SCO2 induces p53-mediated apoptosis by Thr845 phosphorylation of ASK-1 and dissociation of the ASK-1-Trx complex

Prognostic significance of copper metabolism-related genes as risk markers in bladder urothelial carcinoma

Bladder urothelial carcinoma (BLCA), a prevalent malignant neoplasm affecting the human urinary system, is frequently linked with an unfavorable prognosis in a significant proportion of individuals. More effective and sensitive markers are needed to provide a reference for prognostic judgment. We obtained RNA sequencing data and clinical information of individuals from TCGA, and 133 copper metabolism-related genes from literature. Prognostic genes were evaluated by univariate/multivariate Cox regression analysis and LASSO analysis, and a risk-scoring model was established and validated in the GEO dataset. The CIBERSORT method was utilized to explore immune cell infiltration in BLCA individuals. In addition, tumor immune dysfunction and exclusion (TIDE) and immunophenoscore (IPS) were utilized to verify whether the model can foretell the response of BLCA individuals to immunotherapy. We successfully constructed an 8-gene risk scoring model to foretell individuals' overall survival, and the model performed well in TCGA training and GEO validation cohorts. Lastly, a nomogram containing clinical parameters and risk scores was constructed to help individualized result prediction for individuals. Calibration curves demonstrated a high degree of concordance between the observed and projected survival durations, attesting to its exceptional predictive accuracy. Analysis utilizing CIBERSORT unveiled elevated levels of immune cell infiltration in individuals classified as low risk. TIDE and IPS analyses substantiated that low-risk individuals exhibited a more favorable response to immunotherapy. In summary, the model held immense potential for stratifying the risk of survival and guiding tailored treatment approaches for individuals with BLCA, thereby offering valuable insights for personalized therapeutic interventions.

Decoding the mitochondrial connection: development and validation of biomarkers for classifying and treating systemic lupus erythematosus through bioinformatics and machine learning

BACKGROUND

Systemic lupus erythematosus (SLE) is a multifaceted autoimmune disease characterized by clinical and pathological diversity. Mitochondrial dysfunction has been identified as a critical pathogenetic factor in SLE. However, the specific molecular aspects and regulatory roles of this dysfunction in SLE are not fully understood. Our study aims to explore the molecular characteristics of mitochondria-related genes (MRGs) in SLE, with a focus on identifying reliable biomarkers for classification and therapeutic purposes.

METHODS

We sourced six SLE-related microarray datasets (GSE61635, GSE50772, GSE30153, GSE99967, GSE81622, and GSE49454) from the Gene Expression Omnibus (GEO) database. Three of these datasets (GSE61635, GSE50772, GSE30153) were integrated into a training set for differential analysis. The intersection of differentially expressed genes with MRGs yielded a set of differentially expressed MRGs (DE-MRGs). We employed machine learning algorithms-random forest (RF), support vector machine (SVM), and least absolute shrinkage and selection operator (LASSO) logistic regression-to select key hub genes. These genes' classifying potential was validated in the training set and three other validation sets (GSE99967, GSE81622, and GSE49454). Further analyses included differential expression, co-expression, protein-protein interaction (PPI), gene set enrichment analysis (GSEA), and immune infiltration, centered on these hub genes. We also constructed TF-mRNA, miRNA-mRNA, and drug-target networks based on these hub genes using the ChEA3, miRcode, and PubChem databases.

RESULTS

Our investigation identified 761 differentially expressed genes (DEGs), mainly related to viral infection, inflammatory, and immune-related signaling pathways. The interaction between these DEGs and MRGs led to the identification of 27 distinct DE-MRGs. Key among these were FAM210B, MSRB2, LYRM7, IFI27, and SCO2, designated as hub genes through machine learning analysis. Their significant role in SLE classification was confirmed in both the training and validation sets. Additional analyses included differential expression, co-expression, PPI, GSEA, immune infiltration, and the construction of TF-mRNA, miRNA-mRNA, and drug-target networks.

CONCLUSIONS

This research represents a novel exploration into the MRGs of SLE, identifying FAM210B, MSRB2, LYRM7, IFI27, and SCO2 as significant candidates for classifying and therapeutic targeting.

The Relationship between Oxidative Status and Radioiodine Treatment Qualification among Papillary Thyroid Cancer Patients

Total oxidative status (TOS), total antioxidant capacity (TAC), tumor protein 53 (p53), nuclear factor kappa B (NF-κB), forkhead box protein O1 (FOXO), and sirtuin 1 (SIRT1) play crucial roles in oxidative homeostasis and the progression of papillary thyroid cancer (PTC), as previously demonstrated in the literature. Therefore, profiling these markers among PTC patients may be useful in determining their eligibility for radioiodine (RAI) treatment. Since treatment indications are based on multiple and dynamic recommendations, additional criteria for adjuvant RAI therapy are still needed. In our study, we evaluated the TOS, TAC, and serum concentrations of p53, NF-κB, FOXO, and SIRT1 to analyze the relationship between oxidative status and qualification for RAI treatment. For the purpose of this study, we enrolled 60 patients with PTC allocated for RAI treatment as the study group and 25 very low-risk PTC patients not allocated for RAI treatment as a reference group. The serum TOS and SIRT1 concentrations were significantly higher in the study group compared to the reference group (both p < 0.001), whereas the TAC and p53, NK-κB, and FOXO concentrations were significantly lower (all p < 0.05). We also demonstrated the diagnostic utility of TAC (AUC = 0.987), FOXO (AUC = 0.648), TOS (AUC = 0.664), SIRT1 (AUC = 0.709), p53 (AUC = 0.664), and NF-κB (AUC = 0.651) measurements as indications for RAI treatment based on American Thyroid Association recommendations. Our study revealed that oxidative status-related markers may become additional criteria for RAI treatment in PTC patients.

Counteracting Colon Cancer by Inhibiting Mitochondrial Respiration and Glycolysis with a Selective PKCδ Activator

Metabolic reprogramming is a central hub in tumor development and progression. Therefore, several efforts have been developed to find improved therapeutic approaches targeting cancer cell metabolism. Recently, we identified the 7α-acetoxy-6β-benzoyloxy-12-O-benzoylroyleanone (Roy-Bz) as a PKCδ-selective activator with potent anti-proliferative activity in colon cancer by stimulating a PKCδ-dependent mitochondrial apoptotic pathway. Herein, we investigated whether the antitumor activity of Roy-Bz, in colon cancer, could be related to glucose metabolism interference. The results showed that Roy-Bz decreased the mitochondrial respiration in human colon HCT116 cancer cells, by reducing electron transfer chain complexes I/III. Consistently, this effect was associated with downregulation of the mitochondrial markers cytochrome c oxidase subunit 4 (COX4), voltage-dependent anion channel (VDAC) and mitochondrial import receptor subunit TOM20 homolog (TOM20), and upregulation of synthesis of cytochrome c oxidase 2 (SCO2). Roy-Bz also dropped glycolysis, decreasing the expression of critical glycolytic markers directly implicated in glucose metabolism such as glucose transporter 1 (GLUT1), hexokinase 2 (HK2) and monocarboxylate transporter 4 (MCT4), and increasing TP53-induced glycolysis and apoptosis regulator (TIGAR) protein levels. These results were further corroborated in tumor xenografts of colon cancer. Altogether, using a PKCδ-selective activator, this work evidenced a potential dual role of PKCδ in tumor cell metabolism, resulting from the inhibition of both mitochondrial respiration and glycolysis. Additionally, it reinforces the antitumor therapeutic potential of Roy-Bz in colon cancer by targeting glucose metabolism.

Structural Insights Support Targeting ASK1 Kinase for Therapeutic Interventions

Apoptosis signal-regulating kinase (ASK) 1, a member of the mitogen-activated protein kinase kinase kinase (MAP3K) family, modulates diverse responses to oxidative and endoplasmic reticulum (ER) stress and calcium influx. As a crucial cellular stress sensor, ASK1 activates c-Jun N-terminal kinases (JNKs) and p38 MAPKs. Their excessive and sustained activation leads to cell death, inflammation and fibrosis in various tissues and is implicated in the development of many neurological disorders, such as Alzheimer’s, Parkinson’s and Huntington disease and amyotrophic lateral sclerosis, in addition to cardiovascular diseases, diabetes and cancer. However, currently available inhibitors of JNK and p38 kinases either lack efficacy or have undesirable side effects. Therefore, targeted inhibition of their upstream activator, ASK1, stands out as a promising therapeutic strategy for treating such severe pathological conditions. This review summarizes recent structural findings on ASK1 regulation and its role in various diseases, highlighting prospects for ASK1 inhibition in the treatment of these pathologies.

Comparative analysis of aneurysm subtypes associated genes based on protein-protein interaction network

The arterial aneurysm refers to localized dilation of blood vessel wall and is common in general population. The majority of aneurysm cases remains asymptomatic until a sudden rupture which is usually fatal and of extremely high mortality (~ 50-60%). Therefore, early diagnosis, prevention and management of aneurysm are in urgent need. Unfortunately, current understanding of disease driver genes of various aneurysm subtypes is still limited, and without appropriate biomarkers and drug targets no specialized drug has been developed for aneurysm treatment. In this research, aneurysm subtypes were analyzed based on protein-protein interaction network to better understand aneurysm pathogenesis. By measuring network-based proximity of aneurysm subtypes, we identified a relevant closest relationship between aortic aneurysm and aortic dissection. An improved random walk method was performed to prioritize candidate driver genes of each aneurysm subtype. Thereafter, transcriptomes of 6 human aneurysm subtypes were collected and differential expression genes were identified to further filter potential driver genes. Functional enrichment of above driver genes indicated a general role of ubiquitination and programmed cell death in aneurysm pathogenesis. Especially, we further observed participation of BCL-2-mediated apoptosis pathway and caspase-1 related pyroptosis in the development of cerebral aneurysm and aneurysmal subarachnoid hemorrhage in corresponding transcriptomes.

Loss of Functional SCO2 Attenuates Oxidative Stress in Diabetic Kidney Disease

Increased oxidative stress in glomerular endothelial cells (GEnCs) contributes to early diabetic kidney disease (DKD). While mitochondrial respiratory complex IV activity is reduced in DKD, it remains unclear whether this is a driver or a consequence of oxidative stress in GEnCs. Synthesis of cytochrome C oxidase 2 (SCO2), a key metallochaperone in the electron transport chain, is critical to the biogenesis and assembly of subunits required for functional respiratory complex IV activity. Here, we investigated the effects of Sco2 hypomorphs (Sco2 KO/KI , Sco2 KI/KI ), with a functional loss of SCO2, in the progression of DKD using a murine model of Type II Diabetes Mellitus, db/db mice. Diabetic Sco2 KO/KI and Sco2 KI/KI hypomorphs exhibited a reduction in complex IV activity, but an improvement in albuminuria, serum creatinine, and histomorphometric evidence of early DKD as compared to db/db mice. Single-nucleus RNA sequencing with gene set enrichment analysis of differentially expressed genes in the endothelial cluster of Sco2 KO/KI ;db/db mice demonstrated an increase in genes involved in VEGF-VEGFR2 signaling and reduced oxidative stress as compared to db/db mice. These data suggest that reduced complex IV activity due to a loss of functional SCO2 might be protective in GEnCs in early DKD.

TCF19 and p53 regulate transcription of TIGAR and SCO2 in HCC for mitochondrial energy metabolism and stress adaptation

Alteration in glucose homeostasis during cancer metabolism is an important phenomenon. Though several important transcription factors have been well studied in the context of the regulation of metabolic gene expression, the role of epigenetic readers in this regard remains still elusive. Epigenetic reader protein transcription factor 19 (TCF19) has been recently identified as a novel glucose and insulin-responsive factor that modulates histone posttranslational modifications to regulate glucose homeostasis in hepatocytes. Here we report that TCF19 interacts with a non-histone, well-known tumor suppressor protein 53 (p53) and co-regulates a wide array of metabolic genes. Among these, the p53-responsive carbohydrate metabolic genes Tp53-induced glycolysis and apoptosis regulator (TIGAR) and Cytochrome C Oxidase assembly protein 2 (SCO2), which are the key regulators of glycolysis and oxidative phosphorylation respectively, are under direct regulation of TCF19. Remarkably, TCF19 can form different transcription activation/repression complexes which show substantial overlap with that of p53, depending on glucose-mediated variant stress situations as obtained from IP/MS studies. Interestingly, we observed that TCF19/p53 complexes either have CBP or HDAC1 to epigenetically program the expression of TIGAR and SCO2 genes depending on short-term high glucose or prolonged high glucose conditions. TCF19 or p53 knockdown significantly altered the cellular lactate production and led to increased extracellular acidification rate. Similarly, OCR and cellular ATP production were reduced and mitochondrial membrane potential was compromised upon depletion of TCF19 or p53. Subsequently, through RNA-Seq analysis from patients with hepatocellular carcinoma, we observed that TCF19/p53-mediated metabolic regulation is fundamental for sustenance of cancer cells. Together the study proposes that TCF19/p53 complexes can regulate metabolic gene expression programs responsible for mitochondrial energy homeostasis and stress adaptation.

Mechanistic Analysis of an Extracellular Signal-Regulated Kinase 2-Interacting Compound that Inhibits Mutant BRAF-Expressing Melanoma Cells by Inducing Oxidative Stress

Constitutively active extracellular signal–regulated kinase (ERK) 1/2 signaling promotes cancer cell proliferation and survival. We previously described a class of compounds containing a 1,1-dioxido-2,5-dihydrothiophen-3-yl 4-benzenesulfonate scaffold that targeted ERK2 substrate docking sites and selectively inhibited ERK1/2-dependent functions, including activator protein-1–mediated transcription and growth of cancer cells containing active ERK1/2 due to mutations in Ras G-proteins or BRAF, Proto-oncogene B-RAF (Rapidly Acclerated Fibrosarcoma) kinase. The current study identified chemical features required for biologic activity and global effects on gene and protein levels in A375 melanoma cells containing mutant BRAF (V600E). Saturation transfer difference-NMR and mass spectrometry analyses revealed interactions between a lead compound (SF-3-030) and ERK2, including the formation of a covalent adduct on cysteine 252 that is located near the docking site for ERK/FXF (DEF) motif for substrate recruitment. Cells treated with SF-3-030 showed rapid changes in immediate early gene levels, including DEF motif–containing ERK1/2 substrates in the Fos family. Analysis of transcriptome and proteome changes showed that the SF-3-030 effects overlapped with ATP-competitive or catalytic site inhibitors of MAPK/ERK Kinase 1/2 (MEK1/2) or ERK1/2. Like other ERK1/2 pathway inhibitors, SF-3-030 induced reactive oxygen species (ROS) and genes associated with oxidative stress, including nuclear factor erythroid 2–related factor 2 (NRF2). Whereas the addition of the ROS inhibitor N-acetyl cysteine reversed SF-3-030–induced ROS and inhibition of A375 cell proliferation, the addition of NRF2 inhibitors has little effect on cell proliferation. These studies provide mechanistic information on a novel chemical scaffold that selectively regulates ERK1/2-targeted transcription factors and inhibits the proliferation of A375 melanoma cells through a ROS-dependent mechanism.

p53 as a hub in cellular redox regulation and therapeutic target in cancer

The TP53 tumor suppressor gene encodes a DNA-binding transcription factor that regulates multiple cellular processes including cell growth and cell death. The ability of p53 to bind to DNA and activate transcription is tightly regulated by post-translational modifications and is dependent on a reducing cellular environment. Some p53 transcriptional target genes are involved in regulation of the cellular redox homeostasis, e.g. TIGAR and GLS2. A large fraction of human tumors carry TP53 mutations, most commonly missense mutations that lead to single amino acid substitutions in the core domain. Mutant p53 proteins can acquire so called gain-of-function activities and influence the cellular redox balance in various ways, for instance by binding of the Nrf2 transcription factor, a major regulator of cellular redox state. The DNA-binding core domain of p53 has 10 cysteine residues, three of which participate in holding a zinc atom that is critical for p53 structure and function. Several novel compounds that refold and reactivate missense mutant p53 bind to specific p53 cysteine residues. These compounds can also react with other thiols and target components of the cellular redox system, such as glutathione. Dual targeting of mutant p53 and redox homeostasis may allow more efficient treatment of cancer.

Discovery and development of ASK1 inhibitors

Aberrant activation of mitogen-activated protein kinases (MAPKs) like c-Jun N-terminal kinase (JNK) and p38 is an event involved in the pathophysiology of numerous human diseases. The apoptosis signal-regulating kinase 1 (ASK1) is an upstream target that gets activated only under pathological conditions and as such is a promising target for therapeutic intervention. In the first part of this review the molecular mechanisms leading to ASK1 activation and regulation will be described as well as the evidences supporting a pathogenic role for ASK1 in human disease. In the second part, an update on drug discovery efforts towards the discovery and development of ASK1-targeting therapies will be provided.

Cold atmospheric plasma generated reactive species aided inhibitory effects on human melanoma cells: an in vitro and in silico study

Malignant melanoma is considered to be a heterogeneous disease that arises from altered genes and transformed melanocytes. In this study, special softjet cold atmospheric plasma was used to treat three different human melanoma cells using air and N₂ gases to check the anti-melanoma activity. The physical effects by plasma revealed an increase in the temperature with the gradual reduction in pH at 60 sec, 180 sec and 300 sec air and N₂ plasma treatment. Cellular toxicity revealed a decreased in cell survival (~50% cell survival using air gas and <~60% cell survival using N₂ gas at 60 sec plasma treatment in G-361 cells). Gene analysis by q-PCR revealed that 3 min and 5 min air and N₂ plasma treatment activated apoptotic pathways by triggering apoptotic genes in all three melanoma cell lines. The apoptosis was confirmed by DAPI staining and its related pathways were further explored according to protein-protein docking, and their probable activation mechanism was revealed. The pathways highlighted that activation of apoptosis which leads to cellular cascades and hence stimulation ASK1 (docking method) revealed that softjet plasma can be an effective modality for human melanoma treatment.

SLMP53-1 Inhibits Tumor Cell Growth through Regulation of Glucose Metabolism and Angiogenesis in a P53-Dependent Manner

The Warburg effect is an emerging hallmark of cancer, which has the tumor suppressor p53 as its major regulator. Herein, we unveiled that p53 activation by (S)-tryptophanol-derived oxazoloisoindolinone (SLMP53-1) mediated the reprograming of glucose metabolism in cancer cells and xenograft human tumor tissue, interfering with angiogenesis and migration. Particularly, we showed that SLMP53-1 regulated glycolysis by downregulating glucose transporter 1 (GLUT1), hexokinase-2 (HK2), and phosphofructokinase-2 isoform 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase-3 (PFKFB3) (key glycolytic enzymes), while upregulating the mitochondrial markers synthesis of cytochrome c oxidase 2 (SCO2), cytochrome c oxidase subunit 4 (COX4), and OXPHOS mitochondrial complexes. SLMP53-1 also downregulated the monocarboxylate transporter 4 (MCT4), causing the subsequent reduction of lactate export by cancer cells. Besides the acidification of the extracellular environment, SLMP53-1 further increased E-cadherin and reduced metalloproteinase-9 (MMP-9) expression levels in both cancer cells and xenograft human tumor tissue, which suggested the interference of SLMP53-1 in extracellular matrix remodeling and epithelial-to-mesenchymal transition. Consistently, SLMP53-1 depleted angiogenesis, decreasing endothelial cell tube formation and vascular endothelial growth factor (VEGF) expression levels. SLMP53-1 also exhibited synergistic growth inhibitory activity in combination with the metabolic modulator dichloroacetic acid. These data reinforce the promising application of the p53-activating agent SLMP53-1 in cancer therapy, by targeting p53-mediated pathways of growth and dissemination.

Arabidopsis SCO Proteins Oppositely Influence Cytochrome c Oxidase Levels and Gene Expression during Salinity Stress

SCO (synthesis of cytochrome c oxidase) proteins are involved in the insertion of copper during the assembly of cytochrome c oxidase (COX), the final enzyme of the mitochondrial respiratory chain. Two SCO proteins, namely, homolog of copper chaperone 1 and 2 (HCC1 and HCC2) are present in seed plants, but HCC2 lacks the residues involved in copper binding, leading to uncertainties about its function. In this study, we performed a transcriptomic and phenotypic analysis of Arabidopsis thaliana plants with reduced expression of HCC1 or HCC2. We observed that a deficiency in HCC1 causes a decrease in the expression of several stress-responsive genes, both under basal growth conditions and after applying a short-term high salinity treatment. In addition, HCC1 deficient plants show a faster decrease in chlorophyll content, photosystem II quantum efficiency and COX levels after salinity stress, as well as a faster increase in alternative oxidase capacity. Notably, HCC2 deficiency causes opposite changes in most of these parameters. Bimolecular fluorescence complementation analysis indicated that both proteins are able to interact. We postulate that HCC1 is a limiting factor for COX assembly during high salinity conditions and that HCC2 probably acts as a negative modulator of HCC1 activity through protein-protein interactions. In addition, a direct or indirect role of HCC1 and HCC2 in the gene expression response to stress is proposed.

Flower isoforms promote competitive growth in cancer

In humans, the adaptive immune system uses the exchange of information between cells to detect and eliminate foreign or damaged cells; however, the removal of unwanted cells does not always require an adaptive immune system^1,2. For example, cell selection in Drosophila uses a cell selection mechanism based on 'fitness fingerprints', which allow it to delay ageing³, prevent developmental malformations^3,4 and replace old tissues during regeneration⁵. At the molecular level, these fitness fingerprints consist of combinations of Flower membrane proteins^3,4,6. Proteins that indicate reduced fitness are called Flower-Lose, because they are expressed in cells marked to be eliminated⁶. However, the presence of Flower-Lose isoforms at a cell's membrane does not always lead to elimination, because if neighbouring cells have similar levels of Lose proteins, the cell will not be killed^4,6,7. Humans could benefit from the capability to recognize unfit cells, because accumulation of damaged but viable cells during development and ageing causes organ dysfunction and disease^8-17. However, in Drosophila this mechanism is hijacked by premalignant cells to gain a competitive growth advantage¹⁸. This would be undesirable for humans because it might make tumours more aggressive^19-21. It is unknown whether a similar mechanism of cell-fitness comparison is present in humans. Here we show that two human Flower isoforms (hFWE1 and hFWE3) behave as Flower-Lose proteins, whereas the other two isoforms (hFWE2 and hFWE4) behave as Flower-Win proteins. The latter give cells a competitive advantage over cells expressing Lose isoforms, but Lose-expressing cells are not eliminated if their neighbours express similar levels of Lose isoforms; these proteins therefore act as fitness fingerprints. Moreover, human cancer cells show increased Win isoform expression and proliferate in the presence of Lose-expressing stroma, which confers a competitive growth advantage on the cancer cells. Inhibition of the expression of Flower proteins reduces tumour growth and metastasis, and induces sensitivity to chemotherapy. Our results show that ancient mechanisms of cell recognition and selection are active in humans and affect oncogenic growth.

Cytotoxic phenanthroline derivatives alter metallostasis and redox homeostasis in neuroblastoma cells

Copper homeostasis is generally investigated focusing on a single component of the metallostasis network. Here we address several of the factors controlling the metallostasis for neuroblastoma cells (SH-SY5Y) upon treatment with 2,9-dimethyl-1,10-phenanthroline-5,6-dione (phendione) and 2,9-dimethyl-1,10-phenanthroline (cuproindione). These compounds bind and transport copper inside cells, exert their cytotoxic activity through the induction of oxidative stress, causing apoptosis and alteration of the cellular redox and copper homeostasis network. The intracellular pathway ensured by copper transporters (Ctr1, ATP7A), chaperones (CCS, ATOX, COX 17, Sco1, Sco2), small molecules (GSH) and transcription factors (p53) is scrutinised.

LACE1 interacts with p53 and mediates its mitochondrial translocation and apoptosis

p53 is a major cellular tumor suppressor that in addition to its nuclear, transcription-dependent activity is also known to function extranuclearly. Cellular stressors such as reactive oxygen species can promote translocation of p53 into mitochondria where it acts to protect mitochondrial genome or trigger cell death via transcription-independent manner. Here we report that the mammalian homologue of yeast mitochondrial Afg1 ATPase (LACE1) promotes translocation of p53 into mitochondria. We further show that LACE1 exhibits significant pro-apoptotic activity, which is dependent on p53, and that the protein is required for normal mitochondrial respiratory function. LACE1 physically interacts with p53 and is necessary for mitomycin c-induced translocation of p53 into mitochondria. Conversely, increased expression of LACE1 partitions p53 to mitochondria, causes reduction in nuclear p53 content and induces apoptosis. Thus, LACE1 mediates mitochondrial translocation of p53 and its transcription-independent apoptosis.

Apolipoprotein E4 Elicits Lysosomal Cathepsin D Release, Decreased Thioredoxin-1 Levels, and Apoptosis

The major genetic risk factor for Alzheimer’s disease (AD), apolipoprotein E4 (ApoE4), has been suggested to have detrimental effects on neurons, including direct toxicity via apoptosis. Thioredoxin-1 (Trx1) is an endogenous antioxidant protein important for redox regulation and participates in the regulation of apoptosis through the inhibition of apoptosis signal-regulating kinase-1 (Ask-1). In this study, we have investigated the effects of ApoE on Trx1 in the brain. Our results showed that the protein levels of Trx1 were reduced in the hippocampus of ApoE4 targeted replacement (TR) mice compared to ApoE3 TR mice. The reduction was also seen in vitro after treatment of both human primary cortical neurons and neuroblastoma cells with human recombinant ApoE4 (rApoE4). Furthermore, ApoE4 caused a disruption of lysosomal integrity and a shift in the localization of Cathepsin D, an enzyme known to degrade Trx1. ApoE4 treatment induced in addition apoptosis through translocation of Death-domain associated protein-6 (Daxx) from the nucleus to the cytosol, suggesting an activation of the Ask-1 pathway. This toxicity was prevented by overexpression of Trx1 and other endogenous Ask-1 inhibitors. Our data suggests that down-regulation of Trx1 is involved in the toxicity caused by ApoE4. An activated ASK-1 pathway might indeed make cells more vulnerable to other insults such as amyloid-β, which could partially explain the mechanism behind the strongest genetic risk factor for AD.

KRAB-type zinc-finger proteins PITA and PISA specifically regulate p53-dependent glycolysis and mitochondrial respiration

Few p53 regulators participate in selective control of p53-mediated cellular metabolism. How p53-mediated aerobic and glycolytic pathways are negatively regulated remains largely unclear. Here, we identified two KRAB-type zinc-finger proteins, PITA (p53 inhibitor of TIGAR activation) and PISA (p53 inhibitor of SCO2 activation), as selective regulators of p53 in metabolic control. PITA and PISA interact with p53 and specifically suppress transcription of the glycolysis regulator TIGAR and the oxidation phosphorylation regulator SCO2, respectively. Importantly, PITA transgenic mice exhibited increased 6-phosphofructokinase 1 (PFK1) activity and an elevated glycolytic rate, whereas PISA transgenic mice had decreased cytochrome c oxidase activity and reduced mitochondrial respiration. In response to glucose starvation, PITA dissociates from p53, resulting in activation of p53 and induction of TIGAR, which inhibited aerobic glycolysis. Prolonged starvation leads to PISA dissociation from p53 and induction of SCO2 and p53-promoted mitochondrial respiration. The dynamic regulation of PITA and PISA upon metabolic stress is dependent on ATM kinase-mediated phosphorylation of PITA and PISA. Furthermore, in human colorectal cancers, the elevated expression of PITA and PISA correlates with cancer progression. Depletion of PITA or PISA in colorectal cancer cells reduced the cell proliferation, migration and invasion. These results identify PITA and PISA as selective regulators of p53-mediated glycolysis and mitochondrial respiration and provide novel insights into the role of p53 network in cell metabolic control.

The curcumin analog HO-3867 selectively kills cancer cells by converting mutant p53 protein to transcriptionally active wildtype p53

p53 is an important tumor-suppressor protein that is mutated in more than 50% of cancers. Strategies for restoring normal p53 function are complicated by the oncogenic properties of mutant p53 and have not met with clinical success. To counteract mutant p53 activity, a variety of drugs with the potential to reconvert mutant p53 to an active wildtype form have been developed. However, these drugs are associated with various negative effects such as cellular toxicity, nonspecific binding to other proteins, and inability to induce a wildtype p53 response in cancer tissue. Here, we report on the effects of a curcumin analog, HO-3867, on p53 activity in cancer cells from different origins. We found that HO-3867 covalently binds to mutant p53, initiates a wildtype p53-like anticancer genetic response, is exclusively cytotoxic toward cancer cells, and exhibits high anticancer efficacy in tumor models. In conclusion, HO-3867 is a p53 mutant-reactivating drug with high clinical anticancer potential.

ASK family and cancer

Cancer is a major problem in public health and is one of the leading causes of mortality worldwide. Many types of cancer cells exhibit aberrant cellular signal transduction in response to stress, which often leads to oncogenesis. Mitogen-activated protein kinase (MAPK) signal cascades are one of the important intracellular stress signaling pathways closely related to cancer. The key molecules in MAPK signal cascades that respond to various types of stressors are apoptosis signal-regulating kinase (ASK) family members; ASK1, ASK2 and ASK3. ASK family members are activated by a wide variety of stressors, and they regulate various cellular responses, such as cell proliferation, inflammation and apoptosis. In this review, we will discuss both the oncogenic and anti-oncogenic roles of the ASK family members in various contexts of cancer development with deeper insights into the involvement of ASK family members in cancer pathology.

Reactive oxygen species (ROS) are a key determinant of cancer's metabolic phenotype

Cancer cells exhibit a wide range of metabolic phenotypes, ranging from strict aerobic glycolysis to increased mitochondrial respiration. The cause and utility of this metabolic variation is poorly understood. Given that cancer cells experience heavy selection within their microenvironment, survival requires metabolic adaptation to both extracellular and intracellular conditions. Herein, we suggest that reactive oxygen species (ROS) are a key determinant of cancer's metabolic phenotype. Intracellular ROS levels can be modified by an assortment of critical parameters including oxygenation, glucose availability and growth factors. ROS act as integrators of environmental information as well as downstream effectors of signaling pathways. Maintaining ROS within a narrow range allows malignant cells to enhance growth and invasion while limiting their apoptotic susceptibility. Cancer cells actively modify their metabolism to optimize intracellular ROS levels and thereby improve survival. Furthermore, we highlight distinct metabolic phenotypes in response to oxidative stress and their tumorigenic drivers.

Chaetocin induces cell cycle arrest and apoptosis by regulating the ROS-mediated ASK-1/JNK signaling pathways

The present study demonstrated that chaetocin, a natural small-molecule product produced by Chaetomium fungal species and a potential anticancer agent, inhibited the viability and invasive ability of the human intrahepatic cholangio-carcinoma cell line CCLP-1 in vivo and in vitro as revealed by CCK-8 and Transwell invasion assays and mouse xenograft tumor experiments. As determined using flow cytometry and intracellular ROS assays, chaetocin was found to induce cell cycle arrest and oxidative stress, leading to CCLP-1 cell apoptosis. Cell apoptosis can be initiated via different apoptotic signaling pathways under oxidative stress. As determined by western blot analysis, expression levels of the apoptosis signal-regulating kinase 1 (ASK-1) signalosome and its downstream c-Jun N-terminal kinase (JNK) signaling pathway were increased under oxidative stress stimulation. These findings indicate that chaetocin arrests the cell cycle and induces apoptosis by regulating the reactive oxygen species-mediated ASK-1/JNK signaling pathways.

Thioredoxin 1 modulates apoptosis induced by bioactive compounds in prostate cancer cells

Accumulating evidence suggests that natural bioactive compounds, alone or in combination with traditional chemotherapeutic agents, could be used as potential therapies to fight cancer. In this study, we employed four natural bioactive compounds (curcumin, resveratrol, melatonin, and silibinin) and studied their role in redox control and ability to promote apoptosis in androgen sensitive and insensitive prostate cancer cells. Here is shown that curcumin and resveratrol promote ROS production and induce apoptosis in LNCaP and PC-3. An increase in reactive species is a trigger event in curcumin-induced apoptosis and a consequence of resveratrol effects on other pathways within these cells. Moreover, here we demonstrated that these four compounds affect differently one of the main intracellular redox regulator, the thioredoxin system. Exposure to curcumin and resveratrol promoted TRX1 oxidation and altered its subcellular location. Furthermore, resveratrol diminished TRX1 levels in PC-3 cells and increased the expression of its inhibitor TXNIP. Conversly, melatonin and silibinin only worked as cytostatic agents, reducing ROS levels and showing preventive effects against TRX oxidation. All together, this work explores the effect of compounds currently tested as chemo-preventive agents in prostate cancer therapy, on the TRX1 redox state and function. Our work shows the importance that the TRX system might have within the differences found in their mechanisms of action. These bioactive compounds trigger different responses and affect ROS production and redox systems in prostate cancer cells, suggesting the key role that redox-related pathways might play in processes like differentiation or survival in prostate cancer.

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Resveratrol decreases TRX1 by increasing TXNIP while curcumin induces TRX1 oxidation.

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Antioxidants decrease TRX1 oxidation and nuclear translocation to prevent cell death.

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TRX1 oxidation and nuclear translocation play a key role in apoptosis.

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Differences in the apoptosis induction of bioactive compounds relay on TRX1 oxidation.

The oncoprotein HBXIP promotes glucose metabolism reprogramming via downregulating SCO2 and PDHA1 in breast cancer

The glucose metabolism reprogramming is a hallmark of cancer. The oncoprotein hepatitis B X-interacting protein (HBXIP) functions in the development of breast cancer. In this study, we supposed that HBXIP might be involved in the glucose metabolism reprogramming in breast cancer. We showed that HBXIP led to increases in generation of intracellular glucose and lactate, as well as decreases in generation of reactive oxygen species. Expression of synthesis of cytochrome c oxidase 2 (SCO2) and pyruvate dehydrogenase alpha 1 (PDHA1), two factors of metabolic switch from oxidative phosphorylation to aerobic glycolysis, was suppressed by HBXIP. In addition, miR-183/182 and miR-96 directly inhibited the expression of SCO2 and PDHA1 through targeting their mRNA coding sequences (CDSs), respectively. Interestingly, HBXIP elevated the miR-183/96/182 cluster expression through hypoxia-inducible factor 1α (HIF1α). The stability of HIF1α was enhanced by HBXIP through disassociating interaction of von Hippel-Lindau protein (pVHL) with HIF1α. Moreover, miR-183 increased the levels of HIF1α protein through directly targeting CDS of VHL mRNA, forming a feedback loop of HIF1α/miR-183/pVHL/HIF1α. In function, HBXIP-elevated miR-183/96/182 cluster enhanced the glucose metabolism reprogramming in vitro. HBXIP-triggered glucose metabolism reprogramming promoted the growth of breast cancer in vivo. Thus, we conclude that the oncoprotein HBXIP enhances glucose metabolism reprogramming through suppressing SCO2 and PDHA1 in breast cancer.

p53 and mitochondrial dysfunction: novel insight of neurodegenerative diseases

Mitochondria are organelles responsible for vital cell functions. p53 is a transcription factor that regulates the DNA stability and cell growth normality. Recent studies revealed that p53 can influence mitochondrial function changing from normal condition to abnormal condition under different stress levels. In normal state, p53 can maintain mitochondrial respiration through transactivation of SCO2. When stress stimuli presents, SCO2 overexpresses and leads to ROS generation. ROS promotes p53 inducing MALM (Mieap-induced accumulation of lysosome-like organelles within mitochondria) to repair dysfunctional mitochondria and MIV (Mieap-induced vacuole) to accomplish damaged mitochondria degradation. If stress or damage is irreversible, p53 will translocate to mitochondria, leading into apoptosis or necrosis. Neurodegenerative diseases including Parkinson’s disease, Huntington’s disease and Alzheimer’s disease are still lack of clear explanations of mechanisms, but more studies have revealed the functional relationship between mitochondria and p53 towards the pathological development of these diseases. In this review, we discuss that p53 plays the vital role in the function of mitochondria in the aspect of pathological change metabolism. We also analyze these diseases with novel targeted treating molecules which are related to p53 and mitochondria, hoping to present novel therapies in future clinic.

Role of Endoplasmic Reticulum Stress and Unfolded Protein Responses in Health and Diseases

Endoplasmic reticulum (ER) is the site of protein synthesis, protein folding, maintainance of calcium homeostasis, synthesis of lipids and sterols. Genetic or environmental insults can alter its function generating ER stress. ER senses stress mainly by three stress sensor pathways, namely protein kinase R-like endoplasmic reticulum kinase-eukaryotic translation-initiation factor 2α, inositol-requiring enzyme 1α-X-box-binding protein 1 and activating transcription factor 6-CREBH, which induce unfolded protein responses (UPR) after the recognition of stress. Recent studies have demonstrated that ER stress and UPR signaling are involved in cancer, metabolic disorders, inflammatory diseases, osteoporosis and neurodegenerative diseases. However, the precise knowledge regarding involvement of ER stress in different disease processes is still debatable. Here we discuss the possible role of ER stress in various disorders on the basis of existing literature. An attempt has also been made to highlight the present knowledge of this field which may help to elucidate and conjure basic mechanisms and novel insights into disease processes which could assist in devising better future diagnostic and therapeutic strategies.

Cardiac deficiency of single cytochrome oxidase assembly factor scox induces p53-dependent apoptosis in a Drosophila cardiomyopathy model

The heart is a muscle with high energy demands. Hence, most patients with mitochondrial disease produced by defects in the oxidative phosphorylation (OXPHOS) system are susceptible to cardiac involvement. The presentation of mitochondrial cardiomyopathy includes hypertrophic, dilated and left ventricular noncompaction, but the molecular mechanisms involved in cardiac impairment are unknown. One of the most frequent OXPHOS defects in humans frequently associated with cardiomyopathy is cytochrome c oxidase (COX) deficiency caused by mutations in COX assembly factors such as Sco1 and Sco2. To investigate the molecular mechanisms that underlie the cardiomyopathy associated with Sco deficiency, we have heart specifically interfered scox expression, the single Drosophila Sco orthologue. Cardiac-specific knockdown of scox reduces fly lifespan, and it severely compromises heart function and structure, producing dilated cardiomyopathy. Cardiomyocytes with low levels of scox have a significant reduction in COX activity and they undergo a metabolic switch from OXPHOS to glycolysis, mimicking the clinical features found in patients harbouring Sco mutations. The major cardiac defects observed are produced by a significant increase in apoptosis, which is dp53-dependent. Genetic and molecular evidence strongly suggest that dp53 is directly involved in the development of the cardiomyopathy induced by scox deficiency. Remarkably, apoptosis is enhanced in the muscle and liver of Sco2 knock-out mice, clearly suggesting that cell death is a key feature of the COX deficiencies produced by mutations in Sco genes in humans.

Understanding the non-canonical pathways involved in p53-mediated tumor suppression

In the last three decades since the discovery of p53, it has become increasingly apparent that p53 plays a very important role in tumor suppression. Previously, it was thought that the tumor suppressive functions lied solely in the canonical p53-mediated apoptosis, cell cycle arrest and senescence. However, more recent research has shown that anti-oncogenic activity of p53 can still occur in the absence of these downstream functions. These results suggest that more non-canonical roles of p53 may have a much larger impact on other p53-regulated programs then initially anticipated. Recently, the non-canonical activities of p53 such as cell metabolism, autophagy and necrosis have been the subject of intense study. p53 affects many aspects of cellular metabolism including catabolism, anabolism and reactive oxygen species levels. p53 has a dual role in autophagy regulation. Initiation of autophagy occurs through direct transcription of pro-autophagy genes and inhibition transpires through a transcription-independent mechanism. The role of p53 in these cellular processes is quite complex and evidence suggests that p53 can play both a pro- and anti-oncogenic role in these non-conical pathways. Despite of more than 60,000 publications on p53 in the literature, the mechanisms for p53-mediated tumor suppression apparently needs to be further elucidated.

p53 increases intra-cellular calcium release by transcriptional regulation of calcium channel TRPC6 in GaQ3-treated cancer cells

p53 and calcium signaling are inter-dependent and are known to show both synergistic and antagonistic effects on each other in the cellular environment. However, no molecular mechanism or cellular pathway is known which shows direct regulation between these important cellular signaling molecules. Here we have shown that in cancer cells treated with anti-neoplastic drug GaQ₃, p53, there is an increase in intracellular calcium levels by transcriptional regulation of a novel calcium channel gene TRPC6. p53 directly binds to a 22 bp response element in the TRPC6 gene promoter and increase its mRNA and protein expression. Over-expression of TRPC6 results in calcium-dependent apoptotic death and activation of apoptotic genes in a variety of cancer cells. This research work shows that p53 and its transcriptional activity is critical in regulation of calcium signaling and an increase in the intracellular calcium level might be one of the anti-cancer strategies to induce apoptosis in cancer cells.

Alpha particle-induced bystander effect is mediated by ROS via a p53-dependent SCO2 pathway in hepatoma cells

PURPOSE

The radiation-induced bystander effect (RIBE) has important implications for the efficiency of radiotherapy but the underlying role of cellular metabolism is widely unknown. The roles of synthesis of cytochrome c oxidase 2 (SCO2), a key effector for respiratory chain, and related signaling factors in α-particle-induced bystander damage were currently investigated in a liver cell co-culture system.

MATERIALS AND METHODS

Human hepatoma cells of HepG2 with wild-type p53 (wtp53) and Hep3B (p53 null) were irradiated with 0.4 Gy of α-particles and co-cultured with non-irradiated normal liver cells HL-7702 for 6 h, then the incidence of micronucleus (MN) in the bystander HL-7702 cells was analyzed. The expressions of total P53, phospho-P53 (p-P53), SCO2, and reactive oxygen species (ROS) in the irradiated hepatoma cells were detected. In some experiments, the hepatoma cells were respectively treated with p53 siRNA, SCO2 siRNA, or dimethyl sulfoxide (DMSO) before irradiation.

RESULTS

Bystander damage in HL-7702 cells was induced by α-irradiated HepG2 cells but not by α-irradiated Hep3B cells, and this bystander effect was diminished when the irradiated HepG2 cells were pretreated with p53 siRNA, SCO2 siRNA, or DMSO. Meanwhile, the expressions of p-P53 protein and SCO2 mRNA, the activity of SCO2 protein, and intracellular ROS were all increased in the irradiated HepG2 cells but not Hep3B cells and these expressions were eliminated by p53 siRNA treatment. Moreover, the radiation-enhanced expressions of SCO2 and ROS were inhibited by SCO2 siRNA.

CONCLUSION

α-particle-induced bystander effect was regulated by p53 and its downstream SCO2 in the irradiated hepatoma cells, and ROS generation could be an early event for triggering this bystander response.