NOX1-Dependent mTORC1 Activation via S100A9 Oxidation in Cancer Stem-like Cells Leads to Colon Cancer Progression

Evaluation of the Use of Cell Lines in Studies of Selenium-Dependent Glutathione Peroxidase 2 (GPX2) Involvement in Colorectal Cancer

Hydroperoxides (ROOHs) are known as damaging agents capable of mediating mutation, while a role as signaling agents through oxidation of protein sulfhydryls that can alter cancer-related pathways has gained traction. Glutathione peroxidase 2 (GPX2) is an antioxidant enzyme that reduces ROOHs at the expense of glutathione (GSH). GPX2 is noted for a tendency of large increases or decreases in expression levels during tumorigenesis that leads to investigators focusing on its role in cancer. However, GPX2 is only one component of multiple enzyme families that metabolize ROOH, and GPX2 levels are often very low in the context of these other ROOH-reducing activities. Colorectal cancer (CRC) was selected as a case study for examining GPX2 function, as colorectal tissues and cancers are sites where GPX2 is highly expressed. A case can be made for a significant impact of changes in expression levels. There is also a link between GPX2 and NADPH oxidase 1 (NOX1) from earlier studies that is seldom addressed and is discussed, presenting data on a unique association in colon and CRC. Tumor-derived cell lines are quite commonly used for pre-clinical studies involving the role of GPX2 in CRC. Generally, selection for this type of work is limited to identifying cell lines based on high and low GPX2 expression with the standard research scheme of overexpression in low-expressing lines and suppression in high-expressing lines to identify impacted pathways. This overlooks CRC subtypes among cell lines involving a wide range of gene expression profiles and a variety of driver mutation differences, along with a large difference in GPX2 expression levels. A trend for low and high GPX2 expressing cell lines to segregate into different CRC subclasses, indicated in this report, suggests that choices based solely on GPX2 levels may provide misleading and conflicting results by disregarding other properties of cell lines and failing to factor in differences in potential protein targets of ROOHs. CRC and cell line classification schemes are presented here that were intended to assist workers in performing pre-clinical studies but are largely unnoted in studies on GPX2 and CRC. Studies are often initiated on the premise that the transition from normal to CRC is associated with upregulation of GPX2. This is probably correct. However, the source normal cells for CRC could be almost any colon cell type, some with very high GPX2 levels. These factors are addressed in this study.

Prohibitin 2 confers NADPH oxidase 1-mediated cytosolic oxidative signaling to promote gastric cancer progression by ERK activation

Oxidative signaling plays a dual role in tumor initiation and progression to malignancy; however, the regulatory mechanisms of oxidative stress in gastric cancer remain to be explored. In this study, we discovered that Prohibitin 2 (PHB2) specifically regulates cytosolic reactive oxygen species production in gastric cancer and facilitates its malignant progression. Previously, we found that PHB2 is upregulated in gastric cancer, correlating with increased tumorigenicity of gastric cancer cells and poor patient prognosis. Here, we discovered that PHB2 expression correlates with the activation of the ERK/MAPK cascade, positively regulating the top gene NADPH oxidase 1 (NOX1) within this pathway. Further mechanistic investigation reveals that PHB2 enhances NOX1 transcription by interacting with the transcription factor C/EBP-beta and promoting its translocation into the nucleus, resulting in elevated intracellular oxidative signaling driven by NOX1, which subsequently activates ERK. Therefore, we propose that targeting PHB2-C/EBP-beta-NOX1-mediated cytosolic oxidative stress could offer a promising therapeutic avenue for combating gastric cancer malignant progression.

Targeting PDGF signaling of cancer-associated fibroblasts blocks feedback activation of HIF-1α and tumor progression of clear cell ovarian cancer

Ovarian clear cell carcinoma (OCCC) is a gynecological cancer with a dismal prognosis; however, the mechanism underlying OCCC chemoresistance is not well understood. To explore the intracellular networks associated with the chemoresistance, we analyze surgical specimens by performing integrative analyses that combine single-cell analyses and spatial transcriptomics. We find that a chemoresistant OCCC subpopulation with elevated HIF activity localizes mainly in areas populated by cancer-associated fibroblasts (CAFs) with a myofibroblastic phenotype, which is corroborated by quantitative immunostaining. CAF-enhanced chemoresistance and HIF-1α induction are recapitulated in co-culture assays, which show that cancer-derived platelet-derived growth factor (PDGF) contributes to the chemoresistance and HIF-1α induction via PDGF receptor signaling in CAFs. Ripretinib is identified as an effective receptor tyrosine kinase inhibitor against CAF survival. In the co-culture system and xenograft tumors, ripretinib prevents CAF survival and suppresses OCCC proliferation in the presence of carboplatin, indicating that combination of conventional chemotherapy and CAF-targeted agents is effective against OCCC.

S100a9 inhibits Atg9a transcription and participates in suppression of autophagy in cardiomyocytes induced by β1-adrenoceptor autoantibodies

BACKGROUND

Cardiomyocyte death induced by autophagy inhibition is an important cause of cardiac dysfunction. In-depth exploration of its mechanism may help to improve cardiac dysfunction. In our previous study, we found that β1-adrenergic receptor autoantibodies (β1-AAs) induced a decrease in myocardial autophagy and caused cardiomyocyte death, thus resulting in cardiac dysfunction. Through tandem mass tag (TMT)-based quantitative proteomics, autophagy-related S100a9 protein was found to be significantly upregulated in the myocardial tissue of actively immunized mice. However, whether S100a9 affects the cardiac function in the presence of β1-AAs through autophagy and the specific mechanism are currently unclear.

METHODS

In this study, the active immunity method was used to establish a β1-AA-induced mouse cardiac dysfunction model, and RT-PCR and western blot were used to detect changes in gene and protein expression in cardiomyocytes. We used siRNA to knockdown S100a9 in cardiomyocytes. An autophagy PCR array was performed to screen differentially expressed autophagy-related genes in cells transfected with S100a9 siRNA and negative control siRNA. Cytoplasmic nuclear separation, co-immunoprecipitation (Co-IP), and immunofluorescence were used to detect the binding of S100a9 and hypoxia inducible factor-1α (HIF-1α). Finally, AAV9-S100a9-RNAi was injected into mice via the tail vein to knockdown S100a9 in cardiomyocytes. Cardiac function was detected via ultrasonography.

RESULTS

The results showed that β1-AAs induced S100a9 expression. The PCR array indicated that Atg9a changed significantly in S100a9siRNA cells and that β1-AAs increased the binding of S100a9 and HIF-1α in cytoplasm. Knockdown of S100a9 significantly improved autophagy levels and cardiac dysfunction.

CONCLUSION

Our research showed that β1-AAs increased S100a9 expression in cardiomyocytes and that S100a9 interacted with HIF-1α, which prevented HIF-1α from entering the nucleus normally, thus inhibiting the transcription of Atg9a. This resulted in autophagy inhibition and cardiac dysfunction.

PROX1 induction by autolysosomal activity stabilizes persister-like state of colon cancer via feedback repression of the NOX1-mTORC1 pathway

Cancer chemoresistance is often attributed to slow-cycling persister populations with cancer stem cell (CSC)-like features. However, how persister populations emerge and prevail in cancer remains obscure. We previously demonstrated that while the NOX1-mTORC1 pathway is responsible for proliferation of a fast-cycling CSC population, PROX1 expression is required for chemoresistant persisters in colon cancer. Here, we show that enhanced autolysosomal activity mediated by mTORC1 inhibition induces PROX1 expression and that PROX1 induction in turn inhibits NOX1-mTORC1 activation. CDX2, identified as a transcriptional activator of NOX1, mediates PROX1-dependent NOX1 inhibition. PROX1-positive and CDX2-positive cells are present in distinct populations, and mTOR inhibition triggers conversion of the CDX2-positive population to the PROX1-positive population. Inhibition of autophagy synergizes with mTOR inhibition to block cancer proliferation. Thus, mTORC1 inhibition-mediated induction of PROX1 stabilizes a persister-like state with high autolysosomal activity via a feedback regulation that involves a key cascade of proliferating CSCs.

Sensitization of colon cancer cells to cisplatin by Fbxw7 via negative regulation of the Nox1-mTOR pathway

Colorectal cancer (CRC) is a human malignancy which associates with high mortality rate and poor prognosis. Despite the initial effectiveness in clinical applications of chemotherapeutic agents, a fraction of patients develops chemoresistance. Fbxw7 is an F-box protein serving as a substrate recognition subunit of E3 ubiquitin ligase, leading to degradation of various oncoproteins. In this study, Fbxw7 was significantly downregulated in CRC tumors as well as CRC cells. Fbxw7 suppressed CRC cell proliferation and migration. Moreover, we observed Fbxw7 was positively associated with cisplatin sensitivity. Fbxw7 was significantly downregulated in cisplatin resistant CRC cells. Overexpression of Fbxw7 effectively increased the cisplatin sensitivity of cisplatin resistant CRC cells. Co-immunoprecipitation and GST pull-down assays showed Fbxw7 bond with Nox1 which was a superoxide-generating NADPH oxidase and showed oncogenic roles in colon cancer cells. Interestingly, Fbxw7 downregulated Nox1 through binding it to degrade Nox1 protein. We demonstrated that Fbxw7 negatively regulated mTOR activity through downregulation of Nox1. Finally, overexpression of Fbxw7 effectively increased the cisplatin sensitivity of CRC cells. This process could be further overturned by Nox1 restoration in Fbxw7-overexpressing colon cancer cells. In summary, these results unveiled that Fbxw7 targeted Nox1 for degradation, resulting in blocking the downstream Nox1-mTORC1 signaling to sensitize CRC cells to cisplatin. Our study potentiates that targeting the Fbxw7-Nox1-mTOR pathway could be an effective approach to overcome chemoresistance of colon cancer cells.

Role of VPS39, a key tethering protein for endolysosomal trafficking and mitochondria-lysosome crosstalk, in health and disease

The coordinated interaction between mitochondria and lysosomes, mainly manifested by mitophagy, mitochondria-derived vesicles, and direct physical contact, is essential for maintaining cellular life activities. The VPS39 subunit of the homotypic fusion and protein sorting complex could play a key role in the regulation of organelle dynamics, such as endolysosomal trafficking and mitochondria-vacuole/lysosome crosstalk, thus contributing to a variety of physiological functions. The abnormalities of VPS39 and related subunits have been reported to be involved in the pathological process of some diseases. Here, we analyze the potential mechanisms and the existing problems of VPS39 in regulating organelle dynamics, which, in turn, regulate physiological functions and disease pathogenesis, so as to provide new clues for facilitating the discovery of therapeutic targets for mitochondrial and lysosomal diseases.

S100A8 and S100A9 in Cancer

S100A8 and S100A9 are Ca²⁺ binding proteins that belong to the S100 family. Primarily expressed in neutrophils and monocytes, S100A8 and S100A9 play critical roles in modulating various inflammatory responses and inflammation-associated diseases. Forming a common heterodimer structure S100A8/A9, S100A8 and S100A9 are widely reported to participate in multiple signaling pathways in tumor cells. Meanwhile, S100A8/A9, S100A8, and S100A9, mainly as promoters, contribute to tumor development, growth and metastasis by interfering with tumor metabolism and the microenvironment. In recent years, the potential of S100A8/A9, S100A9, and S100A8 as tumor diagnostic or prognostic biomarkers has also been demonstrated. In addition, an increasing number of potential therapies targeting S100A8/A9 and related signaling pathways have emerged. In this review, we will first expound on the characteristics of S100A8/A9, S100A9, and S100A8 in-depth, focus on their interactions with tumor cells and microenvironments, and then discuss their clinical applications as biomarkers and therapeutic targets. We also highlight current limitations and look into the future of S100A8/A9 targeted anti-cancer therapy.

Regularized survival learning and cross-database analysis enabled identification of colorectal cancer prognosis-related immune genes

Colon adenocarcinoma is the most common type of colorectal cancer. The prognosis of advanced colorectal cancer patients who received treatment is still very poor. Therefore, identifying new biomarkers for prognosis prediction has important significance for improving treatment strategies. However, the power of biomarker analyses was limited by the used sample size of individual database. In this study, we combined Genotype-Tissue Expression (GTEx) and The Cancer Genome Atlas (TCGA) databases to expand the number of healthy tissue samples. We screened differentially expressed genes between the GTEx healthy samples and TCGA tumor samples. Subsequently, we applied least absolute shrinkage and selection operator (LASSO) regression and multivariate Cox analysis to identify nine prognosis-related immune genes: ANGPTL4, IDO1, NOX1, CXCL3, LTB4R, IL1RL2, CD72, NOS2, and NUDT6. We computed the risk scores of samples based on the expression levels of these genes and divided patients into high- and low-risk groups according to this risk score. Survival analysis results showed a significant difference in survival rate between the two risk groups. The high-risk group had a significantly lower overall survival rate and poorer prognosis. We found the receiver operating characteristic based on the risk score was showed to accurately predict patients' prognosis. These prognosis-related immune genes may be potential biomarkers for colorectal cancer diagnosis and treatment. Our open-source code is freely available from GitHub at https://github.com/gutmicrobes/Prognosis-model.git.

Role of Phosphoinositide 3-Kinase in Regulation of NOX-Derived Reactive Oxygen Species in Cancer

Activation of NADPH oxidases (NOX) and the ensuing formation of reactive oxygen species (ROS) is a vital aspect of antimicrobial defense but may also promote tumorigenesis. Enhanced NOX activity has been associated with aberrant activation of oncogenic cascades such as the phosphoinositide 3-kinase (PI3K) signaling pathway, which is upregulated in several malignancies. In this review, we examine the role of PI3K on the regulation of NOX-induced ROS formation in cancer.

Hypoxia-induced LINC00674 facilitates hepatocellular carcinoma progression by activating the NOX1/mTOR signaling pathway

The hypoxic tumor microenvironment, a fundamental feature of solid tumors, drives hepatocellular carcinoma (HCC) progression through regulating the transcriptional activities of protein-coding and noncoding genes. However, long noncoding RNA (lncRNA)-mediated HCC progression in hypoxic microenvironment remains largely unknown yet. In this study, we found that LINC00674 was upregulated under hypoxic conditions in a HIF-1-dependent manner, and the occupancy of HIF-1 to HRE of LINC00674 gene promoter was essential for its transcription. In addition, LINC00674 level was increased in HCC cell lines and tissues. Clinically, statistical analysis showed that LINC00674 expression was significantly associated with tumor size, venous infiltration, tumor stage and poor prognosis of HCC. Functionally, loss-of-function assays revealed that LINC00674 knockdown inhibited the migration, proliferation and invasion of HCC cells. Furthermore, LINC00674 silencing prominently repressed the mTOR signaling pathway. LINC00674 overexpression-enhanced HCC cell proliferation, migration and invasion were markedly abolished by an mTOR inhibitor rapamycin. NADPH oxidase 1 (NOX1) was positively regulated by LINC00674 in HCC cells. NOX1 knockdown markedly reversed LINC00674-upregulated the p-mTOR level and HCC cells' malignant behaviors. Finally, we found that LINC00674 knockdown attenuated the growth of HCC cells in vivo. Our finding demonstrated that LINC00674 was a new HIF-1 target gene, and hypoxia-induced LINC00674 exerted a pro-proliferative and pro-metastatic role in HCC, possibly by activating the NOX1/mTOR signaling pathway. This study suggested LINC00674 as a promising therapeutic target for HCC.

A Comprehensive Overview of the Complex Role of Oxidative Stress in Aging, The Contributing Environmental Stressors and Emerging Antioxidant Therapeutic Interventions

Introduction

Aging is a normal, inevitable, irreversible, and progressive process which is driven by internal and external factors. Oxidative stress, that is the imbalance between prooxidant and antioxidant molecules favoring the first, plays a key role in the pathophysiology of aging and comprises one of the molecular mechanisms underlying age-related diseases. However, the oxidative stress theory of aging has not been successfully proven in all animal models studying lifespan, meaning that altering oxidative stress/antioxidant defense systems did not always lead to a prolonged lifespan, as expected. On the other hand, animal models of age-related pathological phenotypes showed a well-correlated relationship with the levels of prooxidant molecules. Therefore, it seems that oxidative stress plays a more complicated role than the one once believed and this role might be affected by the environment of each organism. Environmental factors such as UV radiation, air pollution, and an unbalanced diet, have also been implicated in the pathophysiology of aging and seem to initiate this process more rapidly and even at younger ages.

Aim

The purpose of this review is to elucidate the role of oxidative stress in the physiology of aging and the effect of certain environmental factors in initiating and sustaining this process. Understanding the pathophysiology of aging will contribute to the development of strategies to postpone this phenomenon. In addition, recent studies investigating ways to alter the antioxidant defense mechanisms in order to prevent aging will be presented.

Conclusions

Careful exposure to harmful environmental factors and the use of antioxidant supplements could potentially affect the biological processes driving aging and slow down the development of age-related diseases. Maybe a prolonged lifespan could not be achieved by this strategy alone, but a longer healthspan could also be a favorable target.

Osteopontin promotes hepatocellular carcinoma progression through inducing JAK2/STAT3/NOX1-mediated ROS production

Osteopontin (OPN) is a multifunctional cytokine that can impact cancer progression. Therefore, it is crucial to determine the key factors involved in the biological role of OPN for the development of treatment. Here, we investigated that OPN promoted hepatocellular carcinoma (HCC) cell proliferation and migration by increasing Reactive oxygen species (ROS) production and disclosed the underlying mechanism. Knockdown of OPN suppressed ROS production in vitro and in vivo, whereas treatment with human recombinant OPN produced the opposite effect. N-Acetyl-L-cysteine (NAC, ROS scavenger) partially blocked HCC cell proliferation and migration induced by OPN. Mechanistically, OPN induced ROS production in HCC cells by upregulating the expression of NADPH oxidase 1 (NOX1). NOX1 knockdown in HCC cells partially abrogated the cell proliferation and migration induced by OPN. Moreover, inhibition of JAK2/STAT3 phosphorylation effectively decreased the transcription of NOX1, upregulated by OPN. In addition, NOX1 overexpression increased JAK2 and STAT3 phosphorylation by increasing ROS production, creating a positive feedback loop for stimulating JAK2/STAT3 signaling induced by OPN. This study for the first time demonstrated that HCC cells utilized OPN to generate ROS for tumor progression, and disruption of OPN/NOX1 axis might be a promising therapeutic strategy for HCC.

Tumor collection/processing under physioxia uncovers highly relevant signaling networks and drug sensitivity

Preclinical studies of primary cancer cells are typically done after tumors are removed from patients or animals at ambient atmospheric oxygen (O2, ~21%). However, O2 concentrations in organs are in the ~3 to 10% range, with most tumors in a hypoxic or 1 to 2% O2 environment in vivo. Although effects of O2 tension on tumor cell characteristics in vitro have been studied, these studies are done only after tumors are first collected and processed in ambient air. Similarly, sensitivity of primary cancer cells to anticancer agents is routinely examined at ambient O2. Here, we demonstrate that tumors collected, processed, and propagated at physiologic O2 compared to ambient air display distinct differences in key signaling networks including LGR5/WNT, YAP, and NRF2/KEAP1, nuclear reactive oxygen species, alternative splicing, and sensitivity to targeted therapies. Therefore, evaluating cancer cells under physioxia could more closely recapitulate their physiopathologic status in the in vivo microenvironment.

NF-κB suppression synergizes with E7386, an inhibitor of CBP/β-catenin interaction, to block proliferation of patient-derived colon cancer spheroids

Dysregulated activation of the WNT/β-catenin signaling pathway is essential for the initiation and development of various cancers. E7386, a small-molecule compound, attenuates WNT signaling by blocking the interaction between β-catenin and CREB-binding protein (CBP); hence, it is regarded as a therapeutic candidate for cancers with activated WNT signaling. In the present study, we evaluated the biological characteristics associated with E7386 sensitivity by using a panel of patient-derived colon cancer spheroids. An integrative approach that combined E7386 sensitivity and gene expression profiles revealed that the resistance of the cancer spheroids to E7386 was associated with the activation of the NF-κB pathway. NF-κB pathway inhibitors acted synergistically with E7386 to block proliferation and induce cell cycle arrest in E7386-resistant spheroids. These findings suggest a possibility that a combination of E7386 and NF-κB inhibition may effectively block the proliferation of a subset of colon cancer cells.

Response to FEC Chemotherapy and Oncolytic HSV-1 Is Associated with Macrophage Polarization and Increased Expression of S100A8/A9 in Triple Negative Breast Cancer

Simple Summary

We have previously reported that a combination of clinical chemotherapies and oncolytic HSV-1 works to sensitize tumors to respond to immune checkpoint blockade. We further showed that this therapeutic platform worked via the upregulation of B cells and the concomitant control of immunosuppressive myeloid cells. In this manuscript, we sought to further dissect the mechanism of myeloid cell regulation and differentiation and to identify a therapeutically driven gene signature that is associated with the switch in the myeloid phenotype. This work not only impacts triple-negative breast cancer but all solid tumor phenotypes as we aim to better understand the underlying immunology associated with responses to immune checkpoint therapies in these typically refractory disease types.

Abstract

The era of immunotherapy has seen an insurgence of novel therapies driving oncologic research and the clinical management of the disease. We have previously reported that a combination of chemotherapy (FEC) and oncolytic virotherapy (oHSV-1) can be used to sensitize otherwise non-responsive tumors to immune checkpoint blockade and that tumor-infiltrating B cells are required for the efficacy of our therapeutic regimen in a murine model of triple-negative breast cancer. In the studies herein, we have performed gene expression profiling using microarray analyses and have investigated the differential gene expression between tumors treated with FEC + oHSV-1 versus untreated tumors. In this work, we uncovered a therapeutically driven switch of the myeloid phenotype and a gene signature driving increased tumor cell killing.

Synergistic antitumor activity of pan-PI3K inhibition and immune checkpoint blockade in bladder cancer

Background

Immune checkpoint blockade (ICB) induces durable response in approximately 20% of patients with advanced bladder urothelial cancer (aUC). Over 50% of aUCs harbor genomic alterations along the phosphoinositide 3-kinase (PI3K) pathway. The goal of this project was to determine the synergistic effects and mechanisms of action of PI3K inhibition and ICB combination in aUC.

Methods

Alterations affecting the PI3K pathway were examined in The Cancer Genome Atlas (TCGA) and the Cancer Dependency Map databases. Human and mouse cells with Pten deletion were used for in vitro studies. C57BL/6 mice carrying syngeneic tumors were used to determine in vivo activity, mechanisms of action and secondary resistance of pan-PI3K inhibition, ICB and combination.

Results

Alterations along the PI3K pathway occurred in 57% of aUCs in TCGA. CRISPR (clustered regularly interspaced short palindromic repeats) knockout of PIK3CA induced pronounced inhibition of cell proliferation (p=0.0046). PI3K inhibition suppressed cancer cell growth, migration and colony formation in vitro. Pan-PI3K inhibition, antiprogrammed death 1 (aPD1) therapy and combination improved the overall survival (OS) of syngeneic mice with PTEN-deleted tumors from 27 days of the control to 48, 37, and 65 days, respectively. In mice with tumors not containing a PI3K pathway alteration, OS was prolonged by the combination but not single treatments. Pan-PI3K inhibition significantly upregulated CD80, CD86, MHC-I, and MHC-II in dendritic cells, and downregulated the transforming growth factor beta pathway with a false discovery rate-adjusted q value of 0.001. Interferon alpha response was significantly upregulated with aPD1 therapy (q value: <0.001) and combination (q value: 0.027). Compared with the control, combination treatment increased CD8⁺ T-cell infiltration (p=0.005), decreased T_reg-cell infiltration (p=0.036), and upregulated the expression of multiple immunostimulatory cytokines and granzyme B (p<0.01). Secondary resistance was associated with upregulation of the mammalian target of rapamycin (mTOR) pathway and multiple Sprr family genes.

Conclusions

The combination Pan-PI3K inhibition and ICB has significant antitumor effects in aUC with or without activated PI3K pathway and warrants further clinical investigation. This combination creates an immunostimulatory tumor milieu. Secondary resistance is associated with upregulation of the mTOR pathway and Sprr family genes.

Reactive oxygen species (ROS) in cancer pathogenesis and therapy: An update on the role of ROS in anticancer action of benzophenanthridine alkaloids

Reactive oxygen species play crucial role in biological homeostasis and pathogenesis of human diseases including cancer. In this line, now it has become evident that ROS level/concentration is a major factor in the growth, progression and stemness of cancer cells. Moreover, cancer cells maintain a delicate balance between ROS and antioxidants to promote pathogenesis and clinical challenges via targeting a battery of signaling pathways converging to cancer hallmarks. Recent findings also entail the therapeutic importance of ROS for the better clinical outcomes in cancer patients as they induce apoptosis and autophagy. Moreover, poor clinical outcomes associated with cancer therapies are the major challenge and use of natural products have been vital in attenuation of these challenges due to their multitargeting potential with less adverse effects. In fact, most available drugs are derived from natural resources, either directly or indirectly and available evidence show the clinical importance of natural products in the management of various diseases, including cancer. ROS play a critical role in the anticancer actions of natural products, particularly phytochemicals. Benzophenanthridine alkaloids of the benzyl isoquinoline family of alkaloids, such as sanguinarine, possess several pharmacological properties and are thus being studied for the treatment of different human diseases, including cancer. In this article, we review recent findings, on how benzophenanthridine alkaloid-induced ROS play a critical role in the attenuation of pathological changes and stemness features associated with human cancers. In addition, we highlight the role of ROS in benzophenanthridine alkaloid-mediated activation of the signaling pathway associated with cancer cell apoptosis and autophagy.

Protein Transnitrosylation Signaling Networks Contribute to Inflammaging and Neurodegenerative Disorders

Significance: Physiological concentrations of nitric oxide (NO^•) and related reactive nitrogen species (RNS) mediate multiple signaling pathways in the nervous system. During inflammaging (chronic low-grade inflammation associated with aging) and in neurodegenerative diseases, excessive RNS contribute to synaptic and neuronal loss. "NO signaling" in both health and disease is largely mediated through protein S-nitrosylation (SNO), a redox-based posttranslational modification with "NO" (possibly in the form of nitrosonium cation [NO⁺]) reacting with cysteine thiol (or, more properly, thiolate anion [R-S^-]). Recent Advances: Emerging evidence suggests that S-nitrosylation occurs predominantly via transnitros(yl)ation. Mechanistically, the reaction involves thiolate anion, as a nucleophile, performing a reversible nucleophilic attack on a nitroso nitrogen to form an SNO-protein adduct. Prior studies identified transnitrosylation reactions between glyceraldehyde-3-phosphate dehydrogenase (GAPDH)-nuclear proteins, thioredoxin-caspase-3, and X-linked inhibitor of apoptosis (XIAP)-caspase-3. Recently, we discovered that enzymes previously thought to act in completely disparate biochemical pathways can transnitrosylate one another during inflammaging in an unexpected manner to mediate neurodegeneration. Accordingly, we reported a concerted tricomponent transnitrosylation network from Uch-L1-to-Cdk5-to-Drp1 that mediates synaptic damage in Alzheimer's disease. Critical Issues: Transnitrosylation represents a critical chemical mechanism for transduction of redox-mediated events to distinct subsets of proteins. Although thousands of thiol-containing proteins undergo S-nitrosylation, how transnitrosylation regulates a myriad of neuronal attributes is just now being uncovered. In this review, we highlight recent progress in the study of the chemical biology of transnitrosylation between proteins as a mechanism of disease. Future Directions: We discuss future areas of study of protein transnitrosylation that link our understanding of aging, inflammation, and neurodegenerative diseases. Antioxid. Redox Signal. 35, 531-550.

Differences in molecular phenotype in mouse and human hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is characterized by phenotypic heterogeneity. We investigated the molecular basis of the cardiac phenotype in two mouse models at established disease stage (mouse-HCM), and human myectomy tissue (human-HCM). We analyzed the transcriptome in 2 mouse models with non-obstructive HCM (R403Q-MyHC, R92W-TnT)/littermate-control hearts at 24 weeks of age, and in myectomy tissue of patients with obstructive HCM/control hearts (GSE36961, GSE36946). Additionally, we examined myocyte redox, cardiac mitochondrial DNA copy number (mtDNA-CN), mt-respiration, mt-ROS generation/scavenging and mt-Ca²⁺ handling in mice. We identified distinct allele-specific gene expression in mouse-HCM, and marked differences between mouse-HCM and human-HCM. Only two genes (CASQ1, GPT1) were similarly dysregulated in both mutant mice and human-HCM. No signaling pathway or transcription factor was predicted to be similarly dysregulated (by Ingenuity Pathway Analysis) in both mutant mice and human-HCM. Losartan was a predicted therapy only in TnT-mutant mice. KEGG pathway analysis revealed enrichment for several metabolic pathways, but only pyruvate metabolism was enriched in both mutant mice and human-HCM. Both mutant mouse myocytes demonstrated evidence of an oxidized redox environment. Mitochondrial complex I RCR was lower in both mutant mice compared to controls. MyHC-mutant mice had similar mtDNA-CN and mt-Ca²⁺ handling, but TnT-mutant mice exhibited lower mtDNA-CN and impaired mt-Ca²⁺ handling, compared to littermate-controls. Molecular profiling reveals differences in gene expression, transcriptional regulation, intracellular signaling and mt-number/function in 2 mouse models at established disease stage. Further studies are needed to confirm differences in gene expression between mouse and human-HCM, and to examine whether cardiac phenotype, genotype and/or species differences underlie the divergence in molecular profiles.

Downregulation of SUN2 promotes metastasis of colon cancer by activating BDNF/TrkB signalling by interacting with SIRT1

Distant metastasis is the major cause of colon cancer (CC) treatment failure. SAD1/UNC84 domain protein-2 (SUN2) is a key component of linker of the nucleoskeleton and cytoskeleton (LINC) complexes that may be relevant for metastasis in several cancers. Here, we first confirmed that SUN2 levels were significantly lower in primary CC tissues and distant metastasis than in normal colon tissues, and high SUN2 expression predicted good overall survival. Overexpression of SUN2 or knockdown of SUN2 inhibited or promoted cell migration and invasion in vitro, respectively. Moreover, silencing of SUN2 promoted metastasis in vivo. Mechanistically, we showed that SUN2 exerts its tumour suppressor functions by decreasing the expression of brain derived neurotrophic factor (BDNF) to inhibit BDNF/tropomyosin-related kinase B (TrkB) signalling. Additionally, SUN2 associated with SIRT1 and increased the acetylation of methyl-CpG binding protein 2 (MeCP2) to increase its occupancy at the BDNF promoter. Taken together, our findings indicate that SUN2 is a key component in CC progression that acts by inhibiting metastasis and that novel SUN2-SIRT1-MeCP2-BDNF signalling may prove to be useful for the development of new strategies for treating patients with CC. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Conflicting metabolic alterations in cancer stem cells and regulation by the stromal niche

Recent studies have revealed that cancer stem cells (CSCs) undergo metabolic alterations that differentiate them from non-CSCs. Inhibition of specific metabolic pathways in CSCs has been conducted to eliminate the CSC population in many types of cancer. However, there is conflicting evidence about whether CSCs depend on glycolysis or mitochondrial oxidative phosphorylation (OXPHOS) to maintain their stem cell properties. This review summarizes the latest knowledge regarding CSC-specific metabolic alterations and offers recent evidence that the surrounding microenvironments may play an important role in the maintenance of CSC properties.

The S6k/4E-BP mediated growth promoting sub-pathway of insulin signalling cascade is essential to restrict pathogenesis of poly(Q) disorders in Drosophila

Human neurodegenerative polyglutamine [poly(Q)] disorders, such as Huntington's disease (HD) and spinocerebellar ataxias (SCA), are characterised by an abnormal expansion of CAG repeats in the affected gene. The mutated proteins misfold and aggregate to form inclusion bodies that sequester important factors involved in cellular transcription, growth, stress and autophagic response and other essential functions. The insulin signalling pathway has been demonstrated as a major modifier and a potential drug target to ameliorate the poly(Q) mediated neurotoxicity in various model systems. Insulin signalling cascade harbours several downstream sub-pathways, which are synergistically involved in discharging indispensable biological functions such as growth and proliferation, metabolism, autophagy, regulation of cell death pathways etc. Hence, it is difficult to conclude whether the mitigation of poly(Q) neurotoxicity is an accumulative outcome of the insulin cascade, or the result of a specific sub-pathway. For the first time, we report that the ligand binding domain of insulin receptor mediated downstream growth promoting sub-pathway plays the pivotal role in operating the rescue event. We show that the growth promoting activity of insulin cascade is essential to minimize the abundance of inclusion bodies, to restrict neurodegeneration, and to restore the cellular transcriptional balance. Subsequently, we noted the involvement of the mTOR/S6k/4E-BP candidates in mitigating poly(Q) mediated neurotoxicity. Due to the conserved cellular functioning of the insulin cascade across species, and availability of several growth promoting molecules, our results in Drosophila poly(Q) models indicate towards a possibility of designing novel therapeutic strategies to restrict the pathogenesis of devastating human poly(Q) disorders.

The Role of Oxidative Stress and Its Counteractive Utility in Colorectal Cancer (CRC)

An altered redox status accompanied by an elevated generation of reactive oxygen/nitrogen species (ROS/RNS) has been implicated in a number of diseases including colorectal cancer (CRC). CRC, being one of the most common cancers worldwide, has been reported to be associated with multiple environmental and lifestyle factors (e.g., dietary habits, obesity, and physical inactivity) and harboring heightened oxidative stress that results in genomic instability. Although under normal condition ROS regulate many signal transduction pathways including cell proliferation and survival, overwhelming of the antioxidant capacity due to metabolic abnormalities and oncogenic signaling leads to a redox adaptation response that imparts drug resistance. Nevertheless, excessive reliance on elevated production of ROS makes the tumor cells increasingly vulnerable to further ROS insults, and the abolition of such drug resistance through redox perturbation could be instrumental to preferentially eliminate them. The goal of this review is to demonstrate the evidence that links redox stress to the development of CRC and assimilate the most up-to-date information that would facilitate future investigation on CRC-associated redox biology. Concomitantly, we argue that the exploitation of this distinct biochemical property of CRC cells might offer a fresh avenue to effectively eradicate these cells.

Isolation and Characterization of Two Novel Colorectal Cancer Cell Lines, Containing a Subpopulation with Potential Stem-Like Properties: Treatment Options by MYC/NMYC Inhibition

Simple Summary

The aim of this study was to gain a better understanding of cancer stem cells, which are a small subpopulation of tumor cells with high plasticity driving tumor growth and metastasis. Here we isolated two novel colorectal cancer cell lines originating from a rectal neuroendocrine carcinoma and a colorectal adenocarcinoma, depicting stem-like properties. These in vitro models offer the possibility to evaluate pathophysiological mechanisms in order to develop tailored therapeutic strategies for distinct colorectal malignancies. Investigations revealed gene copy number gain of the N-myc proto-oncogene for both. Accordingly, inhibition of the protein–protein interaction of myc and N-myc proto-oncogenes with the myc-associated factor X utilizing small molecule KJ-Pyr-9, exhibited a significant reduction in survival of both cell lines by the induction of apoptosis. Consequently, the blockage of these interactions may serve as a possible treatment strategy for colorectal cancer cell lines with gene copy number gain of the N-myc proto-oncogene.

Abstract

Cancer stem cells (CSC) are crucial mediators of cancer relapse. Here, we isolated two primary human colorectal cancer cell lines derived from a rectal neuroendocrine carcinoma (BKZ-2) and a colorectal adenocarcinoma (BKZ-3), both containing subpopulations with potential stem-like properties. Protein expression of CSC-markers prominin-1 and CD44 antigen was significantly higher for BKZ-2 and BKZ-3 in comparison to well-established colon carcinoma cell lines. High sphere-formation capacity further confirmed the existence of a subpopulation with potential stem-like phenotype. Epithelial–mesenchymal transition markers as well as immune checkpoint ligands were expressed more pronounced in BKZ-2. Both cell populations demonstrated N-myc proto-oncogene (NMYC) copy number gain. Myc proto-oncogene (MYC)/NMYC activity inhibitor all-trans retinoic acid (ATRA) significantly reduced the number of tumor spheres for both and the volume of BKZ-2 spheres. In contrast, the sphere volume of ATRA-treated BKZ-3 was increased, and only BKZ-2 cell proliferation was reduced in monolayer culture. Treatment with KJ-Pyr-9, a specific inhibitor of MYC/NMYC-myc-associated factor X interaction, decreased survival by the induction of apoptosis of both. In summary, here, we present the novel colorectal cancer cell lines BKZ-2 and BKZ-3 as promising cellular in vitro models for colorectal carcinomas and identify the MYC/NMYC molecular pathway involved in CSC-induced carcinogenesis with relevant therapeutic potential.

Photodynamic therapy regulates fate of cancer stem cells through reactive oxygen species

Photodynamic therapy (PDT) is an effective and promising cancer treatment. PDT directly generates reactive oxygen species (ROS) through photochemical reactions. This oxygen-dependent exogenous ROS has anti-cancer stem cell (CSC) effect. In addition, PDT may also increase ROS production by altering metabolism, endoplasmic reticulum stress, or potential of mitochondrial membrane. It is known that the half-life of ROS in PDT is short, with high reactivity and limited diffusion distance. Therefore, the main targeting position of PDT is often the subcellular localization of photosensitizers, which is helpful for us to explain how PDT affects CSC characteristics, including differentiation, self-renewal, apoptosis, autophagy, and immunogenicity. Broadly speaking, excess ROS will damage the redox system and cause oxidative damage to molecules such as DNA, change mitochondrial permeability, activate unfolded protein response, autophagy, and CSC resting state. Therefore, understanding the molecular mechanism by which ROS affect CSCs is beneficial to improve the efficiency of PDT and prevent tumor recurrence and metastasis. In this article, we review the effects of two types of photochemical reactions on PDT, the metabolic processes, and the biological effects of ROS in different subcellular locations on CSCs.

Dichotomous role of the human mitochondrial Na+/Ca2+/Li+ exchanger NCLX in colorectal cancer growth and metastasis

Despite the established role of mitochondria in cancer, the mechanisms by which mitochondrial Ca²⁺ (mtCa²⁺) regulates tumorigenesis remain incompletely understood. The crucial role of mtCa²⁺ in tumorigenesis is highlighted by altered expression of proteins mediating mtCa²⁺ uptake and extrusion in cancer. Here, we demonstrate decreased expression of the mitochondrial Na⁺/Ca²⁺/Li⁺ exchanger NCLX (SLC8B1) in human colorectal tumors and its association with advanced-stage disease in patients. Downregulation of NCLX causes mtCa²⁺ overload, mitochondrial depolarization, decreased expression of cell-cycle genes and reduced tumor size in xenograft and spontaneous colorectal cancer mouse models. Concomitantly, NCLX downregulation drives metastatic spread, chemoresistance, and expression of epithelial-to-mesenchymal, hypoxia, and stem cell pathways. Mechanistically, mtCa²⁺ overload leads to increased mitochondrial reactive oxygen species, which activate HIF1α signaling supporting metastasis of NCLX-null tumor cells. Thus, loss of NCLX is a novel driver of metastasis, indicating that regulation of mtCa²⁺ is a novel therapeutic approach in metastatic colorectal cancer.

Precision Nutrition and Cancer Relapse Prevention: A Systematic Literature Review

Cancer mortality rates are undergoing a global downward trend; however, metastasis and relapse after surgery and adjuvant treatments still correlate with poor prognosis and represent the most significant challenges in the treatment of this disease. Advances in genomics, metabolomics, and proteomics are improving our understanding regarding cancer metabolic diversity, resulting in detailed classifications of tumors and raising the effectiveness of precision medicine. Likewise, the growing knowledge of interactions between nutrients and the expression of certain genes could lead to cancer therapies based on precision nutrition strategies. This review aims to identify the recent advances in the knowledge of the mechanistic role of bioactive phytochemicals in foodstuffs in tumor progression, metastasis, and chemo-resistance in order to assess their potential use in precision nutrition therapies targeting relapse in lung, breast, colon, and prostate cancer, and leukemia. A considerable number of bioactive phytochemicals in foodstuffs were identified in the literature with proven effects modulating tumor growth, progression, and metastasis. In addition, the use of foodstuffs in cancer, and specifically in relapse therapies, is being reinforced by the development of different formulations that significantly increase the therapeutic efficiency of these products. This can open the possibility for testing combinations of bioactive phytochemicals with cancer relapse treatments as a potential prevention strategy.