Nitric oxide inhibits autophagy and promotes apoptosis in hepatocellular carcinoma

Nitric oxide synthase 1 inhibits the progression of esophageal cancer through interacting with nitric oxide synthase 1 adaptor protein

BACKGROUND

Esophageal cancer (ESCA) is among the most prevalent and lethal tumors globally. While nitric oxide synthase 1 (NOS1) is recognized for its important involvement in various cancers, its specific function in ESCA remains unclear.

AIM

To explore the potential role and underlying mechanisms of NOS1 in ESCA.

METHODS

Survival rates were analyzed using GeneCards and Gene Expression Profiling Interactive Analysis. The effects and mechanisms of NOS1 on ESCA cells were evaluated via the Cell Counting Kit-8 assay, scratch assay, Transwell assay, flow cytometry, quantitative polymerase chain reaction, western blotting, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling staining. The protein interaction network was used to screen the interacting proteins of NOS1 and validate these interactions through co-immunoprecipitation and dual luciferase assays. Additionally, a nude mouse xenograft model was established to evaluate the effect of NOS1 in vivo.

RESULTS

The survival rate of patients with ESCA with high NOS1 expression was higher than that of patients with low NOS1 expression. NOS1 expression in ESCA cell lines was lower than that in normal esophageal epithelial cells. Overexpression of NOS1 (oe-NOS1) inhibited proliferation, invasion, and migration abilities in ESCA cell lines, resulting in decreased autophagy levels and increased apoptosis, pyroptosis, and ferroptosis. Protein interaction studies confirmed the interaction between NOS1 and NOS1 adaptor protein (NOS1AP). Following oe-NOS1 and the silencing of NOS1AP, levels of P62 and microtubule-associated protein 1 light chain 3 beta increased both in vitro and in vivo. Furthermore, the expression levels of E-cadherin, along with the activation of phosphatidylinositol 3-kinase (PI3K) and protein kinase B (AKT), were inhibited in ESCA cell lines.

CONCLUSION

NOS1 and NOS1 proteins interact to suppress autophagy, activate the PI3K/AKT pathway, and exert anti-cancer effects in ESCA.

Lysine-arginine imbalance overcomes therapeutic tolerance governed by the transcription factor E3-lysosome axis in glioblastoma

Recent advances in cancer therapy have underscored the importance of targeting specific metabolic pathways. In this study, we propose a precision nutrition approach aimed at lysosomal function in glioblastoma multiforme (GBM). Using patient-derived GBM cells, we identify lysosomal activity as a unique metabolic biomarker of tumorigenesis, controlling the efficacy of temozolomide (TMZ), a standard GBM therapy. Employing combined analyses of clinical patient samples and xenograft models, we further elucidate the pivotal role of Transcription Factor Binding To IGHM Enhancer 3 (TFE3), a master regulator of lysosomal biogenesis, in modulating malignant properties, particularly TMZ tolerance, by regulating peroxisome proliferator-activated receptor-gamma coactivator 1-alpha (PGC1α)-mediated mitochondrial activity. Notably, we find that lysine protects GBM cells from lysosomal stress by counteracting arginine's effects on nitric oxide production. The lysine restriction mimetic, homoarginine administration, significantly enhances the efficacy of anticancer therapies through lysosomal dysfunction. This study underscores the critical role of lysosomal function modulated by amino acid metabolism in GBM pathogenesis and treatment.

Targeted delivery of polymeric NO-donor micelles to hepatic stellate cells for restoration of liver function and inhibition of hepatic fibrosis

Liver fibrosis is a prevalent liver disease associated with significant morbidity, and the activation of hepatic stellate cells (HSCs) serves as the primary causative factor driving the progression of liver fibrosis. However, capillarization of liver sinusoidal endothelial cells (LSECs) induced by hepatic fibrosis can reduce nitric oxide (NO) production and bioavailability, which consequently loses the ability to retain HSCs dormant, leading to amplified HSCs activation. Herein, an elaborate micelle (VN-M@BN) loaded with benazepril (BN) was constructed by self-assembly of polymeric NO donor, aiming for the controlled release of NO in liver fibrosis lesions thereby impeding the progression of liver fibrosis. VN-M@BN with the vitamin A (VA) ligand modification was designed to target HSCs for efficient liver fibrosis inhibition. Controlled NO release significantly downregulated α-smooth muscle actin (α-SMA) and induced apoptosis of activated HSCs, thus enhancing the inhibition effects of BN towards HSCs. Furthermore, the in suit antifibrotic treatment results confirmed that VN-M@BN possessed good circulatory stability and targetability to liver fibrotic tissues, thereby effectively ameliorating the collagen deposition and fibrosis process in damaged liver tissues. The NO-based targeted nanodrug system enabled precise delivery of therapeutic drugs to activated HSCs, thereby synergizing the efficacy in treating liver fibrosis with minimal adverse effects.

Nitric oxide-based multi-synergistic nanomedicine: an emerging therapeutic for anticancer

Gas therapy has emerged as a promising approach for treating cancer, with gases like NO, H2S, and CO showing positive effects. Among these, NO is considered a key gas molecule with significant potential in stopping cancer progression. However, due to its high reactivity and short half-life, delivering NO directly to tumors is crucial for enhancing cancer treatment. NO-driven nanomedicines (NONs) have been developed to effectively deliver NO donors to tumors, showing great progress in recent years. This review provides an overview of the latest advancements in NO-based cancer nanotherapeutics. It discusses the types of NO donors used in current research, the mechanisms of action behind NO therapy for cancer, and the different delivery systems for NO donors in nanotherapeutics. It also explores the potential of combining NO donors with other treatments for enhanced cancer therapy. Finally, it examines the future prospects and challenges of using NONs in clinical settings for cancer treatment.

Autophagy and the pancreas: Healthy and disease states

Macroautophagy/autophagy is an intracellular degradation pathway that has an important effect on both healthy and diseased pancreases. It protects the structure and function of the pancreas by maintaining organelle homeostasis and removing damaged organelles. A variety of pancreas-related diseases, such as diabetes, pancreatitis, and pancreatic cancer, are closely associated with autophagy. Genetic studies that address autophagy confirm this view. Loss of autophagy homeostasis (lack or overactivation) can lead to a series of adverse reactions, such as oxidative accumulation, increased inflammation, and cell death. There is growing evidence that stimulating or inhibiting autophagy is a potential therapeutic strategy for various pancreatic diseases. In this review, we discuss the multiple roles of autophagy in physiological and pathological conditions of the pancreas, including its role as a protective or pathogenic factor.

The role of nitric oxide synthase/ nitric oxide in infection-related cancers: Beyond antimicrobial activity

As a free radical and endogenous effector molecule, mammalian endogenous nitric oxide (NO) is mainly derived from nitric oxide synthase (NOS) via L-arginine. NO participates in normal physiological reactions and provides immune responses to prevent the invasion of foreign bacteria. However, NO also has complex and contradictory biological effects. Abnormal NO signaling is involved in the progression of many diseases, such as cancer. In the past decades, cancer research has been closely linked with NOS/ NO, and many tumors with poor prognosis are associated with high expression of NOS. In this review, we give a overview of the biological effects of NOS/ NO. Then we focus on the oncogenic role of iNOS/ NO in HPV, HBV, EBV and H. pylori related tumors. In fact, there is growing evidence that iNOS could be used as a potential therapeutic target in cancer therapy. We emphasize that the pro-tumor effect of NOS/ NO is greater than the anti-tumor effect.

Crosstalk between metabolism and cell death in tumorigenesis

It is generally recognized that tumor cells proliferate more rapidly than normal cells. Due to such an abnormally rapid proliferation rate, cancer cells constantly encounter the limits of insufficient oxygen and nutrient supplies. To satisfy their growth needs and resist adverse environmental events, tumor cells modify the metabolic pathways to produce both extra energies and substances required for rapid growth. Realizing the metabolic characters special for tumor cells will be helpful for eliminating them during therapy. Cell death is a hot topic of long-term study and targeting cell death is one of the most effective ways to repress tumor growth. Many studies have successfully demonstrated that metabolism is inextricably linked to cell death of cancer cells. Here we summarize the recently identified metabolic characters that specifically impact on different types of cell deaths and discuss their roles in tumorigenesis.

High nitric oxide-adapted head and neck cancer cell lines demonstrate altered autophagy and apoptosis

Background/purpose

Autophagy is an intracellular degradative process occurring under stressful conditions. Nitric oxide (NO), a free radical, regulates autophagy and apoptosis in several cancers. However, the effect of head and neck squamous cell carcinoma (HNSCC) cell adaptation to high nitric oxide (HNO) on autophagy remains unknown. We investigated the autophagy and apoptotic changes in the HNO-adapted HNSCC cell lines.

Materials and methods

Isogenic primary HNSCC (HN18/HN30) and metastatic (HN17/HN31) cell lines were evaluated. The cells were induced with 1, 2, 3 and 4 mM DEA-NONOate, an NO donor, for 72 h and assessed for cell viability by MTT assay. "HNO-adapted cells" were defined when the cell viability in the treatment group was <10%. The surviving cells were re-treated with HNO to confirm their adaptation. HNO-adapted cells were quantified for apoptosis using flow cytometry. Autophagic structures (autophagosomes) and proteins (LC3A/B and LC3B-II) were investigated using transmission electron and confocal microscopy, respectively.

Results

HNO-adapted concentration for HN18, HN17, HN30 and HN31 cells was 3, 2, 4 and 4 mM, respectively. The HNO-adapted HN18 cells demonstrated a significantly increased apoptotic percentage, whereas no significant apoptotic change was detected in the HNO-adapted HN17, HN30 and HN31 cells compared with the parent cells. Autophagosomes were widely observed across the HNO-adapted cells. Moreover, LC3A/B and LC3B-II proteins were increased in all HNO-adapted cells.

Conclusion

Our results demonstrate that apoptosis and/or autophagy are increased during HNO adaptation in HNSCC cell lines.

An Overview of the Unfolded Protein Response (UPR) and Autophagy Pathways in Human Viral Oncogenesis

Autophagy and Unfolded Protein Response (UPR) can be regarded as the safe keepers of cells exposed to intense stress. Autophagy maintains cellular homeostasis, ensuring the removal of foreign particles and misfolded macromolecules from the cytoplasm and facilitating the return of the building blocks into the system. On the other hand, UPR serves as a shock response to prolonged stress, especially Endoplasmic Reticulum Stress (ERS), which also includes the accumulation of misfolded proteins in the ER. Since one of the many effects of viral infection on the host cell machinery is the hijacking of the host translational system, which leaves in its wake a plethora of misfolded proteins in the ER, it is perhaps not surprising that UPR and autophagy are common occurrences in infected cells, tissues, and patient samples. In this book chapter, we try to emphasize how UPR, and autophagy are significant in infections caused by six major oncolytic viruses-Epstein-Barr (EBV), Human Papilloma Virus (HPV), Human Immunodeficiency Virus (HIV), Human Herpesvirus-8 (HHV-8), Human T-cell Lymphotropic Virus (HTLV-1), and Hepatitis B Virus (HBV). Here, we document how whole-virus infection or overexpression of individual viral proteins in vitro and in vivo models can regulate the different branches of UPR and the various stages of macro autophagy. As is true with other viral infections, the relationship is complicated because the same virus (or the viral protein) exerts different effects on UPR and Autophagy. The nature of this response is determined by the cell types, or in some cases, the presence of diverse extracellular stimuli. The vice versa is equally valid, i.e., UPR and autophagy exhibit both anti-tumor and pro-tumor properties based on the cell type and other factors like concentrations of different metabolites. Thus, we have tried to coherently summarize the existing knowledge, the crux of which can hopefully be harnessed to design vaccines and therapies targeted at viral carcinogenesis.

Autophagy modulates physiologic and adaptive response in the liver

Autophagy is a physiological process that is ubiquitous and essential to the disposal or recycling of damaged cellular organelles and misfolded proteins to maintain organ homeostasis and survival. Its importance in the regulation of liver function in normal and pathological conditions is increasingly recognized. This review summarizes how autophagy regulates epithelial cell- and non-epithelial cell-specific function in the liver and how it differentially participates in hepatic homeostasis, hepatic injury response to stress-induced liver damage such as cholestasis, sepsis, non-alcoholic and alcohol-associated liver disease, viral hepatitis, hepatic fibrosis, hepatocellular and cholangiocellular carcinoma, and aging. Autophagy-based interventional studies for liver diseases that are currently registered in clinicatrials.gov are summarized. Given the broad and multidirectional autophagy response in the liver, a more refined understanding of the liver cell-specific autophagy activities in a context-dependent manner is necessary.

Network Pharmacology Combined with Machine Learning to Reveal the Action Mechanism of Licochalcone Intervention in Liver Cancer

There are reports indicating that licochalcones can inhibit the proliferation, migration, and invasion of cancer cells by promoting the expression of autophagy-related proteins, inhibiting the expression of cell cycle proteins and angiogenic factors, and regulating autophagy and apoptosis. This study aims to reveal the potential mechanisms of licochalcone A (LCA), licochalcone B (LCB), licochalcone C (LCC), licochalcone D (LCD), licochalcone E (LCE), licochalcone F (LCF), and licochalcone G (LCG) inhibition in liver cancer through computer-aided screening strategies. By using machine learning clustering analysis to search for other structurally similar components in licorice, quantitative calculations were conducted to collect the structural commonalities of these components related to liver cancer and to identify key residues involved in the interactions between small molecules and key target proteins. Our research results show that the seven licochalcones molecules interfere with the cancer signaling pathway via the NF-κB signaling pathway, PDL1 expression and PD1 checkpoint pathway in cancer, and others. Glypallichalcone, Echinatin, and 3,4,3',4'-Tetrahydroxy-2-methoxychalcone in licorice also have similar structures to the seven licochalcones, which may indicate their similar effects. We also identified the key residues (including ASN364, GLY365, TRP366, and TYR485) involved in the interactions between ten flavonoids and the key target protein (nitric oxide synthase 2). In summary, we provide valuable insights into the molecular mechanisms of the anticancer effects of licorice flavonoids, providing new ideas for the design of small molecules for liver cancer drugs.

Cancer Resistance Is Mediated by the Upregulation of Several Anti-Apoptotic Gene Products via the Inducible Nitric Oxide Synthase/Nitric Oxide Pathway: Therapeutic Implications

Significance: Several therapeutic strategies for cancer treatments have been developed with time, and significant milestones have been achieved recently. However, with these novel therapies, not all cancer types respond and in the responding cancer types only a subset is affected. The failure to respond is principally the result that these cancers develop several mechanisms of resistance. Thus, a focus of current research investigations is to unravel the various mechanisms that regulate resistance and identify suitable targets for new therapeutics. Recent Advances: Hence, many human cancer types have been reported to overexpress the inducible nitric oxide synthase (iNOS) and it has been suggested that iNOS/nitric oxide (NO) plays a pivotal role in the regulation of resistance. We have postulated that iNOS overexpression or NO regulates the overexpression of pivotal anti-apoptotic gene products such as B-cell lymphoma 2 (Bcl-2), B-cell lymphoma extra large (Bcl-xL), myeloid cell leukemia-1 (Mcl-1), and survivin. In this report, we describe the various mechanisms, transcriptional, post-transcriptional, and post-translational, by which iNOS/NO regulates the expression of the above anti-apoptotic gene products. Critical Issues: The iNOS/NO-mediated regulation of the four gene products is not the same with both specific and overlapping pathways. Our findings are, in large part, validated by bioinformatic analyses demonstrating, in several cancers, several direct correlations between the expression of iNOS and each of the four examined anti-apoptotic gene products. Future Directions: We have proposed that targeting iNOS may be highly efficient since it will result in the underexpression of multiple anti-apoptotic proteins and shifting the balance toward the proapoptotic gene products and reversal of resistance. Antioxid. Redox Signal. 39, 853-889.

Combating drug resistance in hepatocellular carcinoma: No awareness today, no action tomorrow

Hepatocellular carcinoma (HCC), the sixth most common cancer worldwide, is associated with a high degree of malignancy and poor prognosis. Patients with early HCC may benefit from surgical resection to remove tumor tissue and a margin of healthy tissue surrounding it. Unfortunately, most patients with HCC are diagnosed at an advanced or distant stage, at which point resection is not feasible. Systemic therapy is now routinely prescribed to patients with advanced HCC; however, drug resistance has become a major obstacle to the treatment of HCC and exploring purported mechanisms promoting drug resistance remains a challenge. Here, we focus on the determinants of drug resistance from the perspective of non-coding RNAs (ncRNAs), liver cancer stem cells (LCSCs), autophagy, epithelial-mesenchymal transition (EMT), exosomes, ferroptosis, and the tumor microenvironment (TME), with the aim to provide new insights into HCC treatment.

S-Nitrosylated Proteins Involved in Autophagy in Triticum aestivum Roots: A Bottom-Up Proteomics Approach and In Silico Predictive Algorithms

Autophagy is a highly conserved catabolic process in eukaryotic cells. Reactive nitrogen species play roles as inductors and signaling molecules of autophagy. A key mechanism of NO-mediated signaling is S-nitrosylation, a post-translational modification (PTM) of proteins at cysteine residues. In the present work, we analyzed the patterns of protein S-nitrosylation during the induction of autophagy in Triticum aestivum roots. The accumulation of S-nitrosylated proteins in the cells during autophagy induced with KNO2 and antimycin A was visualized using monoclonal antibodies with a Western blot analysis, and proteins were identified using a standard bottom-up proteomics approach. Protein S-nitrosylation is a labile and reversible PTM, and therefore the SNO group can be lost during experimental procedures. A subsequent bioinformatic analysis using predictive algorithms and protein-ligand docking showed that identified proteins possess hypothetical S-nitrosylation sites. Analyzing protein-protein interaction networks enabled us to discover the targets that can directly interact with autophagic proteins, and those that can interact with them indirectly via key multifunctional regulatory proteins. In this study, we show that S-nitrosylation is a key mechanism of NO-mediated regulation of autophagy in wheat roots. A combination of in silico predictive algorithms with a mass spectrometry analysis provides a targeted approach for the identification of S-nitrosylated proteins.

Pathogenesis of Hepatocellular Carcinoma: The Interplay of Apoptosis and Autophagy

The pathogenesis of hepatocellular carcinoma (HCC) is a multifactorial process that has not yet been fully investigated. Autophagy and apoptosis are two important cellular pathways that are critical for cell survival or death. The balance between apoptosis and autophagy regulates liver cell turnover and maintains intracellular homeostasis. However, the balance is often dysregulated in many cancers, including HCC. Autophagy and apoptosis pathways may be either independent or parallel or one may influence the other. Autophagy may either inhibit or promote apoptosis, thus regulating the fate of the liver cancer cells. In this review, a concise overview of the pathogenesis of HCC is presented, with emphasis on new developments, including the role of endoplasmic reticulum stress, the implication of microRNAs and the role of gut microbiota. The characteristics of HCC associated with a specific liver disease are also described and a brief description of autophagy and apoptosis is provided. The role of autophagy and apoptosis in the initiation, progress and metastatic potential is reviewed and the experimental evidence indicating an interplay between the two is extensively analyzed. The role of ferroptosis, a recently described specific pathway of regulated cell death, is presented. Finally, the potential therapeutic implications of autophagy and apoptosis in drug resistance are examined.

Molecular mechanisms of autophagy and implications in liver diseases

Autophagy is a highly conserved process in which cytosolic contents are degraded by the lysosome, which plays an important role in energy and nutrient balance, and protein or organelle quality control. The liver is the most important organ for metabolism. Studies to date have revealed a significant role of autophagy in the maintenance of liver homeostasis under basal and stressed conditions, and the impairment of autophagy has been closely linked to various liver diseases. Therefore, a comprehensive understanding of the roles of autophagy in liver diseases may help in the development of therapeutic strategies via targeting autophagy. In this review, we will summarize the latest understanding of the molecular mechanisms of autophagy and systematically discuss its implications in various liver diseases, including alcohol-related liver disease, non-alcoholic fatty liver disease, viral hepatitis, hepatocellular carcinoma, and acetaminophen-induced liver injury.

TGF-β/IFN-γ Antagonism in Subversion and Self-Defense of Phase II Coxiella burnetii-Infected Dendritic Cells

Dendritic cells (DCs) belong to the first line of innate defense and come into early contact with invading pathogens, including the zoonotic bacterium Coxiella burnetii, the causative agent of Q fever. However, the pathogen-host cell interactions in C. burnetii-infected DCs, particularly the role of mechanisms of immune subversion beyond virulent phase I lipopolysaccharide (LPS), as well as the contribution of cellular self-defense strategies, are not understood. Using phase II Coxiella-infected DCs, we show that impairment of DC maturation and MHC I downregulation is caused by autocrine release and action of immunosuppressive transforming growth factor-β (TGF-β). Our study demonstrates that IFN-γ reverses TGF-β impairment of maturation/MHC I presentation in infected DCs and activates bacterial elimination, predominantly by inducing iNOS/NO. Induced NO synthesis strongly affects bacterial growth and infectivity. Moreover, our studies hint that Coxiella-infected DCs might be able to protect themselves from mitotoxic NO by switching from oxidative phosphorylation to glycolysis, thus ensuring survival in self-defense against C. burnetii. Our results provide new insights into DC subversion by Coxiella and the IFN-γ-mediated targeting of C. burnetii during early steps in the innate immune response.

Targeting and regulation of autophagy in hepatocellular carcinoma: revisiting the molecular interactions and mechanisms for new therapy approaches

Autophagy is an evolutionarily conserved process that plays a role in regulating homeostasis under physiological conditions. However, dysregulation of autophagy is observed in the development of human diseases, especially cancer. Autophagy has reciprocal functions in cancer and may be responsible for either survival or death. Hepatocellular carcinoma (HCC) is one of the most lethal and common malignancies of the liver, and smoking, infection, and alcohol consumption can lead to its development. Genetic mutations and alterations in molecular processes can exacerbate the progression of HCC. The function of autophagy in HCC is controversial and may be both tumor suppressive and tumor promoting. Activation of autophagy may affect apoptosis in HCC and is a regulator of proliferation and glucose metabolism. Induction of autophagy may promote tumor metastasis via induction of EMT. In addition, autophagy is a regulator of stem cell formation in HCC, and pro-survival autophagy leads to cancer cell resistance to chemotherapy and radiotherapy. Targeting autophagy impairs growth and metastasis in HCC and improves tumor cell response to therapy. Of note, a large number of signaling pathways such as STAT3, Wnt, miRNAs, lncRNAs, and circRNAs regulate autophagy in HCC. Moreover, regulation of autophagy (induction or inhibition) by antitumor agents could be suggested for effective treatment of HCC. In this paper, we comprehensively review the role and mechanisms of autophagy in HCC and discuss the potential benefit of targeting this process in the treatment of the cancer. Video Abstract.

Thymol ameliorates ethanol-induced hepatotoxicity via regulating metabolism and autophagy

Alcoholic liver disease represents a serious threat to human health. In terms of safety and acceptability, thymol is widely used in or on foodstuffs to generate odour and taste. The present study aimed to investigate the therapeutic effect and mechanism of thymol against ethanol-induced injury in liver cells. Here we found that thymol is an effective agent for reducing ethanol-induced reactive oxygen species production in mouse liver cells. Thymol improves ethanol-induced lipid accumulation, and this corresponded to altered DGAT2 mRNA expression levels. Metabolomics data analysis showed that thymol alleviated ethanol-induced changes in the levels of thirty-four metabolites including nicotinic acid and l-arginine. By utilizing pathway enrichment analysis, altered metabolites in cells treated with ethanol and ethanol plus thymol were enriched in fourteen pathways including metabolic pathways and arginine and proline metabolism. We further confirmed the alleviation of overdose nitric oxide production in cells treated with ethanol plus thymol compared with that in ethanol-treated cells. It was interesting that up-regulated LC3-II/LC3-I ratio together with higher SQSTM1 protein abundance in ethanol-treated cells were attenuated by treatment with ethanol plus thymol. Thymol ameliorated ethanol-induced reduction of HSPA8 protein abundance. In addition, chloroquine-treated cells exhibited lower HSPA8 protein abundance compared with cells simulated with ethanol plus thymol. These data reveal that improving effect of thymol on ethanol-induced metabolic alteration is related to autophagic flux restoration. Our findings indicate that thymol is an attractive option for treating ethanol-induced liver damage.

Multi-action of a Fluorophore in the Sight of Light: Release of NO, Emergence of FONs, and Organelle Switching

Light, as an external stimulus, has begun to engage a phenomenal role in the diverse field of science. Encouraged by recent progress from biology to materials chemistry, various light-responsive fluorescent probes have been developed. Herein, we present a 1,8-naphthalimide-based probe NIT-NO₂ capable of releasing nitric oxide (NO) along with the formation of fluorescent organic nanoparticles (FONs) upon exposure to near-visible UV light. By synthesizing the photoproduct NIT-OH, we unveiled that initially NIT-NO₂ released NO and converted to NIT-OH, while prolonged irradiation led to the formation of FONs that is corroborated by the red-edge excitation shift as well as microscopic investigation. Finally, we have successfully applied NIT-NO₂ and NIT-OH for specific labeling of lipid droplets and plasma membranes, respectively, and demonstrated the switching from lipid droplets to plasma membranes by using light as a stimulus. These two probes show unique imaging applications inside the cells depending on the polarity and hydrophobicity of the environment. This work paves a fascinating way for the generation of excitation-dependent FONs from a small organic fluorophore and highlights its potency as an exclusive imaging tool.

Influence of nitric oxide signaling mechanisms in cancer

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

Opportunities for Nitric Oxide in Potentiating Cancer Immunotherapy

Despite nearly 30 years of development and recent highlights of nitric oxide (NO) donors and NO delivery systems in anticancer therapy, the limited understanding of exogenous NO's effects on the immune system has prevented their advancement into clinical use. In particular, the effects of exogenously delivered NO differing from that of endogenous NO has obscured how the potential and functions of NO in anticancer therapy may be estimated and exploited despite the accumulating evidence of NO's cancer therapy-potentiating effects on the immune system. After introducing their fundamentals and characteristics, this review discusses the current mechanistic understanding of NO donors and delivery systems in modulating the immunogenicity of cancer cells as well as the differentiation and functions of innate and adaptive immune cells. Lastly, the potential for the complex modulatory effects of NO with the immune system to be leveraged for therapeutic applications is discussed in the context of recent advancements in the implementation of NO delivery systems for anticancer immunotherapy applications. SIGNIFICANCE STATEMENT: Despite a 30-year history and recent highlights of nitric oxide (NO) donors and delivery systems as anticancer therapeutics, their clinical translation has been limited. Increasing evidence of the complex interactions between NO and the immune system has revealed both the potential and hurdles in their clinical translation. This review summarizes the effects of exogenous NO on cancer and immune cells in vitro and elaborates these effects in the context of recent reports exploiting NO delivery systems in vivo in cancer therapy applications.

New insights into the interplay between autophagy and oxidative and endoplasmic reticulum stress in neuronal cell death and survival

Autophagy is a dynamic process that maintains the normal homeostasis of cells by digesting and degrading aging proteins and damaged organelles. The effect of autophagy on neural tissue is still a matter of debate. Some authors suggest that autophagy has a protective effect on nerve cells, whereas others suggest that autophagy also induces the death of nerve cells and aggravates nerve injury. In mammals, oxidative stress, autophagy and endoplasmic reticulum stress (ERS) constitute important defense mechanisms to help cells adapt to and survive the stress conditions caused by physiological and pathological stimuli. Under many pathophysiological conditions, oxidative stress, autophagy and ERS are integrated and amplified in cells to promote the progress of diseases. Over the past few decades, oxidative stress, autophagy and ERS and their interactions have been a hot topic in biomedical research. In this review, we summarize recent advances in understanding the interactions between oxidative stress, autophagy and ERS in neuronal cell death and survival.

Serum Nitric Oxide Level Serves as a Potential Prognostic Biomarker in ACLF Patients

Background and Aim

Fewer than 50% of patients with acute-on-chronic liver failure (ACLF) recover spontaneously, and without liver transplantation, ACLF is associated with high death rates. Nitric oxide (NO) has a role in the pathogenesis of various liver disorders. We investigated if serum NO level could be used as a biomarker to predict the severity and prognosis of patients with ACLF.

Methods

Between January 2018 and September 2020, a retrospective cohort of 120 ACLF patients, as well as healthy and cirrhotic controls, was investigated. The serum NO levels were measured using a commercial ELISA kit, and Kaplan-Meier survival analysis was conducted.

Results

ACLF patients had significantly higher serum NO levels than healthy and cirrhotic controls. Multivariate analysis indicated that the serum NO level (HR=1.078, 95% CI 1.031-1.126, P<0.01), as well as the Model for End-stage Liver Disease (MELD) score, may be an affordable, easily available, and significant independent predictive marker for mortality. In ACLF patients, a serum NO level of > 53.5 μmol/L was associated with a significant increase in the risk of mortality or liver transplantation. A combination of serum NO level and MELD score to assess the severity and prognosis of ACLF patients showed enhanced performance.

Conclusion

Based on serum NO levels at the time of hospital admission, ACLF patients may be divided into high-risk and low-risk groups. The combination of serum NO level and MELD score is more closely linked to the patient's outcome than either value alone. This method might be used to evaluate patient prognoses and select candidates for liver transplantation.

The change rate in serum nitric oxide may affect lenvatinib therapy in hepatocellular carcinoma

Background

Lenvatinib is appropriate for reducing the production of nitric oxide (NO) and facilitating as block angiogenesis. However, to our knowledge, there are no data that support the correlation between NO and clinical response in patients who received lenvatinib therapy for HCC. Therefore, we investigated the correlation between the change rate of NO levels and clinical responses including adverse events (AEs) after lenvatinib therapy for unresectable hepatocellular carcinoma (HCC).

Methods

This study was conducted using previously collected data from another study. We enrolled 70 patients who received lenvatinib for advanced or unresectable HCC. NO was measured by converting nitrate (NO₃⁻) to nitrite (NO₂⁻) with nitrate reductase, followed by quantitation of NO₂⁻ based on Griess reagent. To determine whether lenvatinib influences NO in unresectable HCC, we evaluated the influence of the change rate of NO from baseline after administration of lenvatinib on maximal therapeutic response and SAE.

Results

After lenvatinib administration, a change rate in the NO from 0.27 to 4.16 was observed. There was no difference between the clinical response to lenvatinib and the change rate of NO (p = 0.632). However, the change rate of NO was significantly lower in patients with AEs than in those without AEs (p = 0.030). When a reduction in NO rate of < 0.8 was defined as a clinically significant reduction of NO (CSRN), the CSRN group had significantly worse progression-free survival (PFS) and overall survival (OS) than the non-CSRN group (p = 0.029 and p = 0.005, respectively).

Conclusion

Decreased NO levels were associated with the occurrence of AEs and worse prognosis after lenvatinib administration. Change rate in serum NO can be used as predictive markers in patients receiving lenvatinib therapy for HCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-10002-x.

Nitric oxide-containing supramolecular polypeptide nanomedicine based on [2]biphenyl-extended-pillar[6]arenes for drug resistance reversal

A kind of supramolecular polypeptide nanomedicine (BPC/DOX-ICG) was constructed with an anionic water-soluble [2]biphenyl-extended-pillar[6]arene (AWBpP6), and pyridinium-terminal- and S-nitrosothiol (SNO)-modified polypeptide (PPNC) via host-guest interactions to co-deliver doxorubicin (DOX) and indocyanine green (ICG) for drug resistance reversal. Upon near-infrared (NIR) irradiation, the NO generation could down-regulate the P-glycoprotein (P-gp) expression level to reverse multidrug resistance (MDR). Subsequently, the resulting reverse MDR could sensitize the free DOX and assist photothermal therapy (PTT) to enhance the tumoricidal potential. This supramolecular polypeptide nanomedicine provides an effective strategy for the multimodal synergistic therapies of photothermal therapy, NO generation therapy, and chemotherapy (i.e., PTT-NO-CT) to overcome MDR.

The Role of Nitric Oxide in Stem Cell Biology

Nitric oxide (NO) is a gaseous biomolecule endogenously synthesized with an essential role in embryonic development and several physiological functions, such as regulating mitochondrial respiration and modulation of the immune response. The dual role of NO in embryonic stem cells (ESCs) has been previously reported, preserving pluripotency and cell survival or inducing differentiation with a dose-dependent pattern. In this line, high doses of NO have been used in vitro cultures to induce focused differentiation toward different cell lineages being a key molecule in the regenerative medicine field. Moreover, optimal conditions to promote pluripotency in vitro are essential for their use in advanced therapies. In this sense, the molecular mechanisms underlying stemness regulation by NO have been studied intensively over the current years. Recently, we have reported the role of low NO as a hypoxia-like inducer in pluripotent stem cells (PSCs), which supports using this molecule to maintain pluripotency under normoxic conditions. In this review, we stress the role of NO levels on stem cells (SCs) fate as a new approach for potential cell therapy strategies. Furthermore, we highlight the recent uses of NO in regenerative medicine due to their properties regulating SCs biology.

Antibody-drug conjugate as targeted therapeutics against hepatocellular carcinoma: preclinical studies and clinical relevance

An antibody-drug conjugate (ADC) is an advanced chemotherapeutic option with immense promises in treating many tumor. They are designed to selectively attack and kill neoplastic cells with minimal toxicity to normal tissues. ADCs are complex engineered immunoconjugates that comprise a monoclonal antibody for site-directed delivery and cytotoxic payload for targeted destruction of malignant cells. Therefore, it enables the reduction of off-target toxicities and enhances the therapeutic index of the drug. Hepatocellular carcinoma (HCC) is a solid tumor that shows high heterogeneity of molecular phenotypes and is considered the second most common cause of cancer-related death. Studies show enormous potential for ADCs targeting GPC3 and CD24 and other tumor-associated antigens in HCC with their high, selective expression and show potential outputs in preclinical evaluations. The review mainly highlights the preclinical evaluation of different antigen-targeted ADCs such as MetFab-DOX, Anti-c-Met IgG-OXA, Anti CD 24, ANC-HN-01, G7mab-DOX, hYP7-DCand hYP7-PC, Anti-CD147 ILs-DOX and AC133-vcMMAF against hepatocellular carcinoma and its future relevance.

Sirtuin 7 Regulates Nitric Oxide Production and Apoptosis to Promote Mycobacterial Clearance in Macrophages

The host immune system plays a pivotal role in the containment of Mycobacterium tuberculosis (Mtb) infection, and host-directed therapy (HDT) is emerging as an effective strategy to treat tuberculosis (TB), especially drug-resistant TB. Previous studies revealed that expression of sirtuin 7 (SIRT7), a nicotinamide adenine dinucleotide (NAD⁺)-dependent deacetylase, was downregulated in macrophages after Mycobacterial infection. Inhibition of SIRT7 with the pan-sirtuin family inhibitor nicotinamide (NAM), or by silencing SIRT7 expression, promoted intracellular growth of Mtb and restricted the generation of nitric oxide (NO). Addition of the exogenous NO donor SNAP abrogated the increased bacterial burden in NAM-treated or SIRT7-silenced macrophages. Furthermore, SIRT7-silenced macrophages displayed a lower frequency of early apoptotic cells after Mycobacterial infection, and this could be reversed by providing exogenous NO. Overall, this study clarified a SIRT7-mediated protective mechanism against Mycobacterial infection through regulation of NO production and apoptosis. SIRT7 therefore has potential to be exploited as a novel effective target for HDT of TB.

Pseudomonas aeruginosa PcrV Enhances the Nitric Oxide-Mediated Tumoricidal Activity of Tumor-Associated Macrophages via a TLR4/PI3K/AKT/mTOR-Glycolysis-Nitric Oxide Circuit

Tumor-associated macrophages (TAMs), which display a tumor-supportive M2 phenotype, are closely related to tumor growth and metastasis. The reprogramming of TAMs toward a tumoricidal M1 profile has emerged as an attractive strategy for cancer immunotherapy. In this study, we found that the intratumoral injection of PcrV protein, a component of the Pseudomonas aeruginosa type 3 secretion system, suppressed tumor growth and increased apoptosis, inducible nitric oxide synthase (iNOS) expression, and the percentage of M1-polarized TAMs in tumor tissues. Furthermore, the intratumoral injection of PcrV-primed macrophages exerted a similar tumoricidal effect. In vitro analyses revealed that PcrV reeducated TAMs toward an antitumoral M1 phenotype and augmented their nitric oxide (NO)-mediated cytotoxicity against cancer cells. Mechanistically, we found that these effects were dependent on the activation of Toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)-mediated regulation of a PI3K/AKT/mTOR-glycolysis-NO feedback loop via direct interaction with TLR4. Collectively, these results revealed a potential role for PcrV in cancer immunotherapy through the targeting of TAM plasticity.

Unfolding the role of autophagy in the cancer metabolism

Autophagy is considered an indispensable process that scavenges toxins, recycles complex macromolecules, and sustains the essential cellular functions. In addition to its housekeeping role, autophagy plays a substantial role in many pathophysiological processes such as cancer. Certainly, it adapts cancer cells to thrive in the stress conditions such as hypoxia and starvation. Cancer cells indeed have also evolved by exploiting the autophagy process to fulfill energy requirements through the production of metabolic fuel sources and fundamentally altered metabolic pathways. Occasionally autophagy as a foe impedes tumorigenesis and promotes cell death. The complex role of autophagy in cancer makes it a potent therapeutic target and has been actively tested in clinical trials. Moreover, the versatility of autophagy has opened new avenues of effective combinatorial therapeutic strategies. Thereby, it is imperative to comprehend the specificity of autophagy in cancer-metabolism. This review summarizes the recent research and conceptual framework on the regulation of autophagy by various metabolic pathways, enzymes, and their cross-talk in the cancer milieu, including the implementation of altered metabolism and autophagy in clinically approved and experimental therapeutics.

NSAIDs: Old Acquaintance in the Pipeline for Cancer Treatment and Prevention─Structural Modulation, Mechanisms of Action, and Bright Future

The limitations of current chemotherapeutic drugs are still a major issue in cancer treatment. Thus, targeted multimodal therapeutic approaches need to be strategically developed to successfully control tumor growth and prevent metastatic burden. Inflammation has long been recognized as a hallmark of cancer and plays a key role in the tumorigenesis and progression of the disease. Several epidemiological, clinical, and preclinical studies have shown that traditional nonsteroidal anti-inflammatory drugs (NSAIDs) exhibit anticancer activities. This Perspective reports the most recent outcomes for the treatment and prevention of different types of cancers for several NSAIDs alone or in combination with current chemotherapeutic drugs. Furthermore, an extensive review of the most promising structural modifications is reported, such as phospho, H₂S, and NO releasing-, selenium-, metal complex-, and natural product-NSAIDs, among others. We also provide a perspective about the new strategies used to obtain more efficient NSAID- or NSAID derivative- formulations for targeted delivery.

Functional Amino Acids and Autophagy: Diverse Signal Transduction and Application

Functional amino acids provide great potential for treating autophagy-related diseases by regulating autophagy. The purpose of the autophagy process is to remove unwanted cellular contents and to recycle nutrients, which is controlled by many factors. Disordered autophagy has been reported to be associated with various diseases, such as cancer, neurodegeneration, aging, and obesity. Autophagy cannot be directly controlled and dynamic amino acid levels are sufficient to regulate autophagy. To date, arginine, leucine, glutamine, and methionine are widely reported functional amino acids that regulate autophagy. As a signal relay station, mammalian target of rapamycin complex 1 (mTORC1) turns various amino acid signals into autophagy signaling pathways for functional amino acids. Deficiency or supplementation of functional amino acids can immediately regulate autophagy and is associated with autophagy-related disease. This review summarizes the mechanisms currently involved in autophagy and amino acid sensing, diverse signal transduction among functional amino acids and autophagy, and the therapeutic appeal of amino acids to autophagy-related diseases. We aim to provide a comprehensive overview of the mechanisms of amino acid regulation of autophagy and the role of functional amino acids in clinical autophagy-related diseases and to further convert these mechanisms into feasible therapeutic applications.

Gene Expression Characteristics of Liver Tissue Reveal the Underlying Pathogenesis of Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) is high-mortality primary liver cancer and the most common malignant tumor in the world. This study is based on a hepatocellular carcinoma-related dysfunction module designed to explore the dysregulation of genes in liver cancer tissue.

Methods

By downloading the relevant data on the GEO database, we performed a differential analysis of healthy liver tissue and liver cancer tissues as well as healthy liver tissue and hepatocellular carcinoma tissue and then obtained two sets of differential genes and combined them. We performed a cointerpretation analysis of these differential genes and constructed related functional disorder modules. A hypergeometric test was performed to calculate the potential regulatory effects of multiple factors on the module, and a series of ncRNA and TF regulators were identified. We obtained a total of 4479 differentially expressed genes in hepatocellular carcinoma, and these genes were clustered into ten hepatocellular carcinoma-related functional interpretation disorder modules.

Results

Enrichment analysis revealed that these modular genes are mainly involved in signal transduction including cell cycle, TGF-beta signal transduction, and p53 signal transduction. Depending on the predictive analysis of multidimensional regulators, 323 ncRNAs and 52 TF-mediated hepatocellular carcinoma-related dysregulation modules were found to regulate disease progression.

Conclusions

Based on a series of investigations, it was found that miR-30b-5p may participate in the peroxisome signal transduction by downregulating ABCD3-mediated module 1, thereby promoting the development and progression of hepatocellular carcinoma. Our research results not only provide a theoretical basis for biologists to study hepatocellular carcinoma further but also offer new methods and new ideas for the personalized care and treatment of hepatocellular carcinoma.

Inherently nitric oxide containing polymersomes remotely regulated by NIR for improving multi-modal therapy on drug resistant cancer

The therapeutic potential of nitric oxide (NO) has been highly attractive to tumor treatment, especially for surmounting the multidrug resistance (MDR) of cancer. However, the NO-involved therapy remains extremely challenging because of the difficulty to simultaneously control the NO release rate and real-time concentration. Herein, we construct NO-containing polymersomes with high amount of NO donors inherently grown on the polymer chains to keep the stability. These polymersomes can be simultaneously loaded with photosensitizer of IR780 iodide on the membrane layer and chemotherapeutic of DOX·HCl in the lumen. NO release can be triggered by the reduction conditions, and further accelerated by remote NIR irradiation due to the increased local temperature. The instantaneous NO release with high concentration significantly inhibits the P-gp expression and sensitize the chemotherapy, thus overcoming the tumor MDR and improving the anti-tumor activity. Meanwhile, DOX·HCl release is highly promoted at the intracellular conditions because of the cleavage of acid-labile cis-aconitic amide at endo/lysosomal pH, and the improved hydrophilicity of the membrane layer after NO release. The in vivo results show that the single intravenous injection of polymersome formulation companying with NIR irradiation exerts multi-modal therapies of chemotherapy, PTT/PDT, and NO-therapy on the MCF-7/R tumor models, showing superior and combinational treatment efficacy with the complete eradication of tumors and few side effects.

The Etiology and Pathophysiology Genesis of Benign Prostatic Hyperplasia and Prostate Cancer: A New Perspective

Background: The etiology of benign prostatic hyperplasia and prostate cancer are unknown, with ageing being the greatness risk factor. Methods: This new perspective evaluates the available interdisciplinary evidence regarding prostate ageing in terms of the cell biology of regulation and homeostasis, which could explain the timeline of evolutionary cancer biology as degenerative, inflammatory and neoplasm progressions in these multifactorial and heterogeneous prostatic diseases. Results: This prostate ageing degeneration hypothesis encompasses the testosterone-vascular-inflamm-ageing triad, along with the cell biology regulation of amyloidosis and autophagy within an evolutionary tumorigenesis microenvironment. Conclusions: An understanding of these biological processes of prostate ageing can provide potential strategies for early prevention and could contribute to maintaining quality of life for the ageing individual along with substantial medical cost savings.

Role of Nitric Oxide in Gene Expression Regulation during Cancer: Epigenetic Modifications and Non-Coding RNAs

Nitric oxide (NO) has been identified and described as a dual mediator in cancer according to dose-, time- and compartment-dependent NO generation. The present review addresses the different epigenetic mechanisms, such as histone modifications and non-coding RNAs (ncRNAs), miRNA and lncRNA, which regulate directly or indirectly nitric oxide synthase (NOS) expression and NO production, impacting all hallmarks of the oncogenic process. Among lncRNA, HEIH and UCA1 develop their oncogenic functions by inhibiting their target miRNAs and consequently reversing the inhibition of NOS and promoting tumor proliferation. The connection between miRNAs and NO is also involved in two important features in cancer, such as the tumor microenvironment that includes key cellular components such as tumor-associated macrophages (TAMs), cancer associated fibroblasts (CAFs) and cancer stem cells (CSCs).

Autophagy, an accomplice or antagonist of drug resistance in HCC?

Hepatocellular carcinoma (HCC) is a highly lethal malignancy characterized by poor prognosis and a low 5-year survival rate. Drug treatment is proving to be effective in anti-HCC. However, only a small number of HCC patients exhibit sensitive responses, and drug resistance occurs frequently in advanced patients. Autophagy, an evolutionary process responsible for the degradation of cellular substances, is closely associated with the acquisition and maintenance of drug resistance for HCC. This review focuses on autophagic proteins and explores the intricate relationship between autophagy and cancer stem cells, tumor-derived exosomes, and noncoding RNA. Clinical trials involved in autophagy inhibition combined with anticancer drugs are also concerned.

Micromonospora species from rarely-exploited Egyptian habitats: chemical profile, antimicrobial, and antitumor activities through antioxidant property

The development of new anticancer agents with a selective action mechanism has become a significant scientific challenge, especially as cancers remain the world's leading cause of death. Actinobacteria and its bioactive compounds have recently become a promising perspective alternative to cancer therapy. In this study, some extracted metabolites of Micromonospora exhibited potent antimicrobial with microbial inhibition zone ≥ 7 mm, and cytotoxic activities against MCF-7 and HepG2 cell lines with promising activities ≥ 85%. Additionally, treatment of DENA/CCl4 rats with the strain Micromonospora sp1 has induced a substantial amelioration of the liver functions, enhancing liver architecture near normal and antioxidant properties through elevation of antioxidant enzyme levels. So that these preliminary results can provide metabolites from Micromonospora sp1 as an anti-liver cancer therapy. Finally, we introduced the chemical profiling of Micromonospora sp1 metabolic extract by LC-QTOF-MS-MS technique, where eight compounds with reported antioxidant property anti-liver cancer activity were targeted, validated as iNOS inhibitor through molecular docking studies. The findings in this study can be a significant step towards studying natural bioactive products produced by Micromonospora spp. as agents for anti-liver cancer. KEY POINTS: • Metabolites of Micromonospora strain from unexploited Egyptian habitats were investigated with LC/MS library-based chemical profile and molecular docking studies as iNOS inhibitors. • Some Micromonospora strains exhibited potent antimicrobial with microbial inhibition zone ≥ 7 mm, and cytotoxic activities against MCF-7 and HepG2 cell lines with promising activities ≥ 85%. • Micromonospora extract exhibited anti-liver cancer activity in vivo through the antioxidant property by inhibiting the liver cancer biomarkers (LDH and AFP) and enhancing other biochemical parameters.

Suppression of optineurin impairs the progression of hepatocellular carcinoma through regulating mitophagy

Autophagy removes damaged organelles to inhibit malignant transformation during tumor initiation. Once a cancer matures, it uses the autophagic pathway as an energy source. Optineurin (OPTN) is an autophagy adaptor protein that recruits microtubule‐associated protein 1 light chain 3, an autophagosome marker, to the autophagosome. Despite studies of the relation between cancer progression and autophagy adaptor proteins, there are no reports to our knowledge of a correlation between hepatocellular carcinoma (HCC) and OPTN. We aimed here to investigate the effects of OPTN expression on HCC progression through autophagy. Immunohistochemistry was used to measure the OPTN expression in the tissues of 141 Japanese patients with HCC. The effects of OPTN expression on HCC progression and mitophagy were assessed using an OPTN knockout (KO) cell line in vitro. We used this KO cell line to establish and exploit a mouse model of HCC to determine the effects of OPTN expression on tumor progression. Immunohistochemical analysis showed that patients with elevated expression of OPTN experienced shorter overall survival (OS) and recurrence‐free survival (RFS). OPTN KO cells proliferated relatively slower versus wild‐type (WT) cells in vitro. Western blot analysis showed that mitophagy was suppressed in OPTN KO cells, and ATP synthesis and beta‐oxidation were reduced. The mouse model of HCC showed that OPTN KO cells formed smaller tumors versus WT cells less 10 weeks after implantation. Overall, the present findings suggest that OPTN is a key mediator of mitophagy that contributes to HCC progression through mitochondrial energy production.

Overview of bile acid signaling in the cardiovascular system

Bile acids (BAs) are classically known to play a vital role in the metabolism of lipids and in absorption. It is now well established that BAs act as signaling molecules, activating different receptors (such as farnesoid X receptor, vitamin D receptor, Takeda G-protein-coupled receptor 5, sphingosine-1-phosphate, muscarinic receptors, and big potassium channels) and participating in the regulation of energy homeostasis and lipid and glucose metabolism. In addition, increased BAs can impair cardiovascular function in liver cirrhosis. Approximately 50% of patients with cirrhosis develop cirrhotic cardiomyopathy. Exposure to high concentrations of hydrophobic BAs has been shown to be related to adverse effects with respect to vascular tension, endothelial function, arrhythmias, coronary atherosclerotic heart disease, and heart failure. The BAs in the serum BA pool have relevant through their hydrophobicity, and the lipophilic BAs are more harmful to the heart. Interestingly, ursodeoxycholic acid is a hydrophilic BA, and it is used as a therapeutic drug to reverse and protect the harmful cardiac effects caused by hydrophobic elevated BAs. In order to elucidate the mechanism of BAs and cardiovascular function, abundant experiments have been conducted in vitro and in vivo. The aim of this review was to explore the mechanism of BAs in the cardiovascular system.

Nitric oxide induces HepG2 cell death via extracellular signal-regulated protein kinase activation by regulating acid sphingomyelinase

Nitric oxide (NO) plays a vital role in the occurrence and development of tumours. Acid sphingomyelinase (ASM) participates in cell apoptosis, cell proliferation, metabolism and other biological processes. However, whether ASM has an effect on NO-treated HepG2 cells remains unknown, and the role of the extracellular signal-regulated protein kinase (ERK) pathway is also unclear. In the present study, the effects of NO on cell viability and apoptosis were assayed, followed by investigating the mRNA and protein levels of ASM and ERK phosphorylation in NO-treated HepG2 cells. The results showed that diethylenetriamine/NO (DETA-NO), an NO donor, promoted HepG2 cell death and apoptosis in a concentration-dependent manner and that the mRNA and protein expression levels of ASM were significantly decreased in DETA-NO-treated HepG2 cells. Moreover, ERK phosphorylation was significantly increased in DETA-NO-treated HepG2 cells. The inhibition of ERK phosphorylation increased DETA-NO-induced cell apoptosis. In summary, DETA-NO can promote HepG2 cell death in a concentration-dependent manner by activating ERK and NO might activate ERK by regulating ASM and then inducing HepG2 cell death.

Complex interplay between autophagy and oxidative stress in the development of pulmonary disease

The autophagic pathway involves the encapsulation of substrates in double-membraned vesicles, which are subsequently delivered to the lysosome for enzymatic degradation and recycling of metabolic precursors. Autophagy is a major cellular defense against oxidative stress, or related conditions that cause accumulation of damaged proteins or organelles. Selective forms of autophagy can maintain organelle populations or remove aggregated proteins. Dysregulation of redox homeostasis under pathological conditions results in excessive generation of reactive oxygen species (ROS), leading to oxidative stress and the associated oxidative damage of cellular components. Accumulating evidence indicates that autophagy is necessary to maintain redox homeostasis. ROS activates autophagy, which facilitates cellular adaptation and diminishes oxidative damage by degrading and recycling intracellular damaged macromolecules and dysfunctional organelles. The cellular responses triggered by oxidative stress include the altered regulation of signaling pathways that culminate in the regulation of autophagy. Current research suggests a central role for autophagy as a mammalian oxidative stress response and its interrelationship to other stress defense systems. Altered autophagy phenotypes have been observed in lung diseases such as chronic obstructive lung disease, acute lung injury, cystic fibrosis, idiopathic pulmonary fibrosis, and pulmonary arterial hypertension, and asthma. Understanding the mechanisms by which ROS regulate autophagy will provide novel therapeutic targets for lung diseases. This review highlights our current understanding on the interplay between ROS and autophagy in the development of pulmonary disease.

Nitric oxide affects cisplatin cytotoxicity oppositely in A2780 and A2780-CDDP cells via the connexin32/gap junction

Chemoresistance is a main obstacle in ovarian cancer therapy and new treatment strategies and further information regarding the mechanism of the medication cisplatin are urgently needed. Nitric oxide has a critical role in modulating the activity of chemotherapeutic drugs. Our previous work showed that connexin32 contributed to cisplatin resistance. However, whether nitric oxide is involved in connexin32-mediated cisplatin resistance remains unknown. In this study, using A2780 and A2780 cisplatin-resistant cells, we found that S-nitroso-N-acetyl-penicillamine, a nitric oxide donor, attenuated cisplatin toxicity by decreasing gap junctions in A2780 cells. Enhancement of gap junctions using retinoic acid reversed the effects of S-nitroso-N-acetyl-penicillamine on cisplatin toxicity. In A2780 cisplatin-resistant cells, however, S-nitroso-N-acetyl-penicillamine enhanced cisplatin toxicity by decreasing connexin32 expression. Downregulation of connexin32 expression by small interfering RNA exacerbated the effects of S-nitroso-N-acetyl-penicillamine on cisplatin cytotoxicity and upregulation of connexin32 expression by pcDNA transfection reversed the effects of S-nitroso-N-acetyl-penicillamine on cisplatin cytotoxicity. Our study suggests for the first time that combining cisplatin with nitric oxide in clinical therapies for ovarian cancer should be avoided before cisplatin resistance emerges. The present study provides a productive area of further study for increasing the efficacy of cisplatin by combining cisplatin with the specific inhibitors or enhancers of nitric oxide in clinical treatment.

Natural compounds modulate the crosstalk between apoptosis- and autophagy-regulated signaling pathways: Controlling the uncontrolled expansion of tumor cells

Due to the high number of annual cancer-related deaths, and the economic burden that this malignancy affects today's society, the study of compounds isolated from natural sources should be encouraged. Most cancers are the result of a combined effect of lifestyle, environmental factors, and genetic and hereditary components. Recent literature reveals an increase in the interest for the study of phytochemicals from traditional medicine, this being a valuable resource for modern medicine to identify novel bioactive agents with potential medicinal applications. Phytochemicals are components of traditional medicine that are showing promising application in modern medicine due to their antitumor activities. Recent studies regarding two major mechanisms underlying cancer development and regulation, apoptosis and autophagy, have shown that the signaling pathways of both these processes are significantly interconnected through various mechanisms of crosstalk. Phytochemicals are able to activate pro-autophagic and pro-apoptosis mechanisms. Understanding the molecular mechanism involved in apoptosis-autophagy relationship modulated by phytochemicals plays a key role in development of a new therapeutic strategy for cancer treatment. The purpose of this review is to outline the bioactive properties of the natural phytochemicals with validated antitumor activity, focusing particularly on their role in the regulation of apoptosis and autophagy crosstalk that triggers the uncontrolled expansion of tumor cells. Furthermore, we have also critically discussed the limitations and challenges of existing research strategies and the prospective research directions in this field.

Sensitizing activities of nitric oxide donors for cancer resistance to anticancer therapeutic drugs

Cancer is not a single disease but it constitutes a large variety of different types that are also different from each other phenotypically and molecularly. Although the standard treatments have resulted in clinical responses in a subset of patients, though, many patients relapse and no longer respond to further treatments. Hence, both the innate and adaptive resistance to treatments are the main challenges in today's treatment strategies. Noteworthy, several novel treatment strategies, particularly immunotherapies, used alone or in combination, have been developed and that have significantly improved the therapeutic response of many unresponsive cancer patients. Nevertheless, even with the latest new developments of therapeutics that were effective in a larger subset of patients, there is still an urgent need to treat the remaining unresponsive subset of patients. This requires the development of new targeting agents of superior antitumor activities that will lead to overcoming the unaffected resistance by current treatments. There has been accumulating evidence suggesting nitric oxide donors as such targeting agents and considering their pleiotropic antitumor activities, including both the reversal of chemo and immuno-resistance of various unresponsive resistant cancers. The in vitro and in vivo preclinical findings corroborate the sensitizing antitumor activities of nitric oxide donors. In addition, a few clinical findings with NO donors that have been applied in patients have corroborated their antitumor and sensitizing activities in combination with standard therapies. In this review, the role and underlying mechanisms by which nitric oxide donors sensitize cancer resistant cells to both chemotherapy and immunotherapy are briefly described.