ROS and p53: a versatile partnership

Phillyrin Mitigates Apoptosis and Oxidative Stress in Hydrogen Peroxide-Treated RPE Cells through Activation of the Nrf2 Signaling Pathway

Oxidative stress-induced dysfunction or apoptosis in retinal pigment epithelial (RPE) cells is an important cause of dry age-related macular degeneration (AMD). Although phillyrin has been shown to exert significant antioxidant effects, the underlying mechanism of action remains unclear. The purpose of this study was to investigate the protective effect of phillyrin on hydrogen peroxide- (H2O2-) induced oxidative stress damage in RPE cells and the potential mechanism involved. It was found that phillyrin significantly protected RPE cells from H2O2 cytotoxicity. Furthermore, phillyrin alleviated oxidative stress-induced apoptosis via inhibition of endogenous and exogenous apoptotic pathways. Compared with the H2O2-treated group, the expressions of cleaved caspase-3, cleaved caspase-9, cleaved polymerase (PARP), death receptor Fas, and cleaved caspase-8, as well as Bax/Bcl-2 ratio were decreased in RPE cells after the phillyrin intervention. In addition, phillyrin reversed the oxidative stress-induced reductions in superoxide dismutase (SOD) and glutathione (GSH) levels and annulled the elevations in reactive oxygen species (ROS) and malondialdehyde (MDA), thereby restoring oxidant-antioxidant homeostasis. Phillyrin treatment upregulated the expressions of cyclin E, cyclin-dependent kinase 2 (CDK2), and cyclin A and downregulated the expressions of p21 and p-p53, thereby reversing the G0/G1 cell cycle arrest in H2O2-treated RPE cells. Pretreatment with phillyrin also increased the expressions of nuclear factor-erythroid 2-related factor 2 (Nrf2), total Nrf2, heme oxygenase-1 (HO-1), and NAD(P)H: quinone oxidoreductases-1 (NQO-1) in RPE cells and inhibited the formation of Kelch-like ECH-associated protein 1 (Keap1)/Nrf2 protein complex. Thus, phillyrin effectively protected RPE cells from oxidative stress through activation of the Nrf2 signaling pathway and inhibition of the mitochondria-dependent apoptosis pathway.

Cross-talk between oxidative stress signaling and microRNA regulatory systems in carcinogenesis: Focused on gastrointestinal cancers

Molecular mechanisms underlying development and progression of gastrointestinal (GI) cancers are mediated by both oxidative stress (OS) and microRNAs (miRNAs) involvement. Notably, OS signaling may regulate the expression of miRNAs, and miRNAs function as imperative players in OS-initiated tumors. Given the defined biological roles of both OS systems and miRNAs in GI carcinogenesis, a possible interplay between these two key cellular networks is considered. A growing body of evidence has indicated a reciprocal connection between OS signaling pathways and miRNA regulatory machines in GI cancer development and progression. Illumination of the molecular cross-talking between miRNAs and the OS would improve our pathophysiological insight into carcinogens. Also, understanding the molecular mechanisms in which these systems are reciprocally regulated may imply in future medical practice mainly GI cancer therapy. Nowadays, therapeutic strategies focusing on miRNA and OS in GI cancer treatment are increasingly delineated. Since the use of antioxidants is limited owing to the contrasting consequences of OS signaling in cancer, the discovery of OS-responsive miRNAs may provide a potential new strategy to overcome OS-mediated GI carcinogenesis. Given the possible interaction between OS and miRNAs in GI cancers, this review aimed to elucidate the existing evidence on the interaction between OS and miRNA regulatory machinery and its role in GI carcinogenesis. In this regard, we will illustrate the function of miRNAs which target OS systems during homeostasis and tumorigenesis. We also discuss the biological cross-talk between OS systems and miRNAs and corresponding cell signaling pathways.

Ligation-Mediated Polymerase Chain Reaction Detection of 8-Oxo-7,8-Dihydro-2'-Deoxyguanosine and 5-Hydroxycytosine at the Codon 176 of the p53 Gene of Hepatitis C-Associated Hepatocellular Carcinoma Patients

Molecular mechanisms underlying Hepatitis C virus (HCV)-associated hepatocellular carcinoma (HCC) pathogenesis are still unclear. Therefore, we analyzed the levels of 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) and other oxidative lesions at codon 176 of the p53 gene, as well as the generation of 3-(2-deoxy-β-d-erythro-pentafuranosyl)pyrimido[1,2-α]purin-10(3H)-one deoxyguanosine (M₁dG), in a cohort of HCV-related HCC patients from Italy. Detection of 8-oxodG and 5-hydroxycytosine (5-OHC) was performed by ligation mediated-polymerase chain reaction assay, whereas the levels of M₁dG were measured by chromatography and mass-spectrometry. Results indicated a significant 130% excess of 8-oxodG at –TGC– position of p53 codon 176 in HCV-HCC cases as compared to controls, after correction for age and gender, whereas a not significant increment of 5-OHC at –TGC– position was found. Then, regression models showed an 87% significant excess of M₁dG in HCV-HCC cases relative to controls. Our study provides evidence that increased adduct binding does not occur randomly on the sequence of the p53 gene but at specific sequence context in HCV-HCC patients. By-products of lipid peroxidation could also yield a role in HCV-HCC development. Results emphasize the importance of active oxygen species in inducing nucleotide lesions at a p53 mutational hotspot in HCV-HCC patients living in geographical areas without dietary exposure to aflatoxin B₁.

Protective Effects of Boron on Cyclophosphamide-Induced Bladder Damage and Oxidative Stress in Rats

This study aims to investigate protective effects of boron against cyclophosphamide-induced bladder toxicity that produces oxidative stress and leads to apoptosis of the cells. In total, 24 rats were divided into 4 equal groups. The control group received saline. The 2nd experimental group received 200 mg kg of cyclophosphamide i.p. on the 4th day while the 3rd group was given only boron (200 mg kg, i.p.) for 6 days. In the 4th group, boron was given for 6 days and cyclophosphamide (200 mg kg, i.p.) was administrated on the 4th day. Twenty-four hours after the last boron or cyclophosphamide administration, rats were sacrificed under anesthesia. Bladder tissues of rats were taken for histological and immunohistochemical (apoptotic markers such as caspase-3, bcl-2, and bax) and blood was taken for the biochemical (serum total thiol, serum natural thiol, serum thiol-disulfide) analysis. Transient epithelial thinning, edema, marked inflammatory reaction, and bleeding were observed in bladders of the group that received cyclophosphamide. Also, the activity of bax and caspase-3-positive cells increased while the number of bcl-2-positive cells decreased. In the same group, serum natural thiol and total thiol levels decreased while serum disulfide levels increased, which indicates oxidative stress. On the other hand, in the boron+cyclophosphamide group pretreatment with boron protected, the bladder tissue and the number of bcl-2-positive cells increased, and bax and caspase-3-positive cells decreased, showing antiapoptotic effects of boron against cyclophosphamide-induced toxicity. In parallel with the findings of this group, native thiol and total thiol levels increased and serum disulfide levels decreased pointing out to a decreased oxidative stress. Our results indicate that boron pretreatment significantly protects rat bladder against cyclophosphamide-induced bladder damage due to its antiapoptotic and antioxidant properties.

Protective and inhibitory effects of acteoside from Abeliophyllum distichum Nakai against oxidative DNA damage

Abeliophyllum distichum Nakai is a Korean endemic plant of the Oleaceae family that contains acteoside, a glycosylated caffeic acid, with neuroprotective, anti‑inflammatory and antibacterial properties. Previous studies, involving Accelerated Chromatographic Isolation, a high‑performance liquid chromatography‑photodiode array detector and a liquid chromatograph‑mass selective detector, isolated and identified acteoside in A. distichum (AAD) and documented its antioxidant and anti‑inflammatory activities. The aim of the present study was to determine whether AAD could protect from DNA damage by reducing oxidative stress. AAD treatment protected plasmid DNA against damage to DNA double‑strands induced by reactive oxygen species (ROS) and decreased the levels of phosphorylated p53 and γ‑H2AX in ROS‑treated NIH 3T3 cells. These findings suggested that AAD could reduce ROS‑mediated cellular damage and may represent an effective, natural antioxidant with the ability to protect genetic material.

MDM2 Antagonists Induce a Paradoxical Activation of Erk1/2 through a P53-Dependent Mechanism in Dedifferentiated Liposarcomas: Implications for Combinatorial Strategies

The MDM2 gene is amplified in dedifferentiated liposarcoma (DDLPS). Treatment with MDM2 antagonists is a promising strategy to treat DDLPS; however, drug resistance is a major limitation when these drugs are used as a single agent. This study examined the impact of MDM2 antagonists on the mitogen-activated protein kinase (MAPK) pathway in DDLPS and investigated the potential synergistic activity of a MAPK kinase (MEK) inhibitor in combination with MDM2 antagonists. We identified a synergistic effect and identified the mechanism behind it. Combination effects of MDM2 antagonists and a MEK inhibitor were analyzed in a patient-derived xenograft mouse model and in DDLPS and leiomyosarcoma cell lines using different cell proliferation assays and immunoblot analysis. MDM2 antagonist (RG7388)-resistant IB115 [P4] cells and p53-silenced DDLPS cells were also established to understand the importance of functional p53. We found that MDM2 antagonists induced an upregulation of phosphorylated extracellular signal-regulated kinase (p-ERK) in DDLPS cells. The upregulation of p-ERK occurred due to mitochondrial translocation of p53, which resulted in increased production of reactive oxygen species, causing the activation of receptor tyrosine kinases (RTKs). Activated RTKs led to the activation of the downstream MEK/ERK signaling pathway. Treatment with a MEK inhibitor resulted in decreased expression of p-ERK, causing significant anti-tumor synergy when combined with MDM2 antagonists. Our results provide a framework for designing clinical studies of combination therapies in DDLPS patients.

Trifolium pratense L. (red clover) extract and doxorubicin synergistically inhibits proliferation of 4T1 breast cancer in tumor-bearing BALB/c mice through modulation of apoptosis and increase antioxidant and anti-inflammatory related pathways

Therapeutic strategies against triple-negative breast cancer (TNBC) are associated with drug-induced toxicities. The tropical edible red clover (Trifolium pratense L.) is rich in polyphenolic compounds which confer the plant potential anticancer properties. The aim of this study was to investigate the effects of T. pratense and doxorubicin (DOX) on the apoptosis and proliferation of 4T1 tumor cells in an allograft model of tumor-bearing BALB/c mice. Fifty-six female 4T1-tumor bearing- BALB/c mice were randomly divided into 7 groups (n = 8/group) to receive different doses and combinations of DOX and T. pratense extract for 35 days. On the 36th day, serum estradiol (E2), IL-12 and IFN-γ cytokines, and glutathione peroxidase (GPx) activity were measured. Tumor's ferric reducing antioxidant power (FRAP) and the expressions of apoptosis-related genes (p53, Bax, Bcl-2, and caspase-3) were also evaluated. Immunohistochemical staining for Ki-67 and p53 were performed. Our results showed that the co-treatment of DOX and T. pratense (100-400 mg/kg) inhibited the proliferation of 4T1 tumor cells in dose- and time-dependent manners. The co-treatment of DOX and T. pratense (especially at the dose of 400 mg/kg) decreased the serum level of E2 (as a stimulant for breast tumor growth) and increased the serum levels of IL-12 and IFN-γ along with significant increments in serum GPx and tumor FRAP activities. The co-administration of DOX and T. pratense also decreased the expression of Ki-67 proliferation marker and increased the number p53 positive (i.e., apoptotic) cells within tumors. This was accompanied with the upregulation of pro-apoptotic and down-regulation of antiapoptotic genes. The key findings indicated the synergistic effects of DOX and T. pratense against TNBC xenografts.

Awakening the HSC: Dynamic Modeling of HSC Maintenance Unravels Regulation of the TP53 Pathway and Quiescence

Hematopoietic stem cells (HSCs) provide all types of blood cells during the entire life of the organism. HSCs are mainly quiescent and can eventually enter the cell cycle to differentiate. HSCs are maintained and tightly regulated in a particular environment. The stem cell niche regulates dormancy and awakening. Deregulations of this interplay can lead to hematopoietic failure and diseases. In this paper, we present a Boolean network model that recapitulates HSC regulation in virtue of external signals coming from the niche. This Boolean network integrates and summarizes the current knowledge of HSC regulation and is based on extensive literature research. Furthermore, dynamic simulations suggest a novel systemic regulation of TP53 in homeostasis. Thereby, our model indicates that TP53 activity is balanced depending on external stimulations, engaging a regulatory mechanism involving ROS regulators and RAS activated transcription factors. Finally, we investigated different mouse models and compared them to in silico knockout simulations. Here, the model could recapitulate in vivo observed behaviors and thus sustains our results.

Serum deprivation initiates adaptation and survival to oxidative stress in prostate cancer cells

Inadequate nutrient intake leads to oxidative stress disrupting homeostasis, activating signaling, and altering metabolism. Oxidative stress serves as a hallmark in developing prostate lesions, and an aggressive cancer phenotype activating mechanisms allowing cancer cells to adapt and survive. It is unclear how adaptation and survival are facilitated; however, literature across several organisms demonstrates that a reversible cellular growth arrest and the transcription factor, nuclear factor-kappaB (NF-κB), contribute to cancer cell survival and therapeutic resistance under oxidative stress. We examined adaptability and survival to oxidative stress following nutrient deprivation in three prostate cancer models displaying varying degrees of tumorigenicity. We observed that reducing serum (starved) induced reactive oxygen species which provided an early oxidative stress environment and allowed cells to confer adaptability to increased oxidative stress (H₂O₂). Measurement of cell viability demonstrated a low death profile in stressed cells (starved + H₂O₂), while cell proliferation was stagnant. Quantitative measurement of apoptosis showed no significant cell death in stressed cells suggesting an adaptive mechanism to tolerate oxidative stress. Stressed cells also presented a quiescent phenotype, correlating with NF-κB nuclear translocation, suggesting a mechanism of tolerance. Our data suggests that nutrient deprivation primes prostate cancer cells for adaptability to oxidative stress and/or a general survival mechanism to anti-tumorigenic agents.

p53 isoform Δ113p53 promotes zebrafish heart regeneration by maintaining redox homeostasis

Neonatal mice and adult zebrafish can fully regenerate their hearts through proliferation of pre-existing cardiomyocytes. Previous studies have revealed that p53 signalling is activated during cardiac regeneration in neonatal mice and that hydrogen peroxide (H₂O₂) generated near the wound site acts as a novel signal to promote zebrafish heart regeneration. We recently demonstrated that the expression of the p53 isoform Δ133p53 is highly induced upon stimulation by low-level reactive oxygen species (ROS) and that Δ133p53 coordinates with full-length p53 to promote cell survival by enhancing the expression of antioxidant genes. However, the function of p53 signalling in heart regeneration remains uncharacterised. Here, we found that the expression of Δ113p53 is activated in cardiomyocytes at the resection site in the zebrafish heart in a full-length p53- and ROS signalling-dependent manner. Cell lineage tracing showed that Δ113p53-positive cardiomyocytes undergo cell proliferation and contribute to myocardial regeneration. More importantly, heart regeneration is impaired in Δ113p53^M/M mutant zebrafish. Depletion of Δ113p53 significantly decreases the proliferation frequency of cardiomyocytes but has little effect on the activation of gata4-positive cells, their migration to the edge of the wound site, or apoptotic activity. Live imaging of intact hearts showed that induction of H₂O₂ at the resection site is significantly higher in Δ113p53^M/M mutants than in wild-type zebrafish, which may be the result of reduced induction of antioxidant genes in Δ113p53^M/M mutants. Our findings demonstrate that induction of Δ113p53 in cardiomyocytes at the resection site functions to promote heart regeneration by increasing the expression of antioxidant genes to maintain redox homeostasis.

ROS Homeostasis in Abiotic Stress Tolerance in Plants

Climate change-induced abiotic stress results in crop yield and production losses. These stresses result in changes at the physiological and molecular level that affect the development and growth of the plant. Reactive oxygen species (ROS) is formed at high levels due to abiotic stress within different organelles, leading to cellular damage. Plants have evolved mechanisms to control the production and scavenging of ROS through enzymatic and non-enzymatic antioxidative processes. However, ROS has a dual function in abiotic stresses where, at high levels, they are toxic to cells while the same molecule can function as a signal transducer that activates a local and systemic plant defense response against stress. The effects, perception, signaling, and activation of ROS and their antioxidative responses are elaborated in this review. This review aims to provide a purview of processes involved in ROS homeostasis in plants and to identify genes that are triggered in response to abiotic-induced oxidative stress. This review articulates the importance of these genes and pathways in understanding the mechanism of resistance in plants and the importance of this information in breeding and genetically developing crops for resistance against abiotic stress in plants.

Effective treatment of drug-resistant lung cancer via a nanogel capable of reactivating cisplatin and enhancing early apoptosis

Cisplatin resistance is a daunting obstacle in cancer therapy and one of the major causes for treatment failure due to the inadequate drug activity and apoptosis induction. To overcome cisplatin resistance, we proposed a multifunctional nanogel (designated as Valproate-D-Nanogel) capable of reactivating cisplatin and enhancing early apoptosis. This Valproate-D-Nanogel was prepared through copolymerizing carboxymethyl chitosan with diallyl disulfide and subsequent grafting with valproate to reverse the drug-resistance in cisplatin-resistant human lung adenocarcinoma cancer. It can significantly increase the proportion of G2/M phase (up to 3.2-fold enhancement) to reactivate cisplatin via high level of G2/M arrest induced by valproate. Meanwhile, the intracellular ROS-P53 crosstalk can be upregulated by diallyl disulfide (up to 8-fold increase of ROS) and valproate (up to 18-fold increase of P53) to enhance early apoptosis. The synchronization of enhanced G2/M arrest and ROS-P53 crosstalk devotes to reverse the cisplatin resistance with a high level of resistance reversion index (50.22). As a result, improved in vivo tumor inhibition (up to 15-fold higher compared to free cisplatin) and decreased systemic toxicity was observed after treatment with Valproate-D-Nanogels. Overall, this nanogel can effectively inhibit cisplatin-resistance cancer through combined pathways and provides an effective approach for overcoming cisplatin-resistance in cancer treatment.

Effect of Quercetin on Dexamethasone-Induced C2C12 Skeletal Muscle Cell Injury

Glucocorticoids are widely used anti-inflammatory drugs in clinical settings. However, they can induce skeletal muscle atrophy by reducing fiber cross-sectional area and myofibrillar protein content. Studies have proven that antioxidants can improve glucocorticoid-induced skeletal muscle atrophy. Quercetin is a potent antioxidant flavonoid widely distributed in fruits and vegetables and has shown protective effects against dexamethasone-induced skeletal muscle atrophy. In this study, we demonstrated that dexamethasone significantly inhibited cell growth and induced cell apoptosis by stimulating hydroxyl free radical production in C2C12 skeletal muscle cells. Our results evidenced that quercetin increased C2C12 skeletal cell viability and exerted antiapoptotic effects on dexamethasone-treated C2C12 cells by regulating mitochondrial membrane potential (ΔΨm) and reducing oxidative species. Quercetin can protect against dexamethasone-induced muscle atrophy by regulating the Bax/Bcl-2 ratio at the protein level and abnormal ΔΨm, which leads to the suppression of apoptosis.

Protection of the Retinal Ganglion Cells: Intravitreal Injection of Resveratrol in Mouse Model of Ocular Hypertension

Purpose

To investigate the efficacy of intravitreal administration of resveratrol (RSV) in a microbead-induced high intraocular pressure (IOP) murine model for glaucoma.

Methods

Experiments were performed using adult C57BL/6JJcl mice. Polystyrene microbeads were injected into the anterior chamber to induce IOP elevation. Retinal flat-mounts and sections were assessed by immunohistochemistry to detect the expression of reactive oxygen species and acetyl-p53 in retinal ganglion cells (RGCs), brain-derived neurotrophic factor (BDNF) in Müller glial cells (MGCs), and the receptor tropomyosin receptor kinase B (TrkB) in RGCs. Light cycler real-time PCR was also used for confirming gene expression of BDNF in primary cultured MGCs exposed to RSV.

Results

Microbeads induced high IOP followed by RGC death and axon loss. Administration of RSV rescued RGCs via decreased reactive oxygen species generation and acetyl-p53 expression in RGCs and upregulated BDNF in MGCs and TrkB expression in RGCs, which exhibited a strong cytoprotective action against cell death through multiple pathways under high IOP.

Conclusions

Our data suggest that administration of RSV may delay the progress of visual dysfunction during glaucoma and may therefore have therapeutic potential.

Sappanchalcone, a flavonoid isolated from Caesalpinia sappan L., induces caspase-dependent and AIF-dependent apoptosis in human colon cancer cells

The present study examined the apoptotic effects and the underlying mechanism of sappanchalcone, a major bioactive compound isolated from Caesalpinia sappan L. on human colon cancer cells. To achieve this, we used two different colon cancer cell lines, namely HCT116 (as wild-type p53 cells) and SW480 (as p53-mutant cells) cells. Our results illustrated that sappanchalcone treatment decreased the proliferation and further promoted apoptosis in HCT116 cells compared with the findings in SW480 cells. Sappanchalcone triggered phosphorylation of p53, which is involved in the activation of caspases and increased expression of Bax in HCT116 cells. Conversely, sappanchalcone-treated SW480 cells displayed no change in p53 phosphorylation or caspase activation. In addition, sappanchalcone further increased reactive oxygen species (ROS) levels and apoptosis-inducing factor (AIF) release in both HCT116 and SW480 cells. These data suggest that sappanchalcone induces apoptosis through caspase-dependent and caspases-independent mechanisms that were characterized by decreased Bcl-2 expression, mitochondrial targeting, and altered ROS production and AIF translocation to the nuclei.

Pro-Oxidant Actions of Carotenoids in Triggering Apoptosis of Cancer Cells: A Review of Emerging Evidence

Carotenoids are well known for their potent antioxidant function in the cellular system. However, in cancer cells with an innately high level of intracellular reactive oxygen species (ROS), carotenoids may act as potent pro-oxidant molecules and trigger ROS-mediated apoptosis. In recent years, the pro-oxidant function of several common dietary carotenoids, including astaxanthin, β-carotene, fucoxanthin, and lycopene, has been investigated for their effective killing effects on various cancer cell lines. Besides, when carotenoids are delivered with ROS-inducing cytotoxic drugs (e.g., anthracyclines), they can minimize the adverse effects of these drugs on normal cells by acting as antioxidants without interfering with their cytotoxic effects on cancer cells as pro-oxidants. These dynamic actions of carotenoids can optimize oxidative stress in normal cells while enhancing oxidative stress in cancer cells. This review discusses possible mechanisms of carotenoid-triggered ROS production in cancer cells, the activation of pro-apoptotic signaling by ROS, and apoptotic cell death. Moreover, synergistic actions of carotenoids with ROS-inducing anti-cancer drugs are discussed, and research gaps are suggested.

New phenotypic cytotoxicity assay for ROS-inducing compounds using rat renal epithelial cells

An important mechanism of chemical toxicity is the induction of oxidative stress through the production of excess reactive oxygen species (ROS). In this study, we show that the level of drug-induced ROS production between NRK52E and HepG2 cells is significantly different for several marketed drugs and a number of Takeda's internal proprietary compounds. Nifedipine, a calcium channel blocker and the initial focus of the study, was demonstrated to promote in vitro ROS production and a decrease in cell viability in NRK52E cells but not HepG2 cells. ROS production after nifedipine treatment was inhibited by a NOX inhibitor (GKT136901) but not the mitochondrial NADH dehydrogenase inhibitor, rotenone, suggesting that nifedipine decreases NRK52E cell viability primarily through a NOX-mediated pathway. To understand the breadth of NOX-mediated ROS production, 12 commercially available compounds that are structurally and/or pharmacologically related to nifedipine as well as 172 internal Takeda candidate drugs, were also evaluated against these two cell types. Over 15 % of compounds not cytotoxic to HepG2 cells (below 50 μM) were cytotoxic to NRK52E cells. Our results suggest that a combination of cell viability data from both NRK52E and HepG2 cells was superior for the prediction of in vivo toxicity findings when compared to use of only one cell line. Further, the NRK52E cell viability assay is a good predictor of NOX-mediated ROS production and can be used as a follow up assay following a negative HepG2 response to aid in the selection of suitable compounds for in vivo toxicity studies.

Maslinic acid induces anticancer effects in human neuroblastoma cells mediated via apoptosis induction and caspase activation, inhibition of cell migration and invasion and targeting MAPK/ERK signaling pathway

Maslinic acid is an active member of pentacyclic triterpenes predominantly found in dietary plants including hawthorn berries and olive fruit skins. It has been reported to show immense pharmacological and biological importance including anticancer property. This research was initiated to explore the anticancer potential of maslinic acid against human neuroblastoma. The effects of maslinic acid on cellular apoptosis, ROS generation, cell migration and invasion, caspase activation and targeting MAPK/ERK signaling pathway were investigated. The proliferation percentage was calculated by performing of MTT assay. AO/EB and annexin V/PI staining assays along with western blotting were used to monitor the apoptosis and expressions of apoptosis connected proteins. Spectrofluorometry was used for ROS monitoring. To assess the anti-metastatic effects of maslinic acid on neuroblastoma cells, transwell chambers assays for migration as well as invasion were executed. Western blotting was implemented to establish the expressions of MAPK/ERK signaling pathway connected proteins. Results evidenced remarkable anticancer potential of maslinic acid against human neuroblastoma. It induced dose as well as time reliant anti-proliferative effects against SHSY-5Y cells selectively. The underlying mechanism of cancer suppressive effects of maslinic acid was found to mediate via caspase-dependent apoptosis. Further, ROS production amplified terrifically with exposure of SHSY-5Y to higher maslinic acid doses. Cell migration and invasion in SHSY-5Y cells were both reduced remarkably by maslinic acid. Finally, the activity of proteins associated with MAPK/ERK signaling pathway was found to be significantly reduced with increasing maslinic acid doses. In conclusion, it was observed that maslinic acid possesses a great anti-neuroblastoma potential and could be considered for its chemotherapy provided further investigations are recommended.

Nanomodified strategies to overcome EGFR-tyrosine kinase inhibitors resistance in non-small cell lung cancer

Lung cancer is the primary cause of cancer-related death worldwide. 85%-90% of cases are non-small cell lung cancer (NSCLC) which characteristically exhibits altered epidermal growth factor receptor (EGFR) signaling is a major driver pathway. Unfortunately, therapeutic outcomes in treating NSCLC are compromised by the emergence of drug resistance in response to EGFR-tyrosine kinase inhibitor (TKI) targeted therapy due to the acquired resistance mutation EGFR T790M or activation of alternative pathways. There is current need for a new generation of TKIs to be developed to treat EGFR-TKI-resistant NSCLC. To overcome the above problems and improve clinical efficacy, nanotechnology with targeting abilities and sustained release has been proposed for EGFR-TKI-resistant NSCLC treatment and has already achieved success in in vitro or in vivo models. In this review, we summarize and illustrate representative nano-formulations targeting EGFR-TKI-resistant NSCLC. The described advances may pave the way to better understanding and design of nanocarriers and multifunctional nanosystems for efficient treatment for drug resistant NSCLC.

Replicative and radiation-induced aging: a comparison of gene expression profiles

All living organisms are subject to the aging process and experience the effect of ionizing radiation throughout their life. There have been a number of studies that linked ionizing radiation process to accelerated aging, but comprehensive signalome analysis of both processes was rarely conducted. Here we present a comparative signaling pathway based analysis of the transcriptomes of fibroblasts irradiated with different doses of ionizing radiation, replicatively aged fibroblasts and fibroblasts collected from young, middle age and old patients. We demonstrate a significant concordance between irradiation-induced and replicative senescence signalome signatures of fibroblasts. Additionally, significant differences in transcriptional response were also observed between fibroblasts irradiated with high and low dose. Our data shows that the transcriptome of replicatively aged fibroblasts is more similar to the transcriptome of the cells irradiated with 2 Gy, than with 5 сGy.This work revealed a number of signaling pathways that are shared between senescence and irradiation processes and can potentially be targeted by the new generation of gero- and radioprotectors.

The ameliorating effects of anthocyanins on the cross-linked signaling pathways of cancer dysregulated metabolism

Cancer cells underlie the dysregulated metabolism of carbohydrate, lipid and protein and thereby, employ interconnected cross-linked signaling pathways to supply adequate energy for growth and related biosynthetic procedures. In the present study, a comprehensive review of cancer metabolism and anthocyanin's effect was conducted using the existing electronic databases, including Medline, PubMed, Scopus, and Web of Science, as well as related articles in the field. Such keywords as "cancer", and "cancer metabolism" in the title/abstract/keyword and all the "anthocyanins" in the whole text were used. Data were collected without time restriction until February 2020. The results indicated the involvement of several signaling pathways, including inflammatory PI3K/Akt/mTOR pathway, Bax/Bcl-2/caspases as apoptosis modulators, and NF-κB/Nrf2 as oxidative stress mediators in the cancer dysregulated metabolism. Compelling studies have shown that targeting these pathways, as critical hallmarks of cancer, plays a critical role in combating cancer dysregulated metabolism. The complexity of cancer metabolism signaling pathways, along with toxicity, high costs, and resistance to conventional drugs urge the need to investigate novel multi-target agents. Increasing evidence has introduced plant-derived secondary metabolites as hopeful anticancer candidates which target multiple dysregulated cross-linked pathways of cancer metabolism. Amongst these metabolites, anthocyanins have demonstrated positive anticancer effects by targeting inflammation, oxidative stress, and apoptotic signaling pathways. The current study revealed the cross-linked signaling pathways of cancer metabolism, as well as the promising pharmacological mechanisms of anthocyanins in targeting the aforementioned signaling mediators. To overcome the pharmacokinetic limitations of anthocyanins in cancer treatment, their interactions with gut microbiota and the need to develop related nano-formulations were also considered.

P53: A Guardian of Immunity Becomes Its Saboteur through Mutation

Awareness of the importance of immunity in controlling cancer development triggered research into the impact of its key oncogenic drivers on the immune response, as well as their value as targets for immunotherapy. At the heart of tumour suppression is p53, which was discovered in the context of viral infection and now emerges as a significant player in normal and cancer immunity. Wild-type p53 (wt p53) plays fundamental roles in cancer immunity and inflammation. Mutations in p53 not only cripple wt p53 immune functions but also sinisterly subvert the immune function through its neomorphic gain-of-functions (GOFs). The prevalence of mutant p53 across different types of human cancers, which are associated with inflammatory and immune dysfunction, further implicates mutant p53 in modulating cancer immunity, thereby promoting tumorigenesis, metastasis and invasion. In this review, we discuss several mutant p53 immune GOFs in the context of the established roles of wt p53 in regulating and responding to tumour-associated inflammation, and regulating innate and adaptive immunity. We discuss the capacity of mutant p53 to alter the tumour milieu to support immune dysfunction, modulate toll-like receptor (TLR) signalling pathways to disrupt innate immunity and subvert cell-mediated immunity in favour of immune privilege and survival. Furthermore, we expose the potential and challenges associated with mutant p53 as a cancer immunotherapy target and underscore existing therapies that may benefit from inquiry into cancer p53 status.

Reactive Oxygen Species, Metabolic Plasticity, and Drug Resistance in Cancer

The metabolic abnormality observed in tumors is characterized by the dependence of cancer cells on glycolysis for their energy requirements. Cancer cells also exhibit a high level of reactive oxygen species (ROS), largely due to the alteration of cellular bioenergetics. A highly coordinated interplay between tumor energetics and ROS generates a powerful phenotype that provides the tumor cells with proliferative, antiapoptotic, and overall aggressive characteristics. In this review article, we summarize the literature on how ROS impacts energy metabolism by regulating key metabolic enzymes and how metabolic pathways e.g., glycolysis, PPP, and the TCA cycle reciprocally affect the generation and maintenance of ROS homeostasis. Lastly, we discuss how metabolic adaptation in cancer influences the tumor’s response to chemotherapeutic drugs. Though attempts of targeting tumor energetics have shown promising preclinical outcomes, the clinical benefits are yet to be fully achieved. A better understanding of the interaction between metabolic abnormalities and involvement of ROS under the chemo-induced stress will help develop new strategies and personalized approaches to improve the therapeutic efficiency in cancer patients.

Methanolic Bark Extract of Abroma augusta (L.) Induces Apoptosis in EAC Cells through Altered Expression of Apoptosis Regulatory Genes

Abroma augusta (L.), one of the herbal medicinal plants, is widely used for treatment of various maladies. The present study was initiated to determine the antioxidant, hemolytic, cytotoxicity, and anticancer activities of methanolic extract from the bark of the plant. The phytochemical screening was done by analyzing different phytochemicals present in the extract. We observed the presence of alkaloids, steroids, terpenoids, flavonoids, reducing sugars, and glycosides in the bark extract which showed the highest antioxidant capacity. Antioxidant potential of the methanolic extract was evaluated in vitro by DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging assay method. This extract showed prominent scavenging activity with IC₅₀ value of 38.65 μg/ml. The hemolytic activity of the extract was evaluated at concentrations ranging from 250 to 1000 μg/ml. It was observed that the extract induced hemolysis percentage of 9.41% to 4.1%, which implies that the extract has no potent hemolytic activity. Cytotoxicity and anticancer activities were observed on Ehrlich ascites carcinoma (EAC) cells. In addition, the bark showed promising cytotoxicity with IC₅₀ value of 329.41 μg/ml, and the study indicated that the extract was capable of inhibiting EAC cell growth by 75.5% when administered at 100 mg/kg/day body weight intraperitoneally for five consecutive days to Swiss albino mice. Morphological change of apoptotic cell was determined by fluorescence and optical microscopy. DNA fragmentation is another marker for apoptosis, and the bark extract-treated EAC cells showed smeared and fragmented DNA bands. Apoptosis correlated well with the upregulation of p53 and Bax and also with the downregulation of NF-κB and Bcl-2. Furthermore, activity and interaction of two A. augusta compounds were tested through molecular docking simulation study. In conclusion, our results suggest that A. augusta bark has the potential to be considered as an anticancer agent.

Reactive oxygen species (ROS) as pleiotropic physiological signalling agents

'Reactive oxygen species' (ROS) is an umbrella term for an array of derivatives of molecular oxygen that occur as a normal attribute of aerobic life. Elevated formation of the different ROS leads to molecular damage, denoted as 'oxidative distress'. Here we focus on ROS at physiological levels and their central role in redox signalling via different post-translational modifications, denoted as 'oxidative eustress'. Two species, hydrogen peroxide (H₂O₂) and the superoxide anion radical (O₂^·-), are key redox signalling agents generated under the control of growth factors and cytokines by more than 40 enzymes, prominently including NADPH oxidases and the mitochondrial electron transport chain. At the low physiological levels in the nanomolar range, H₂O₂ is the major agent signalling through specific protein targets, which engage in metabolic regulation and stress responses to support cellular adaptation to a changing environment and stress. In addition, several other reactive species are involved in redox signalling, for instance nitric oxide, hydrogen sulfide and oxidized lipids. Recent methodological advances permit the assessment of molecular interactions of specific ROS molecules with specific targets in redox signalling pathways. Accordingly, major advances have occurred in understanding the role of these oxidants in physiology and disease, including the nervous, cardiovascular and immune systems, skeletal muscle and metabolic regulation as well as ageing and cancer. In the past, unspecific elimination of ROS by use of low molecular mass antioxidant compounds was not successful in counteracting disease initiation and progression in clinical trials. However, controlling specific ROS-mediated signalling pathways by selective targeting offers a perspective for a future of more refined redox medicine. This includes enzymatic defence systems such as those controlled by the stress-response transcription factors NRF2 and nuclear factor-κB, the role of trace elements such as selenium, the use of redox drugs and the modulation of environmental factors collectively known as the exposome (for example, nutrition, lifestyle and irradiation).

MDM2-Associated Clusterization-Triggered Emission and Apoptosis Induction Effectuated by a Theranostic Spiropolymer

Heteroatom-containing spiropolymers were constructed in a facile manner by a catalyst-free multicomponent spiropolymerization route. P1a2b as the most potent of these spiropolymers, demonstrates cluster-triggered emission resulting from strong interactions with the MDM2 protein. By preventing the anti-apoptotic p53/MDM2 interaction, P1a2b triggers apoptosis in cancerous cells, while demonstrating a good biocompatibility and non-toxicity in non-cancerous cells. The combined results from solution and cell-based cluster-triggered emission studies, docking, protein expression experiments and cytotoxicity data strongly support the MDM2-binding hypothesis and indicate a potential application as a fluorescent cancer marker as well as therapeutic for this spiropolymer.

Interaction of apoptosis and pluripotency related transcripts for developmental potential of ovine embryos produced in vitro at different oxygen concentrations

The present study in sheep model was to find out the interaction of apoptotic transcripts, that is, Bcl2, Bax, Casp3, PCNA and p53 and pluripotency related transcripts, that is, Sox2, Nanog and Oct4 in ovine embryos produced in vitro at different O₂ concentrations (20% and 5% O₂) to compare their developmental potential. Oxygen concentrations did not influence the maturation and cleavage rate but the percentage of morula and blastocysts was significantly more at 5% as compared to 20% O₂. A significant upregulated expression of Bcl2 and PCNA genes and significantly downregulated expression of Casp3 and p53 were observed in the blastocysts at 5% than those at 20% O₂. The expression of Bax was not influenced by the O₂ concentration. Among the pluripotency related transcripts, the expression of Oct4 was significantly upregulated and the expression of Sox2 and Nanog was significantly downregulated in embryos at 5% than at 20% O₂. The study concluded that the embryos produced in vitro at low O₂ (5%) concentration regulate the expression of developmental genes related to apoptosis and pluripotency to improve the developmental potential of embryos as compared to high O₂ (20%) concentration.

Nicotine exposure potentiates lung tumorigenesis by perturbing cellular surveillance

BACKGROUND

Nicotine is a major tobacco component and found at circulating concentrations in smokers' bloodstreams. Although considered a non-carcinogenic substance, nicotine rapidly defuses to tissues after being inhaled, inviting effects on cellular physiology, particularly in the lung. Widespread increased use of nicotine-based e-cigarettes, especially in younger adults, creates an urgent need for improved understanding of nicotine's potential to impact human health.

METHODS

Biological and biochemistry methods were used to interrogate the potential for nicotine to weaken the genetic integrity of murine and human-lung epithelial cells.

RESULTS

We demonstrate that nicotine potentiates the growth of the lung epithelial cells in a dose-response fashion. Nicotine elicits an acute increase in reactive oxygen species (ROS), which persists at moderately high levels throughout the duration of nicotine exposure. The aberrant increases in ROS appear to induce ER stress and UPR activation, as reflected by BIP upregulation and PERK phosphorylation. Furthermore, prolonged nicotine exposure interferes with p53 function triggered by sodium arsenite. Unless p53 is suppressed, persistent nicotine exposure does not induce colony formation by lung epithelial cells in soft agar.

CONCLUSION

The data suggest that nicotine treatment, by perturbing intracellular redox state and altering p53 function, can create a pro-tumorigenic environment in lung epithelium. The results suggest caution in using nicotine replacement therapies and e-cigarettes.

Application of non-invasive low-intensity pulsed electric field with thermal cycling-hyperthermia for synergistically enhanced anticancer effect of chlorogenic acid on PANC-1 cells

Most existing cancer treatments involve high-cost chemotherapy and radiotherapy, with major side effects, prompting effort to develop alternative treatment modalities. It was reported that the combination of thermal-cycling hyperthermia (TC-HT) and phenolic compound exhibited a moderate cytotoxic effect against human pancreatic cancer PANC-1 cells. In this study, we investigate the efficacy of triple combination in PANC-1 cancer cells by adopting low-intensity pulsed electric field (LIPEF) to couple with TC-HT and CGA (chlorogenic acid). The study finds that this triple combination can significantly impede the proliferation of PANC-1 cells, with only about 20% viable cells left after 24h, whereas being non-toxic to normal cells. The synergistic activity against the PANC-1 cells was achieved by inducing G2/M phase arrest and apoptosis, which were associated with up-regulation of p53 and coupled with increased expression of downstream proteins p21 and Bax. Further mechanism investigations revealed that the cytotoxic activity could be related to mitochondrial apoptosis, characterized by the reduced level of Bcl-2, mitochondrial dysfunction, and sequential activation of caspase-9 and PARP. Also, we found that the triple treatment led to the increase of intracellular reactive oxygen species (ROS) production. Notably, the triple treatment-induced cytotoxic effects and the elevated expression of p53 and p21 proteins as well as the increased Bax/Bcl-2 ratio, all could be alleviated by the ROS scavenger, N-acetyl-cysteine (NAC). These findings indicate that the combination of CGA, TC-HT, and LIPEF may be a promising modality for cancer treatment, as it can induce p53-dependent cell cycle arrest and apoptosis through accumulation of ROS in PANC-1 cells.

Antitumoral effects of mitochondria-targeting neutral and cationic cis-[bis(1,3-dibenzylimidazol-2-ylidene)Cl(L)]Pt(ii) complexes

cis-[Bis(1,3-dibenzylimidazol-2-ylidene)Pt^IICl(L)] complexes target mitochondria regardless of charge and size of ligands L, yet show different anticancer effects.

ROS/p53/miR‑335‑5p/Sp1 axis modulates the migration and epithelial to mesenchymal transition of JEG‑3 cells

Differential expression of microRNA (miR)-335-5p, a key tumor suppressor, has been detected in pre-eclampsia (PE) placentas. However, the role of miR-335-5p in the pathogenesis of PE and the factor modulating its aberrant expression remain unknown. The present study used JEG-3 cells in vitro to investigate these mechanisms. The role of miR-335-5p in proliferation, apoptosis and migration of JEG-3 cells was investigated using MTT, Annexin V-FITC/PI, Transwell migration and wound healing assays, respectively. miR-335-5p expression levels were analyzed using reverse transcription-quantitative PCR. The expression levels of E-cadherin, N-cadherin, Snail, specificity protein 1 (Sp1) and p53 were assessed using western blot analysis. Cell viability analysis was performed using the Cell Counting Kit-8 assay. The intracellular reactive oxygen species (ROS) levels were detected using a 2,7-dichlorodihydrofluorescein diacetate assay. The present results suggested that miR-335-5p did not affect the proliferation or apoptotic rate of JEG-3 cells. Overexpression of miR-335-5p significantly inhibited the migration of JEG-3 cells, decreased the expression levels of Sp1, N-cadherin and Snail, and increased E-cadherin expression. Sp1 silencing produced similar results in JEG-3 cells. H₂O₂ significantly increased the intracellular ROS levels and miR-335-5p expression, whereas N-acetyl-cysteine pretreatment prior to H₂O₂ treatment reversed the increases in miR-335-5p expression. Knockdown of p53 significantly decreased the expression levels of miR-335-5p in JEG-3 cells and in H₂O₂-treated cells. The present results suggested that miR-335-5p expression levels in trophoblast cells could be increased by ROS in a p53-dependent manner, leading to the downregulation of Sp1 and subsequent inhibition of epithelial to mesenchymal transition and cell migration. The present results may provide novel evidence on the etiology of PE.

Molecular and Cellular Response of Co-cultured Cells toward Cobalt Chloride (CoCl2)-Induced Hypoxia

Cobalt chloride (CoCl₂) is a well-known hypoxia mimetic mediator that induces hypoxia-like responses. CoCl₂, a mediator confirmed to alleviate hypoxia-inducible factor-1 (HIF-1), has been associated with a variety of hypoxic responses. HIF-1 is the foremost transcriptionfactor that is particularly activated during hypoxia and regulates various genes. Therefore, this study aimed to investigate the cellular and molecular responses of the co-cultured cells under the influence of the CoCl₂-induced hypoxic condition. Mono- and co-cultured C2C12 and 3T3-L1 cells were exposed to CoCl₂, and a significant induction in HIF-1, reactive oxygen species and lipid peroxidase and a reduction in glutathione and catalase were observed. The expressions of proapoptotic genes like Bax, p53, caspase-9, and caspase-3 were notably increased, whereas the antiapoptotic gene, i.e., Bcl2, was downregulated during hypoxia in mono- as well as co-cultured C2C12 cells. However, the co-cultured C2C12 cells show significantly lower induction in oxidative stress and expression of apoptotic genes in comparison to monocultured C2C12 cells. Whereas, the co-cultured 3T3-L1 cells show comparatively higher oxidative stress and apoptotic event in comparison to monocultured 3T3-L1 cells. The reason may be the communication between the cells and some soluble factors that help in cell survival/death from hypoxia. Moreover, it may also be due to the fact that fat and muscle cells interact and communicate via proximity and mutual ability when growing together. Therefore, the co-culture system provides a unique approach to intercellular communication between the two different cell types.

ROS and diseases: role in metabolism and energy supply

Researches dedicated to reactive oxygen species (ROS) had been performed for decades, yet the outcomes remain controversial. With the relentless effort of studies, researchers have explored the role of ROS in biosystem and various diseases. ROS are beneficial for biosystem presenting as signalling molecules and enhancing immunologic defence. However, they also have harmful effects such as causing tissue and organ damages. The results are controversial in studies focusing on ROS and ROS-related diseases by regulating ROS with inhibitors or promotors. These competing results hindered the process for further investigation of the specific mechanisms lying behind. The opinions presented in this review interpret the researches of ROS from a different dimension that might explain the competing results of ROS introduced so far from a broader perspective. This review brings a different thinking to researchers, with the neglected features and potentials of ROS, to relate their works with ROS and to explore the mechanisms between their subject and ROS.

Mechanistic Insights into Oxidative Stress and Apoptosis Mediated by Tannic Acid in Human Liver Hepatocellular Carcinoma Cells

The study investigated the cytotoxic effect of a natural polyphenolic compound Tannic acid (TA) on human liver hepatocellular carcinoma (HepG2) cells and elucidated the possible mechanisms that lead to apoptosis and oxidative stress HepG2 cell. The HepG2 cells were treated with TA for 24 h and various assays were conducted to determine whether TA could induce cell death and oxidative stress. The cell viability assay was used to determine the half maximal inhibitory concentration (IC₅₀), caspase activity and cellular ATP were determined by luminometry. Microscopy was employed to determine deoxyribonucleic acid (DNA) integrity, while thiobarbituric acid (TBARS) and nitric oxide synthase (NOS) assays were used to elucidate cellular reactive oxygen species (ROS) and reactive nitrogen species (RNS), respectively. Western blotting was used to confirm protein expression. The results revealed that tannic acid induced caspase activation and increased the presence of cellular ROS and RNS, while downregulating antioxidant expression. Tannic acid also showed increased cell death and increased DNA fragmentation. In conclusion, TA was able to induce apoptosis by DNA fragmentation via caspase-dependent and caspase-independent mechanism. It was also able to induce oxidative stress, consequently contributing to cell death.

Analysis of apoptosis related genes in nurses exposed to anti-neoplastic drugs

BACKGROUND

Anti-neoplastic agents are widely used in the treatment of cancer and some non-neoplastic diseases. These drugs have been proved to be carcinogens, teratogens, and mutagens. Concern exists regarding the possible dangers of the staff handling anti-cancer drugs. The long-term exposure of nurses to anti-neoplastic drugs is still a controversial issue. The purpose of this study was to monitor cellular toxicity parameters and gene expression in nurses who work in chemotherapy wards and compare them to nurses who work in other wards.

METHODS

To analyze the apoptosis-related genes overexpression and cytotoxicity effects, peripheral blood lymphocytes obtained from oncology nurses and the control group.

THE RESULTS

Significant alterations in four analyzed apoptosis-related genes were observed in oncology nurses. In most individual samples being excavated, Bcl-2 overexpression is superior to that of Bax. Prominent P53 and Hif-1α up-regulation were observed in oncology nurses. Moreover, all cytotoxicity parameters (cell viability, ROS formation, MMP collapse, Lysosomal membrane damage, Lipid peroxidation, Caspase 3 activity and Apoptosis phenotype) in exposed oncology nurses were significantly (p < 0.001) higher than those of unexposed control nurses. Up-regulation of three analyzed apoptosis-related genes were observed in nurses occupationally exposed to anti-cancer drugs.

CONCLUSION

Our data show that oxidative stress and mitochondrial toxicity induced by anti-neoplastic drugs lead to overexpression of apoptosis-related genes in oncology nurses.

Electrochemical detection of different p53 conformations by using nanostructured surfaces

Protein electrochemistry represents a powerful technique for investigating the function and structure of proteins. Currently available biochemical assays provide limited information related to the conformational state of proteins and high costs. This work provides novel insights into the electrochemical investigation of the metalloprotein p53 and its redox products using label-free direct electrochemistry and label-based antibody-specific approaches. First, the redox activities of different p53 redox products were qualitatively investigated on carbon-based electrodes. Then, focusing on the open p53 isoform (denatured p53), a quantitative analysis was performed, comparing the performances of different bulk and nanostructured materials (carbon and platinum). Overall, four different p53 products could be successfully discriminated, from wild type to denatured. Label-free analysis suggested a single electron exchange with electron transfer rate constants on the order of 1 s-1. Label-based analysis showed decreasing affinity of pAb240 towards denatured, oxidized and nitrated p53. Furthermore, platinum nanostructured electrodes showed the highest enhancement of the limit of detection in the quantitative analysis (100 ng/ml). Overall, the obtained results represent a first step towards the implementation of highly requested complex integrated devices for clinical practices, with the aim to go beyond simple protein quantification.

G1 phase cell cycle arrest in NSCLC in response to LZ-106, an analog of enoxacin, is orchestrated through ROS overproduction in a P53-dependent manner

LZ-106, a newly synthetized analog of quinolone, has been shown to be highly effective in non-small cell lung cancer (NSCLC) in both cultured cells and xenograft mouse model with low toxicity, yet the molecular mechanisms still require exploration. Here, we substantiated the involvement of P53 activation in intracellular reactive oxygen species (ROS) generation upon LZ-106 treatment and related P53 to the ROS-induced viability inhibition and apoptosis, which was exhibited in the previous research. P53 was shown to play an indispensable role in the elevated levels of intracellular ROS in LZ-106-treated NSCLC cells through ROS detection. We further identified the anti-proliferation effect of LZ-106 in NSCLC cells through G1 phase cell cycle arrest by cell cycle analysis, with the expression analysis of the key proteins, and discovered that the cell cycle arrest effect is also mediated by induction of ROS in a P53-dependent manner. In addition, the tumor suppression effect exhibited in vivo was demonstrated to be similar to that in vitro, which requires the participation of P53. Thus, LZ-106 is a potent antitumor drug possessing potent proliferation inhibition and apoptosis induction ability through the P53-dependent ROS modulation both in vitro and in vivo.

Emerging Anticancer Potentials of Selenium on Osteosarcoma

Selenium is a trace element essential to humans and forms complexes with proteins, which exert physiological functions in the body. In vitro studies suggested that selenium possesses anticancer effects and may be effective against osteosarcoma. This review aims to summarise current evidence on the anticancer activity of inorganic and organic selenium on osteosarcoma. Cellular studies revealed that inorganic and organic selenium shows cytotoxicity, anti-proliferative and pro-apoptotic effects on various osteosarcoma cell lines. These actions may be mediated by oxidative stress induced by selenium compounds, leading to the activation of p53, proapoptotic proteins and caspases. Inorganic selenium is selective towards cancer cells, but can cause non-selective cell death at a high dose. This condition challenges the controlled release of selenium from biomaterials. Selenium treatment in animals inoculated with osteosarcoma reduced the tumour size, but did not eliminate the incidence of osteosarcoma. Only one study investigated the relationship between selenium and osteosarcoma in humans, but the results were inconclusive. In summary, although selenium may exert anticancer properties on osteosarcoma in experimental model systems, its effects in humans require further investigation.

p53-Mediated Oxidative Stress Enhances Indirubin-3'-Monoxime-Induced Apoptosis in HCT116 Colon Cancer Cells by Upregulating Death Receptor 5 and TNF-Related Apoptosis-Inducing Ligand Expression

Indirubin-3′-monoxime (I3M) exhibits anti-proliferative activity in various cancer cells; however, its anti-cancer mechanism remains incompletely elucidated. This study revealed that I3M promotes the expression of death receptor 5 (DR5) and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) in HCT116 p53^+/+ cells, resulting in caspase-mediated apoptosis. However, this study demonstrated that HCT116 p53^−/− cells were insensitive to I3M-mediated apoptosis, indicating that I3M-induced apoptosis depends on the p53 status of HCT116 cells. Additionally, in HCT116 p53^-/- cells, I3M significantly increased Ras expression, while in HCT116 p53^+/+ cells, it reduced Ras expression. Furthermore, I3M remarkably increased the production of reactive oxygen species (ROS), which were reduced in transient p53 knockdown, indicating that I3M-mediated apoptosis was promoted by p53-mediated ROS production. Our results also showed that I3M enhanced transcription factor C/EBP homologous protein (CHOP) expression, resulted in endoplasmic reticulum (ER) stress-mediated DR5 expression, which was upregulated by ROS production in HCT116 p53^+/+ cells. Moreover, co-treatment with I3M and TRAIL enhanced DR5 expression, thereby triggering TRAIL-induced apoptosis of HCT116 p53^+/+ cells, which was interfered by a DR5-specific blocking chimeric antibody. In summary, I3M potently enhances TRAIL-induced apoptosis by upregulating DR5 expression via p53-mediated ROS production in HCT116 p53^+/+ cells. However, HCT116 p53^−/− cells were less sensitive to I3M-mediated apoptosis, suggesting that I3M could be a promising anti-cancer candidate against TRAIL-resistant p53^+/+ cancer cells. Additionally, this study also revealed that I3M sensitizes colorectal cancer cells such as HT29 and SW480 to TRAIL-mediated apoptosis.

Molecular Mechanisms of Glucose Fluctuations on Diabetic Complications

Accumulating evidence indicates the occurrence and development of diabetic complications relates to not only constant high plasma glucose, but also glucose fluctuations which affect various kinds of molecular mechanisms in various target cells and tissues. In this review, we detail reactive oxygen species and their potentially damaging effects upon glucose fluctuations and resultant downstream regulation of protein signaling pathways, including protein kinase C, protein kinase B, nuclear factor-κB, and the mitogen-activated protein kinase signaling pathway. A deeper understanding of glucose-fluctuation-related molecular mechanisms in the development of diabetic complications may enable more potential target therapies in future.

The Thioredoxin System is Regulated by the ASK-1/JNK/p38/Survivin Pathway During Germ Cell Apoptosis

The aim is to explore the mechanism of the apoptosis signal-regulating kinase-1 (ASK-1) signaling pathway and the involvement of the thioredoxin (Trx) system during testicular ischemia reperfusion injury (tIRI) by using ASK-1 specific inhibitor, NQDI-1. Male Sprague-Dawley rats (n = 36, 250–300 g) were equally divided into 3 groups: sham, tIRI, and tIRI + NQDI-1 (10 mg/kg, i.p, pre-reperfusion). For tIRI induction, the testicular cord and artery were occluded for 1 h followed by 4 h of reperfusion. Histological analyses, protein immunoexpression, biochemical assays, and real-time PCR were used to evaluate spermatogenesis, ASK-1/Trx axis expression, enzyme activities, and relative mRNA expression, respectively. During tIRI, ipsilateral testes underwent oxidative stress indicated by low levels of superoxide dismutase (SOD) and Glutathione (GSH), increased oxidative damage to lipids and DNA, and spermatogenic damage. This was associated with induced mRNA expression of pro-apoptosis genes, downregulation of antiapoptosis genes, increased caspase 3 activity and activation of the ASK-1/JNK/p38/survivin apoptosis pathway. In parallel, the expression of Trx, Trx reductase were significantly reduced, while the expression of Trx interacting protein (TXNIP) and the NADP⁺/ nicotinamide Adenine Dinucleotide phosphate (NADPH) ratio were increased. These modulations were attenuated by NQDI-1 treatment. In conclusion, the Trx system is regulated by the ASK-1/Trx/TXNIP axis to maintain cellular redox homeostasis and is linked to tIRI-induced germ cell apoptosis via the ASK-1/JNK/p38/survivin apoptosis pathway.

p53-Bad: A Novel Tumor Suppressor/Proapoptotic Factor Hybrid Directed to the Mitochondria for Ovarian Cancer Gene Therapy

Clinical trials involving p53 gene therapy for ovarian cancer failed due to the dominant negative inhibition of wild-type p53 and multiple genetic aberrations in ovarian cancer. To overcome this problem, we have designed a more potent chimeric gene fusion, called p53-Bad, that combines p53 with the mitochondrial pro-apoptotic factor Bad. Unlike wild-type p53, which acts as a nuclear transcription factor, this novel p53-Bad construct has multiple unique mechanisms of action including a direct and rapid apoptotic effect at the mitochondria. The mitochondrial localization, transcription activity, and apoptotic activity of the constructs were tested. The results suggest that p53 can be effectively targeted to the mitochondria by controlling the phosphorylation of pro-apoptotic Bad, which can only localize to the mitochondria when Ser-112 and Ser-136 of Bad are unphosphorylated. By introducing S112A and S136A mutations, p53-Bad fusion cannot be phosphorylated at these two sites and always localizes to the mitochondria. p53-Bad constructs also have superior activity over p53 and Bad alone. The apoptotic activity is consistent in many ovarian cancer cell lines regardless of the endogenous p53 status. Both p53 and the BH3 domain of Bad contribute to the superior activity of p53-Bad. Our data suggests that p53-Bad fusions are capable of inducing apoptosis and should be further pursued for gene therapy for ovarian cancer.