The Tumorigenic Roles of the Cellular REDOX Regulatory Systems

Targeting mutant p53 with arsenic trioxide: A preclinical study focusing on triple negative breast cancer

New treatments are urgently required for triple-negative breast cancer (TNBC). As TP53 is mutated in approximately 80% of TNBC, it is theoretically an attractive target for new drugs for this disease. Arsenic trioxide (ATO), which is used to treat promyelocytic leukaemia, was recently shown to reactivate mutant p53 and restore wild-type functionality. The aim of this study was to evaluate ATO as a potential new treatment for TNBC. Using a panel of 20 cell lines, we found that TNBC cell lines were more sensitive to ATO than non-TNBC cell lines (P = 0.045). Consistent with its ability to reactivate mutant p53, ATO was a more potent inhibitor of proliferation in cell lines with mutant TP53 than the wildtype TP53 (P = 0.027). Direct evidence of mutant p53 reactivation was the induction of multiple wild-type p53 canonical target genes such as CDKN1A, SLC7A11, BBC3, PMAIP1, SESN2, SRXN1 and TXNRD1. Our findings support the activation of mutant p53 by ATO and, furthermore, the possible repurposing of ATO to treat TP53-mutated TNBC.

The role of pentraxin 3 and oxidative status in the prognosis of multiple myeloma

Multiple myeloma (MM) is a bone marrow malignancy characterized by plasma cell proliferation. It was aimed to investigate pentraxin 3 (PTX3) levels, oxidative/antioxidative status, and their correlation in MM. In the study, four groups were established, including newly diagnosed MM (NDMM), MM in remission (Rem-MM), relapsed/refractory MM (RRMM) patients, and a healthy control group. PTX3 levels were measured using enzyme-linked immunosorbent assay, and the total antioxidant status (TAS) and total oxidant status (TOS) were assessed with an autoanalyzer. The oxidative stress index (OSI) was calculated using the formula: OSI (arbitrary unit) = TOS (µmol H2O2 Eq/L)/TAS (mmol Trolox Eq/L) × 100. The study involved comparing PTX3, TAS, TOS, and OSI levels among these four groups. PTX3 levels were significantly elevated in NDMM and RRMM groups compared to controls and the Rem-MM group (NDMM vs control; p < 0.001, NDMM vs Rem-MM; p < 0.001, RRMM vs control; p < 0.001, and RRMM vs Rem-MM; p = 0.006). TAS was higher in NDMM and RRMM groups versus controls (p = 0.009 and p < 0.001, respectively), and TOS was higher in rem-MM group versus NDMM and control groups (p < 0.001 and p = 0.016, respectively). OSI was higher in the Rem-MM group than in NDMM and RRMM groups (p < 0.001 and p = 0.009, respectively). Multivariate analysis confirmed associations between MM groups and PTX3 levels. Receiver operating characteristic analysis revealed high specificity (90%) and sensitivity (79%) for PTX3 in NDMM at a >0.56 ng/mL cut-off value. This study suggests that PTX3 levels may have diagnostic and prognostic potential in MM and its relationship with oxidative stress requires further exploration.

The anticancer and anti-inflammatory activity screening of pyridazinone-based analogs against human epidermoid skin cancer with detailed mechanistic analyses

3(2H)-Pyridazinone derivatives based on 4-biphenyl, naphtha-2-yl, pyridine, or piperidine moiety were synthesized and characterized using I-R and 1HNMR spectra. The activity and cytotoxicity of some synthesized compounds on the skin epidermoid cancer cell proliferation and progression were investigated. The pyridazine isomer with pyridine revealed a significant decrease in the level of nitric oxide p < 0.01 than the activity of caffeine phenecyl ester. The activity of the three active isomers recorded significant activity for their total antioxidant content that triggers their ability for the scavenging the oxygen free radicals significantly p < 0.01. Moreover, revealing the pharmaceutical activity of the isomers as anti-inflammatory agents, IL-6, IL10, and IL12 have been decreased by variable significant values. Additionally, the active isomers revealed variable actions on the skin cancer cell to induce apoptosis using annexin V-FITC/PI. Pyridine was the highest isomer to induce late apoptosis and necrosis for the skin cancer cells against the use of cisplatin. Importantly, Molecular modeling experiments including docking and dynamic simulations were done for the most active 3 analogs to explore the ligand binding and stability leading to exploring the structure-activity relationship with biological target PARP1 which showed a good binding propensity to pyridazine binding site which supports the in vitro data. In conclusion, the pyridazine moieties with piperdine, naphthayl, and pyridine have pharmacological activities against skin cancer epidermoid by triggering action in inhibition of the proliferation and progression with an up-regulated apoptotic mechanism that evades the emergence of cisplatin resistance among different cancer cells.Communicated by Ramaswamy H. Sarma.

Piperlongumine is a ligand for the orphan nuclear receptor 4A1 (NR4A1)

Piperlongumine and derivatives are being developed as anticancer agents which act primarily as inducers of reactive oxygen species (ROS) in cancer cell lines. Many of the anticancer activities of piperlongumine resemble those observed for bis-indole derived compounds that bind the orphan nuclear receptor 4A1 (NR4A1) and act as inverse receptor agonists to inhibit NR4A1-regulated pro-oncogenic pathways and genes. In this study we show that like other NR4A1 inverse agonists piperlongumine inhibited RKO, SW480 and HCT116 colon cancer cell growth migration and invasion and induced apoptosis. Piperlongumine also downregulated the pro-reductant isocitrate dehydrogenase 1 (IDH1) and thioredoxin domain-containing 5 (TXNDC5) gene products resulting in the induction of ROS as previously observed for other inverse NR4A1 agonists. ROS also induced sestrin2 and this resulted in activation of AMPK phosphorylation and inhibition of mTOR pathway signaling. It has previously been reported that these pathways/genes are also regulated by inverse NR4A1 agonists or by knockdown of NR4A1. We also observed that piperlongumine directly bound NR4A1, inhibited NR4A1-dependent transactivation and interactions of the NR4A1/Sp1 complex bound to the GC-rich promoter of the NR4A1-regulated G9a gene.

Modulation of NRF2/KEAP1-Mediated Oxidative Stress for Cancer Treatment by Natural Products Using Pharmacophore-Based Screening, Molecular Docking, and Molecular Dynamics Studies

Oxidative stress plays a significant role in the development of cancer. Inhibiting the protein-protein interaction (PPI) between Keap1 and Nrf2 offers a promising strategy to activate the Nrf2 antioxidant pathway, which is normally suppressed by the binding of Keap1 to Nrf2. This study aimed to identify natural compounds capable of targeting the kelch domain of KEAP1 using structure-based drug design methods. A pharmacophore model was constructed based on the KEAP1-inhibitor complex, leading to the selection of 6178 compounds that matched the model. Subsequently, docking and MM/GBSA analyses were conducted, resulting in the identification of 10 compounds with superior binding energies compared to the reference compound. From these, three compounds (ZINC000002123788, ZINC000002111341, and ZINC000002125904) were chosen for further investigation. Ligand-residue interaction analysis revealed specific interactions between these compounds and key residues, indicating their stability within the binding site. ADMET analysis confirmed that the selected compounds possessed desirable drug-like properties. Furthermore, molecular dynamics simulations were performed, demonstrating the stability of the ligand-protein complexes over a 100 ns duration. These findings underscore the potential of the selected natural compounds as agents targeting KEAP1 and provide valuable insights for future experimental studies.

Phellodendronoside A Exerts Anticancer Effects Depending on Inducing Apoptosis Through ROS/Nrf2/Notch Pathway and Modulating Metabolite Profiles in Hepatocellular Carcinoma

Purpose

To reveal the potential mechanism of PDA on hepatocellular carcinoma SMMC-7721 cells in vitro.

Methods

The cytotoxic activity, colony formation, cell cycle distribution, apoptosis and their associated protein analysis, intracellular reactive oxygen species (ROS) and Ca²⁺ levels, proteins in Nrf2 and Ntoch pathways and metabolite profiles of PDA against hepatocellular carcinoma were investigated.

Results

PDA with cytotoxic activity inhibited cell proliferation and migration, increased intracellular ROS, Ca²⁺ levels and MCUR1 protein expression in a dose-dependent manner, caused cell cycle arrest in the S phase and induced apoptosis via adjusting the levels of Bcl-2, Bax, and Caspase 3 proteins, and inhibited the activation of Notch1, Jagged, Hes1, Nrf2 and HO-1 proteins. Metabonomics data showed that PDA significantly regulated 144 metabolite levels tend to be normal level, especially carnitine derivatives, bile acid metabolites associated with hepatocellular carcinoma, and mainly enriched in ABC transporter, arginine and proline metabolism, primary bile acid biosynthesis, Notch signaling pathway, etc, and proved that PDA markedly adjusted Notch signaling pathway.

Conclusion

PDA exhibited the proliferation inhibition of SMMC-7721 cells by inhibiting ROS/Nrf2/Notch signaling pathway and significantly affected the metabolic profile, suggesting PDA could be a potential therapeutic agent for patients with hepatocellular carcinoma.

Glioblastoma Microenvironment and Invasiveness: New Insights and Therapeutic Targets

Glioblastoma (GBM) is the most common and malignant primary brain cancer in adults. Without treatment the mean patient survival is approximately 6 months, which can be extended to 15 months with the use of multimodal therapies. The low effectiveness of GBM therapies is mainly due to the tumor infiltration into the healthy brain tissue, which depends on GBM cells' interaction with the tumor microenvironment (TME). The interaction of GBM cells with the TME involves cellular components such as stem-like cells, glia, endothelial cells, and non-cellular components such as the extracellular matrix, enhanced hypoxia, and soluble factors such as adenosine, which promote GBM's invasiveness. However, here we highlight the role of 3D patient-derived glioblastoma organoids cultures as a new platform for study of the modeling of TME and invasiveness. In this review, the mechanisms involved in GBM-microenvironment interaction are described and discussed, proposing potential prognosis biomarkers and new therapeutic targets.

Novel Phthalic-Based Anticancer Tyrosine Kinase Inhibitors: Design, Synthesis and Biological Activity

In this work, fragments of isophthalic and terephthalic acids are proposed as a structural scaffold to develop potential inhibitors of protein kinases. Novel isophthalic and terephthalic acid derivatives were designed as type-2 protein kinase inhibitors, synthesized and subjected to physicochemical characterization. The screening of their cytotoxic actions against a panel of cell lines derived from different types of tumors (liver, renal, breast and lung carcinomas, as well as chronic myelogenous and promyelocytic leukemia) and normal human B lymphocyte, for the sake of comparison, was performed. Compound 5 showed the highest inhibitory activity against four cancer cell lines, K562, HL-60, MCF-7 and HepG2 (IC50 = 3.42, 7.04, 4.91 and 8.84 µM, respectively). Isophthalic derivative 9 revealed a high potency against EGFR and HER2, at the levels of 90% and 64%, respectively, being comparable to lapatinib at 10 µM. In general, tumor cell cultures were more sensitive to isophthalic acid derivatives than to terephthalic acid ones. In cell cycle studies, isophthalic analogue 5 showed a pronounced dose-dependent effect, and with the increase in its concentration up to 10.0 µM, the number of living cells decreased to 38.66%, while necrosis reached 16.38%. The considered isophthalic compounds had a similar docking performance to that of sorafenib against the VEGFR-2 (PDB id: 4asd, 3wze). The correct binding of compounds 11 and 14 with VEGFR-2 was validated using MD simulations and MM-GPSA calculations.

Therapy-induced shaping of the glioblastoma microenvironment: Macrophages at play

The intricate cross-talks between tumor cells and their microenvironment play a key role in cancer progression and resistance to treatment. In recent years, targeting pro-tumorigenic components of the tumor microenvironment (TME) has emerged as a tantalizing strategy to improve the efficacy of standard-of-care (SOC) treatments, particularly for hard-to-treat cancers such as glioblastoma. In this review, we explore how the distinct microenvironmental niches characteristic of the glioblastoma TME shape response to therapy. In particular, we delve into the interplay between tumor-associated macrophages (TAM) and glioblastoma cells within angiogenic and hypoxic niches, and interrogate their dynamic co-evolution upon SOC therapies that fuels malignancy. Resolving the complexity of therapy-induced alterations in the glioblastoma TME and their impact on disease relapse is a stepping stone to identify targetable pro-tumorigenic pathways and TAM subsets, and may open the way to efficient combination therapies that will improve clinical outcomes.

Cytotoxic activity of l-lysine alpha-oxidase against leukemia cells

Cancer cells exhibit higher proliferation rates than normal cells, and as a consequence, a higher nutritional demand for metabolites such as amino acids. Such cells demonstrate high expression of amino acid transporters and are significantly dependent on the external uptake of amino acids. Moreover, some types of cancer cells exhibit oncogenic mutations that render them auxotrophic to certain amino acids. This metabolic difference between tumor and normal cells has been explored for developing anticancer drugs. Enzymes capable of depleting certain amino acids in the bloodstream can be employed to inhibit the proliferation of cancer cells and promote cell death. Certain microbial enzymes, such as l-asparaginase and l-amino acid oxidases, have been studied for this purpose. In this paper, we discuss the role of l-asparaginase, the only enzyme currently used as a chemotherapeutic agent. We also review the studies on a new potential antineoplastic agent, l-lysine α-oxidase, an enzyme of l-amino acid oxidase family.

Epigenetic Therapeutics Targeting NRF2/KEAP1 Signaling in Cancer Oxidative Stress

The transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) and its negative regulator kelch-like ECH-associated protein 1 (KEAP1) regulate various genes involved in redox homeostasis, which protects cells from stress conditions such as reactive oxygen species and therefore exerts beneficial effects on suppression of carcinogenesis. In addition to their pivotal role in cellular physiology, accumulating innovative studies indicated that NRF2/KEAP1-governed pathways may conversely be oncogenic and cause therapy resistance, which was profoundly modulated by epigenetic mechanism. Therefore, targeting epigenetic regulation in NRF2/KEAP1 signaling is a potential strategy for cancer treatment. In this paper, the current knowledge on the role of NRF2/KEAP1 signaling in cancer oxidative stress is presented, with a focus on how epigenetic modifications might influence cancer initiation and progression. Furthermore, the prospect that epigenetic changes may be used as therapeutic targets for tumor treatment is also investigated.

Cisplatin Chemotherapy and Cochlear Damage: Otoprotective and Chemosensitization Properties of Polyphenols

Significance: Cisplatin is an important component of treatment regimens for different cancers. Notwithstanding that therapeutic success often results from partial efficacy or stabilizing the disease, chemotherapy failure is driven by resistance to drug treatment and occurrence of side effects, such as progressive irreversible ototoxicity. Cisplatin's side effects, including ototoxicity, are often dose limiting. Recent Advances: Cisplatin ototoxicity results from several mechanisms, including redox imbalance caused by reactive oxygen species production and lipid peroxidation, activation of inflammation, and p53 and its downstream pathways that culminate in apoptosis. Considerable efforts in research have targeted development of molecular interventions that can be concurrently administered with cisplatin or other chemotherapies to reduce side effect toxicities while preserving or enhancing the antineoplastic effects. Evidence from studies has indicated some polyphenols, such as curcumin, can help to regulate redox signaling and inflammatory effects. Furthermore, polyphenols can exert opposing effects in different types of tissues, that is, normal cells undergoing stressful conditions versus cancer cells. Critical Issues: This review article summarizes evidence of curcumin antioxidant effect against cisplatin-induced ototoxicity that is converted to a pro-oxidant activity in cisplatin-treated cancer cells, thus providing an ideal chemosensitivity combined with otoprotection. Polyphenols can modulate the adaptive responses to stress in the cisplatin-exposed cochlea. These adaptive effects can result from the interaction/cross talk between the cell's defenses, inflammatory molecules, and the key signaling molecules of signal transducers and activators of transcription 3 (STAT-3), nuclear factor κ-B (NF-κB), p53, and nuclear factor erythroid 2-related factor 2 (Nrf-2). Future Directions: We provide molecular evidence for alternative strategies for chemotherapy with cisplatin addressing the otoprotection and chemosensitization properties of polyphenols. Antioxid. Redox Signal. 36, 1229-1245.

Comprehensive Analysis of the PRDXs Family in Head and Neck Squamous Cell Carcinoma

The peroxidase family of peroxiredoxins (PRDXs) plays a vital role in maintaining the intracellular balance of ROS. However, their function in head and neck squamous cell carcinoma (HNSCC) has not been investigated. We therefore explored the value of PRDXs in HNSCC. We found that the expression of PRDX1, PRDX4, and PRDX5 in HNSCC increased while the expression of PRDX2 decreased. Moreover, the high expression of PRDX4/5/6 indicated a poor prognosis. Lower expression of PRDX1/5 was linked to more immune cell infiltration, higher expression of immune-related molecules and a more likely response to anti-PD-1 treatment. Moreover, PRDX5 knockdown inhibited HNSCC cell proliferation, invasion and metastasis and it might promote apoptosis through its antioxidant property. Taken together, our study highlights the potential role of PRDXs in HNSCC. The function of PRDX5 in the development of HNSCC and the formation of the immune microenvironment makes it a promising potential therapeutic target.

Chemotherapy Resistance: Role of Mitochondrial and Autophagic Components

Simple Summary

Chemotherapy resistance is a common occurrence during cancer treatment that cancer researchers are attempting to understand and overcome. Mitochondria are a crucial intracellular signaling core that are becoming important determinants of numerous aspects of cancer genesis and progression, such as metabolic reprogramming, metastatic capability, and chemotherapeutic resistance. Mitophagy, or selective autophagy of mitochondria, can influence both the efficacy of tumor chemotherapy and the degree of drug resistance. Regardless of the fact that mitochondria are well-known for coordinating ATP synthesis from cellular respiration in cellular bioenergetics, little is known its mitophagy regulation in chemoresistance. Recent advancements in mitochondrial research, mitophagy regulatory mechanisms, and their implications for our understanding of chemotherapy resistance are discussed in this review.

Abstract

Cancer chemotherapy resistance is one of the most critical obstacles in cancer therapy. One of the well-known mechanisms of chemotherapy resistance is the change in the mitochondrial death pathways which occur when cells are under stressful situations, such as chemotherapy. Mitophagy, or mitochondrial selective autophagy, is critical for cell quality control because it can efficiently break down, remove, and recycle defective or damaged mitochondria. As cancer cells use mitophagy to rapidly sweep away damaged mitochondria in order to mediate their own drug resistance, it influences the efficacy of tumor chemotherapy as well as the degree of drug resistance. Yet despite the importance of mitochondria and mitophagy in chemotherapy resistance, little is known about the precise mechanisms involved. As a consequence, identifying potential therapeutic targets by analyzing the signal pathways that govern mitophagy has become a vital research goal. In this paper, we review recent advances in mitochondrial research, mitophagy control mechanisms, and their implications for our understanding of chemotherapy resistance.

A portable NIR fluorimeter directly quantifies singlet oxygen generated by nanostructures for Photodynamic Therapy

This paper reports on the setting up and calibration of a portable NIR fluorimeter specifically developed for quantitative direct detection of the highly reactive singlet oxygen (¹O₂) chemical specie, of great importance in Photodynamic therapies. This quantification relies on the measurement of fluorescence emission of ¹O₂, which is peaked in the near-infrared (NIR) at λ=1270nm. In recent years, several nanostructures capable of generating reactive oxygen species (ROS) when activated by penetrating radiation (X-rays, NIR light) have been developed to apply Photodynamic Therapy (PDT) to tumours in deep tissue, where visible light cannot penetrate. A bottleneck in the characterization of these nanostructures is the lack of a fast and reliable technique to quantitatively assess their performances in generating ROS, and in particular ¹O₂. For instance, the widely used PDT "Singlet Oxygen Sensor Green" kit suffers from self-activation under X-ray irradiation. To solve this difficulty, we propose here direct detection of ¹O₂ by spectroscopic means, using an apparatus developed by us around a recent thermoelectrically-cooled InGaAs single photon avalanche photodiode (SPAD). The SPAD is coupled to a custom-made integrating sphere designed for use under irradiation with high-energy X-ray beams from clinical Radiotherapy sources. We determine the detection threshold for our apparatus, which turns to be ∼9·10⁸¹O₂ in realistic experimental condition and for measurements extending to 1 min of integration. After calibrations on standard photosensitizers, we demonstrate the potentiality of this instrument characterizing some photosensitizing nanostructures developed by us.

cAMP-Mediated Autophagy Promotes Cell Survival via ROS-Induced Activation of PARP1: Implications for Treatment of Acute Lymphoblastic Leukemia

DNA-damaging therapy is the basis for treatment of most cancers, including B-cell precursor acute lymphoblastic leukemia (BCP-ALL, hereafter ALL). We have previously shown that cAMP-activating factors present in the bone marrow render ALL cells less sensitive to DNA damage-induced apoptosis, by enhancing autophagy and suppressing p53. To sensitize ALL cells to DNA-damaging therapy, we have searched for novel targets that may counteract the effects induced by cAMP signaling. In the current study, we have identified PARP1 as a potential target. We show that the PARP1 inhibitors olaparib or PJ34 inhibit cAMP-mediated autophagy and thereby potentiate the DNA-damaging treatment. Furthermore, we reveal that cAMP-mediated PARP1 activation is preceded by induction of reactive oxygen species (ROS) and results in depletion of nicotinamide adenine dinucleotide (NAD), both of which are autophagy-promoting events. Accordingly, we demonstrate that scavenging ROS by N-acetylcysteine and repleting NAD independently reduce DNA damage-induced autophagy. In addition, olaparib augmented the effect of DNA-damaging treatment in a human xenograft model of ALL in NOD-scidIL2Rgamma^null mice. On the basis of the current findings, we suggest that PARP1 inhibitors may enhance the efficiency of conventional genotoxic therapies and thereby provide a novel treatment strategy for pediatric patients with ALL. IMPLICATIONS: PARP1 inhibitors augment the DNA damage-induced killing of ALL cells by limiting the opposing effects of cAMP-mediated autophagy, which involves ROS-induced PARP1 activation and depletion of cellular NAD levels.

Redox-sensitive cyclophilin A elicits chemoresistance through realigning cellular oxidative status in colorectal cancer

Cancer cells utilize rapidly elevated cellular antioxidant programs to accommodate chemotherapy-induced oxidative stress; however, the underlying mechanism remains largely unexplored. Here we screen redox-sensitive effectors as potential therapeutic targets for colorectal cancer (CRC) treatment and find that cyclophilin A (CypA) is a compelling candidate. Our results show that CypA forms an intramolecular disulfide bond between Cys115 and Cys161 upon oxidative stress and the oxidized cysteines in CypA are recycled to a reduced state by peroxiredoxin-2 (PRDX2). Furthermore, CypA reduces cellular reactive oxygen species levels and increases CRC cell survival under insults of H₂O₂ and chemotherapeutics through a CypA-PRDX2-mediated antioxidant apparatus. Notably, CypA is upregulated in chemoresistant CRC samples, which predicts poor prognosis. Moreover, targeting CypA by cyclosporine A exhibits promising efficacy against chemoresistant CRC when combined with chemotherapeutics. Collectively, our findings highlight CypA as a component of cellular noncanonical antioxidant defense and as a potential druggable therapeutic target to ameliorate CRC chemoresistance.

Peroxiredoxin 6 Plays Essential Role in Mediating Fertilization and Early Embryonic Development in Rabbit Oviduct

The oviduct is a site for early reproductive events including gamete maturation, fertilization, and early embryo development. Secretory cells lining the oviduct lumen synthesize and secrete proteins that interact with gametes and developing embryos. Although previous studies have identified some of the secretory proteins in the oviduct, however, knowledge and their precise specific functions in the oviduct are poorly understood. In this study, by using proteomic approach, we identified a secretory protein, Peroxiredoxin 6 (PRDX6), and evaluated its role in mediating early pregnancy events, fertilization, and embryo development in rabbit oviduct. The expression of PRDX6 was significantly higher in ampulla and isthmus sections of the oviduct in mated animal groups compared to non-mated controls. Furthermore, significant reduction in number of embryos recovered from PRDX6 siRNA-transfected oviductal horn was observed compared to the control contralateral horn. Moreover, in animals receiving PRDX6 siRNA in their oviductal horn, the number of implanted blastocysts was significantly less in the uterus as observed on day 9 post-coital (p.c.). Further, during embryo-rabbit oviduct epithelial cell (ROEC) co-culture, siRNA-mediated PRDX6 silencing attenuated the early embryonic development. Mechanistically, increased levels of ROS and expression of oxidative stress- and inflammation-related proteins were found in PRDX6 siRNA-treated ROEC cells as compared to control cells, implicating that ablation of PRDX6 in the oviduct creates a stress-induced micro-environment detrimental to early embryonic development in oviduct. Taken together, our data suggest that PRDX6 maintains an optimal micro-environment conducive to successful embryo development and can be considered as a candidate to evaluate its therapeutic potential in IVF strategies.

The Effect of p53-R249S on the Suppression of Hepatocellular Carcinoma Cells Survival Induced by Podophyllum Derivatives

BACKGROUND

Hepatocellular Carcinoma (HCC), the second leading cause of cancer-related mortality with over half a million new cases diagnosed annually in the world, accounts for nearly 70% of cancer deaths in parts of Asia and Africa. Podophyllum, one of the important members of the lignane class of natural products derived from plants in Podophyllum peltatum L., has been shown to suppress tumor growth in various cancers. However, the effects of Podophyllum compounds on HCC and the mechanisms for its tumor-suppressive function remain unknown.

METHODS

A molecular docking study was employed to the analysis of the interaction between compounds and their targeted proteins. Cell proliferation was measured by MTT assay. Western blot analysis was used to evaluate protein expression. qRT-PCR was performed to assess RNA expression.

RESULTS

Molecular docking analysis was consistent with the beneficial effect of fluorine atom substituent in the 3-position of 2-aminopyridine in our previous study. Also, P-3F and D-3F displayed the most potent cytotoxicities against PLC/PRF/5 with p53-R249S and weakest inhibition of L02 (normal liver cell) growth. However, these derivatives had no effect on the suppression of HepG2 (wild-type p53) and Hep3B (p53-null) proliferation significantly. Further study showed that both compounds increase γ-H2AX expression in PLC/PRF/5 cell, along with repression of the c-Myc activation, purportedly by induction of p53 level and transcriptional activation.

CONCLUSION

The results suggested that podophyllum derivatives containing fluorine atom in the 3-position of 2- aminopyridine could inhibit the growth of HCC harboring p53-R249S by restoring the activity of p53 with decreasing the level of c-Myc.

Nitrofurazone repurposing towards design and synthesis of novel apoptotic-dependent anticancer and antimicrobial agents: Biological evaluation, kinetic studies and molecular modeling

Drug repurposing has gained much attention as a cost-effective strategy that plays an exquisite role in identifying undescribed biological activities in clinical drugs. In the present work, we report the repurposing of the antibacterial drug nitrofurazone (NFZ) as a potential anticancer agent against CaCo-2, MDA-MB 231 and HepG-2 cancer cell lines. Novel series of nitrofurazone analogs were then designed considering the important pharmacologic features present in NFZ. Synthesis and biological evaluation of the target compounds revealed their promising anticancer activities endowed with antimicrobial potential and possessing better lipophilicity than NFZ. Compound 7, exclusively, inhibited the growth of all tested cancer cells more potently than NFZ with the least cytotoxicity against normal cells, displaying anti Gram-positive bacterial activities and antifungal potential. Analysis of the stereo-electronic properties of compound 7 via investigating the energies of HOMO, LUMO, HOMO-LUMO energy gap and MEP maps demonstrated its high reactivity and the expected molecular mechanism of action through reduction of the 5-nitrofuryl moiety. Data of the bioactivity studies indicated that the potent anticancer activity of 7 is mainly through increasing intracellular ROS levels and induction of apoptosis via significantly down-regulating the expression of Bcl-2 while up-regulating BAX, p53 and caspase 3 expression levels. Compound 7 potently inhibited the cellular expression levels of antioxidant enzymes GPx1 and GR compared to NFZ. Antioxidant enzymes kinetic studies and blind molecular docking simulations disclosed the mechanistic and structural aspects of the interaction between 7 and both GR and GPx1. Thus, the successful discovery of 7 as a potential dual anticancer-antimicrobial nitrofurazone analog might validate the applicability of drug repurposing strategy in unravelling the unrecognized bioactivity of the present conventional drugs, besides furnishing the way towards more optimization and development studies.

Moonlighting Metabolic Enzymes in Cancer: New Perspectives on the Redox Code

Significance: Metabolic reprogramming is considered to be a critical adaptive biological event that fulfills the energy and biomass demands for cancer cells. One hallmark of metabolic reprogramming is reduced oxidative phosphorylation and enhanced aerobic glycolysis. Such metabolic abnormalities contribute to the accumulation of reactive oxygen species (ROS), the by-products of metabolic pathways. Emerging evidence suggests that ROS can in turn directly or indirectly affect the expression, activity, or subcellular localization of metabolic enzymes, contributing to the moonlighting functions outside of their primary roles. This review summarizes the multifunctions of metabolic enzymes and the involved redox modification patterns, which further reveal the inherent connection between metabolism and cellular redox state. Recent Advances: These noncanonical functions of metabolic enzymes involve the regulation of epigenetic modifications, gene transcription, post-translational modification, cellular antioxidant capacity, and many other fundamental cellular events. The multifunctional properties of metabolic enzymes further expand the metabolic dependencies of cancer cells, and confer cancer cells with a means of adapting to diverse environmental stimuli. Critical Issues: Deciphering the redox-manipulated mechanisms with specific emphasis on the moonlighting function of metabolic enzymes is important for clarifying the pertinence between metabolism and redox processes. Future Directions: Investigation of the redox-regulated moonlighting functions of metabolic enzymes will shed new lights into the mechanism by which metabolic enzymes gain noncanonical functions, and yield new insights into the development of novel therapeutic strategies for cancer treatment by targeting metabolic-redox abnormalities. Antioxid. Redox Signal. 34, 979-1003.

Metallothionein MT1M Suppresses Carcinogenesis of Esophageal Carcinoma Cells through Inhibition of the Epithelial-Mesenchymal Transition and the SOD1/PI3K Axis

Metallothionein (MT1M) belongs to a family of cysteine-rich cytosolic protein and has been reported to be a tumor suppressor gene in multiple cancers. However, its role in esophageal carcinoma carcinogenesis remains unclear. In this study, MT1M expression was correlated with tumor type, stage, drinking and smoking history, as well as patient survival. We also studied the regulation and biological function of MT1M in esophageal squamous cell carcinoma (ESCC). We have found that MT1M is significantly downregulated in ESCC tissues compared with adjacent non-cancer tissues. Furthermore, restoration of expression by treatment with the demethylation agent A + T showed that MT1M downregulation might be closely related to hypermethylation in its promoter region. Over-expression of MT1M in ESCC cells significantly altered cell morphology, induced apoptosis, and reduced colony formation, cell viability, migration and epithelial-mesenchymal transition. Moreover, based on reactive oxygen species (ROS) levels, a superoxide dismutase 1 (SOD1) activity assay and protein analysis, we verified that the tumor-suppressive function of MT1M was at least partially caused by its upregulation of ROS levels, downregulation of SOD1 activity and phosphorylation of the SOD1 downstream pathway PI3K/AKT. In conclusion, our results demonstrated that MT1M was a novel tumor-suppressor in ESCC and may be disrupted by promoter CpG methylation during esophageal carcinogenesis.

A Functional Food Inhibits Azoxymethane/Dextran Sulfate Sodium-Induced Inflammatory Colorectal Cancer in Mice

Purpose

This study aimed to investigate the potential antitumor effects and mechanisms underlying the action of a functional food containing 55 different natural food ingredients.

Materials and Methods

Azoxymethane/dextran sulfate sodium was used to establish a mouse model of colorectal cancer. Serum levels of cytokines, diamine oxidase, D-lactate, and endotoxin were measured using enzyme-linked immunosorbent assays. Immune cells from the mouse spleen and tumor tissue were analyzed by flow cytometry. Finally, 16S rRNA gene sequencing and liquid chromatography–mass spectrometry were used to study the fecal microbiota and microbial metabolites, respectively.

Results

The tumor growth was significantly lower in the FFD group than in the model group. The intestinal barrier function, fat mass, and lean body mass were significantly improved in the FFD group compared with the model group. The levels of interleukin-6 and tumor necrosis factor-α were significantly lower in the FFD group, while the proportions of total T cells, CD3⁺CD4⁺, CD3⁺CD8⁺, and interferon-γ-producing CD4⁺ T cells were significantly higher. Analysis of the diversity of the gut microbiota identified 60 differential bacterial genera between the FFD and model groups, with lower abundances of Desulfovibrio and unclassified Ruminococcaceae and higher abundances of the beneficial bacterial genera Bacteroides and Parasutterella in the FFD group. The fecal metabolite analysis revealed 635 differential metabolites between the FFD and model groups, with lower levels of deuteroporphyrin IX and citrulline and higher levels of acetic acid and ascorbic acid in the FFD group.

Conclusion

Our results demonstrate that the functional food tested can inhibit the growth of colorectal cancer. This effect may be due to the ability of this food to improve nutritional status, enhance intestinal barrier function, and regulate the tumor microenvironment via changes in the intestinal microbiota and metabolites.

The Role of Hypoxia in Glioblastoma Radiotherapy Resistance

Glioblastoma (GB) (grade IV astrocytoma) is the most malignant type of primary brain tumor with a 16 months median survival time following diagnosis. Despite increasing attention regarding the development of targeted therapies for GB that resulted in around 450 clinical trials currently undergoing, radiotherapy still remains the most clinically effective treatment for these patients. Nevertheless, radiotherapy resistance (radioresistance) is commonly observed in GB patients leading to tumor recurrence and eventually patient death. It is therefore essential to unravel the molecular mechanisms underpinning GB cell radioresistance in order to develop novel strategies and combinational therapies focused on enhancing tumor cell sensitivity to radiotherapy. In this review, we present a comprehensive examination of the current literature regarding the role of hypoxia (O2 partial pressure less than 10 mmHg), a main GB microenvironmental factor, in radioresistance with the ultimate goal of identifying potential molecular markers and therapeutic targets to overcome this issue in the future.

Molecules and Mechanisms to Overcome Oxidative Stress Inducing Cardiovascular Disease in Cancer Patients

Reactive oxygen species (ROS) are molecules involved in signal transduction pathways with both beneficial and detrimental effects on human cells. ROS are generated by many cellular processes including mitochondrial respiration, metabolism and enzymatic activities. In physiological conditions, ROS levels are well-balanced by antioxidative detoxification systems. In contrast, in pathological conditions such as cardiovascular, neurological and cancer diseases, ROS production exceeds the antioxidative detoxification capacity of cells, leading to cellular damages and death. In this review, we will first describe the biology and mechanisms of ROS mediated oxidative stress in cardiovascular disease. Second, we will review the role of oxidative stress mediated by oncological treatments in inducing cardiovascular disease. Lastly, we will discuss the strategies that potentially counteract the oxidative stress in order to fight the onset and progression of cardiovascular disease, including that induced by oncological treatments.

Hyaluronic Acid Improves Hydrogen Peroxide Modulatory Effects on Calcium Channel and Sodium-Potassium Pump in 4T1 Breast Cancer Cell Line

Maintaining homeostasis of ion concentrations is critical in cancer cells. Under hypoxia, the levels of channels and pumps in cancer cells are more active than normal cells suggesting ion channels as a suitable therapeutic target. One of the contemporary ways for cancer therapy is oxidative stress. However, the effective concentration of oxidative stress on tumor cells has been reported to be toxic for normal cells as well. In this study, we benefited from the modifying effects of hyaluronic acid (HA) on H2O2, as a free radical source, to make a gradual release of oxidative stress on cancer cells while preventing/decreasing damage to normal cells under normoxia and hypoxic conditions. To do so, we initially investigated the optimal concentration of HA antioxidant capacity by the DPPH test. In the next step, we found optimum H2O2 dose by treating the 4T1 breast cancer cell line with increasing concentrations (0, 10, 20, 50,100, 200, 500, and 1000 μM) of H2O2 alone or H2O2 + HA (83%) for 24 hrs. The calcium channel and the sodium-potassium pumps were then evaluated by measuring the levels of calcium, sodium, and potassium ions using an atomic absorption flame spectrophotometer. The results revealed that treatment with H2O2 or H2O2+ HA led to an intracellular increase of calcium, sodium, and potassium in the normoxic and hypoxic circumstances in a dose-dependent manner. It is noteworthy that H2O2 + HA treatment had more favorable and controllable effects compared with H2O2 alone. Moreover, HA optimizes the antitumor effect of oxidative stress exerted by H2O2 making H2O2 + HA suitable for clinical use in cancer treatment along with chemotherapy.

Reactive oxygen species in immune cells: A new antitumor target

Immune cells have the potential to control the growth of tumor. However, this effect could be offset by immunosuppression associated with an increased production of reactive oxygen species. Multiple studies indicate that the antitumor effect of immune cells is correlated with their antioxidant capacity. This review discusses the role of reactive oxygen species in the tumor microenvironment by describing their distinct effects on different immune cells, including myeloid-derived suppressor cells, regulatory T cells, tumor-associated macrophages, cytotoxic T lymphocytes, natural killer cells, and dendritic cells. In the end, we conclude with the prospect of treatment for cancer by targeting antioxidant defense in immune cells.

Emerging role of NRF2 in ROS-mediated tumor chemoresistance

Chemoresistance is a central cause for the tumor management failure. Cancer cells disrupt the redox homeostasis through reactive oxygen species (ROS) regulatory mechanisms, leading to tumor progression and chemoresistance. The transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) is a master regulator of neutralizing cellular ROS and restoring redox balance. Understanding the role of NRF2 in ROS-mediated chemoresistance can be helpful in the development of chemotherapy strategies with better efficiency. In this review, we sum up the roles of ROS in the development of chemoresistance to classical chemotherapy agents including cisplatin, 5-fluorouracil, gemcitabine, oxaliplatin, paclitaxel, and doxorubicin, and how to overcome ROS-mediated tumor chemoresistance by targeting NRF2. Finally, we propose that targeting NRF2 might be a promising strategy to resist ROS-driven chemoresistance and acquire better efficacy in cancer treatment.

African Vegetables (Clerodendrum volibile Leaf and Irvingia gabonensis Seed Extracts) Effectively Mitigate Trastuzumab-Induced Cardiotoxicity in Wistar Rats

Trastuzumab (TZM) is a humanized monoclonal antibody that has been approved for the clinical management of HER2-positive metastatic breast and gastric cancers but its use is limited by its cumulative dose and off-target cardiotoxicity. Unfortunately, till date, there is no approved antidote to this off-target toxicity. Therefore, an acute study was designed at investigating the protective potential and mechanism(s) of CVE and IGE in TZM-induced cardiotoxicity utilizing cardiac enzyme and oxidative stress markers and histopathological endpoints. 400 mg/kg/day CVE and IGE dissolved in 5% DMSO in sterile water were investigated in Wistar rats injected with 2.25 mg/kg/day/i.p. route of TZM for 7 days, using serum cTnI and LDH, complete lipid profile, cardiac tissue oxidative stress markers assays, and histopathological examination of TZM-intoxicated heart tissue. Results showed that 400 mg/kg/day CVE and IGE profoundly attenuated increases in the serum cTnI and LDH levels but caused no significant alterations in the serum lipids and weight gain pattern in the treated rats. CVE and IGE profoundly attenuated alterations in the cardiac tissue oxidative stress markers' activities while improving TZM-associated cardiac histological lesions. These results suggest that CVE and IGE could be mediating its cardioprotection via antioxidant, free radical scavenging, and antithrombotic mechanisms, thus, highlighting the therapeutic potentials of CVE and IGE in the management of TZM-mediated cardiotoxicity.

Investigating Glioblastoma Response to Hypoxia

Glioblastoma (GB) is the most common and deadly type of primary malignant brain tumor with an average patient survival of only 15–17 months. GBs typically have hypoxic regions associated with aggressiveness and chemoresistance. Using patient derived GB cells, we characterized how GB responds to hypoxia. We noted a hypoxia-dependent glycolytic switch characterized by the up-regulation of HK2, PFKFB3, PFKFB4, LDHA, PDK1, SLC2A1/GLUT-1, CA9/CAIX, and SLC16A3/MCT-4. Moreover, many proangiogenic genes and proteins, including VEGFA, VEGFC, VEGFD, PGF/PlGF, ADM, ANGPTL4, and SERPINE1/PAI-1 were up-regulated during hypoxia. We detected the hypoxic induction of invasion proteins, including the plasminogen receptor, S100A10, and the urokinase plasminogen activator receptor, uPAR. Furthermore, we observed a hypoxia-dependent up-regulation of the autophagy genes, BNIP-3 and DDIT4 and of the multi-functional protein, NDRG1 associated with GB chemoresistance; and down-regulation of EGR1 and TFRC (Graphical abstract). Analysis of GB patient cohorts’ revealed differential expression of these genes in patient samples (except SLC16A3) compared to non-neoplastic brain tissue. High expression of SLC2A1, LDHA, PDK1, PFKFB4, HK2, VEGFA, SERPINE1, TFRC, and ADM was associated with significantly lower overall survival. Together these data provide important information regarding GB response to hypoxia which could support the development of more effective treatments for GB patients.

Targeting p53 for the treatment of cancer

Dysfunction of the TP53 (p53) gene occurs in most if not all human malignancies. Two principal mechanisms are responsible for this dysfunction; mutation and downregulation of wild-type p53 mediated by MDM2/MDM4. Because of its almost universal inactivation in malignancy, p53 is a highly attractive target for the development of new anticancer drugs. Although multiple strategies have been investigated for targeting dysfunctional p53 for cancer treatment, only 2 of these have so far yielded compounds for testing in clinical trials. These strategies include the identification of compounds for reactivating the mutant form of p53 back to its wild-type form and compounds for inhibiting the interaction between wild-type p53 and MDM2/MDM4. Currently, multiple p53-MDM2/MDM4 antagonists are undergoing clinical trials, the most advanced being idasanutlin which is currently undergoing testing in a phase III clinical trial in patients with relapsed or refractory acute myeloid leukemia. Two mutant p53-reactivating compounds have progressed to clinical trials, i.e., APR-246 and COTI-2. Although promising data has emerged from the testing of both MDM2/MDM4 inhibitors and mutant p53 reactivating compounds in preclinical models, it is still unclear if these agents have clinical efficacy. However, should any of the compounds currently being evaluated in clinical trials be shown to have efficacy, it is likely to usher in a new era in cancer treatment, especially as p53 dysfunction is so prevalent in human cancers.

In vitro and in vivo studies of cancer cell behavior under nutrient deprivation

Cancer cells are confronted with nutrient deprivation because of high proliferation rate, especially at the early stage of their development. There is a frequent assumption that nutrient deprivation decreases the basal activity of cancer cells. Contrarily, there are recent evidence suggesting that cancer cells are able to modulate signaling pathways to adapt with new condition and continue their survival. This property of cancer cells is believed to be one of the prerequisites for cancer progression and chemoresistance. Moreover, recent experiments show that serum starvation in vitro as a mimic situation of nutrient deprivation in vivo triggers different signaling pathways leading to changes in cancer cell behavior, which may interfere with experimental results. Considering these facts, a better understanding of the effect of nutrient deprivation on cancer cell behavior will help us to give more accurate conclusions regarding results of in vitro studies and also to develop new strategies to treat different cancers in vivo.

Modifying the Tumour Microenvironment: Challenges and Future Perspectives for Anticancer Plasma Treatments

Tumours are complex systems formed by cellular (malignant, immune, and endothelial cells, fibroblasts) and acellular components (extracellular matrix (ECM) constituents and secreted factors). A close interplay between these factors, collectively called the tumour microenvironment, is required to respond appropriately to external cues and to determine the treatment outcome. Cold plasma (here referred as ‘plasma’) is an emerging anticancer technology that generates a unique cocktail of reactive oxygen and nitrogen species to eliminate cancerous cells via multiple mechanisms of action. While plasma is currently regarded as a local therapy, it can also modulate the mechanisms of cell-to-cell and cell-to-ECM communication, which could facilitate the propagation of its effect in tissue and distant sites. However, it is still largely unknown how the physical interactions occurring between cells and/or the ECM in the tumour microenvironment affect the plasma therapy outcome. In this review, we discuss the effect of plasma on cell-to-cell and cell-to-ECM communication in the context of the tumour microenvironment and suggest new avenues of research to advance our knowledge in the field. Furthermore, we revise the relevant state-of-the-art in three-dimensional in vitro models that could be used to analyse cell-to-cell and cell-to-ECM communication and further strengthen our understanding of the effect of plasma in solid tumours.

N-Acetylcysteine Serves as Substrate of 3-Mercaptopyruvate Sulfurtransferase and Stimulates Sulfide Metabolism in Colon Cancer Cells

Hydrogen sulfide (H₂S) is an endogenously produced signaling molecule. The enzymes 3-mercaptopyruvate sulfurtransferase (MST), partly localized in mitochondria, and the inner mitochondrial membrane-associated sulfide:quinone oxidoreductase (SQR), besides being respectively involved in the synthesis and catabolism of H₂S, generate sulfane sulfur species such as persulfides and polysulfides, currently recognized as mediating some of the H₂S biological effects. Reprogramming of H₂S metabolism was reported to support cellular proliferation and energy metabolism in cancer cells. As oxidative stress is a cancer hallmark and N-acetylcysteine (NAC) was recently suggested to act as an antioxidant by increasing intracellular levels of sulfane sulfur species, here we evaluated the effect of prolonged exposure to NAC on the H₂S metabolism of SW480 colon cancer cells. Cells exposed to NAC for 24 h displayed increased expression and activity of MST and SQR. Furthermore, NAC was shown to: (i) persist at detectable levels inside the cells exposed to the drug for up to 24 h and (ii) sustain H₂S synthesis by human MST more effectively than cysteine, as shown working on the isolated recombinant enzyme. We conclude that prolonged exposure of colon cancer cells to NAC stimulates H₂S metabolism and that NAC can serve as a substrate for human MST.

Reduced chemotherapeutic sensitivity in high glucose condition: implication of antioxidant response

Resistance to chemotherapy represents a major obstacle to successful treatment. The generation of reactive oxygen species (ROS) has been directly linked to the cytotoxic effects of several antitumor agents, including Adriamycin (ADR), and modulation of the oxidative balance has been implicated in the development and/or regulation of resistance to chemotherapeutic drugs. We recently showed that high glucose (HG) markedly diminished the cancer cell death induced by anticancer agents such as ADR. In the present study we attempted to evaluate the mechanism that impaired the cytotoxic effect of ADR in HG. We found that, in colon cancer cells, HG attenuated ADR-induced ROS production that consequently diminished ADR-induced H2AX phosphorylation and micronuclei (MN) formation. Mechanistically, HG attenuation of ADR-induced ROS production correlated with increased antioxidant response promoted by NRF2 activity. Thus, pharmacologic inhibition of NRF2 pathway by brusatol re-established the ADR cytotoxic effect impaired by HG. Together, the data provide new insights into chemotherapeutic-resistance mechanisms in HG condition dictated by increased NRF2-induced antioxidant response and how they may be overcome in order to restore chemosensitivity and ADR-induced cell death.

Potential Use of Gluconate in Cancer Therapy

We have recently discovered that cancer cells take up extracellular citrate through plasma membrane citrate transporter (pmCiC) and advantageously use citrate for their metabolism. Citrate uptake can be blocked with gluconate and this results in decreased tumor growth and altered metabolic characteristics of tumor tissue. Interestingly, gluconate, considered to be physiologically neutral, is incidentally used in medicine as a cation carrier, but not as a therapeutically active substance. In this review we discuss the results of our recent research with available literature and suggest that gluconate may be useful in the treatment of cancer.

Annexin A2 Regulates AKT Upon H₂O₂-Dependent Signaling Activation in Cancer Cells

Hydrogen peroxide (H₂O₂) is a main second messenger in oncogenic signaling networks including the Ras and the growth factor receptor pathways. This is achieved predominantly through the oxidation of redox-sensitive cysteine (Cys) residues in proteins resulting in changes to their structure and function. We previously identified annexin A2 (ANXA2) as a redox regulatory protein that plays an important cellular role during oxidative stress and also promoting tumorigenesis. Here we investigated the role of ANXA2 in the regulation of H₂O₂-dependent signaling that drives tumor progression. We show that depletion of ANXA2 leads to the enhanced activation of AKT following either EGF/EGFR stimulation or oncogenic Ras transformation. The phosphatase and tensin homologue (PTEN) protein negatively regulates the PI3K/AKT pathway. We demonstrate that ANXA2 via its reactive Cys-8 residue, binds to PTEN and that the co-expression of PTEN and ANXA2, but not ANXA2 Cys-8-Ala mutant, inhibits AKT phosphorylation on Ser 473. These results indicate that ANXA2 is important for PTEN regulation within the PI3K/AKT signaling cascade. Furthermore, we also reveal that ANXA2 inversely regulates the expression of the peroxidase, peroxiredoxin 2, in a reactive oxygen species dependent manner.

The medicinal uses, toxicities and anti-inflammatory activity of Polyalthia species (Annonaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Polyalthia is one of the largest and notable genera in Annonaceae family. Polyalthia species have been widely used in folklore medicine for the treatment of rheumatic fever, gastrointestinal ulcer and generalized body pain. Numerous in vitro and in vivo studies on Polyalthia Species have also corroborated the significant anti-inflammatory potential of its extracts and secondary metabolites.

AIM OF THE STUDY

This review is an attempt to assess the anti-inflammatory activity of Polyalthia species by giving critical appraisal and establishing evidences of their traditional uses. Moreover this review will highlight the lead compounds for future drug development that can serve as a potential anti-inflammatory drug with comparative efficacy and minimum side effects.

MATERIALS AND METHODS

An extensive literature review, focusing the anti-inflammatory potential of Polyalthia species was conducted using the following databases:PubMed, ScienceDirect, SpringerLink, Ovid, Scopus and ProQuest, as well as the locally available books, journals and relevant documents. The reference lists of retrieved papers were also searched for additional studies.

RESULTS

The Polyalthia species have shown significant anti-inflammatory activity through various mechanism of action. The most significant anti-inflammatory mechanism includes the inhibition of nuclear factor kappa B (NF-κB), prostaglandins (PGs), pro-inflammatory cytokines, inducible nitric oxide synthase (iNOS) and reactive oxygen species (ROS). The data suggests that hydroxycleroda-3,13-dien-15,16-olide and 16-oxocleroda-3,13-dien-15-oic acid, quercetin, rutin, spinasterol, α-spinasterol, goniothalamin and (-)-5-hydroxygoniothalamin are the most potent anti-inflammatory compounds from Polyalthia species with comparable IC₅₀ with positive controls.

CONCLUSIONS

Numerous pharmacological studies have supported the use of Polyalthia species against pain, rheumatic fever, haemorrhages and inflammation in traditional medicine. Flavonoids, diterpenoids, sterols and styrylpyrones from genus Polyalthia are the most significant class of compounds with potent anti-inflammatory activity. Secondary metabolites from these classes should be brought into further research to fill the gaps of knowledge in pharmacokinetics, pharmacodynamics, bioavailability, and toxicity in order to convert the pre-clinical results into clinical data for further investigation.

The dietary flavonoid isoliquiritigenin is a potent cytotoxin for human neuroblastoma cells

Neuroblastoma (NB) is the most common extracranial solid tumor of early childhood; it accounts for approximately 8–10% of all childhood cancers and is the most common cancer in children in the first year of life. Patients in the high-risk group have a poor prognosis, with relapses being common and often refractory to drug treatment in those that survive. Moreover, the drug treatment itself can lead to a range of long-term sequelae. Therefore, there is a critical need to identify new therapeutics for NB. Isoliquiritigenin (ISLQ) is a naturally-occurring, dietary chalcone-type flavonoid with a range of biological effects that depend on the cell type and context. ISLQ has potential as an anticancer agent. Here we show that ISLQ has potent cytotoxic effects on SK-N-BE(2) and IMR-32 human NB cells, which carry amplification of the MYCN gene, the main prognostic marker of poor survival in NB. ISLQ was found to increase cellular reactive oxygen species (ROS). The cytotoxic effect of ISLQ was blocked by small molecule inhibitors of oxidative stress-induced cell death, and by the antioxidant N-acetyl-l-cysteine (NAC). Combined treatment of either SK-N-B-E(2) or IMR-32 cells with ISLQ and the anticancer agent cisplatin resulted in loss of cell viability that was greater than that induced by cisplatin alone. This study provides proof-of-principle that ISLQ is a potent cytotoxin for MYCN-amplified human NB cells. This is an important first step in rationalizing the further study of ISLQ as a potential adjunct therapy for high-risk NB.

MicroRNA-mediated redox regulation modulates therapy resistance in cancer cells: clinical perspectives

BACKGROUND

Chemotherapy and radiation therapy are the most common types of cancer therapy. The development of chemo/radio-resistance remains, however, a major obstacle. Altered redox balances are among of the main factors mediating therapy resistance. Therefore, redox regulatory strategies are urgently needed to overcome this problem. Recently, microRNAs have been found to act as major redox regulatory factors affecting chemo/radio-resistance. MicroRNAs play critical roles in regulating therapeutic resistance through the regulation of antioxidant enzymes, redox-sensitive signaling pathways, cancer stem cells, DNA repair mechanisms and autophagy.

CONCLUSIONS

Here, we summarize current knowledge on microRNA-mediated redox regulatory mechanisms underlying chemo/radio-resistance. This knowledge may form a basis for a better clinical management of cancer patients.

Oxidative stress: therapeutic approaches for cervical cancer treatment

Oxidative stress results from an imbalance between the generation and elimination of oxidant species. This condition may result in DNA, RNA and protein damage, leading to the accumulation of genetic alterations that can favor malignant transformation. Persistent infection with high-risk human papillomavirus types is associated with inflammatory responses and reactive oxygen species production. In this context, oxidative stress, chronic inflammation and high-risk human papillomavirus can act in a synergistic manner. To counteract the harmful effects of oxidant species, protective molecules, known as antioxidant defenses, are produced by cells to maintain redox homeostasis. In recent years, the use of natural antioxidants as therapeutic strategies for cancer treatment has attracted the attention of the scientific community. This review discusses specific molecules and mechanisms that can act against or together with oxidative stress, presenting alternatives for cervical cancer prevention and treatment.

NOS1 upregulates ABCG2 expression contributing to DDP chemoresistance in ovarian cancer cells

Nitric oxide synthase 1 (NOS1) has been reported to promote various cancer processes including chemoresistance. However, the role of NOS1 in chemoresistance has remained unclear. ATP-binding cassette, subfamily G, member 2 (ABCG2) has been identified as a molecular cause of multidrug resistance in a number of cancer types, including ovarian cancer. The present study observed that in ovarian cancer cells, the expression of ABCG2 was significantly upregulated in response to cis-diamminedichloroplatinum (cisplatin/DDP) treatment, in addition the expression of NOS1 exhibited an increasing trend. Additionally, the levels of NOS1 and ABCG2 in chemoresistant ovarian cancer profiles in Gene Expression Omnibus datasets (GSE26712 and GSE51373) were higher than in chemosensitive profiles. Furthermore, overexpression of NOS1 could upregulate ABCG2 expression, and expression of ABCG2 was inhibited by NOS1 selective inhibitor (N-PLA). In assays of cell survival, NOS1 appeared to increase the potential for DDP resistance, and this effect was reversed by addition of ABCG2 inhibitor (verapamil). The present study indicated that NOS1-induced chemoresistance was partly mediated by the upregulation of ABCG2 expression. This result suggests a link between the expression of NOS1 and the ABCG2-associated chemoresistance in ovarian cancer.

Stressing the (Epi)Genome: Dealing with Reactive Oxygen Species in Cancer

SIGNIFICANCE

Growing evidence indicates cross-talk between reactive oxygen species (ROS) and several key epigenetic processes such as DNA methylation, histone modifications, and miRNAs in normal physiology and human pathologies including cancer. This review focuses on how ROS-induced oxidative stress, metabolic intermediates, and epigenetic processes influence each other in various cancers. Recent Advances: ROS alter chromatin structure and metabolism that impact the epigenetic landscape in cancer cells. Several site-specific DNA methylation changes have been identified in different cancers and are discussed in the review. We also discuss the interplay of epigenetic enzymes and miRNAs in influencing malignant transformation in an ROS-dependent manner.

CRITICAL ISSUES

Loss of ROS-mediated signaling mostly by epigenetic regulation may promote tumorigenesis. In contrast, augmented oxidative stress because of high ROS levels may precipitate epigenetic alterations to effect various phases of carcinogenesis. We address both aspects in the review.

FUTURE DIRECTIONS

Several drugs targeting ROS are under various stages of clinical development. Recent analysis of human cancers has revealed pervasive deregulation of the epigenetic machinery. Thus, a better understanding of the cross-talk between ROS and epigenetic alterations in cancer could lead to the identification of new drug targets and more effective treatment modalities.

New CeF3-ZnO nanocomposites for self-lighted photodynamic therapy that block adenocarcinoma cell life cycle

AIM

To synthesize and characterize the performances of a new all-inorganic nanocomposite (NC) for self-lighted photodynamic therapy against cancer. This NC could allow radiotherapy doses to be reduced, as it enhances the effects of x-rays, generating cytotoxic reactive oxygen species as singlet oxygen.

MATERIALS & METHODS

The proposed NC combines CeF₃ and ZnO; CeF₃ absorbs 6-MeV x-rays and activates the photosensitizer ZnO. Characterization is performed by transmission electron microscopy (TEM), scanning-TEM, energy dispersive x-ray spectrometry and fluorescence spectroscopies. Efficiency on human adenocarcinoma cells (A549) was tested by fluorescence spectroscopy, cytofluorimetry, viability assays, clonogenic assays, cell cycle progression assays.

RESULTS

NC blocks A549's cell cycle before mitosis in the dark. Upon low-dose x-ray irradiation (2 Gy), reactive oxygen species/singlet oxygen are generated, further blocking cell cycle and reducing viability by 18% with respect to the sum of x-ray irradiation and NC dark activity.

CONCLUSION

These novel NCs promise to reduce doses in radiotherapy, helping to reduce unwanted side effects.

Reactive Chemicals and Electrophilic Stress in Cancer: A Minireview

Exogenous reactive chemicals can impair cellular homeostasis and are often associated with the development of cancer. Significant progress has been achieved by studying the macromolecular interactions of chemicals that possess various electron-withdrawing groups and the elucidation of the protective responses of cells to chemical interventions. However, the formation of electrophilic species inside the cell and the relationship between oxydative and electrophilic stress remain largely unclear. Derivatives of nitro-benzoxadiazole (also referred as nitro-benzofurazan) are potent producers of hydrogen peroxide and have been used as a model to study the generation of reactive species in cancer cells. This survey highlights the pivotal role of Cu/Zn superoxide dismutase 1 (SOD1) in the production of reactive oxygen and electrophilic species in cells exposed to cell-permeable chemicals. Lipophilic electrophiles rapidly bind to SOD1 and induce stable and functionally active dimers, which produce excess hydrogen peroxide leading to aberrant cell signalling. Moreover, reactive oxygen species and reactive electrophilic species, simultaneously generated by redox reactions, behave as independent entities that attack a variety of proteins. It is postulated that the binding of the electrophilic moiety to multiple proteins leading to impairing different cellular functions may explain unpredictable side effects in patients undergoing chemotherapy with reactive oxygen species (ROS)-inducing drugs. The identification of proteins susceptible to electrophiles at early steps of oxidative and electrophilic stress is a promising way to offer rational strategies for dealing with stress-related malignant tumors.

Cysteine residues are essential for dimerization of Hippo pathway components YAP2L and TAZ

Hippo signalling pathway is an emerging signalling pathway that plays important roles in organ size control, tumorigenesis, metastasis, stress response, apoptosis, stem cell differentiation and renewal during development and tissue homeostasis. Recent studies reported that human serine/threonine protein kinase, Mst1, a core component of the Hippo pathway can be activated through formation of homodimer. However, it is still unclear whether or not other components of the Hippo pathway are also regulated through dimerization. Here we provide the first evidence that Hippo components and oncoprotein YAP2L and TAZ can form homodimer in vitro and in vivo by forming disulphide bond through cysteine residue(s). We have also shown that the homodimers of YAP2L/TAZ are more stable and showed more oncogenic behaviour than their corresponding monomers as revealed by colony formation and cell transformation assay. Since cysteine post-translational regulation plays important roles in redox signalling, tumorigenesis and drug resistance, further studies on the functional effect of this dimerization through post-translational modulation of cysteine residues in YAP2L/TAZ will provide a significant contribution to our understanding of the roles of YAP2L/TAZ in cancer development and therapy.

Anti-neoplastic drugs increase caveolin-1-dependent migration, invasion and metastasis of cancer cells

Expression of the scaffolding protein Caveolin-1 (CAV1) enhances migration and invasion of metastatic cancer cells. Yet, CAV1 also functions as a tumor suppressor in early stages of cancer, where expression is suppressed by epigenetic mechanisms. Thus, we sought to identify stimuli/mechanisms that revert epigenetic CAV1 silencing in cancer cells and evaluate how this affects their metastatic potential. We reasoned that restricted tissue availability of anti-neoplastic drugs during chemotherapy might expose cancer cells to sub-therapeutic concentrations, which activate signaling pathways and the expression of CAV1 to favor the acquisition of more aggressive traits. Here, we used in vitro [2D, invasion] and in vivo (metastasis) assays, as well as genetic and biochemical approaches to address this question. Colon and breast cancer cells were identified where CAV1 levels were low due to epigenetic suppression and could be reverted by treatment with the methyltransferase inhibitor 5’-azacytidine. Exposure of these cells to anti-neoplastic drugs for short periods of time (24-48 h) increased CAV1 expression through ROS production and MEK/ERK activation. In colon cancer cells, increased CAV1 expression enhanced migration and invasion in vitro via pathways requiring Src-family kinases, as well as Rac-1 activity. Finally, elevated CAV1 expression in colon cancer cells following exposure in vitro to sub-cytotoxic drug concentrations increased their metastatic potential in vivo. Therefore exposure of cancer cells to anti-neoplastic drugs at non-lethal drug concentrations induces signaling events and changes in transcription that favor CAV1-dependent migration, invasion and metastasis. Importantly, this may occur in the absence of selection for drug-resistance.

Mitochondrial ROS control of cancer

Mitochondria serves a primary role in energy maintenance but also function to govern levels of mitochondria-derived reactive oxygen species (mROS). ROS have long been established to play a critical role in tumorigenesis and are now considered to be integral to the regulation of diverse signaling networks that drive proliferation, tumor cell survival and malignant progression. mROS can damage DNA, activate oncogenes, block the function of tumor suppressors and drive migratory signaling. The mitochondrion's oxidant scavenging systems including SOD2, Grx2, GPrx, Trx and TrxR are key of the cellular redox tone. These mitochondrial antioxidant systems serve to tightly control the levels of the primary ROS signaling species, H2O2. The coordinated control of mROS levels is also coupled to the activity of the primary H2O2 consuming enzymes of the mitochondria which are reliant on the epitranscriptomic control of selenocysteine incorporation. This review highlights the interplay between these many oncogenic signaling networks, mROS and the H2O2 emitting and consuming capacity of the mitochondria.