Autophagy, Oxidative Stress and Cancer Development

Mitochondria-associated endoplasmic reticulum membranes tethering protein VAPB-PTPIP51 protects against ischemic stroke through inhibiting the activation of autophagy

AIMS

Mitochondria-associated endoplasmic reticulum membranes (MAMs) serve as a crucial bridge connecting the endoplasmic reticulum (ER) and mitochondria within cells. Vesicle-associated membrane protein-associated protein B (VAPB) and protein tyrosine phosphatase interacting protein 51 (PTPIP51) are responsible for the formation and stability of MAMs, which have been implicated in the pathogenesis of various diseases. However, the role of MAMs in ischemic stroke (IS) remains unclear. We aimed to investigate the role of MAMs tethering protein VAPB-PTPIP51 in experimental cerebral ischemia.

METHODS

We simulated cerebral ischemia-reperfusion injury (CIRI) by using a mouse middle cerebral artery occlusion (MCAO) model.

RESULTS

We observed a decrease in VAPB-PTPIP51 expression in the brain tissue. Our findings suggested compromised MAMs after MCAO, as a decreased mitochondria-ER contact (MERC) coverage and an increased distance were observed through the transmission electron microscope (TEM). Upon VAPB or PTPIP51 knockdown, the damage to MAMs was exacerbated, accompanied by excessive autophagy activation and increased reactive oxygen species (ROS) production, resulting in an enlarged infarct area and exacerbated neurological deficits. Notably, we observed that this damage was concomitant with the inhibition of the PI3K/AKT/mTOR pathway and was successfully mitigated by the treatment with the PI3K activator.

CONCLUSIONS

Our findings suggest that the downregulation of VAPB-PTPIP51 expression after IS mediates structural damage to MAMs. This may exacerbate CIRI by inhibiting the PI3K pathway and activating autophagy, thus providing new therapeutic targets for IS.

Relative quantitation of chiral thiol compounds labeled based on isotope novel mass spectrometry probes: Monitoring of the dynamic changes of chiral thiol compounds in human urine during normal, exercise, and rest recovery states

Monitoring changes in the content of chiral thiol compounds in the human body is crucial for the early diagnosis of oxidative stress-related diseases and the exploration of their pathogenesis. To address this, we synthesized a novel isotope mass spectrometry (MS) probe, denoted as (R)-(5-(3-isothiocyanato (13C) pyrrolidin-1-yl)-5-oxopentyl) triphenylphosphonium (N13CS-OTPP), with triphenylphosphine as its parent structure. In this study, we established a new ultra-high-performance liquid chromatography high-resolution mass spectrometry (UHPLCHRMS) relative quantitative method to monitor chiral thiol compounds in human urine under varying oxidative stress conditions. This method relies on the ratio of 12C/13C isotope-labeled peak areas. To assess the chiral separation efficiency of N13CS-OTPP, we employed three types of thiol compounds (D/L-GSH, D/L-Cys, and D/L-Hcy) and observed separation degrees (Rs) ranging from 1.82 to 1.89. We further validated the accuracy and feasibility of our relative quantitative methods using D/L-Cys-as a model compound. N12C/13CS-OTPP-Cys-exhibited excellent linearity (R2 = 0.9993-0.9994) across different molar ratios (D/L-Cys = 10:1, 4:1, 2:1, 1:1, 1:2, 1:4, 1:10) and achieved a low limit of detection (LOD) of 2.5 fmol. Additionally, we monitored the dynamic changes in urine D/L-Cys-and D/L-Hcy ratios in 12 healthy volunteers (six males and six females) under various oxidative stress states. We generated fitting curves and investigated the trends in chiral thiol compounds in vivo. This study introduces a novel method for the relative quantitative monitoring of chiral thiol compounds in different oxidative stress states within the human body. It also presents a new strategy for understanding the pathogenesis of related diseases resulting from the abnormal metabolism of thiol compounds.

Role of autophagy in skin photoaging: A narrative review

As the largest organ of the human body, the skin serves as the primary barrier against external damage. The continuous increase in human activities and environmental pollution has resulted in the ongoing depletion of the ozone layer. Excessive exposure to ultraviolet (UV) radiation enhances the impact of external factors on the skin, leading to photoaging. Photoaging causes physical and psychological damage to the human body. The prevention and management of photoaging have attracted increased attention in recent years. Despite significant progress in understanding and mitigating UV-induced photoaging, the precise mechanisms through which autophagy contributes to the prevention of photoaging remain unclear. Given the important role of autophagy in repairing UV-induced DNA damage and scavenging oxidized lipids, autophagy is considered a novel strategy for preventing the occurrence of photoaging and other UV light-induced skin diseases. This review aims to elucidate the biochemical and clinical features of photoaging, the relationship of skin photoaging and chronological aging, the mechanisms underlying skin photoaging and autophagy, and the role of autophagy in skin photoaging.

Lipid peroxidation products' role in autophagy regulation

Autophagy, which is responsible for removing damaged molecules, prevents their accumulation in cells, thus maintaining intracellular homeostasis. It is also responsible for removing the effects of oxidative stress, so its activation takes place during increased reactive oxygen species (ROS) generation and lipid peroxidation. Therefore, the aim of this review was to summarize all the available knowledge about the effect of protein modifications by lipid peroxidation products on autophagy activation and the impact of this interaction on the functioning of cells. This review shows that reactive aldehydes (including 4-hydroxynonenal and malondialdehyde), either directly or by the formation of adducts with autophagic proteins, can activate or prevent autophagy, depending on their concentration. This effect relates not only to the initial stages of autophagy, when 4-hydroxynonenal and malondialdehyde affect the levels of proteins involved in autophagy initiation and phagophore formation, but also to the final stage, degradation, when reactive aldehydes, by binding to the active center of cathepsins, inactivate their proteolytic functions. Moreover, this review also shows how little research exists on analyzing the impact of lipid peroxidation products and their protein adducts on autophagy. Such knowledge could be used in the therapy of diseases related to autophagy disorders.

Oxidative stress enhances rotavirus oncolysis in breast cancer and leukemia, except in melanoma with abundant matrix

OBJECTIVES

This study aimed to explore the impact of oxidative stress and extracellular matrix integrity on rotavirus infection in various cancer cells, including breast cancer, acute lymphoblastic leukemia, and melanoma.

METHODS

We induced oxidative stress using ROS-inducing drugs (cisplatin, metronidazole, melatonin, valproic acid, doxorubicin, losartan, nitrofurantoin, and DHA) and investigated the effects on viral infection in MCF-7, Reh, A375, B16-F1, and SK-MEL-28 cells and the generation of virions from infected cells by harvesting the supernatants every two hours, reinfecting other cells, and analyzing cell viability and DNA fragmentation.

FINDINGS

In MCF-7 and Reh cells, rotavirus Wt1-5 infection led to increased ROS generation, virion production, membrane permeability, mitochondrial dysfunction, DNA damage, and cell death. These effects were amplified by ROS-inducing drugs. Conversely, melanoma cells (SK-MEL-28 and A375) with a robust extracellular matrix network showed limited sensitivity to the drugs. Notably, losartan, which modulates the extracellular matrix, enhanced viral infection in melanoma cells (99 %).

CONCLUSIONS

Oxidative stress promotes oncolytic rotavirus infection in breast cancer and acute lymphoblastic leukemia cells, suggesting potential utility in combination with radiotherapy or chemotherapy due to their shared induction of intracellular oxidative stress.

Unraveling the impact of melatonin treatment: Oxidative stress, metabolic responses, and morphological changes in HuH7.5 hepatocellular carcinoma cells

In addition to its highly aggressive nature and late diagnosis, hepatocellular carcinoma (HCC) does not respond effectively to available chemotherapeutic agents. The search is on for an ideal and effective compound with low cost and minimal side effects that can be used as an adjunct to chemotherapeutic regimens. One of the mechanisms involved in the pathology of HCC is the oxidative stress, which plays a critical role in tumor survival and dissemination. Our group has already demonstrated the antitumor potential of melatonin against HuH 7.5 cells. In the present study, we focused on the effects of melatonin on oxidative stress parameters and their consequences on cell metabolism. HuH 7.5 cells were treated with 2 and 4 mM of melatonin for 24 and 48 h. Oxidative stress biomarkers, antioxidant enzyme, mitochondrial membrane potential, formation of lipid bodies and autophagic vacuoles, cell cycle progression, cell death rate and ultrastructural cell alterations were evaluated. The treatment with melatonin increased oxidative stress biomarkers and reduced antioxidant enzyme activities of HuH 7.5 cells. Additionally, melatonin treatment damaged the mitochondrial membrane and increased lipid bodies and autophagic vacuole formation. Melatonin triggered cell cycle arrest and induced cell death by apoptosis. Our results indicate that the treatment of HuH 7.5 cells with melatonin impaired antioxidant defense systems, inhibited cell cycle progression, and caused metabolic stress, culminating in tumor cell death.

Oxidative stress induction by narasin augments doxorubicin's efficacy in osteosarcoma

Complications and fata toxicity induced by chemotherapy are the main challenge for clinical management of osteosarcoma. The identification of agents that can augment the efficacy of chemotherapy at lower doses may represent an alternative therapeutic strategy. Narasin is a polyether antibiotic widely used in veterinary medicine. In this study, we show that narasin is active against osteosarcoma cells at the same concentrations that are less toxic to normal cells. This effect is achieved by growth inhibition and apoptosis induction, which is mediated by oxidative stress and damage, and mitochondrial dysfunction. The antioxidant N-acetyl-l-cysteine (NAC) abolishes the anti-osteosarcoma activity. Importantly, narasin significantly augments doxorubicin's efficacy in both osteosarcoma cell culturing system and subcutaneous implantation mouse model. The combination of narasin and doxorubicin at non-toxic doses completely arrests osteosarcoma growth in mice. Our results suggest that the concurrent administration of doxorubicin and narasin could present a viable alternative therapeutic approach for osteosarcoma.

The Carcinogenic Potential of Bisphenol A in the Liver Based on Transcriptomic Studies

Bisphenol A (BPA) is an environmental toxin widely used in the production of polycarbonate plastics. A correlation exists between BPA tissue contamination and the occurrence of pathological conditions, including cancer. First-passage detoxification of high BPA amounts in the liver promotes hepatotoxicity and morphological alterations of this organ, but there is a lack of knowledge about the molecular mechanisms underlying these phenomena. This prompted us to investigate changes in the liver transcriptomics of 3-month-old female mice exposed to BPA (50 mg/kg) in drinking water for 3 months. Five female mice served as controls. The animals were euthanized, the livers were collected, and RNA was extracted to perform RNA-seq analysis. The multistep transcriptomic bioinformatics revealed 120 differentially expressed genes (DEGs) in the BPA-exposed samples. Gene Ontology (GO) annotations indicated that DEGs have been assigned to many biological processes, including "macromolecule modification" and "protein metabolic process". Several of the revealed DEGs have been linked to the pathogenesis of severe metabolic liver disorders and malignant tumors, in particular hepatocellular carcinoma. Data from this study suggest that BPA has a significant impact on gene expression in the liver, which is predictive of the carcinogenic potential of this compound in this organ.

Vitamin B12-Induced Autophagy Alleviates High Glucose-Mediated Apoptosis of Islet β Cells

High glucose levels can lead to the apoptosis of islet β cells, while autophagy can provide cytoprotection and promote autophagic cell death. Vitamin B12, a water-soluble B vitamin, has been shown to regulate insulin secretion and increase insulin sensitivity. However, the precise mechanism of action remains unclear. In this study, we investigated the influence of vitamin B12 on high glucose-induced apoptosis and autophagy in RIN-m5F cells to elucidate how vitamin B12 modulates insulin release. Our results demonstrate that exposure to 45 mM glucose led to a significant increase in the apoptosis rate of RIN-m5F cells. The treatment with vitamin B12 reduced the apoptosis rate and increased the number of autophagosomes. Moreover, vitamin B12 increased the ratio of microtubule-associated protein 1 light chain 3 beta to microtubule-associated protein 1 light chain 3 alpha (LC3-II/LC3-I), while decreasing the amount of sequestosome 1 (p62) and inhibiting the phosphorylation of p70 ribosomal protein S6 kinase (p70S6K) under both normal- and high-glucose conditions. The additional experiments revealed that vitamin B12 inhibited high glucose-induced apoptosis. Notably, this protective effect was attenuated when the autophagy inhibitor 3-methyladenine was introduced. Our findings suggest that vitamin B12 protects islet β cells against apoptosis induced by high glucose levels, possibly by inducing autophagy.

Advancements in Analyzing Tumor Metabolites through Chemical Derivatization-Based Chromatography

Understanding the metabolic abnormalities of tumors is crucial for early diagnosis, prognosis, and treatment. Accurate identification and quantification of metabolites in biological samples are essential to investigate the relationship between metabolite variations and tumor development. Common techniques like LC-MS and GC-MS face challenges in measuring aberrant metabolites in tumors due to their strong polarity, isomerism, or low ionization efficiency during MS detection. Chemical derivatization of metabolites offers an effective solution to overcome these challenges. This review focuses on the difficulties encountered in analyzing aberrant metabolites in tumors, the principles behind chemical derivatization methods, and the advancements in analyzing tumor metabolites using derivatization-based chromatography. It serves as a comprehensive reference for understanding the analysis and detection of tumor metabolites, particularly those that are highly polar and exhibit low ionization efficiency.

Insect-pathogen crosstalk and the cellular-molecular mechanisms of insect immunity: uncovering the underlying signaling pathways and immune regulatory function of non-coding RNAs

Multicellular organisms are constantly subjected to pathogens that might be harmful. Although insects lack an adaptive immune system, they possess highly effective anti-infective mechanisms. Bacterial phagocytosis and parasite encapsulation are some forms of cellular responses. Insects often defend themselves against infections through a humoral response. This phenomenon includes the secretion of antimicrobial peptides into the hemolymph. Specific receptors for detecting infection are required for the recognition of foreign pathogens such as the proteins that recognize glucans and peptidoglycans, together referred to as PGRPs and βGRPs. Activation of these receptors leads to the stimulation of signaling pathways which further activates the genes encoding for antimicrobial peptides. Some instances of such pathways are the JAK-STAT, Imd, and Toll. The host immune response that frequently accompanies infections has, however, been circumvented by diseases, which may have assisted insects evolve their own complicated immune systems. The role of ncRNAs in insect immunology has been discussed in several notable studies and reviews. This paper examines the most recent research on the immune regulatory function of ncRNAs during insect-pathogen crosstalk, including insect- and pathogen-encoded miRNAs and lncRNAs, and provides an overview of the important insect signaling pathways and effector mechanisms activated by diverse pathogen invaders.

An update on the bridging factors connecting autophagy and Nrf2 antioxidant pathway

Macroautophagy/autophagy is a lysosome-dependent catabolic pathway for the degradation of intracellular proteins and organelles. Autophagy dysfunction is related to many diseases, including lysosomal storage diseases, cancer, neurodegenerative diseases, cardiomyopathy, and chronic metabolic diseases, in which increased reactive oxygen species (ROS) levels are also observed. ROS can randomly oxidize proteins, lipids, and DNA, causing oxidative stress and damage. Cells have developed various antioxidant pathways to reduce excessive ROS and maintain redox homeostasis. Treatment targeting only one aspect of diseases with autophagy dysfunction and oxidative stress shows very limited effects. Herein, identifying the bridging factors that can regulate both autophagy and antioxidant pathways is beneficial for dual-target therapies. This review intends to provide insights into the current identified bridging factors that connect autophagy and Nrf2 antioxidant pathway, as well as their tight interconnection with each other. These factors could be potential dual-purpose targets for the treatment of diseases implicated in both autophagy dysfunction and oxidative stress.

Pepper Fruit Extracts Show Anti-Proliferative Activity against Tumor Cells Altering Their NADPH-Generating Dehydrogenase and Catalase Profiles

Cancer is considered one of the main causes of human death worldwide, being characterized by an alteration of the oxidative metabolism. Many natural compounds from plant origin with anti-tumor attributes have been described. Among them, capsaicin, which is the molecule responsible for the pungency in hot pepper fruits, has been reported to show antioxidant, anti-inflammatory, and analgesic activities, as well as anti-proliferative properties against cancer. Thus, in this work, the potential anti-proliferative activity of pepper (Capsicum annuum L.) fruits from diverse varieties with different capsaicin contents (California < Piquillo < Padrón < Alegría riojana) against several tumor cell lines (lung, melanoma, hepatoma, colon, breast, pancreas, and prostate) has been investigated. The results showed that the capsaicin content in pepper fruits did not correspond with their anti-proliferative activity against tumor cell lines. By contrast, the greatest activity was promoted by the pepper tissues which contained the lowest capsaicin amount. This indicates that other compounds different from capsaicin have this anti-tumor potentiality in pepper fruits. Based on this, green fruits from the Alegría riojana variety, which has negligible capsaicin levels, was used to study the effect on the oxidative and redox metabolism of tumor cell lines from liver (Hep-G2) and pancreas (MIA PaCa-2). Different parameters from both lines treated with crude pepper fruit extracts were determined including protein nitration and protein S-nitrosation (two post-translational modifications (PTMs) promoted by nitric oxide), the antioxidant capacity, as well as the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPX), among others. In addition, the activity of the NADPH-generating enzymes glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH), and NADP-isocitrate dehydrogenase (NADP-ICDH) was followed. Our data revealed that the treatment of both cell lines with pepper fruit extracts altered their antioxidant capacity, enhanced their catalase activity, and considerably reduced the activity of the NADPH-generating enzymes. As a consequence, less H₂O₂ and NADPH seem to be available to cells, thus avoiding cell proliferation and possibly triggering cell death in both cell lines.

Mitochondria: It is all about energy

Mitochondria play a key role in both health and disease. Their function is not limited to energy production but serves multiple mechanisms varying from iron and calcium homeostasis to the production of hormones and neurotransmitters, such as melatonin. They enable and influence communication at all physical levels through interaction with other organelles, the nucleus, and the outside environment. The literature suggests crosstalk mechanisms between mitochondria and circadian clocks, the gut microbiota, and the immune system. They might even be the hub supporting and integrating activity across all these domains. Hence, they might be the (missing) link in both health and disease. Mitochondrial dysfunction is related to metabolic syndrome, neuronal diseases, cancer, cardiovascular and infectious diseases, and inflammatory disorders. In this regard, diseases such as cancer, Alzheimer's, Parkinson's, amyotrophic lateral sclerosis (ALS), chronic fatigue syndrome (CFS), and chronic pain are discussed. This review focuses on understanding the mitochondrial mechanisms of action that allow for the maintenance of mitochondrial health and the pathways toward dysregulated mechanisms. Although mitochondria have allowed us to adapt to changes over the course of evolution, in turn, evolution has shaped mitochondria. Each evolution-based intervention influences mitochondria in its own way. The use of physiological stress triggers tolerance to the stressor, achieving adaptability and resistance. This review describes strategies that could recover mitochondrial functioning in multiple diseases, providing a comprehensive, root-cause-focused, integrative approach to recovering health and treating people suffering from chronic diseases.

Recent Advances in Cellular Signaling Interplay between Redox Metabolism and Autophagy Modulation in Cancer: An Overview of Molecular Mechanisms and Therapeutic Interventions

Autophagy is a fundamental homeostatic process in which certain cellular components are ingested by double-membrane autophagosomes and then degraded to create energy or to maintain cellular homeostasis and survival. It is typically observed in nutrient-deprived cells as a survival mechanism. However, it has also been identified as a crucial process in maintaining cellular homeostasis and disease progression. Normal cellular metabolism produces reactive oxygen (ROS) and nitrogen species at low levels. However, increased production causes oxidative stress, which can lead to diabetes, cardiovascular diseases, neurological disorders, and cancer. It was recently shown that maintaining redox equilibrium via autophagy is critical for cellular responses to oxidative stress. However, little is understood about the molecular cancer processes that connect to the control of autophagy. In cancer cells, oncogenic mutations, carcinogens, and metabolic reprogramming cause increased ROS generation and oxidative stress. Recent studies have suggested that increased ROS generation activates survival pathways that promote cancer development and metastasis. Moreover, the relationship between metabolic programming and ROS in cancer cells is involved in redox homeostasis and the malignant phenotype. Currently, while the signaling events governing autophagy and how redox homeostasis affects signaling cascades are well understood, very little is known about molecular events related to autophagy. In this review, we focus on current knowledge about autophagy modulation and the role of redox metabolism to further the knowledge of oxidative stress and disease progression in cancer regulation. Therefore, this review focuses on understanding how oxidation/reduction events fine-tune autophagy to help understand how oxidative stress and autophagy govern cancer, either as processes leading to cell death or as survival strategies for maintaining redox homeostasis in cancer.

Osmanthus-Loaded PVP/PVA Hydrogel Inhibits the Proliferation and Migration of Oral Squamous Cell Carcinoma Cells CAL-27

Conventional medical agents for oral squamous cell carcinoma (OSCC) with some adverse effects no longer meet the needs of the public. In this study, the prognosis-related hub genes of osmanthus-targeted therapy for OSCC were predicted and analyzed by network pharmacology and molecular docking. Osmanthus was extracted using the ethanol reflux method and osmanthus-loaded PVP/PVA (OF/PVP/PVA) hydrogel was prepared by electron beam radiation. The molecular structure, crystal structure and microscopic morphology of hydrogels were observed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. OSCC cells CAL-27 were cultured with OF/PVP/PVA hydrogel at different concentrations of extract to discover cell proliferation by MTT assay. The scratching test and JC-1 staining were used to observe the migration and mitochondrial membrane potential. Through experimental exploration, we found that a total of six prognosis-related targets were predicted, which are PYGL, AURKA, SQLE, etc., and osmanthus extract had good binding activity to AURKA. In vitro, except for proliferation inhibition, OF/PVP/PVA hydrogel prevented cell migration and changed the mitochondrial membrane potential of CAL-27 cells at a concentration equal to or greater than 50 μg/mL (p < 0.05). The addition of autophagy inhibitor chloroquine and 3-methyladenine weakened the migration inhibition of hydrogel (p < 0.05).

Pyroptosis: A new insight of non-small-cell lung cancer treatment

Non-small cell lung cancer (NSCLC) has become one of the most common malignant tumors. Emerging evidence has shown that tumor resistance to apoptosis by damaging or bypassing apoptotic cell death is a major contributor to poor responses to therapy in patients with NSCLC. Pyroptosis is a new type of cytolytic and inflammatory programmed death distinct from apoptosis. Currently, pyroptosis has been reported to cause a strong inflammatory response and significant tumor suppression. It is considered a promising therapeutic strategy and prognosis for NSCLC. In this review, we summarized the characteristics of pyroptosis from its underlying basis and role in NSCLC, thereby providing the potential of pyroptosis as a therapeutic strategy and highlighting the challenges of activating pyroptosis in NSCLC treatment.

Pathology of Urologic Cancers

We are pleased to present this Special Issue of Cancers, entitled “Pathology of Urologic Cancers” [...]