the absence of vasculature supportive tissues intimates the formation of leaky vessels and pores (100 nm to 2 μm in diameter) and the poor lymphatic system offers great opportunity to treat cancer and the phenomenon is known as Enhanced permeability and retention (EPR) effect. The trends in treating cancer by making use of EPR effect is increasing day by day and generate multitudes of possibility to design novel anticancer therapeutics. This review aimed to present various factors affecting the EPR effect along with important things to know about EPR effect such as tumor perfusion, lymphatic function, interstitial penetration, vascular permeability, nanoparticle retention etc. This manuscript expounds the current advances and cross-talks the developments made in the of EPR effect-based therapeutics in cancer therapy along with a transactional view of its current clinical and industrial aspects.

Nitric oxide synthase inhibitors 1400W and L-NIO inhibit angiogenesis pathway of colorectal cancer

BACKGROUND

It has been widely accepted that angiogenesis plays fundamental roles in colorectal cancer development, and therapeutic targeting of this pathway has achieved promising outcome. Recent reports have highlighted the involvement of nitric oxide synthases (NOS) in the development of angiogenesis in cancer; however, the mechanism and therapeutic value of NOS inhibitors in colon cancer are largely unknown.

OBJECTIVE

In this study, we investigated the effects and mechanism of the NOS inhibitors 1400W and L-NIO on the angiogenesis pathway in colorectal cancer cells.

METHODS

Two colorectal cancer cell lines, HT 29 and HCT 116, were used for in vitro study. The expression of iNOS and eNOS in cells was knocked down via shRNA transfection. MTS assays and wound healing assays were performed to assess cell proliferation and migration after shRNA transfection or treatment with 1400W, L-NIO, and 5-fluorouracil. Human angiogenesis PCR arrays and proteome profiler human angiogenesis arrays were used to detect changes in key genes/proteins involved in modulating angiogenesis after 1400W and L-NIO treatment.

RESULTS

Knockdown of iNOS and eNOS significantly inhibited colorectal cancer cell growth. Treatment with NOS inhibitors inhibited colorectal cancer cell growth and migration, and was associated with suppression of the expression of key genes/proteins involved in the angiogenesis pathway. In addition, the combined use of NOS inhibitors with 5-fluorouracil showed enhanced inhibition of cell proliferation and migration.

CONCLUSION

NOS inhibitors could suppress colorectal cancer cell growth and migration, likely via suppressing the angiogenesis pathway.

Non-touching plasma-liquid interaction - where is aqueous nitric oxide generated?

Nitric oxide is a relatively stable free radical and an important signal molecule in plants, animals, and humans with high relevance for biological processes involving inflammatory processes, e.g. wound healing or cancer. The molecule can be detected in the gas phase of non-thermal plasma jets making it a valuable tool for clinical intervention, but transport efficiency from the gas phase into the liquid phase or tissue remains to be clarified. To elucidate this fact, the nitric oxide concentration in buffered solutions is determined using electron paramagnetic resonance spectroscopy. The origin of the nitric oxide in the liquid could be excluded, therefore, potential precursors such as hydroxyl radicals, superoxide anions, atomic hydrogen and stable species (nitrite, nitrate and hydrogen peroxide) were detected and the potential formation pathway as well as ways of enhancing the production of nitric oxide by alteration of the feed gas and the surrounding gas composition during plasma treatment of the liquid have been pointed out.

Design, Synthesis, and Antibacterial Activity of a Multivalent Polycationic Calix[4]arene-NO Photodonor Conjugate

The role of nitric oxide (NO) as an antimicrobial and anticancer agent continues to stimulate the search of compounds generating NO in a controlled fashion. Photochemical generators of NO are particularly appealing due to the accurate spatiotemporal control that light-triggering offers. This contribution reports a novel molecular construct in which multiple units of 3-(trifluoromethyl)-4-nitrobenzenamine NO photodonor are clustered and spatially organized by covalent linkage to a calix[4]arene scaffold bearing two quaternary ammonium groups at the lower rim. This multivalent calix[4]arene-NO donor conjugate is soluble in hydro-alcoholic solvent where it forms nanoaggregates able to release NO under the exclusive control of visible light inputs. The light-stimulated antibacterial activity of the nanoconstruct is demonstrated by the effective bacterial load reduction of Gram-positive Staphylococcus aureus ATCC 6538 and Gram-negative Escherichia coli ATCC 10536.