Autophagy induced by cathepsin S inhibition induces early ROS production, oxidative DNA damage, and cell death via xanthine oxidase

Cysteine cathepsins: From diagnosis to targeted therapy of cancer

Cysteine cathepsins are a fascinating group of proteolytic enzymes that play diverse and crucial roles in numerous biological processes, both in health and disease. Understanding these proteases is essential for uncovering novel insights into the underlying mechanisms of a wide range of disorders, such as cancer. Cysteine cathepsins influence cancer biology by participating in processes such as extracellular matrix degradation, angiogenesis, immune evasion, and apoptosis. In this comprehensive review, we explore foundational research that illuminates the diverse and intricate roles of cysteine cathepsins as diagnostic markers and therapeutic targets for cancer. This review aims to provide valuable insights into the clinical relevance of cysteine cathepsins and explore their capacity to advance personalised and targeted medical interventions in oncology.

Redox dysregulation as a driver for DNA damage and its relationship to neurodegenerative diseases

Redox homeostasis refers to the balance between the production of reactive oxygen species (ROS) as well as reactive nitrogen species (RNS), and their elimination by antioxidants. It is linked to all important cellular activities and oxidative stress is a result of imbalance between pro-oxidants and antioxidant species. Oxidative stress perturbs many cellular activities, including processes that maintain the integrity of DNA. Nucleic acids are highly reactive and therefore particularly susceptible to damage. The DNA damage response detects and repairs these DNA lesions. Efficient DNA repair processes are therefore essential for maintaining cellular viability, but they decline considerably during aging. DNA damage and deficiencies in DNA repair are increasingly described in age-related neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and Huntington's disease. Furthermore, oxidative stress has long been associated with these conditions. Moreover, both redox dysregulation and DNA damage increase significantly during aging, which is the biggest risk factor for neurodegenerative diseases. However, the links between redox dysfunction and DNA damage, and their joint contributions to pathophysiology in these conditions, are only just emerging. This review will discuss these associations and address the increasing evidence for redox dysregulation as an important and major source of DNA damage in neurodegenerative disorders. Understanding these connections may facilitate a better understanding of disease mechanisms, and ultimately lead to the design of better therapeutic strategies based on preventing both redox dysregulation and DNA damage.

Cathepsin S (CTSS) activity in health and disease - A treasure trove of untapped clinical potential

Amongst the lysosomal cysteine cathepsin family of proteases, cathepsin S (CTSS) holds particular interest due to distinctive properties including a normal restricted expression profile, inducible upregulation and activity at a broad pH range. Consequently, while CTSS is well-established as a member of the proteolytic cocktail within the lysosome, degrading unwanted and damaged proteins, it has increasingly been shown to mediate a number of distinct, more selective roles including antigen processing and antigen presentation, and cleavage of substrates both intra and extracellularly. Increasingly, aberrant CTSS expression has been demonstrated in a variety of conditions and disease states, marking it out as both a biomarker and potential therapeutic target. This review seeks to contextualise CTSS within the cysteine cathepsin family before providing an overview of the broad range of pathologies in which roles for CTSS have been identified. Additionally, current clinical progress towards specific inhibitors is detailed, updating the position of the field in exploiting this most unique of proteases.

Cyclo(-Phe-Phe) alleviates chick embryo liver injury via activating the Nrf2 pathway

Excessive reactive oxygen species (ROS) accumulation is involved in the pathogenesis of liver fibrosis and damage, specifically in the developing embryo that is extremely sensitive to oxidative stress. Herein, a liver injury model in chick embryo was established by using 2,2-azobis (2-amidinopropane) dihydrochloride (AAPH), which was used to investigate the effect of cyclo(-Phe-Phe) (CPP), a natural dipeptide found in foods and beverages. The results showed that CPP significantly alleviated AAPH-induced liver pathological damage, hepatic dysfunction and inhibited the excessive production of ROS in both chick embryo liver and HepG2 cells. Additionally, CPP increased the antioxidative activity of glutathione peroxidase (GPx) and superoxide dismutase (SOD), as well as elevated the level of glutathione (GSH), suggesting that CPP combating liver injury probably depends on its antioxidant capability. Mechanistically, CPP upregulated the mRNA and protein expression of heme oxyense-1 (HO-1) and NADPH quinone oxidoreductase 1 (NQO1) in vivo and in vitro, along with promoting the translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) while inhibiting its degradation through binding with Kelch-like ECH-associated protein 1 (Keap1). In conclusion, this study proposes a potential peptide drug for the treatment of hepatic damage induced by oxidative stress and also unravels its mechanism of action.

The double faced role of xanthine oxidoreductase in cancer

Xanthine oxidoreductase (XOR) is a critical, rate-limiting enzyme that controls the last two steps of purine catabolism by converting hypoxanthine to xanthine and xanthine to uric acid. It also produces reactive oxygen species (ROS) during the catalytic process. The enzyme is generally recognized as a drug target for the therapy of gout and hyperuricemia. The catalytic products uric acid and ROS act as antioxidants or oxidants, respectively, and are involved in pro/anti-inflammatory actions, which are associated with various disease manifestations, including metabolic syndrome, ischemia reperfusion injury, cardiovascular disorders, and cancer. Recently, extensive efforts have been devoted to understanding the paradoxical roles of XOR in tumor promotion. Here, we summarize the expression of XOR in different types of cancer and decipher the dual roles of XOR in cancer by its enzymatic or nonenzymatic activity to provide an updated understanding of the mechanistic function of XOR in cancer. We also discuss the potential to modulate XOR in cancer therapy.

Evaluation of serum levels of cathepsin S among colorectal cancer patients

Objective

Colorectal cancer is the third most common cancer worldwide. Cathepsins are protease that are known to be involved in cancer progression and metastasis. The aim of this study is to evaluate the levels of serum cathepsin S in patients and control subjects and its effects on the prognosis of the cancer.

Methods

In this case-control study, colorectal cancer patients referred to our gastroenterology clinic were included. The control group consisted of healthy individuals. Cathepsin S levels were analyzed in these patients and the check list consisting of demographic data, cancer stage, colonoscopy findings, CEA marker and cathepsin S levels were recorded.

Results

Of 80 patients and healthy controls included in the study, age, gender and BMI were not significantly different among the two groups, p = 0.265, p = 0.752 and p = 0.2, respectively. Cathepsin S levels were significantly greater in-patient group p < 0.001 and was significantly correlated with the stage of the tumor. CEA marker was also linear related with the increased levels of cathepsin S, p < 0.001.

Conclusion

Our study concluded that cathepsin S is elevated in the cancer patients and can be a significant marker for the prognosis of colorectal cancer.

Lysosomal peptidases – Intriguing roles in cancer progression and neurodegeneration

Lysosomal peptidases are hydrolytic enzymes capable of digesting waste proteins that are targeted to lysosomes via endocytosis and autophagy. Besides intracellular protein catabolism, they play more specific roles in several other cellular processes and pathologies, either within lysosomes, upon secretion into the cell cytoplasm or extracellular space, or bound to the plasma membrane. In cancer, lysosomal peptidases are generally associated with disease progression, as they participate in crucial processes leading to changes in cell morphology, signaling, migration, and invasion, and finally metastasis. However, they can also enhance the mechanisms resulting in cancer regression, such as apoptosis of tumor cells or antitumor immune responses. Lysosomal peptidases have also been identified as hallmarks of aging and neurodegeneration, playing roles in oxidative stress, mitochondrial dysfunction, abnormal intercellular communication, dysregulated trafficking, and the deposition of protein aggregates in neuronal cells. Furthermore, deficiencies in lysosomal peptidases may result in other pathological states, such as lysosomal storage disease. The aim of this review was to highlight the role of lysosomal peptidases in particular pathological processes of cancer and neurodegeneration and to address the potential of lysosomal peptidases in diagnosing and treating patients.

SPOCD1 regulated by miR-133a-3p promotes hepatocellular carcinoma invasion and metastasis

Objective

To investigate the tumorigenic role of spen paralogue and orthologue C-terminal domain-containing 1 (SPOCD1) in hepatocellular carcinoma (HCC) and identify the upstream regulatory mechanism.

Methods

We analyzed SPOCD1 and miR-133-3p expression in normal and HCC tissues from the Cancer Genome Atlas and UALCAN databases, and in normal hepatocytes and HCC cell lines by real-time quantitative polymerase chain reaction and western blot. We identified the miR-133a-3p-binding site on the SPOCD1 3ʹ-untranslated region using TargetScan. Hierarchical regulation was confirmed by luciferase assay and miR-133a-3p overexpression/silencing. Cell proliferation, migration, invasion, and colony formation were assessed by MTT, scratch, transwell, and clonogenic assays, respectively.

Results

SPOCD1 was highly expressed in HCC tissues and cell lines, while miR-133a-3p expression was significantly downregulated. Kaplan–Meier analysis indicated that high SPOCD1 expression was significantly associated with poor survival. TargetScan and luciferase reporter assay revealed that SPOCD1 was the downstream target of miR-133a-3p. Overexpression of miR-133a-3p significantly inhibited the expression of SPOCD1, while miR-133a-3p knockdown significantly increased SPOCD1 expression.

Conclusion

SPOCD1, regulated by miR-133a-3p, promotes HCC cell proliferation, migration, invasion, and colony formation. This study provides the first evidence for the role of the miR-133a-3p/SPOCD1 axis in HCC tumorigenesis.

The "Dark Side" of autophagy on the maintenance of genome stability: Does it really exist during excessive activation?

Dysregulation of DNA damage response/repair and genomic instability promote tumorigenesis and the development of various neurological diseases. Autophagy is a dynamic catabolic process used for removing unnecessary or dysfunctional proteins and organelles in cells. Despite the consensus in the field that upregulation of autophagy promotes the initiation of the DNA damage response and assists the process of homologous recombination upon genotoxic stress, a few studies showed that upregulation of autophagy (or excessive autophagy), under certain circumstances, triggers caspase/apoptosis-independent DNA damage and promotes genomic instability in cells. As the cytoprotective and the DNA repairing roles of autophagy have been discussed extensively in different reviews, here, we mainly focus on describing the latest studies which reported the "opposite" roles of autophagy (or excessive autophagy). We will discuss whether the "dark side" (i.e., the opposite/unconventional effect) of autophagy on the maintenance of DNA integrity and genomic stability really does exist in cells and if it does, will it be one of the yet-to-be-identified causes of cancer, in this review.

YM155 and BIRC5 downregulation induce genomic instability via autophagy-mediated ROS production and inhibition in DNA repair

Activation of autophagy plays a critical role in DNA repair, especially for the process of homologous recombination. Despite upregulation of autophagy promotes both the survival and the death of cells, the pathways that govern the pro-cell death effects of autophagy are still incompletely understood. YM155 is originally developed as an expression suppressant of BIRC5 (an anti-apoptotic molecule) and it has reached Phase I/II clinical trials for the treatment of variety types of cancer. However, the target-specificity of YM155 has recently been challenged as several studies reported that YM155 exhibits direct DNA damaging effects. Recently, we discovered that BIRC5 is an autophagy negative-modulator. Using function-comparative analysis, we found in the current study that YM155 and BIRC5 siRNA both induced early "autophagy-dependent ROS production-mediated" DNA damage/strand breaks and concurrently downregulated the expression of RAD54L, RAD51, and MRE11, which are molecules known for their important roles in homologous recombination, in human cancer (MCF7, MDA-MB-231, and SK-BR-3) and mouse embryonic fibroblast (MEF) cells. Similar to the effects of YM155 and BIRC5 siRNA, downregulation of RAD54L and RAD51 by siRNA induced autophagy and DNA damage/strand breaks in cells, suggesting YM155/BIRC5 siRNA might also induce autophagy partly through RAD54L and RAD51 downregulations. We further observed that prolonged YM155 and BIRC5 siRNA treatment induced autophagic vesicle formation proximal to the nucleus and triggered DNA leakage. In conclusion, our findings reveal a novel mechanism of action of YM155 (i.e. induces autophagy-dependent ROS production-mediated DNA damage) in cancer cells and show the functional complexity of BIRC5 and autophagy involving the modulation of genome stability, highlighting that upregulation of autophagy is not always beneficial to the DNA repair process. Our findings can aid the development of a variety of BIRC5-directly/indirectly targeted anticancer therapies that are currently under pre-clinical and clinical investigations.

Autophagy inhibition attenuates TGF-β2-induced epithelial-mesenchymal transition in lens epithelial cells

AIMS

Autophagy has been reported to play an essential role in fibrotic disorders. Known as fibrotic cataract, posterior capsular opacification (PCO) result from pathological epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs). This study aims to identify the role and potential mechanism of autophagy in TGF-β2-induced EMT in LECs.

MAIN METHODS

Primary rabbit LECs were treated with TGF-β2 to induce EMT as a model of fibrotic cataract in vitro. 3-methyladenine, chloroquine, bafilomycin A1, and gene silencing of autophagy-related protein 7 (ATG7) were treated in LECs for autophagy inhibition, while rapamycin was utilized for autophagy activation. The expression levels of EMT/autophagy-associated markers were analyzed by qRT-PCR, western blotting, immunofluorescence and transmission electron microscopy. We additionally examined cell migration ability with transwell migration assay and wound healing assay.

KEY FINDINGS

TGF-β2 promoted autophagy flux during EMT progression of LECs in a time-dependent manner. Autophagy activation by rapamycin enhanced TGF-β2-triggered fibrogenic responses and cell migration in LECs, whereas pharmacological inhibition of autophagy alleviated TGF-β2-induced increases of EMT markers and cell migration of LECs. In addition, the phosphorylation of Smad2/3 induced by TGF-β2 was suppressed through autophagy inhibition, while it was promoted upon autophagy activation, indicating that TGF-β2/Smad signaling was involved in the modulation of autophagy on EMT in LECs. Furthermore, ATG7-silenced LECs exerted anti-fibrosis effect induced by TGF-β2 through downregulation of autophagy.

SIGNIFICANCE

Intervention/inhibition of autophagy could attenuate TGF-β2-induced EMT in LECs, which provides autophagy-related insights on preventing and treating the fibrotic cataract or other fibrotic diseases.

Overexpression of microRNA-129-5p in glioblastoma inhibits cell proliferation, migration, and colony-forming ability by targeting ZFP36L1

Glioblastoma multiforme (GBM) is a highly invasive cancer with a high recurrence rate. The prognosis of GBM patients remains poor, even after standard surgical resection combined with chemoradiotherapy. Thus, there is an urgent need for new therapeutic targets in GBM. In recent years, microRNAs have received considerable attention due to their important role in tumor development and progression. In this study, we investigated the role of miR-129-5p and miR-129-5p/ZFP36L1 axis in GBM tumorigenesis. Analysis of GSE103228 microarray data from the GEO database showed that miR-129-5p was significantly downregulated in GBM vs. normal brain tissues. Quantitative reverse transcription PCR analysis of miR-129-5p expression in seven GBM cell lines (LN229, A172, U87, T98G, U251, H4, and LN118) vs. normal human astrocytes (NHA) showed miR-129-5p was significantly downregulated in GBM cells. Overexpression of miR-129-5p in LN229 and A172 cells significantly suppressed cell proliferation, migration, invasion, and colony-forming ability. Target Scan analysis identified ZFP36L1 as the target of miR-129-5p. UALCAN dataset analysis found that ZFP36L1 was significantly upregulated in GBM vs. normal brain tissues, and high ZFP36L1 expression was positively associated with poor survival of GBM patients. Western blot analysis demonstrated that ZFP36L1 was significantly upregulated in seven GBM cell lines vs. NHA. Overexpression of miR-129-5p in LN229 and A172 cells significantly inhibited ZFP36L1 mRNA and protein expression, while overexpression of ZFP36L1 in LN229 and A172 cells reversed miR-129-5p-mediated inhibition on GBM tumorigenesis. Our results revealed an important role of miR-129-5p in the negative regulation of ZFP36L1 expression in GBM, suggesting new candidates for targeted therapy in GBM patients.

Cathepsin Inhibition Modulates Metabolism and Polarization of Tumor-Associated Macrophages

Simple Summary

Stroma-infiltrating tumor-associated macrophages (TAM) play an important role in regulating tumor progression and chemoresistance. Many tumor-infiltrating macrophage populations can be identified by preferential expression of distinct marker genes associated with an M2 phenotype and may execute tumor-promoting functions by enhancing tissue remodeling, facilitating angiogenesis, and suppressing immune responses. In this study, we aimed to characterize the impact of cathepsins in maintaining the TAM phenotype. For this purpose, we investigated the molecular effects of cathepsin inhibition on the viability and polarization of human primary macrophages as well as its metabolic consequences. Pharmacological inhibition of cathepsins B, L, and S using a novel inhibitor, GB111-NH₂, led to a polarization shift from M2- to M1 macrophages, associated with distinct alterations in lysosomal signaling and lipid metabolism. This could be therapeutically exploited in tumors with strong infiltration of M2-macrophages, thereby possibly reverting M2 polarization, overcoming drug resistance, and improving the prognosis of our patients.

Abstract

Stroma-infiltrating immune cells, such as tumor-associated macrophages (TAM), play an important role in regulating tumor progression and chemoresistance. These effects are mostly conveyed by secreted mediators, among them several cathepsin proteases. In addition, increasing evidence suggests that stroma-infiltrating immune cells are able to induce profound metabolic changes within the tumor microenvironment. In this study, we aimed to characterize the impact of cathepsins in maintaining the TAM phenotype in more detail. For this purpose, we investigated the molecular effects of pharmacological cathepsin inhibition on the viability and polarization of human primary macrophages as well as its metabolic consequences. Pharmacological inhibition of cathepsins B, L, and S using a novel inhibitor, GB111-NH₂, led to changes in cellular recycling processes characterized by an increased expression of autophagy- and lysosome-associated marker genes and reduced adenosine triphosphate (ATP) content. Decreased cathepsin activity in primary macrophages further led to distinct changes in fatty acid metabolites associated with increased expression of key modulators of fatty acid metabolism, such as fatty acid synthase (FASN) and acid ceramidase (ASAH1). The altered fatty acid profile was associated with an increased synthesis of the pro-inflammatory prostaglandin PGE₂, which correlated with the upregulation of numerous NF_kB-dependent pro-inflammatory mediators, including interleukin-1 (IL-1), interleukin-6 (IL-6), C-C motif chemokine ligand 2 (CCL2), and tumor necrosis factor-alpha (TNFα). Our data indicate a novel link between cathepsin activity and metabolic reprogramming in macrophages, demonstrated by a profound impact on autophagy and fatty acid metabolism, which facilitates a pro-inflammatory micromilieu generally associated with enhanced tumor elimination. These results provide a strong rationale for therapeutic cathepsin inhibition to overcome the tumor-promoting effects of the immune-evasive tumor micromilieu.

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.

The protective effects of polyamines on salinity stress tolerance in foxtail millet (Setaria italica L.), an important C4 model crop

ABSTRACT

Soil salinity is a major abiotic stress that adversely affects crop growth, development and productivity worldwide. In this study, the individual and synergistic roles of putrescine (Put) and spermidine (Spd) in salinity stress tolerance of foxtail millet (Setaria italica L.) was assessed. In the present study, plants treated with combined biogenic amines Put + Spd possess very efficient antioxidant enzyme systems which help to control the uninhibited oxidation and protect the plants from oxidative damage by ROS scavenging. Additionally, lower concentration of Put + Spd under NaCl stress showed reduced hydrogen peroxide, electrolyte leakage and caspase-like activity than control. FTIR analysis underlying the ability of PAs induced tolerance and the chemical bonds of Put + Spd treated plants were reminiscent of control plants. Moreover, histochemical analysis with 2',7'-dichlorofluorescein diacetate (DCF-DA), 3,3'-Diaminobenzidine (DAB) and nitrotetrazolium blue chloride (NBT) revealed that ROS accumulation was inhibited by combined PAs under salt stress condition. These results showed that Put + Spd significantly improve the endogenous PAs, which enhance high-salinity stress tolerance by detoxifying ROS. For the first time, the synergistic ROS scavenging ability of Put along with Spd was investigated upon salinity tolerance in C4 model foxtail millet crop. Overall, our findings illustrated the implication for improving salinity tolerance of agronomically important crop species.

GRAPHIC ABSTRACT

A novel role of MMP2 in regulating platelet NOX2 activation

NOX2 has a key role for cellular production of reactive oxidant species (ROS) and although the mechanism of its activation is well known, little is known about its regulation. Metallo-proteinases (MMPs) regulate numerous protein activities both in physiological and pathological conditions but their interplay with NOX2 and ROS formation is still unclear. We performed experimental studies in human platelets and polymorphonuclear leukocytes (PMNs) to investigate the interplay of MMP2 with NOX2 activity. In collagen-stimulated platelets and in PMA-stimulated PMNs from healthy subjects, an immediate burst of ROS was detected at 10 min to then decline at 20 min. Coincidentally, sNOX2-dp, a split-off product of NOX2, increased and peaked at 10 min. ROS production was persistent whereas sNOX2dp is not released in cells treated with MMP2 inhibitor compared to other MMPs inhibitors. Western blot analysis showed the highest MMP2 expression on the cell membrane 10 min after stimulation. Moreover, the co-immunoprecipitation assay confirms the interaction between MMP2 and NOX2 that formed an active immuno-complex. Treating cells with NOX2ds-tat, an inhibitor of NADPH oxidase, significantly reduced ROS formation, sNOX2-dp, MMP2 expression and MMP2-NOX2-complex, which were all restored if cells were added with H₂O₂. The study provides the first evidence that MMP2 has a key role in blunting platelet NOX2 activity and eventually ROS formation.

Cathepsin S as a target in gastric cancer

Cathepsin S (Cat S) is a protein expressed in some epithelial cells, which appears to be associated with cancer metastasis and recurrence. The abnormal expression of Cat S has been reported to be associated with the progression of certain types of gastrointestinal neoplasms, including gastric cancer (GC). There is a need to identify novel biomarkers and therapeutic targets associated with the growth, invasion and migration of GC cells, in order to develop non-invasive diagnostic and prognostic procedures and design new therapeutic approaches. The aim of the present study was to assess the association between Cat S and oncogenic processes implicated in the development of GC, focusing on the diagnostic and therapeutic potential of this molecule in GC. A search was conducted through the PubMed and Cochrane Central Register of Controlled Trials electronic databases for relevant literature published between 2003 and 2018, using the mesh terms 'cathepsin S' and 'cancer' and 'gastric cancer'.

Targeted knock-in mice expressing the oxidase-fixed form of xanthine oxidoreductase favor tumor growth

Xanthine oxidoreductase has been implicated in cancer. Nonetheless, the role played by its two convertible forms, xanthine dehydrogenase (XDH) and oxidase (XO) during tumorigenesis is not understood. Here we produce XDH-stable and XO-locked knock-in (ki) mice to address this question. After tumor transfer, XO ki mice show strongly increased tumor growth compared to wild type (WT) and XDH ki mice. Hematopoietic XO expression is responsible for this effect. After macrophage depletion, tumor growth is reduced. Adoptive transfer of XO-ki macrophages in WT mice increases tumor growth. In vitro, XO ki macrophages produce higher levels of reactive oxygen species (ROS) responsible for the increased Tregs observed in the tumors. Blocking ROS in vivo slows down tumor growth. Collectively, these results indicate that the balance of XO/XDH plays an important role in immune surveillance of tumor development. Strategies that inhibit the XO form specifically may be valuable in controlling cancer growth.

The roles of the convertible forms, xanthine dehydrogenase (XDH) and xanthine oxidase (XO) during tumorigenesis is not known. Here, the authors develop XDH-stable and XO-locked knock-in (ki) mice and show increased tumor growth in XO ki mice, via macrophage-mediated immunoregulatory responses.

BIRC5/Survivin is a novel ATG12-ATG5 conjugate interactor and an autophagy-induced DNA damage suppressor in human cancer and mouse embryonic fibroblast cells

BIRC5/Survivin is known as a dual cellular functions protein that directly regulates both apoptosis and mitosis in embryonic cells during embryogenesis and in cancer cells during tumorigenesis and tumor metastasis. However, BIRC5 has seldom been demonstrated as a direct macroautophagy/autophagy regulator in cells. ATG7 expression and ATG12-ATG5-ATG16L1 complex formation are crucial for the phagophore elongation during autophagy in mammalian cells. In this study, we observed that the protein expression levels of BIRC5 and ATG7 were inversely correlated, whereas the expression levels of BIRC5 and SQSTM1/p62 were positively correlated in normal breast tissues and tumor tissues. Mechanistically, we found that BIRC5 negatively modulates the protein stability of ATG7 and physically binds to the ATG12-ATG5 conjugate, preventing the formation of the ATG12-ATG5-ATG16L1 protein complex in human cancer (MDA-MB-231, MCF7, and A549) and mouse embryonic fibroblast (MEF) cells. We also observed a concurrent physical dissociation between BIRC5 and ATG12-ATG5 (but not CASP3/caspase-3) and upregulation of autophagy in MDA-MB-231 and A549 cells under serum-deprived conditions. Importantly, despite the fact that upregulation of autophagy is widely thought to promote DNA repair in cells under genotoxic stress, we found that BIRC5 maintains DNA integrity through autophagy negative-modulations in both human cancer and MEF cells under non-stressed conditions. In conclusion, our study reveals a novel role of BIRC5 in cancer cells as a direct regulator of autophagy. BIRC5 may act as a "bridging molecule", which regulates the interplay between mitosis, apoptosis, and autophagy in embryonic and cancer cells.

ABBREVIATIONS

ACTA1: actin; ATG: autophagy related; BIRC: baculoviral inhibitor of apoptosis repeat-containing; BAF: bafilomycin A₁; CQ: chloroquine; CASP3: caspase 3; HSPB1/Hsp27: heat shock protein family B (small) member 1/heat shock protein 27; IAPs: inhibitors of apoptosis proteins; IP: immunoprecipitation; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; PLA: proximity ligation assay; SQSTM1/p62: sequestosome 1; siRNA: small interfering RNA.

Identification of key genes and molecular mechanisms associated with low egg production of broiler breeder hens in ad libitum

Background

Overfeeding reduces laying performance in broiler breeder hens, which is associated with obesity, hepatic steatosis and systemic inflammation. To unravel the underlying mechanisms governing the effect of feeding regimes on energy metabolism and egg production, a transcriptomics approach was carried out for screening differentially expressed genes (DEGs) in ovary, liver and adipose tissues of broiler chickens under ad libitum and restricted feeding.

Results

It showed that 289, 388 and 204 DEGs were identified in the adipose, liver and ovary, respectively. These DEGs were significantly enriched in phagosome pathway, lipid transport, activity and nutrient reservoir activity in ovary; steroid hormone biosynthesis and metabolism of xenobiotics by cytochrome P450 pathways in adipose tissue; and the metabolic pathways, peroxisome proliferator-activated receptor (PPAR) and Jak-STAT signaling pathway in liver. Estrogen receptor 1, identified as one of important hubs by constructing PPI network, was up-regulated in ad libitum group, which would make more apolipoproteins be transferred to ovary.

Conclusions

High expression of VTGs, APOB, CYBB and CTSS in ovary would induce excess lipid deposit, oxidative stress and potential damage to ovulation. Our results contribute to understanding effects of feeding regimes on metabolic regulation during egg production of broiler breeder hens and also provide new evidence of metabolic regulation from integrated multi-tissue processes.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5801-3) contains supplementary material, which is available to authorized users.

High Beclin-1 and ARID1A expression corelates with poor survival and high recurrence in intrahepatic cholangiocarcinoma: a histopathological retrospective study

Background

Although surgical resection provides a cure for patients with intrahepatic cholangiocarcinoma (ICC), the risk of mortality and recurrence remains high. Several biomarkers are reported to be associated with the prognosis of ICC, including Beclin-1, ARID1A, carbonic anhydrase IX (CA9) and isocitrate dehydrogenase 1 (IDH1), but results are inconsistent. Therefore, a histopathological retrospective study was performed to simultaneously investigate the relationship of these four potential biomarkers with clinicopathological parameters and their prognostic values in patients with ICC.

Methods

A total of 113 patients with ICC were enrolled from Cancer Hospital of Chinese Academy of Medical Sciences between January 1999 and June 2015. The expression of Beclin-1, ARID1A, IDH1 and CA9 were determined by immunohistochemical staining. The prognostic values of the four biomarkers were analyzed by Cox regression and the Kaplan-Meier method.

Results

Beclin-1, ARID1A, CA9 and IDH1 were highly expressed in ICC tumor tissues. Higher mortality was positively associated with Beclin-1 expression (HR = 2.39, 95% CI = 1.09–5.24) and higher recurrence was positively associated with ARID1A expression (HR = 1.71, 95% CI = 1.06–2.78). Neither CA9 nor IDH1 expression was significantly associated with mortality or disease recurrence. Kaplan-Meier survival curves showed that ICC patients with higher Beclin-1 and ARID1A expression had a lower survival rate and a worse recurrence rate than patients with low Beclin-1 and ARID1A expression (p < 0.05).

Conclusions

High Beclin-1 and ARIDIA expression are strongly associated with poor prognosis in ICC patients, and thus Beclin-1 and ARID1A should be simultaneously considered as potential prognostic biomarkers for ICC patients.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5429-3) contains supplementary material, which is available to authorized users.

Z-FL-COCHO, a cathepsin S inhibitor, enhances oxaliplatin-mediated apoptosis through the induction of endoplasmic reticulum stress

Multiple cancer cells highly express cathepsin S, which has pro-tumoral effects. However, it was previously unknown whether knockdown or a pharmacological inhibitor (ZFL) of cathepsin S acts as an inducer of ER stress. Here, ZFL and knockdown of cathepsin S markedly induced ER stress through the up-regulation of calcium levels in the cytosol. Induction of calcium levels by inhibition of cathepsin S is markedly blocked by an inhibitor of the IP3 receptor and the ryanodine receptor Ca²⁺ channel in the ER, but an inhibitor of a mitochondrial Ca²⁺ uniporter had no effect on ZFL-induced calcium levels. Furthermore, production of mitochondrial ROS by ZFL was associated with an increase in cytosolic calcium levels. ZFL-mediated ER stress enhanced anti-cancer drug-induced apoptotic cell death, and pretreatment with chemical chaperones or down-regulation of ATF4 and CHOP by small interfering RNA markedly reduced ZFL plus oxaliplatin-induced apoptosis. Taken together, our findings reveal that inhibition of cathepsin S is an inducer of ER stress; these findings may contribute to the enhancement of therapeutic efficiency in cancer cells.

A drug that inhibits a key cancer enzyme could be used in combination with anti-cancer drugs to improve sensitivity to treatment. The intracellular endoplasmic reticulum (ER) is involved in several vital processes in cells, including folding and processing proteins. Taeg Kyu Kwon at Keimyung University, Daegu, South Korea, and co-workers have demonstrated how inhibition of cathepsin S, which is expressed in many cancer cells, induces ER stress. In trials on human kidney cancer cells grafted onto mice and in vitro, the team found that ZFL (cathepsin S inhibitor) triggered transient ER stress by increasing calcium levels inside cells. Subsequent treatment with the anti-cancer drug oxaliplatin resulted in increased cancer cell death.

Cysteine cathepsins as a prospective target for anticancer therapies-current progress and prospects

Cysteine cathepsins (CTS), being involved in both physiological and pathological processes, play an important role in the human body. During the last 30 years, it has been shown that CTS are highly upregulated in a wide variety of cancer types although they have received a little attention as a potential therapeutic target as compared to serine or metalloproteinases. Studies on the increasing problem of neoplastic progression have revealed that secretion of cell-surface- and intracellular cysteine proteases is aberrant in tumor cells and has an impact on their growth, invasion, and metastasis by taking part in tumor angiogenesis, in apoptosis, and in events of inflammatory and immune responses. Considering the role of CTS in carcinogenesis, inhibition of these enzymes becomes an attractive strategy for cancer therapy. The downregulation of natural CTS inhibitors (CTSsis), such as cystatins, observed in various types of cancer, supports this claim. The intention of this review is to highlight the relationship of CTS with cancer and to present illustrations that explain how some of their inhibitors affect processes related to neoplastic progression.

Sulforaphane suppresses oral cancer cell migration by regulating cathepsin S expression

Sulforaphane has been demonstrated to exert numerous biological effects, such as neuroprotective, anti-inflammatory, and anticancer effects. However, the detailed effects of sulforaphane on human oral cancer cell migration and the underlying mechanisms remain unclear. In this study, we observed that sulforaphane attenuated SCC-9 and SCC-14 cell motility and invasiveness by reducing cathepsin S expression. Moreover, sulforaphane increased microtubule-associated protein 1 light chain 3 (LC3) conversion, and the knockdown of LC3 by siRNA increased cell migration ability. Regarding the mechanism, sulforaphane inhibited the cell motility of oral cancer cells through the extracellular signal-regulated kinase (ERK) pathway, which in turn reversed cell motility. In conclusion, sulforaphane suppress cathepsin S expression by inducing autophage through ERK signaling pathway. Thus, cathepsin S and LC3 may be new targets for oral cancer treatment.

Involvement of autophagy and apoptosis and lipid accumulation in sclerotial morphogenesis of Morchella importuna

Sclerotial formation is a key phase of the morel life cycle and lipids have been recorded as the main cytoplasmic reserves in sclerotia of Morchella fungi without any experimental verification. In this study, the ultrastructural features of the undifferentiated mycelia stage (MS) and three main sclerotial differentiation states (sclerotial initial [SI], sclerotial development [SD] and sclerotial maturation [SM]) were compared by transmission electron microscopy. The nature of the energy-rich substance in hypha and sclerotium of Morchella importuna was qualitatively investigated by confocal laser scanning microscopy and quantitatively studied by extraction of lipids. Sclerotia were observed to form from the repeated branching and enlargement of either terminal hyphae or subordinate hyphal branches, indicating a complex type of sclerotial development. Autophagy and apoptosis were involved in the sclerotial metamorphosis of the cultivated strain of M. importuna. During the SI phase, the characteristic features of autophagy (vacuolation, coalescence of small vacuoles, existence of autophagosomes and engulfment of autophagosomes by vacuoles) were observed. At the SD phase, apoptotic characteristics (condensation of the cytoplasm and nucleus, shrinkage of plasma membrane, extensive plasma membrane blebbing and existence of phagosomes) could be seen in some developing sclerotial cells. In the final stage of sclerotial morphogensis, the sclerotial cells showed a necrotic mode of cell death. In addition, confocal laser imaging studies of live cells indicated that the energy-rich substance in morel hyphae and sclerotia was lipid. The lipid content in sclerotia was significantly more than that in hyphal cells. To the best of our knowledge, this is the first detailed ultrastructural description highlighting the involvement of autophagy and apoptosis in sclerotial metamorphosis of Morchella species and lipid accumulation during morel sclerotial development was also first experimentally verified. This work will promote a better understanding of the mechanism of morel sclerotial metamorphosis.

Targeting of cathepsin C induces autophagic dysregulation that directs ER stress mediated cellular cytotoxicity in colorectal cancer cells

As Autophagy is a pivotal mechanism of cancer cell survival and the development of chemotherapeutic resistance; therefore, new approaches are warranted for its targeting which may be fulfilled by cathepsins regulation. Amongst cathepsins, cathepsin C (CTSC) is highly expressed in various cancers and possesses significant therapeutic potential in autoimmune disorders; however, its role in colorectal cancer has not been explored. Herein, we aimed to investigate the role of CTSC in autophagy regulation mediated colorectal carcinoma cell proliferation. Cathepsin C targeting through inhibitors/siRNA leads to the accumulation of light chain 3 II and p62 without affecting the lysosomal integrity, revealed dysfunctional autolysosomal degradation which is also substantiated by proteolytic studies. Cathepsin C inhibition showed comparable autophagy blockade with E64d and augmented the autophagy blockade mediated by bafilomycin. Loss of CTSC function also induced ER stress-mediated JNK phosphorylation accompanied by the translocation of mitochondrial cyt c followed by apoptotic cell death in colorectal carcinoma cells. Taken together, the study reveals that CTSC targeting plays a key role in the regulation of autophagy mediated colorectal cancer cell proliferation. Further investigations are required to determine the functional role of CTSC in other tumors also which may have implications for the therapeutic prevention of cancer in the future.

Mesenchymal stem cells promote cell invasion and migration and autophagy-induced epithelial-mesenchymal transition in A549 lung adenocarcinoma cells

Mesenchymal stem cells (MSCs) are recruited into the tumour microenvironment and promote tumour growth and metastasis. Tumour microenvironment-induced autophagy is considered to suppress primary tumour formation by impairing migration and invasion. Whether these recruited MSCs regulate tumour autophagy and whether autophagy affects tumour growth are controversial. Our data showed that MSCs promote autophagy activation, reactive oxygen species production, and epithelial-mesenchymal transition (EMT) as well as increased migration and invasion in A549 cells. Decreased expression of E-cadherin and increased expression of vimentin and Snail were observed in A549 cells cocultured with MSCs. Conversely, MSC coculture-mediated autophagy positively promoted tumour EMT. Autophagy inhibition suppressed MSC coculture-mediated EMT and reduced A549 cell migration and invasion slightly. Furthermore, the migratory and invasive abilities of A549 cells were additional increased when autophagy was further enhanced by rapamycin treatment. Taken together, this work suggests that microenvironments containing MSCs can promote autophagy activation for enhancing EMT; MSCs also increase the migratory and invasive abilities of A549 lung adenocarcinoma cells. Mesenchymal stem cell-containing microenvironments and MSC-induced autophagy signalling may be potential targets for blocking lung cancer cell migration and invasion.

Melatonin protects against the pathological cardiac hypertrophy induced by transverse aortic constriction through activating PGC-1β: In vivo and in vitro studies

Melatonin, a circadian molecule secreted by the pineal gland, confers a protective role against cardiac hypertrophy induced by hyperthyroidism, chronic hypoxia, and isoproterenol. However, its role against pressure overload-induced cardiac hypertrophy and the underlying mechanisms remains elusive. In this study, we investigated the pharmacological effects of melatonin on pathological cardiac hypertrophy induced by transverse aortic constriction (TAC). Male C57BL/6 mice underwent TAC or sham surgery at day 0 and were then treated with melatonin (20 mg/kg/day, via drinking water) for 4 or 8 weeks. The 8-week survival rate following TAC surgery was significantly increased by melatonin. Melatonin treatment for 8 weeks markedly ameliorated cardiac hypertrophy. Compared with the TAC group, melatonin treatment for both 4 and 8 weeks reduced pulmonary congestion, upregulated the expression level of α-myosin heavy chain, downregulated the expression level of β-myosin heavy chain and atrial natriuretic peptide, and attenuated the degree of cardiac fibrosis. In addition, melatonin treatment slowed the deterioration of cardiac contractile function caused by pressure overload. These effects of melatonin were accompanied by a significant upregulation in the expression of peroxisome proliferator-activated receptor-gamma co-activator-1 beta (PGC-1β) and the inhibition of oxidative stress. In vitro studies showed that melatonin also protects against angiotensin II-induced cardiomyocyte hypertrophy and oxidative stress, which were largely abolished by knocking down the expression of PGC-1β using small interfering RNA. In summary, our results demonstrate that melatonin protects against pathological cardiac hypertrophy induced by pressure overload through activating PGC-1β.

Melatonin ameliorates myocardial ischemia reperfusion injury through SIRT3-dependent regulation of oxidative stress and apoptosis

Sirtuins are a family of highly evolutionarily conserved nicotinamide adenine nucleotide-dependent histone deacetylases. Sirtuin-3 (SIRT3) is a member of the sirtuin family that is localized primarily to the mitochondria and protects against oxidative stress-related diseases, including myocardial ischemia/reperfusion (MI/R) injury. Melatonin has a favorable effect in ameliorating MI/R injury. We hypothesized that melatonin protects against MI/R injury by activating the SIRT3 signaling pathway. In this study, mice were pretreated with or without a selective SIRT3 inhibitor and then subjected to MI/R operation. Melatonin was administered intraperitoneally (20 mg/kg) 10 minutes before reperfusion. Melatonin treatment improved postischemic cardiac contractile function, decreased infarct size, diminished lactate dehydrogenase release, reduced the apoptotic index, and ameliorated oxidative damage. Notably, MI/R induced a significant decrease in myocardial SIRT3 expression and activity, whereas the melatonin treatment upregulated SIRT3 expression and activity, and thus decreased the acetylation of superoxide dismutase 2 (SOD2). In addition, melatonin increased Bcl-2 expression and decreased Bax, Caspase-3, and cleaved Caspase-3 levels in response to MI/R. However, the cardioprotective effects of melatonin were largely abolished by the selective SIRT3 inhibitor 3-(1H-1,2,3-triazol-4-yl)pyridine (3-TYP), suggesting that SIRT3 plays an essential role in mediating the cardioprotective effects of melatonin. In vitro studies confirmed that melatonin also protected H9c2 cells against simulated ischemia/reperfusion injury (SIR) by attenuating oxidative stress and apoptosis, while SIRT3-targeted siRNA diminished these effects. Taken together, our results demonstrate for the first time that melatonin treatment ameliorates MI/R injury by reducing oxidative stress and apoptosis via activating the SIRT3 signaling pathway.

Inhibition of Cathepsin S Induces Mitochondrial ROS That Sensitizes TRAIL-Mediated Apoptosis Through p53-Mediated Downregulation of Bcl-2 and c-FLIP

AIMS

Cathepsin S is highly expressed in various cancer cells, and it has protumoral effects, including promotion of migration, invasion, and neovascularization. In this study, we show that inhibition of cathepsin S could sensitize cancer cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis.

RESULTS

An inhibitor of cathepsin S (Z-FL-COCHO; ZFL) markedly induced apoptosis in human renal cancer cells treated with TRAIL. In contrast, combined treatment with ZFL and TRAIL had no effect on normal cells. ZFL downregulated Bcl-2 expression at the transcriptional level in a p53-dependent manner, and overexpression of Bcl-2 also markedly blocked apoptosis induced by combined treatment with ZFL and TRAIL. In addition, ZFL induced downregulation of c-FLIP, and overexpression of c-FLIP blocked the apoptosis induced by ZFL plus TRAIL. Moreover, ZFL increased the expression of Cbl, an E3 ligase of c-FLIP, in a p53-dependent manner, and knockdown of Cbl markedly prevented c-FLIP downregulation and the apoptosis induced by ZFL plus TRAIL. Interestingly, ZFL induced p53 expression via production of mitochondrial reactive oxygen species (ROS). We also demonstrated that downregulation of cathepsin S by small interfering RNA sensitized TRAIL-mediated apoptosis in Caki cells.

INNOVATION

These results reveal the importance of cathepsin S on resistance against TRAIL, and inhibition of cathepsin S activity plays a crucial role in TRAIL-mediated cell death of cancer cells.

CONCLUSION

Our results indicated that inhibition of cathepsin S stimulates TRAIL-induced apoptosis through downregulation of Bcl-2 and Cbl-mediated c-FLIP by ROS-mediated p53 expression. Antioxid. Redox Signal. 27, 215-233.

Inhibition of cathepsin S confers sensitivity to methyl protodioscin in oral cancer cells via activation of p38 MAPK/JNK signaling pathways

Oral cancer is one of the most common cancers in the world. Approximately 90% of oral cancers are subtyped to oral squamous cell carcinoma (OSCC). Despite advances in diagnostic techniques and improvement in treatment modalities, the prognosis remains poor. Therefore, an effective chemotherapy mechanism that enhances tumor sensitivity to chemotherapeutics is urgently needed. Methyl protodioscin (MP) is a furostanol bisglycoside with a wide range of beneficial effects, including anti-inflammatory and anti-cancer properties. The aim of the present study was to determine the antitumor activity of MP on OSCC and its underlying mechanisms. Our results show that treatment of OSCC cells with MP potently inhibited cell viability. Moreover, MP leading to cell cycle arrest at G2/M phase, which subsequently activates caspase-3, -8, -9 and PARP to induce cell apoptosis. Meanwhile, we also demonstrate that MP induces a robust autophagy in OSCC cells. The results indicate cathepsin S (CTSS) is involved in MP-induced apoptosis and autophagy by modulation of p38 MAPK and JNK1/2 pathways. These findings may provide rationale to combine MP with CTSS blockade for the effective treatment of OSCC.

The role of nitric oxide signalling in response to salt stress in Chlamydomonas reinhardtii

Nitric oxide signal and GSNOR activity play an essential role for Chlamydomonas reinhardtii response to salt stress. The unicellular alga Chlamydomonas reinhardtii is one of the most important model organisms phylogenetically situated between higher plants and animals. In the present study, we used comparative proteomics and physiological approaches to study the mechanisms underlying the response to salt stress in C. reinhardtii. We identified 74 proteins that accumulated differentially after salt stress, including oxidative enzymes and enzymes associated with nitric oxide (NO) metabolism, cell damage, and cell autophagy processes. A set of antioxidant enzymes, as well as S-nitrosoglutathione reductase (GSNOR) activity, were induced to balance the cellular redox status during short-term salt stress. Enzymes involved in DNA repair and cell autophagy also contribute to adaptation to short-term salt stress. However, under long-term salt stress, antioxidant enzymes and GSNOR were gradually inactivated through protein S-nitrosylation, leading to oxidative damage and a reduction in cell viability. Modulating the protein S-nitrosylation levels by suppressing GSNOR activity or adding thioredoxin affected the plant's adaptation to salt stress, through altering the redox status and DNA damage and autophagy levels. Based on these data, we propose that unicellular algae use multiple strategies to adapt to salt stress, and that, during this process, GSNOR activity and protein S-nitrosylation levels play important roles.

Redox signaling in cardiovascular pathophysiology: A focus on hydrogen peroxide and vascular smooth muscle cells

Oxidative stress represents excessive intracellular levels of reactive oxygen species (ROS), which plays a major role in the pathogenesis of cardiovascular disease. Besides having a critical impact on the development and progression of vascular pathologies including atherosclerosis and diabetic vasculopathy, oxidative stress also regulates physiological signaling processes. As a cell permeable ROS generated by cellular metabolism involved in intracellular signaling, hydrogen peroxide (H₂O₂) exerts tremendous impact on cardiovascular pathophysiology. Under pathological conditions, increased oxidase activities and/or impaired antioxidant systems results in uncontrolled production of ROS. In a pro-oxidant environment, vascular smooth muscle cells (VSMC) undergo phenotypic changes which can lead to the development of vascular dysfunction such as vascular inflammation and calcification. Investigations are ongoing to elucidate the mechanisms for cardiovascular disorders induced by oxidative stress. This review mainly focuses on the role of H₂O₂ in regulating physiological and pathological signals in VSMC.

Up-regulation of miR-455-5p by the TGF-β-SMAD signalling axis promotes the proliferation of oral squamous cancer cells by targeting UBE2B

MicroRNAs (miRNAs) are involved in the tumourigenesis of various cancers by regulating their downstream targets. To identify the changes of miRNAs in oral squamous cell carcinoma (OSCC), we investigated the expression profiles of miRNAs in 40 pairs of OSCC specimens and their matched non-tumour epithelial tissues. Our data revealed higher miR-455-5p expression in the tumour tissues than in the normal tissues; the expression was also higher in oral cancer cell lines than in normal keratinocyte cell lines. MiR-455-5p knockdown reduced both the anchorage-independent growth and the proliferative ability of oral cancer cells, and these factors increased in miR-455-5p-overexpressing cells. Furthermore, by analysing the array data of patients with cancer and cell lines, we identified ubiquitin-conjugating enzyme E2B (UBE2B) as a target of miR-455-5p, and further validated this using 3'-untranslated region luciferase reporter assays and western blot analysis. We also demonstrated that UBE2B suppression rescued the impaired growth ability of miR-455-5p-knockdown cells. Furthermore, we observed that miR-455-5p expression was regulated, at least in part, by the transforming growth factor-β (TGF-β) pathway through the binding of SMAD3 to specific promoter regions. Notably, miR-455-5p expression was associated with the nodal status, stage, and overall survival in our patients, suggesting that miR-455-5p is a potential marker for predicting the prognosis of patients with oral cancer. In conclusion, we reveal that miR-455-5p expression is regulated by the TGF-β-dependent pathway, which subsequently leads to UBE2B down-regulation and contributes to oral cancer tumourigenesis. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Cathepsin S attenuates endosomal EGFR signalling: A mechanical rationale for the combination of cathepsin S and EGFR tyrosine kinase inhibitors

EGF-mediated EGFR endocytosis plays a crucial role in the attenuation of EGFR activation by sorting from early endosomes to late endosomes and transporting them into lysosomes for the final proteolytic degradation. We previously observed that cathepsin S (CTSS) inhibition induces tumour cell autophagy through the EGFR-mediated signalling pathway. In this study, we further clarified the relationship between CTSS activities and EGFR signalling regulation. Our results revealed that CTSS can regulate EGFR signalling by facilitating EGF-mediated EGFR degradation. CTSS inhibition delayed the EGFR degradation process and caused EGFR accumulation in the late endosomes at the perinuclear region, which provides spatial compartments for prolonged EGFR and sustained downstream signal transducer and activator of transcription 3 and AKT signalling. Notably, cellular apoptosis was markedly enhanced by combining treatment with the EGFR inhibitor Iressa and CTSS inhibitor 6r. The data not only reveal a biological role of CTSS in EGFR signalling regulation but also evidence a rationale for its clinical evaluation in the combination of CTSS and EGFR tyrosine kinase inhibitors.

Mycobacterium bovis BCG Interferes with miR-3619-5p Control of Cathepsin S in the Process of Autophagy

Main survival mechanism of pathogenic mycobacteria is to escape inimical phagolysosomal environment inside the macrophages. Many efforts have been made to unravel the molecular mechanisms behind this process. However, little is known about the involvement of microRNAs (miRNAs) in the regulation of phagolysosomal biosynthesis and maturation. Based on a bottom up approach, we searched for miRNAs that were involved in phagolysosomal processing events in the course of mycobacterial infection of macrophages. After infecting THP-1 derived macrophages with viable and heat killed Mycobacterium bovis BCG (BCG), early time points were identified after co-localization studies of the phagosomal marker protein LAMP1 and BCG. Differences in LAMP1 localization on the phagosomes of both groups were observed at 30 min and 4 h. After in silico based pre-selection of miRNAs, expression analysis at the identified time points revealed down-regulation of three miRNAs: miR-3619-5p, miR-637, and miR-324-3p. Consequently, most likely targets were predicted that were supposed to be mutually regulated by these three studied miRNAs. The lysosomal cysteine protease Cathepsin S (CTSS) and Rab11 family-interacting protein 4 (RAB11FIP4) were up-regulated and were considered to be connected to lysosomal trafficking and autophagy. Interaction studies verified the regulation of CTSS by miR-3619-5p. Down-regulation of CTSS by ectopic miR-3619-5p as well as its specific knockdown by siRNA affected the process of autophagy in THP-1 derived macrophages.

Time-course and intensity-based classifications of oxidative stresses and their potential application in biomedical, comparative and environmental research

OBJECTIVE

We propose some clues for classification of oxidative stresses based on their intensity and time-course.

BACKGROUND

Oxidative stress is studied for more than three decades and it is clear that it may differ on the parameters of interest. But up to now there is no any system for formal discrimination between different types of the stress. Such approach can provide important benefits at description of experimental data.

METHOD

We briefly review information on oxidative stresses and show that the theoretical concept is actually poorly developed since introduction of the first definition in 1985 by H. Sies. We argue that the stresses can differ on their intensities and time-curses, but there was no theoretical basis for discrimination between them.

RESULTS

On the basis of these analyses, we propose two systems of classifications of oxidative stresses enabling their description taking into account their intensity and time-course. We analyze essential biomarkers of oxidative stress to be used for classification such as levels of modified by reactive oxygen species proteins, lipids, nucleic acids, and low molecular mass compounds. Finally, we describe potential applications of the proposed classifications to biomedical, comparative and environmental research.

CONCLUSION

The proposed classifications of oxidative stress may facilitate description of experimental data and their comparison between different organisms and methods of induction of oxidative stresses. Additionally this work may provide some clues to develop quantitative approaches for formal categorization of oxidative stresses.

APPLICATION

Most applications of the classifications proposed are theoretical and applied studies where oxidative stress takes place.

Xanthine Oxidoreductase-Derived Reactive Species: Physiological and Pathological Effects

Xanthine oxidoreductase (XOR) is the enzyme that catalyzes the oxidation of hypoxanthine to xanthine and xanthine to uric acid and is widely distributed among species. In addition to this housekeeping function, mammalian XOR is a physiological source of superoxide ion, hydrogen peroxide, and nitric oxide, which can function as second messengers in the activation of various pathways. This review intends to address the physiological and pathological roles of XOR-derived oxidant molecules. The cytocidal action of XOR products has been claimed in relation to tissue damage, in particular damage induced by hypoxia and ischemia. Attempts to exploit this activity to eliminate unwanted cells via the construction of conjugates have also been reported. Moreover, different aspects of XOR activity related to phlogosis, endothelial activation, leukocyte activation, and vascular tone regulation, have been taken into consideration. Finally, the positive and negative outcomes concerning cancer pathology have been analyzed because XOR products may induce mutagenesis, cell proliferation, and tumor progression, but they are also associated with apoptosis and cell differentiation. In conclusion, XOR activity generates free radicals and other oxidant reactive species that may result in either harmful or beneficial outcomes.

Contribution of autophagy to antiviral immunity

Although identified in the 1960's, interest in autophagy has significantly increased in the past decade with notable research efforts oriented at understanding as to how this multi-protein complex operates and is regulated. Autophagy is commonly defined as a "self-eating" process evolved by eukaryotic cells to recycle senescent organelles and expired proteins, which is significantly increased during cellular stress responses. In addition, autophagy can also play important roles during human diseases, such as cancer, neurodegenerative and autoimmune disorders. Furthermore, novel findings suggest that autophagy contributes to the host defense against microbial infections. In this article, we review the role of macroautophagy in antiviral immune responses and discuss molecular mechanisms evolved by viral pathogens to evade this process. A role for autophagy as an effector mechanism used both, by innate and adaptive immunity is also discussed.

Cyclo(phenylalanine-proline) induces DNA damage in mammalian cells via reactive oxygen species

Cyclo(phenylalanine‐proline) is produced by various organisms such as animals, plants, bacteria and fungi. It has diverse biological functions including anti‐fungal activity, anti‐bacterial activity and molecular signalling. However, a few studies have demonstrated the effect of cyclo(phenylalanine‐proline) on the mammalian cellular processes, such as cell growth and apoptosis. In this study, we investigated whether cyclo(phenylalanine‐proline) affects cellular responses associated with DNA damage in mammalian cells. We found that treatment of 1 mM cyclo(phenylalanine‐proline) induces phosphorylation of H2AX (S139) through ATM‐CHK2 activation as well as DNA double strand breaks. Gene expression analysis revealed that a subset of genes related to regulation of reactive oxygen species (ROS) scavenging and production is suppressed by the cyclo(phenylalanine‐proline) treatment. We also found that cyclo(phenylalanine‐proline) treatment induces perturbation of the mitochondrial membrane, resulting in increased ROS, especially superoxide, production. Collectively, our study suggests that cyclo(phenylalanine‐proline) treatment induces DNA damage via elevation of ROS in mammalian cells. Our findings may help explain the mechanism underlying the bacterial infection‐induced activation of DNA damage response in host mammalian cells.

Autophagy-Regulated ROS from Xanthine Oxidase Acts as an Early Effector for Triggering Late Mitochondria-Dependent Apoptosis in Cathepsin S-Targeted Tumor Cells

Cathepsin S (CTSS), which is highly expressed in various malignant tumor cells, has been proposed to promote tumor progression, migration, and invasion. CTSS inhibition not only blocks tumor cell invasion and endothelial tube formation but also induces cellular cytotoxicity. In our previous studies, we have observed that CTSS inhibition induces autophagy, which is responsible for up-regulating xanthine oxidase for early ROS generation and consequent cell death. However, whether the autophagy-regulated early ROS triggers apoptosis remains unclear. We conducted a long-term follow-up study to investigate the relationship between early autophagy and late mitochondria-dependent apoptosis. We demonstrated that early ROS generation is critical for mitochondria damage and the activation of intrinsic apoptotic pathway. Attenuating the early ROS level diminished later mitochondrial damage and downstream apoptotic signaling. Collectively, mitochondria-dependent apoptosis is regulated by autophagy-regulated early ROS, which serves as an early effector that triggers mitochondrial signaling for late apoptosis. The data emphasize the essential role of autophagy-regulated early ROS in triggering late apoptotic signaling.

YM155 down-regulates survivin and XIAP, modulates autophagy and induces autophagy-dependent DNA damage in breast cancer cells

BACKGROUND AND PURPOSE

The aim of this study was to determine the potency and molecular mechanism of action of YM155, a first-in-class survivin inhibitor that is currently under phase I/II clinical investigations, in various drug-resistant breast cancers including the oestrogen receptor positive (ER(+) ) tamoxifen-resistant breast cancer and the caspase-3-deficient breast cancer.

EXPERIMENTAL APPROACH

The potency of YM155 in SK-BR-3, MDA-MB-231, MCF7 and its tamoxifen-resistant sublines, TamR6, TamR7, TamR8, TamC3 and TamC6, were determined by MTT assay. Western blot analysis, flow cytometric analysis, reverse transcription-PCR, fluorescent microscopy and comet assay were used to determine the molecular mechanism of action of YM155 in different breast cancer cell lines.

KEY RESULTS

YM155 was equally potent towards the parental ER(+) /caspase-3-deficient MCF7 breast cancer cells and its tamoxifen-resistant sublines in vitro. The ER(-) /HER2(+) SK-BR-3 breast cancer cells and the triple-negative/caspase-3-expressing metastatic aggressive MDA-MB-231 breast cancer cells were also sensitive to YM155 with IC50 values in the low nanomolar range. Targeting survivin by YM155 modulated autophagy, induced autophagy-dependent caspase-7 activation and autophagy-dependent DNA damage in breast cancer cells. Interestingly, YM155 also induced XIAP degradation and the degradation of XIAP might play an important role in YM155-induced autophagy in breast cancer cells.

CONCLUSIONS AND IMPLICATIONS

YM155 is a potent survivin inhibitor that has potential for the management of various breast cancer subtypes regardless of the expression of ER, HER2 and caspase-3. Importantly, this study provides new insights into YM155's molecular mechanism of action and therapeutic potential in the treatment of tamoxifen-resistant breast cancer.

IGF-1 signaling via the PI3K/Akt pathway confers neuroprotection in human retinal pigment epithelial cells exposed to sodium nitroprusside insult

The pathological increase in the levels of the second messenger nitric oxide (NO) in the vitreous cavity and retina leads to injury and cell death of the retinal pigment epithelium (RPE) cells and eventually may contribute to the occurrence and development of diabetic retinopathy. In this study, we developed a cellular model of retinopathy using D407 cells (a human RPE cell line) exposed to sodium nitroprusside (SNP) and investigated the protective effect of the insulin-like growth factor-1 (IGF-1) towards this insult. Cell death and apoptosis were examined by the methyl thiazolyl tetrazolium assay and Hoechst staining, respectively. Specific inhibitors were used and phosphorylation of relevant signaling proteins was determined by Western blotting. SNP, in a concentration-dependent fashion, increased the production of reactive oxygen species (ROS) and lipid peroxidation process causing cell death by apoptosis of D407 cells. IGF-1, in a time- and dose-dependent manner, conferred protection towards SNP-mediated insult. Both phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt) and mitogen-activated protein kinase (MAPK) were activated by IGF-1 in relation to the protective effect. Blockade of the PI3K/Akt pathway abolished the protective effect of IGF-1 whereas inhibition of the MAPK pathway was ineffective. SNP decreased the phosphorylation of Akt in the cells while IGF-1 reversed this inhibitory effect. These results indicate that the protective effect of IGF-1 on D407 exposed to SNP insult is mediated by the PI3K/Akt pathway. This proposal may be exploited in the clinic to improve the viability of insulted retinal cells for maintaining physiological vision.

Transmissible cytotoxicity of multiple myeloma cells by cord blood-derived NK cells is mediated by vesicle trafficking

Natural killer cells (NK) are important effectors of anti-tumor immunity, activated either by the downregulation of HLA-I molecules on tumor cells and/or the interaction of NK-activating receptors with ligands that are overexpressed on target cells upon tumor transformation (including NKG2D and NKP30). NK kill target cells by the vesicular delivery of cytolytic molecules such as Granzyme-B and Granulysin activating different cell death pathways, which can be Caspase-3 dependent or Caspase-3 independent. Multiple myeloma (MM) remains an incurable neoplastic plasma-cell disorder. However, we previously reported the encouraging observation that cord blood-derived NK (CB-NK), a new source of NK, showed anti-tumor activity in an in vivo murine model of MM and confirmed a correlation between high levels of NKG2D expression by MM cells and increased efficacy of CB-NK in reducing tumor burden. We aimed to characterize the mechanism of CB-NK-mediated cytotoxicity against MM cells. We show a Caspase-3- and Granzyme-B-independent cell death, and we reveal a mechanism of transmissible cell death between cells, which involves lipid-protein vesicle transfer from CB-NK to MM cells. These vesicles are secondarily transferred from recipient MM cells to neighboring MM cells amplifying the initial CB-NK cytotoxicity achieved. This indirect cytotoxicity involves the transfer of NKG2D and NKP30 and leads to lysosomal cell death and decreased levels of reactive oxygen species in MM cells. These findings suggest a novel and unique mechanism of CB-NK cytotoxicity against MM cells and highlight the importance of lipids and lipid transfer in this process. Further, these data provide a rationale for the development of CB-NK-based cellular therapies in the treatment of MM.

Inhibition of cathepsin S induces autophagy and apoptosis in human glioblastoma cell lines through ROS-mediated PI3K/AKT/mTOR/p70S6K and JNK signaling pathways

Cathepsin S is a lysosomal cysteine protease that is overexpressed in various cancer models and plays important role in tumorigenesis, however the mechanisms are unclear. In the present study, we found that inhibition of cathepsin S induced autophagy and mitochondrial apoptosis in human glioblastoma cells. Blockade of autophagy by either a chemical inhibitor or RNA interference attenuated cathespin S inhibition-induced apoptosis. Furthermore, autophagy and apoptosis induction was dependent on the suppression of phosphatidylinositide 3-kinases/protein kinase B/mammalian target of rapamycin/p70S6 kinase (PI3K/AKT/mTOR/p70S6K) signaling pathway and activation of c-Jun N-terminal kinase (JNK) signaling pathway. In addition, reactive oxygen species (ROS) served as an upstream of PI3K/AKT/mTOR/p70S6K and JNK signaling pathways. In conclusion, the current study revealed that cathepsin S played an important role in the regulation of autophagy and apoptosis in human glioblastoma cells.