Presenilin Mutation Suppresses Lung Tumorigenesis via Inhibition of Peroxiredoxin 6 Activity and Expression

The glycyl-l-histidyl-l-lysine-Cu2+ tripeptide complex attenuates lung inflammation and fibrosis in silicosis by targeting peroxiredoxin 6

Silicosis is the most common type of pneumoconiosis, having a high incidence in workers chronically exposed to crystalline silica (CS). No specific medication exists for this condition. GHK, a tripeptide naturally occurring in human blood and urine, has antioxidant effects. We aimed to investigate the therapeutic effect of GHK-Cu on silicosis and its potential underlying molecular mechanism. An experimental silicosis mouse model was established to observe the effects of GHK-Cu on lung inflammation and fibrosis. Moreover, the effects of GHK-Cu on the alveolar macrophages (AM) were examined using the RAW264.7 cell line. Its molecular target, peroxiredoxin 6 (PRDX6), has been identified, and GHK-Cu can bind to PRDX6, thus attenuating lung inflammation and fibrosis in silicosis mice without significant systemic toxicity. These effects were partly related to the inhibition of the CS-induced oxidative stress in AM induced by GHK-Cu. Thus, our results suggest that GHK-Cu acts as a potential drug by attenuating alveolar macrophage oxidative stress. This, in turn, attenuates the progression of pulmonary inflammation and fibrosis, which provides a reference for the treatment of silicosis.

Unveiling the Significance of Peroxiredoxin 6 in Central Nervous System Disorders

Peroxiredoxin 6 (Prdx6), a unique 1-Cys member of the peroxiredoxin family, exhibits peroxidase activity, phospholipase activity, and lysophosphatidylcholine acyltransferase (LPCAT) activity. Prdx6 has been known to be an important enzyme for the maintenance of lipid peroxidation repair, cellular metabolism, inflammatory signaling, and antioxidant damage. Growing research has demonstrated that the altered activity of this enzyme is linked with various pathological processes including central nervous system (CNS) disorders. This review discusses the distinctive structure, enzyme activity, and function of Prdx6 in different CNS disorders, as well as emphasizing the significance of Prdx6 in neurological disorders.

The Role of Peroxiredoxins in Cancer Development

Peroxiredoxins (Prxs) are antioxidant enzymes with ubiquitous expression in human tissues. Prxs are expressed in archaea, bacteria, and eukaryota, often in multiple isoforms. Because of their abundant expression in different cellular organelles and extraordinary sensitivity to H2O2, Prxs are among the first defenses against oxidative stress. Prxs undergo reversible oxidation to disulfides, and some family members perform chaperone or phospholipase functions upon further oxidation. Prxs are upregulated in cancer cells. Research has suggested that Prxs can function as tumor promoters in various cancers. The major objective of this review is to summarize novel findings regarding the roles of Prxs in common cancer types. Prxs have been shown to influence differentiation of inflammatory cells and fibroblasts, remodeling of extracellular matrix, and regulation of stemness. Since aggressive cancer cells have higher intracellular levels of ROS that they can utilize to proliferate and metastasize compared to normal cells, it is critical that we understand the regulation and functions of primary antioxidants such as Prxs. These small but mighty proteins could prove to be key for improving cancer therapeutics and patient survival.

The somatic mutational landscape and role of the ARID1A gene in hepatocellular carcinoma

Introduction

Hepatocellular carcinoma (HCC) is one of the most common malignant tumours worldwide. Clarification of the somatic mutational landscape of important genes could reveal new therapeutic targets and facilitate individualized therapeutic approaches for HCC patients. The mutation and expression changes in the ARID1A gene in HCC remain controversial.

Methods

First, cBioPortal was used to visualize genetic alterations and DNA copy number alterations (CNAs) in ARID1A. The relationships between ARID1A mutation status and HCC patient clinicopathological features and overall survival (OS) were also determined. Then, a meta-analysis was performed to evaluate the effect of ARID1A mutation or expression on the prognosis of HCC patients. Finally, the role of ARID1A in HCC progression was verified by in vitro experiments.

Results

ARID1A mutation was detected in 9.35% (33/353) of sequenced HCC cases, and ARID1A mutation decreased ARID1A mRNA expression. Patients with ARID1A alterations presented worse OS than those without ARID1A alterations. Meta-analysis and human HCC tissue microarray (TMA) analysis revealed that HCC patients with low ARID1A expression had worse OS and relapse-free survival (RFS), and low ARID1A expression was negatively correlated with tumour size. Then, ARID1A gain-of-function and loss-of-function experiments demonstrated the tumour suppressor role of ARID1A in HCC in vitro. In terms of the mechanism, we found that ARID1A could inhibit HCC progression by regulating retinoblastoma-like 1 (RBL1) expression via the JNK/FOXO3 pathway.

Conclusions

ARID1A can be considered a potential prognostic biomarker and candidate therapeutic target for HCC.

Anti-Oxidant and Pro-Oxidant Effects of Peroxiredoxin 6: A Potential Target in Respiratory Diseases

Peroxiredoxin 6 (PRDX6) is widely distributed in several organs, especially the lungs. The role of PRDX6 in oxidative stress is controversial and even contradictory, as indicated by research conducted over the past 20 years. PRDX6 has anti-oxidant or pro-oxidant effects on oxidative stress in different diseases. It can even exhibit both anti-oxidant and pro-oxidant effects in the same disease. These findings are attributed to the fact that PRDX6 is a multifunctional enzyme. The peroxidase and phospholipase A2 activity of PRDX6 is closely related to its anti-oxidant and pro-oxidant effects, which leads to the conflicting regulatory effects of PRDX6 on oxidative stress in respiratory diseases. Moreover, PRDX6 interacts with multiple redox signaling pathways to interfere with cell proliferation and apoptosis. PRDX6 has become a new target in respiratory disease research due to its important regulatory role in oxidative stress. In this paper, the role of PRDX6 in oxidative stress in respiratory diseases and the research progress in targeting PRDX6 are reviewed.

The Roles of Peroxiredoxin 6 in Brain Diseases

Peroxiredoxin 6 (PRDX6), the only mammalian 1-Cys member of the peroxiredoxins (PRDXs) family, has multiple functions of glutathione peroxidase (Gpx) activity, acidic calcium-independent phospholipase (aiPLA2) activity, and lysophosphatidylcholine acyl transferase (LPCAT) activity. It has been documented to be involved in redox homeostasis, phospholipid turnover, glycolipid metabolism, and cellular signaling. Here, we reviewed the characteristics of the available Prdx6 genetic mouse models and the research progresses made with regard to PRDX6 in neuropsychiatric disorders, including neurodegenerative diseases, brain aging, stroke, neurotrauma, gliomas, major depressive disorder, drug addiction, post-traumatic stress disorder, and schizophrenia. The present review highlights the important roles of PRDX6 in neuropsychiatric disorders and may provide novel insights for the development of effective pharmacological treatments and genetic therapies.

Presenilin-Deficient Neurons and Astrocytes Display Normal Mitochondrial Phenotypes

Presenilin 1 (PS1) and Presenilin 2 (PS2) are predominantly known as the catalytic subunits of the γ-secretase complex that generates the amyloid-β (Aβ) peptide, the major constituent of the senile plaques found in the brain of Alzheimer's disease (AD) patients. Apart from their role in γ-secretase activity, a growing number of cellular functions have been recently attributed to PSs. Notably, PSs were found to be enriched in mitochondria-associated membranes (MAMs) where mitochondria and endoplasmic reticulum (ER) interact. PS2 was more specifically reported to regulate calcium shuttling between these two organelles by controlling the formation of functional MAMs. We have previously demonstrated in mouse embryonic fibroblasts (MEF) an altered mitochondrial morphology along with reduced mitochondrial respiration and increased glycolysis in PS2-deficient cells (PS2KO). This phenotype was restored by the stable re-expression of human PS2. Still, all these results were obtained in immortalized cells, and one bottom-line question is to know whether these observations hold true in central nervous system (CNS) cells. To that end, we carried out primary cultures of PS1 knockdown (KD), PS2KO, and PS1KD/PS2KO (PSdKO) neurons and astrocytes. They were obtained from the same litter by crossing PS2 heterozygous; PS1 floxed (PS2+/-; PS1flox/flox) animals. Genetic downregulation of PS1 was achieved by lentiviral expression of the Cre recombinase in primary cultures. Strikingly, we did not observe any mitochondrial phenotype in PS1KD, PS2KO, or PSdKO primary cultures in basal conditions. Mitochondrial respiration and membrane potential were similar in all models, as were the glycolytic flux and NAD+/NADH ratio. Likewise, mitochondrial morphology and content was unaltered by PS expression. We further investigated the differences between results we obtained here in primary nerve cells and those previously reported in MEF cell lines by analyzing PS2KO primary fibroblasts. We found no mitochondrial dysfunction in this model, in line with observations in PS2KO primary neurons and astrocytes. Together, our results indicate that the mitochondrial phenotype observed in immortalized PS2-deficient cell lines cannot be extrapolated to primary neurons, astrocytes, and even to primary fibroblasts. The PS-dependent mitochondrial phenotype reported so far might therefore be the consequence of a cell immortalization process and should be critically reconsidered regarding its relevance to AD.

Chronic Respiratory Diseases and Neurodegenerative Disorders: A Primer for the Practicing Clinician

Chronic respiratory disorders represent a world epidemic. Their incidence and prevalence in the world population is increasing, and especially among elderly subjects, they are commonly associated with other pathologies, often generating a status of high clinical complexity. Neurology, internal medicine, and pneumology specialists should be aware of the common background of these disorders in order to treat correctly the patient's comorbid state and optimize the treatment considering potential overlaps. In this review, we aimed to focus on the relationships between chronic respiratory disorders and chronic neurodegenerative diseases at different levels; we review the shared risk factors and the interactions between disorders, the indications to explore respiratory function in neurodegenerative diseases, pathology-pathology and drug-pathology interactions in patients affected by both chronic neurologic and respiratory diseases.

Celastrol induces ROS-mediated apoptosis via directly targeting peroxiredoxin-2 in gastric cancer cells

Background: Oxidative stress from elevated reactive oxygen species (ROS) has been reported to induce cell apoptosis and may provide a means to target cancer cells. Celastrol is a natural bioactive compound that was recently shown to increase ROS levels and cause apoptosis in cancer cells. However, the underlying mechanism for this cytotoxic action remains unclear and direct molecular targets of Celastrol have not been identified.

Methods: Proteome microarray, surface plasmon resonance, isothermal titration calorimetry and molecular simulation were used to identify the molecular target of Celastrol. Binding and activity assays were used to validate the interaction of Celastrol with target protein in cell-free and gastric cancer cell lysates. We then assessed target transcript levels in in biopsy specimens obtained from patients with gastric cancer. Gastric cancer growth-limiting and cytotoxic activity of Celastrol was evaluated in BALB/c nu/nu mice.

Results: Our data show that Celastrol directly binds to an antioxidant enzyme, peroxiredoxin-2 (Prdx2), which then inhibits its enzyme activity at both molecular and cellular level. Inhibition of Prdx2 by Celastrol increased cellular ROS levels and led to ROS-dependent endoplasmic reticulum stress, mitochondrial dysfunction, and apoptosis in gastric cancer cells. Functional tests demonstrated that Celastrol limits gastric cancer cells, at least in part, through targeting Prdx2. Celastrol treatment of mice implanted with gastric cancer cells also inhibited tumor growth, associated with Prdx2 inhibition and increased ROS. Analysis of human gastric cancer also showed increased Prdx2 levels and correlation with survival.

Conclusion: Our studies have uncovered a potential Celastrol-interacting protein Prdx2 and a ROS-dependent mechanism of its action. The findings also highlight Prdx2 as a potential target for the treatment of gastric cancer.

Elevation of CD109 promotes metastasis and drug resistance in lung cancer via activation of EGFR-AKT-mTOR signaling

Lung cancer is the most commonly diagnosed cancer worldwide, and metastasis in lung cancer is the leading cause of cancer‐related deaths. Thus, understanding the mechanism of lung cancer metastasis will improve the diagnosis and treatment of lung cancer patients. Herein, we found that expression of cluster of differentiation 109 (CD109) was correlated with the invasive and metastatic capacities of lung adenocarcinoma cells. CD109 is upregulated in tumorous tissues, and CD109 overexpression was associated with tumor progression, distant metastasis, and a poor prognosis in patient with lung adenocarcinoma. Mechanistically, expression of CD109 regulates protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling via its association with the epidermal growth factor receptor (EGFR). Inhibition of CD109 decreases EGFR phosphorylation, diminishes EGF‐elicited activation of AKT/mTOR, and sensitizes tumor cells to an EGFR inhibitor. Taken together, our results show that CD109 is a potential diagnostic and therapeutic target in lung cancer patients.

Chitinase 3 like 1 suppresses the stability and activity of p53 to promote lung tumorigenesis

Background

Chitinase 3 like 1 protein (Chi3L1) is expressed in several cancers, and a few evidences suggest that the secreted Chi3L1 contributes to tumor development. However, the molecular mechanisms of intracellular Chi3L1 are unknown in the lung tumor development. Methods: In the present study, we generated Chi3L1 knockout mice (Chi3L1^KO(−/−)) using CRISPR/Cas9 system to investigate the role of Chi3L1 on lung tumorigenesis.

Results

We established lung metastasis induced by i.v. injections of B16F10 in Chi3L1^KO(−/−). The lung tumor nodules were significantly reduced in Chi3L1^KO(−/−) and protein levels of p53, p21, BAX, and cleaved-caspase 3 were significantly increased in Chi3L1^KO(−/−), while protein levels of cyclin E1, CDK2, and phsphorylation of STAT3 were decreased in Chi3L1^KO(−/−). Allograft mice inoculated with B16F10 also suppressed tumor growth and increased p53 and its target proteins including p21 and BAX. In addition, knockdown of Chi3L1 in lung cancer cells inhibited lung cancer cell growth and upregulated p53 expression with p21 and BAX, and a decrease in phosphorylation of STAT3. Furthermore, we found that intracellular Chi3L1 physically interacted and colocalized with p53 to inhibit its protein stability and transcriptional activity for target genes related with cell cycle arrest and apoptosis. In lung tumor patient, we clinically found that Chi3L1 expression was upregulated with a decrease in p53 expression, as well as we validated that intracellular Chi3L1 was colocalized, reversely expressed, and physically interacted with p53, which results in suppression of the expression and function of p53 in lung tumor patient.

Conclusions

Our studies suggest that intracellular Chi3L1 plays a critical role in the lung tumorigenesis by regulating its novel target protein, p53 in both an in vitro and in vivo system.

Peroxiredoxins and Immune Infiltrations in Colon Adenocarcinoma: Their Negative Correlations and Clinical Significances, an In Silico Analysis

Background: Peroxiredoxins (PRDXs) were reported to be associated with inflammation response in previous studies. In colon adenocarcinoma (COAD), however, their correlations and clinical significance were unclear.

Methods: The RNA-seq data of 452 COAD patients with clinical information was downloaded from The Cancer Genome Atlas (TCGA) and transcripts per million (TPM) normalized. Comparisons of relative expressions of PRDXs between COAD tumor and normal controls were applied. PRDXs dy-regulations in COAD were validated via Oncomine, Human Protein Atlas (HPA) and Gene Expression Omnibus (GEO) repository. Through Tumor Immune Estimation Resource (TIMER), the immune estimation of TCGA-COAD patients was downloaded and the dy-regulated PRDXs were analyzed for their correlations with immune infiltrations in COAD. The TCGA-COAD patients were divided into younger group (age≤65 years) and older group (age>65 years) to investigate the prognostic roles of age, TNM stage, dy-regulated PRDXs and the immune infiltrations in different age groups through Kaplan-Meier survival and Cox regression analyses.

Results: Three of the PRDX members showed their expressional differences both at protein and mRNA level. PRDX2 was consistently up-regulated while PRDX6 down-regulated in COAD. PRDX1 was overexpressed (mRNA) while nuclear absent (protein) in the tumor tissues. PRDX1 overexpression and PRDX6 under-expression were also shown in the stem-like colonospheres from colon cancer cells. Via TIMER, PRDX1, PRDX2, and PRDX6 were found to be negatively correlated with the immune infiltrations in COAD. Both in the younger and older patients, TNM stage had prognostic effects on their overall survival (OS) and recurrence-free survival (RFS). CD4⁺ T cell had independent unfavorable effects on OS of the younger patients while age had similar effects on RFS of the older ones. CD8⁺ T cell was independently prognostic for RFS in the two groups.

Conclusions: Late diagnosis indicated poor prognosis in COAD and dy-regulated PRDXs w might be new markers for its early diagnosis. Age was prognostic and should be considered in the treatments of the older patients. Dy-regulated PRDXs were negatively correlated with immune infiltration levels. CD4⁺ T cell and CD8⁺ T cell infiltrations were prognostic in COAD and their potential as immune targets needed further investigation.

A Review of the Familial Alzheimer's Disease Locus PRESENILIN 2 and Its Relationship to PRESENILIN 1

PRESENILIN 1 (PSEN1) and PRESENILIN 2 (PSEN2) genes are loci for mutations causing familial Alzheimer's disease (fAD). However, the function of these genes and how they contribute to fAD pathogenesis has not been fully determined. This review provides a summary of the overlapping and independent functions of the PRESENILINS with a focus on the lesser studied PSEN2. As a core component of the γ-secretase complex, the PSEN2 protein is involved in many γ-secretase-related physiological activities, including innate immunity, Notch signaling, autophagy, and mitochondrial function. These physiological activities have all been associated with AD progression, indicating that PSEN2 plays a particular role in AD pathogenesis.

Catalytic and Signaling Role of Peroxiredoxins in Carcinogenesis

Cancer cells experience strong oxidative stress caused by disorders in cell metabolism and action of external factors. For survival, cancer cells have developed a highly efficient system of antioxidant defense, some of the most important elements of which are peroxiredoxins (Prxs). Prxs are an evolutionarily ancient family of selenium-independent peroxidases that reduce a wide range of organic and inorganic hydroperoxides in the cell and the extracellular space. In addition, some Prxs exhibit chaperone and phospholipase activities. Prxs play an important role in the maintenance of the cell redox homeostasis; they prevent oxidation and aggregation of regulatory proteins, thereby affecting many cell signaling pathways. Prxs are involved in the regulation of cell growth, differentiation, and apoptosis. Due to their versatility and wide representation in all tissues and organs, Prxs participate in the development/suppression of many pathological conditions, among which cancer occupies a special place. This review focuses on the role of Prxs in the development of various forms of cancer. Understanding molecular mechanisms of Prx involvement in these processes will allow to develop new approaches to the prevention and treatment of cancer.

Decreased Lung Tumor Development in SwAPP Mice through the Downregulation of CHI3L1 and STAT 3 Activity via the Upregulation of miRNA342-3p

We previously found that lung tumor development was reduced in a presenilin (PS) Alzheimer's disease (AD) mouse model. Here, we investigated whether this reducing effect could occur in a different AD mouse model. We investigated urethane-induced (1 mg/g) lung tumor development and melanoma growth in Swedish amyloid precursor protein (SwAPP) transgenic mice. The expression of chitinase-3-like-1 (Chi3L1) increased during lung tumor development and melanoma growth, which was accompanied by an increase in the activity of signal transducer and activator of transcription 3 (STAT3) and the downregulation of miRNA342-3p in wild-type mice. Like tumor development, the expression of Chi3L1 and STAT3 activity was reduced in the SwAPP mice, whereas the expression of miRNA342-3p was upregulated. In addition, Chi3L1 knockdown in the lung cancer and melanoma tissues reduced cancer cell growth and STAT3 activity but enhanced miRNA342-3p expression. However, the miRNA342-3p mimic decreased Chi3L1 expression, cancer cell growth, and STAT3 activity. Moreover, a STAT3 inhibitor reduced Chi3L1 expression and cancer cell growth but enhanced miRNA342-3p expression. These data showed that lung tumor development was reduced through the decrease of Chi3L1 expression via the STAT3-dependent upregulation of miRNA342-3p. This study indicates that lung tumor development could be reduced in SwAPP AD mice.

Comprehensive MicroRNAome Analysis of the Relationship Between Alzheimer Disease and Cancer in PSEN Double-Knockout Mice

Purpose

Presenilins are functionally important components of γ-secretase, which cleaves a number of transmembrane proteins. Manipulations of PSEN1 and PSEN2 have been separately studied in Alzheimer disease (AD) and cancer because both involve substrates of γ-secretase. However, numerous clinical studies have reported an inverse correlation between AD and cancer. Interestingly, AD is a neurodegenerative disorder, whereas cancer is characterized by the proliferation of malignant cells. However, this inverse correlation in the PSEN double-knockout (PSEN dKO) mouse model of AD has been not elucidated, although doing so would shed light onto the relationship between AD and cancer.

Methods

To investigate the inverse relationship of AD and cancer under conditions of PSEN loss, we used the hippocampus of 7-month-old and 18-month-old PSEN dKO mice for a microRNA (miRNA) microarray analysis, and explored the tumorsuppressive or oncogenic role of differentially-expressed miRNAs.

Results

The total number of miRNAs that showed changes in expression level was greater at 18 months of age than at 7 months. Most of the putative target genes of the differentially-expressed miRNAs involved Cancer pathways.

Conclusions

Based on literature reviews, many of the miRNAs involved in Cancer pathways were found to be known tumorsuppressive miRNAs, and their target genes were known or putative oncogenes. In conclusion, the expression levels of known tumor-suppressive miRNAs increased at 7 and 18 months, in the PSEN dKO mouse model of AD, supporting the negative correlation between AD and cancer.