Wild-type and mutant p53 differentially regulate NADPH oxidase 4 in TGF-β-mediated migration of human lung and breast epithelial cells

Dissecting the pleiotropic roles of reactive oxygen species (ROS) in lung cancer: From carcinogenesis toward therapy

Lung cancer is a major cause of morbidity and mortality. The specific pulmonary structure to directly connect with ambient air makes it more susceptible to damage from airborne toxins. External oxidative stimuli and endogenous reactive oxygen species (ROS) play a crucial role in promoting lung carcinogenesis and development. The biological properties of higher ROS levels in tumor cells than in normal cells make them more sensitive and vulnerable to ROS injury. Therefore, the strategy of targeting ROS has been proposed for cancer therapy for decades. However, it is embarrassing that countless attempts at ROS-based therapies have had very limited success, and no FDA approval in the anticancer list was mechanistically based on ROS manipulation. Even compared with the untargetable proteins, such as transcription factors, ROS are more difficult to be targeted due to their chemical properties. Thus, the pleiotropic roles of ROS provide therapeutic potential for anticancer drug discovery, while a better dissection of the mechanistic action and signaling pathways is a prerequisite for future breakthroughs. This review discusses the critical roles of ROS in cancer carcinogenesis, ROS-inspired signaling pathways, and ROS-based treatment, exemplified by lung cancer. In particular, an eight considerations rule is proposed for ROS-targeting strategies and drug design and development.

Nicotinamide adenine dinucleotide phosphate oxidase in pancreatic diseases: Mechanisms and future perspectives

Pancreatitis and pancreatic cancer (PC) stand as the most worrisome ailments affecting the pancreas. Researchers have dedicated efforts to unraveling the mechanisms underlying these diseases, yet their true nature continues to elude their grasp. Within this realm, oxidative stress is often believed to play a causal and contributory role in the development of pancreatitis and PC. Excessive accumulation of reactive oxygen species (ROS) can cause oxidative stress, and the key enzyme responsible for inducing ROS production in cells is nicotinamide adenine dinucleotide phosphate hydrogen oxides (NOX). NOX contribute to pancreatic fibrosis and inflammation by generating ROS that injure acinar cells, activate pancreatic stellate cells, and mediate macrophage polarization. Excessive ROS production occurs during malignant transformation and pancreatic carcinogenesis, creating an oxidative microenvironment that can cause abnormal apoptosis, epithelial to mesenchymal transition and genomic instability. Therefore, understanding the role of NOX in pancreatic diseases contributes to a more in-depth exploration of the exact pathogenesis of these diseases. In this review, we aim to summarize the potential roles of NOX and its mechanism in pancreatic disorders, aiming to provide novel insights into understanding the mechanisms underlying these diseases.

FAK Drives Resistance to Therapy in HPV-Negative Head and Neck Cancer in a p53-Dependent Manner

PURPOSE

Radiation and platinum-based chemotherapy form the backbone of therapy in human papillomavirus (HPV)-negative head and neck squamous cell carcinoma (HNSCC). We have correlated focal adhesion kinase (FAK/PTK2) expression with radioresistance and worse outcomes in these patients. However, the importance of FAK in driving radioresistance and its effects on chemoresistance in these patients remains unclear.

EXPERIMENTAL DESIGN

We performed an in vivo shRNA screen using targetable libraries to identify novel therapeutic sensitizers for radiation and chemotherapy.

RESULTS

We identified FAK as an excellent target for both radio- and chemosensitization. Because TP53 is mutated in over 80% of HPV-negative HNSCC, we hypothesized that mutant TP53 may facilitate FAK-mediated therapy resistance. FAK inhibitor increased sensitivity to radiation, increased DNA damage, and repressed homologous recombination and nonhomologous end joining repair in mutant, but not wild-type, TP53 HPV-negative HNSCC cell lines. The mutant TP53 cisplatin-resistant cell line had increased FAK phosphorylation compared with wild-type, and FAK inhibition partially reversed cisplatin resistance. To validate these findings, we utilized an HNSCC cohort to show that FAK copy number and gene expression were associated with worse disease-free survival in mutant TP53, but not wild-type TP53, HPV-negative HNSCC tumors.

CONCLUSIONS

FAK may represent a targetable therapeutic sensitizer linked to a known genomic marker of resistance.

Phenolic-rich extracts from toasted white and tannin sorghum flours have distinct profiles influencing their antioxidant, antiproliferative, anti-adhesive, anti-invasive, and antimalarial activities

Sorghum is a gluten-free cereal commonly used in foods, and its consumption has been associated with the prevention of human chronic conditions such as obesity and cancer, due to the presence of dietary fiber and phenolic compounds. This study aimed to evaluate, for the first time, the antiproliferative, antioxidant, anti-adhesion, anti-invasion, and antimalarial activities of phenolic extracts from toasted white and tannin sorghum flours to understand how different phenolic profiles contribute to sorghum biological activities. Water and 70 % ethanol/water (v/v), eco-friendly solvents, were used to obtain the phenolic extracts of toasted sorghum flours, and their phenolic profile was analyzed by UPLC-MSE. One hundred forty-five (145) phenolic compounds were identified, with 23 compounds common to all extracts. The solvent type affected the phenolic composition, with aqueous extract of both white sorghum (WSA) and tannin sorghum (TSA) containing mainly phenolic acids. White sorghum (WSE) and tannin sorghum (TSE) ethanolic extracts exhibited a higher abundance of flavonoids. WSE demonstrated the lowest IC50 on EA.hy926 (IC50 = 46.6 µg/mL) and A549 cancer cells (IC50 = 33.1 µg/mL), while TSE showed the lowest IC50 (IC50 = 70.8 µg/mL) on HCT-8 cells (human colon carcinoma). Aqueous extracts also demonstrated interesting results, similar to TSE, showing selectivity for cancer cells at higher IC50 concentrations. All sorghum extracts also reduced the adhesion and invasion of HCT-8 cells, suggesting antimetastatic potential. WSE, rich in phenolic acids and flavonoids, exhibited greater toxicity to both the W2 (chloroquine-resistant) and 3D7 (chloroquine-sensitive) strains of Plasmodium falciparum (IC50 = 8 µg GAE/mL and 22.9 µg GAE/mL, respectively). These findings underscore the potential health benefits of toasted sorghum flours, suggesting diverse applications in the food industry as a functional ingredient or even as an antioxidant supplement. Moreover, it is suggested that, besides the phenolic concentration, the phenolic profile is important to understand the health benefits of sorghum flours.

ROCK inhibition reduces the sensitivity of mutant p53 glioblastoma to genotoxic stress through a Rac1-driven ROS production

Resistance to radio and chemotherapy in Glioblastoma (GBM) is correlated with its malignancy, invasiveness, and aggressiveness. The Rho GTPase pathway plays important roles in these processes, but its involvement in the GBM response to genotoxic treatments remains unsolved. Inhibition of this signaling pathway has emerged as a promising approach for the treatment of CNS injuries and diseases, proving to be a strong candidate for therapeutic approaches. To this end, Rho-associated kinases (ROCK), classic downstream effectors of small Rho GTPases, were targeted for pharmacological inhibition using Y-27632 in GBM cells, expressing the wild-type or mutated p53 gene, and exposed to genotoxic stress by gamma ionizing radiation (IR) or cisplatin (PT). The use of the ROCK inhibitor (ROCKi) had opposite effects in these cells: in cells expressing wild-type p53, ROCKi reduced survival and DNA repair capacity (reduction of γH2AX foci and accumulation of strand breaks) after stress promoted by IR or PT; in cells expressing the mutant p53 protein, both treatments promoted longer survival and more efficient DNA repair, responses further enhanced by ROCKi. The target DNA repair mechanisms of ROCK inhibition were, respectively, an attenuation of NHEJ and NER pathways in wild-type p53 cells, and a stimulation of HR and NER pathways in mutant p53 cells. These effects were accompanied by the formation of reactive oxygen species (ROS) induced by genotoxic stress only in mutant p53 cells but potentiated by ROCKi and reversed by p53 knockdown. N-acetyl-L-cysteine (NAC) treatment or Rac1 knockdown completely eliminated ROCKi's p53-dependent actions, since ROCK inhibition specifically elevated Rac-GTP levels only in mutant p53 cells. Combining IR or PT and ROCKi treatments broadens our understanding of the sensitivity and resistance of, respectively, GBM expressing wild-type or mutant p53 to genotoxic agents. Our proposal may be a determining factor in improving the efficiency and assertiveness of CNS antitumor therapies based on ROCK inhibitors. SIGNIFICANCE: The use of ROCK inhibitors in association with radio or chemotherapy modulates GBM resistance and sensitivity depending on the p53 activity, suggesting the potential value of this protein as therapeutic target for tumor pre-sensitization strategies.

Mutant p53 and NOX4 are modulators of a CCL5-driven pro-migratory secretome

Previously, we showed wild-type (WT) and mutant (mt) forms of p53 differentially regulate ROS generation by NADPH oxidase-4 (NOX4). We found that WT-p53 suppresses TGF-β-induced NOX4, ROS production, and cell migration, whereas tumor-associated mt-p53 proteins enhance NOX4 expression and cell migration by TGF-β/SMAD3-dependent mechanisms. In this study, we investigated the role of mutant p53-induced NOX4 on the cancer cell secretome and the effects NOX4 signaling have on the tumor microenvironment (TME). We found conditioned media collected from H1299 lung epithelial cells stably expressing either mutant p53-R248Q or R273H promotes the migration and invasion of naïve H1299 cells and chemotactic recruitment of THP-1 monocytes. These effects were diminished with conditioned media from cells co-transfected with dominant negative NOX4 (P437H). We utilized immunoblot-based cytokine array analysis to identify factors in mutant p53 H1299 cell conditioned media that promote cell migration and invasion. We found CCL5 was significantly reduced in conditioned media from H1299 cells co-expressing p53-R248Q and dominant negative NOX4. Moreover, neutralization of CCL5 reduced autocrine-mediated H1299 cell mobility. Furthermore, CCL5 and TGF-beta from M2-polarized macrophages have a significant role in crosstalk and H1299 cell migration and invasion. Collectively, our findings provide further insight into NOX4-based communication in the tumor microenvironment and its potential as a therapeutic target affecting metastatic disease progression.

Wild-type and mutant p53 in cancer-related ferroptosis. A matter of stress management?

Cancer cells within tumor masses are chronically exposed to stress caused by nutrient deprivation, oxygen limitation, and high metabolic demand. They also accumulate hundreds of mutations, potentially generating aberrant proteins that can induce proteotoxic stress. Finally, cancer cells are exposed to various damages during chemotherapy. In a growing tumor, transformed cells eventually adapt to these conditions, eluding the death-inducing outcomes of signaling cascades triggered by chronic stress. One such extreme outcome is ferroptosis, a form of iron-dependent non-apoptotic cell death mediated by lipid peroxidation. Not surprisingly, the tumor suppressor p53 is involved in this process, with evidence suggesting that it acts as a pro-ferroptotic factor and that its ferroptosis-inducing activity may be relevant for tumor suppression. Missense alterations of the TP53 gene are extremely frequent in human cancers and give rise to mutant p53 proteins (mutp53) that lose tumor suppressive function and can acquire powerful oncogenic activities. This suggests that p53 mutation provides a selective advantage during tumor progression, raising interesting questions on the impact of p53 mutant proteins in modulating the ferroptotic process. Here, we explore the role of p53 and its cancer-related mutants in ferroptosis, using a perspective centered on the resistance/sensitivity of cancer cells to exogenous and endogenous stress conditions that can trigger ferroptotic cell death. We speculate that an accurate molecular understanding of this particular axis may improve cancer treatment options.

p53 regulates the effects of DAPT on Rac1 activation and migration of non-small-cell lung cancer cells

The use of γ-secretase inhibitors to inhibit the activation of Notch receptors can effectively inhibit the malignant process of tumors. Here, we demonstrate that p53 can modulate the effect of DAPT (a γ-secretase inhibitor) on the activation of small GTPase Rac1, thereby affecting cell migration of non-small-cell lung cancer H1299 and A549 cells. After treatment with 20 μM DAPT, activation of Rac1 was increased in H1299 cells but not in A549 cells. We further found that the migration ability of H1299 cells was increased, whereas that of A549 cells was reduced. The effect of DAPT on H1299 migration was repressed by Rac1-T17N, a dominant inactivated mutant of Rac1. H1299 is a p53-deficient cell line. When p53 protein was overexpressed in H1299 cells with a pEGFP-p53 plasmid, DAPT treatment no longer activated Rac1 and increased migration ability. Moreover, DAPT promoted the migration of H1299 cells by increasing the activity of Rac1 through the non-canonical Notch pathway. Taken together, these results indicate that the expression of p53 protein in lung cancer cells regulates the effect of DAPT on cell migration by modulating the activation of Rac1, suggesting that p53 may affect the therapeutic effects of Notch inhibitors in lung cancer patients.

Narrow Leafed Lupin (Lupinus angustifolius L.) β-Conglutin Seed Proteins as a New Natural Cytotoxic Agents against Breast Cancer Cells

Breast cancer (BC) is the most widespread tumor in women and the second type of most common cancer worldwide. Despite all the technical and medical advances in existing therapies, between 30 and 50% of patients with BC will develop metastasis, which contributes to the failure of existing treatments. This situation urges the need to find more effective prevention and treatment strategies like the use of plant-based nutraceutical compounds. In this context, we purified three Narrow Leafed Lupin (NLL) β-conglutins isoforms using affinity-chromatography and evaluated their effectiveness in terms of viability, proliferation, apoptosis, stemness properties, and mechanism of action on both BC cell lines and a healthy one. NLL β-conglutins proteins have very promising effects at the molecular level on BC cells at very low concentrations, emerging as a potential natural cytotoxic agent and preserving the viability of healthy cells. These proteins could act through a dual mechanism involving tumorigenic and stemness-related genes such as SIRT1 and FoxO1, depending on the state of p53. More studies must be carried out to completely understand the underlying mechanisms of action of these nutraceutical compounds in BC in vitro and in vivo, and their potential use for the inhibition of other cancer cell types.

p53 mutation and deletion contribute to tumor immune evasion

TP53 (or p53) is widely accepted to be a tumor suppressor. Upon various cellular stresses, p53 mediates cell cycle arrest and apoptosis to maintain genomic stability. p53 is also discovered to suppress tumor growth through regulating metabolism and ferroptosis. However, p53 is always lost or mutated in human and the loss or mutation of p53 is related to a high risk of tumors. Although the link between p53 and cancer has been well established, how the different p53 status of tumor cells help themselves evade immune response remains largely elusive. Understanding the molecular mechanisms of different status of p53 and tumor immune evasion can help optimize the currently used therapies. In this context, we discussed the how the antigen presentation and tumor antigen expression mode altered and described how the tumor cells shape a suppressive tumor immune microenvironment to facilitate its proliferation and metastasis.

The complexity of p53-mediated metabolic regulation in tumor suppression

Although the classic activities of p53 including induction of cell-cycle arrest, senescence, and apoptosis are well accepted as critical barriers to cancer development, accumulating evidence suggests that loss of these classic activities is not sufficient to abrogate the tumor suppression activity of p53. Numerous studies suggest that metabolic regulation contributes to tumor suppression, but the mechanisms by which it does so are not completely understood. Cancer cells rewire cellular metabolism to meet the energetic and substrate demands of tumor development. It is well established that p53 suppresses glycolysis and promotes mitochondrial oxidative phosphorylation through a number of downstream targets against the Warburg effect. The role of p53-mediated metabolic regulation in tumor suppression is complexed by its function to promote both cell survival and cell death under different physiological settings. Indeed, p53 can regulate both pro-oxidant and antioxidant target genes for complete opposite effects. In this review, we will summarize the roles of p53 in the regulation of glucose, lipid, amino acid, nucleotide, iron metabolism, and ROS production. We will highlight the mechanisms underlying p53-mediated ferroptosis, AKT/mTOR signaling as well as autophagy and discuss the complexity of p53-metabolic regulation in tumor development.

MeCP2 confers 5-fluorouracil resistance in gastric cancer via upregulating the NOX4/PKM2 pathway

Background

Increasing evidence suggests that aberrant methylation is involved in 5-fluorouracil (5-FU) resistance in gastric cancer (GC). Our previous work has identified that Methyl-CpG binding protein 2 (MeCP2) promotes GC progression by binding to the methylation sites of promoter regions of specific genes to affect the downstream signaling pathways. However, the function and molecular mechanisms of MeCP2 in GC 5-FU resistance remain unclear.

Methods

We detected the expression of MeCP2 in 5-FU-resistant GC cells and examined cell behaviors when MeCP2 was silenced. The molecular mechanisms were explored through chromatin immunoprecipitation (ChIP)-qRT-PCR, luciferase reporter assay, clinical tissue samples analysis, and in vivo tumorigenicity assay.

Results

MeCP2 was up-regulated in 5-FU-resistant GC cells. Knockdown of MeCP2 enhanced the sensitivity of the cells to 5-FU. Moreover, MeCP2 promoted NOX4 transcription in the cells by binding to the promoter of NOX4. Silencing NOX4 rescued the inductive effect of MeCP2 overexpression on 5-FU sensitivity of GC cells and reduced the expression of NOX4 and PKM2 in MeCP2 overexpressed 5-FU-resistant GC cells. In addition, our in vivo experiments demonstrated that MeCP2 knockdown enhanced 5-FU sensitivity in tumors.

Conclusion

MeCP2 confers 5-FU resistance in GC cells via upregulating the NOX4/PKM2 pathway, which may lead to a promising therapeutic strategy for GC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02489-y.

Correlation between Oxidative Stress and Transforming Growth Factor-Beta in Cancers

The downregulation of reactive oxygen species (ROS) facilitates precancerous tumor development, even though increasing the level of ROS can promote metastasis. The transforming growth factor-beta (TGF-β) signaling pathway plays an anti-tumorigenic role in the initial stages of cancer development but a pro-tumorigenic role in later stages that fosters cancer metastasis. TGF-β can regulate the production of ROS unambiguously or downregulate antioxidant systems. ROS can influence TGF-β signaling by enhancing its expression and activation. Thus, TGF-β signaling and ROS might significantly coordinate cellular processes that cancer cells employ to expedite their malignancy. In cancer cells, interplay between oxidative stress and TGF-β is critical for tumorigenesis and cancer progression. Thus, both TGF-β and ROS can develop a robust relationship in cancer cells to augment their malignancy. This review focuses on the appropriate interpretation of this crosstalk between TGF-β and oxidative stress in cancer, exposing new potential approaches in cancer biology.

Redox Sensitive Cysteine Residues as Crucial Regulators of Wild-Type and Mutant p53 Isoforms

The wild-type protein p53 plays a key role in preventing the formation of neoplasms by controlling cell growth. However, in more than a half of all cancers, the TP53 gene has missense mutations that appear during tumorigenesis. In most cases, the mutated gene encodes a full-length protein with the substitution of a single amino acid, resulting in structural and functional changes and acquiring an oncogenic role. This dual role of the wild-type protein and the mutated isoforms is also evident in the regulation of the redox state of the cell, with antioxidant and prooxidant functions, respectively. In this review, we introduce a new concept of the p53 protein by discussing its sensitivity to the cellular redox state. In particular, we focus on the discussion of structural and functional changes following post-translational modifications of redox-sensitive cysteine residues, which are also responsible for interacting with zinc ions for proper structural folding. We will also discuss therapeutic opportunities using small molecules targeting cysteines capable of modifying the structure and function of the p53 mutant isoforms in view of possible anticancer therapies for patients possessing the mutation in the TP53 gene.

Heat shock protein 47 confers chemoresistance on pancreatic cancer cells by interacting with calreticulin and IRE1α

Pancreatic ductal adenocarcinoma (PDAC) is one of the most chemoresistant cancers. An understanding of the molecular mechanism by which PDAC cells have a high chemoresistant potential is important for improvement of the poor prognosis of patients with PDAC. Here we show for the first time that disruption of heat shock protein 47 (HSP47) enhances the efficacy of the therapeutic agent gemcitabine for PDAC cells and that the efficacy is suppressed by reconstituting HSP47 expression. HSP47 interacts with calreticulin (CALR) and the unfolded protein response transducer IRE1α in PDAC cells. Ablation of HSP47 promotes both the interaction of CALR with sarcoplasmic/endoplasmic reticulum Ca2+ -ATPase 2 and interaction of IRE1α with inositol 1,4,5-triphosphate receptor, which generates a condition in which an increase in intracellular Ca2+ level is prone to be induced by oxidative stimuli. Disruption of HSP47 enhances NADPH oxidase-induced generation of intracellular reactive oxygen species (ROS) and subsequent increase in intracellular Ca2+ level in PDAC cells after treatment with gemcitabine, resulting in the death of PDAC cells by activation of the Ca2+ /caspases axis. Ablation of HSP47 promotes gemcitabine-induced suppression of tumor growth in PDAC cell-bearing mice. Overall, these results indicated that HSP47 confers chemoresistance on PDAC cells and suggested that disruption of HSP47 may improve the efficacy of chemotherapy for patients with PDAC.

Combination of a p53-activating CP-31398 and an MDM2 or a FAK inhibitor produces growth suppressive effects in mesothelioma with wild-type p53 genotype

A majority of mesothelioma had the wild-type p53 genotype but was defective of p53 functions primarily due to a genetic defect in INK4A/ARF region. We examined a growth suppressive activity of CP-31398 which was developed to restore the p53 functions irrespective of the genotype in mesothelioma with wild-type or mutated p53. CP-31398 up-regulated p53 levels in cells with wild-type p53 genotype but induced cell growth suppression in a p53-independent manner. In contrasts, nutlin-3a, an MDM2 inhibitor, increased p53 and p21 levels in mesothelioma with the wild-type p53 genotype and produced growth suppressive effects. We investigated a combinatory effect of CP-31398 and nutlin-2a and found the combination produced synergistic growth inhibition in mesothelioma with the wild-type p53 but not with mutated p53. Western blot analysis showed that the combination increased p53 and the phosphorylation levels greater than treatments with the single agent, augmented cleavages of PARP and caspase-3, and decreased phosphorylated FAK levels. Combination of CP-31398 and defactinib, a FAK inhibitor, also achieved synergistic inhibitory effects and increased p53 with FAK dephosphorylation levels greater than the single treatment. These data indicated that a p53-activating CP-31398 achieved growth inhibitory effects in combination with a MDM2 or a FAK inhibitor and suggested a possible reciprocal pathway between p53 elevation and FAK inactivation.

NADPH Oxidases (NOX): An Overview from Discovery, Molecular Mechanisms to Physiology and Pathology

The reactive oxygen species (ROS)-producing enzyme NADPH oxidase (NOX) was first identified in the membrane of phagocytic cells. For many years, its only known role was in immune defense, where its ROS production leads to the destruction of pathogens by the immune cells. NOX from phagocytes catalyzes, via one-electron trans-membrane transfer to molecular oxygen, the production of the superoxide anion. Over the years, six human homologs of the catalytic subunit of the phagocyte NADPH oxidase were found: NOX1, NOX3, NOX4, NOX5, DUOX1, and DUOX2. Together with the NOX2/gp91phox component present in the phagocyte NADPH oxidase assembly itself, the homologs are now referred to as the NOX family of NADPH oxidases. NOX are complex multidomain proteins with varying requirements for assembly with combinations of other proteins for activity. The recent structural insights acquired on both prokaryotic and eukaryotic NOX open new perspectives for the understanding of the molecular mechanisms inherent to NOX regulation and ROS production (superoxide or hydrogen peroxide). This new structural information will certainly inform new investigations of human disease. As specialized ROS producers, NOX enzymes participate in numerous crucial physiological processes, including host defense, the post-translational processing of proteins, cellular signaling, regulation of gene expression, and cell differentiation. These diversities of physiological context will be discussed in this review. We also discuss NOX misregulation, which can contribute to a wide range of severe pathologies, such as atherosclerosis, hypertension, diabetic nephropathy, lung fibrosis, cancer, or neurodegenerative diseases, giving this family of membrane proteins a strong therapeutic interest.

IR-Surviving NSCLC Cells Exhibit Different Patterns of Molecular and Cellular Reactions Relating to the Multifraction Irradiation Regimen and p53-Family Proteins Expression

Simple Summary

For the first time, we demonstrated that the significant decrease in p63/p73 expression together with the absence of functional p53 could underlie an increase in the fraction of polyploid cells, transformation rates, and the glycolytic NAD(P)H production in multifraction X-ray radiation exposure (MFR)-surviving cancer cells, providing conditions for radioresistance associated with epithelial–mesenchymal transition (EMT)-like process activation. During radiation therapy (RT), the treatment dose, fractionation, and dose limits for organs at risk (OARs) do not change between patients and are still prescribed mainly based on the Tumor, Node, Metastasis (TNM) stage, performance status, and comorbidities, taking no account of the tumor biology. Our data once again emphasize that non-small cell lung cancer (NSCLC) therapy approaches should become more personalized according to RT regimen, tumor histology, and molecular status of critical proteins.

Abstract

Radiotherapy is a primary treatment modality for patients with unresectable non-small cell lung cancer (NSCLC). Tumor heterogeneity still poses the central question of cancer radioresistance, whether the presence of a particular cell population inside a tumor undergoing a selective outgrowth during radio- and chemotherapy give rise to metastasis and tumor recurrence. In this study, we examined the impact of two different multifraction X-ray radiation exposure (MFR) regimens, fraction dose escalation (FDE) in the split course and the conventional hypofractionation (HF), on the phenotypic and molecular signatures of four MFR-surviving NSCLC cell sublines derived from parental A549 (p53 wild-type) and H1299 (p53-null) cells, namely A549FR/A549HR, H1299FR/H1299HR cells. We demonstrate that sublines surviving different MFR regimens in a total dose of 60 Gy significantly diverge in their molecular traits related to irradiation regimen and p53 status. The observed changes regarding radiosensitivity, transformation, proliferation, metabolic activity, partial epithelial-to-mesenchymal transition (EMT) program activation and 1D confined migratory behavior (wound healing). For the first time, we demonstrated that MFR exposure led to the significant decrease in the expression of p63 and p73, the p53-family members, in p53null cells, which correlated with the increase in cell polyploidy. We could not find significant differences in FRA1 expression between parental cells and their sublines that survived after any MFR regimen regardless of p53 status. In our study, the FDE regimen probably causes partial EMT program activation in MFR-survived NSCLC cells through either Vimentin upregulation in p53null or an aberrant N-cadherin upregulation in p53wt cells. The HF regimen likely less influences the EMT activation irrespectively of the p53 status of MFR-survived NSCLC cells. Our data highlight that both MFR regimens caused overall higher cell transformation of p53null H1299FR and H1299HR cells than their parental H1299 cells. Moreover, our results indicate that the FDE regimen raised the radioresistance and transformation of MFR-surviving NSCLC cells irrespectively of their p53 status, though the HF regimen demonstrated a similar effect on p53null NSCLC cells only. Our data once again emphasize that NSCLC therapy approaches should become more personalized according to radiation therapy (RT) regimen, tumor histology, and molecular status of critical proteins.

Oxidative Stress and the Intersection of Oncogenic Signaling and Metabolism in Squamous Cell Carcinomas

Squamous cell carcinomas (SCCs) arise from both stratified squamous and non-squamous epithelium of diverse anatomical sites and collectively represent one of the most frequent solid tumors, accounting for more than one million cancer deaths annually. Despite this prevalence, SCC patients have not fully benefited from recent advances in molecularly targeted therapy or immunotherapy. Rather, decades old platinum-based or radiation regimens retaining limited specificity to the unique characteristics of SCC remain first-line treatment options. Historically, a lack of a consolidated perspective on genetic aberrations driving oncogenic transformation and other such factors essential for SCC pathogenesis and intrinsic confounding cellular heterogeneity in SCC have contributed to a critical dearth in effective and specific therapies. However, emerging evidence characterizing the distinct genomic, epigenetic, and metabolic landscapes of SCC may be elucidating unifying features in a seemingly heterogeneous disease. In this review, by describing distinct metabolic alterations and genetic drivers of SCC revealed by recent studies, we aim to establish a conceptual framework for a previously unappreciated network of oncogenic signaling, redox perturbation, and metabolic reprogramming that may reveal targetable vulnerabilities at their intersection.

Pan-Cancer Analysis Shows TP53 Mutations Modulate the Association of NOX4 with Genetic Programs of Cancer Progression and Clinical Outcome

Previously, we have shown TGF-β-induced NOX4 expression is involved in the epithelial-to-mesenchymal transition (EMT), a process critical for cancer metastasis, and that wild-type (WT) and mutant (Mut) p53 have divergent effects on TGF-β induction of NOX4: WT-p53 suppresses whereas Mut-p53 augments NOX4 mRNA and protein production in several tumor cell models. We sought to validate and extend our model by analyzing whole-exome data of primary tumor samples in The Cancer Genome Atlas (TCGA). We constructed a Pan-Cancer dataset from 23 tumor types and explored NOX4 expression patterns in relation to EMT and patient survival. NOX4 mRNA levels increase as a function of cancer progression in several cancers and correlate with Mut-p53 mRNA and genes involved in programs of EMT, cellular adhesion, migration, and angiogenesis. Tumor macrophages appear to be a source of NOX2, whose association with genetic programs of cancer progression emulate that of NOX4. Notably, increased NOX4 expression is linked to poorer survival in patients with Mut-TP53, but better survival in patients with WT-TP53. NOX4 is negatively associated with markers of apoptosis and positively with markers of proliferation in patients with Mut-TP53, consistent with their poorer survival. These findings suggest that TP53 mutations could “switch” NOX4 from being protective and an indicator of good prognosis to deleterious by promoting programs favoring cancer progression.

Hypoxia promotes the metastasis of pancreatic cancer through regulating NOX4/KDM5A-mediated histone methylation modification changes in a HIF1A-independent manner

Background

Hypoxia is a characteristic of the tumor microenvironments within pancreatic cancer (PC), which has been linked to its malignancy. Recently, hypoxia has been reported to regulate the activity of important carcinogenic pathways by changing the status of histone modification. NOX4, a member of NADPH oxidase (NOX), has been found to be activated by hypoxia and promote cancer progression in several cancers. But whether it is involved in the epigenetic changes of tumor cells induced by hypoxia is still unclear, and its biological roles in PC also need to be explored.

Methods

A hypoxic-related gene signature and its associated pathways in PC were identified by analyzing the pancreatic cancer gene expression data from GEO and TCGA database. Candidate downstream gene (NOX4), responding to hypoxia, was validated by RT-PCR and western blot. Then, we evaluated the relationship between NOX4 expression and clinicopathologic parameters in 56 PC patients from our center. In vitro and in vivo assays were preformed to explore the phenotype of NOX4 in PC. Immunofluorescence, western blot and chromatin immunoprecipitation assays were further applied to search for a detailed mechanism.

Results

We quantified hypoxia and developed a hypoxia signature, which was associated with worse prognosis and elevated malignant potential in PC. Furthermore, we found that NADPH oxidase 4 (NOX4), which was induced by hypoxia and upregulated in PC in a HIF1A-independent manner, caused inactivation of lysine demethylase 5A (KDM5A), increased the methylation modification of histone H3 and regulated the transcription of EMT-associated gene_ snail family transcriptional repressor 1 (SNAIL1). This served to promote the invasion and metastasis of PC. NOX4 deficiency repressed hypoxia-induced EMT, reduced expression of H3K4ME3 and impaired the invasion and metastasis of PC cells; however, knockdown of KDM5A reversed the poor expression of H3KEME3 induced by NOX4 deficiency, thereby promoting EMT.

Conclusions

This study highlights the prognostic role of hypoxia-related genes in PC and strong correlation with EMT pathway. Our results also creatively discovered that NOX4 was an essential mediator for hypoxia-induced histone methylation modification and EMT in PC cells.

Protein disulfide isomerase A1 regulates breast cancer cell immunorecognition in a manner dependent on redox state

Oxidoreductase protein disulphide isomerases (PDI) are involved in the regulation of a variety of biological processes including the modulation of endoplasmic reticulum (ER) stress, unfolded protein response (UPR), ER-mitochondria communication and the balance between pro-survival and pro-death pathways. In the current study the role of the PDIA1 family member in breast carcinogenesis was investigated by measuring ROS generation, mitochondrial membrane disruption, ATP production and HLA-G protein levels on the surface of the cellular membrane in the presence or absence of PDIA1. The results showed that this enzyme exerted pro-apoptotic effects in estrogen receptor (ERα)-positive breast cancer MCF-7 and pro-survival in triple negative breast cancer (TNBC) MDA-MB-231 cells. ATP generation was upregulated in PDIA1-silenced MCF-7 cells and downregulated in PDIA1-silenced MDA-MB-231 cells in a manner dependent on the cellular redox status. Furthermore, MCF-7 and MDA-MB-231 cells in the presence of PDIA1 expressed higher surface levels of the non-classical human leukocyte antigen (HLA-G) under oxidative stress conditions. Evaluation of the METABRIC datasets showed that low PDIA1 and high HLA-G mRNA expression levels correlated with longer survival in both ERα-positive and ERα-negative stage 2 breast cancer patients. In addition, analysis of the PDIA1 vs. the HLA-G mRNA ratio in the subgroup of the living stage 2 breast cancer patients exhibiting low PDIA1 and high HLA-G mRNA levels revealed that the longer the survival time of the ratio was high PDIA1 and low HLA-G mRNA and occurred predominantly in ERα-positive breast cancer patients whereas in the same subgroup of the ERα-negative breast cancer mainly this ratio was low PDIA1 and high HLA-G mRNA. Taken together these results provide evidence supporting the view that PDIA1 is linked to several hallmarks of breast cancer pathways including the process of antigen processing and presentation and tumor immunorecognition.

The role of NOX4 in pulmonary diseases

Nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) is a subtype of the NOX family, which is mainly expressed in the pulmonary vasculature and pulmonary endothelial cells in the respiratory system. NOX4 has unique characteristics, and is a constitutively active enzyme that primarily produces hydrogen peroxide. The signaling pathways associated with NOX4 are complicated. Negative and positive feedback play significant roles in regulating NOX4 expression. The role of NOX4 is controversial because NOX4 plays a protective or damaging role in different respiratory diseases. This review summarizes the structure, enzymatic properties, regulation, and signaling pathways of NOX4. This review then introduces the roles of NOX4 in different diseases in the respiratory system, such as acute respiratory distress syndrome, chronic obstructive pulmonary disease, and pulmonary fibrosis.

Redox Regulation of NOX Isoforms on FAK(Y397)/SRC(Y416) Phosphorylation Driven Epithelial-to-Mesenchymal Transition in Malignant Cervical Epithelial Cells

Epithelial-to-mesenchymal transition (EMT) promulgates epithelial cell associated disease-defining characteristics in tumorigenesis and organ fibrosis. Growth factors such as epidermal growth factor and fibroblast growth factor in addition to cytokines such as transforming growth factor-β1 (TGF-β1) is said to play a prominent role in remodeling related pathological events of cancer progression such as invasion, metastasis, apoptosis, EMT, etc. through redox related cellular secondary messengers, in particular the reactive oxygen species (ROS). However, the signaling cascade underlying the redox mechanism and thereby the progression of EMT remains largely unknown. In this study, upon TGF-β1 treatment, we observed an induction in NOX isoforms-NOX2 and NOX4-that have time (early and late) and cellular localization (nucleus and autophagosome co-localized) dependent effects in mediating EMT associated cell proliferation and migration through activation of the focal adhesion kinase (FAK)/SRC pathway in HeLa, human cervical cancer cells. Upon silencing NOX2/4 gene expression and using the SRC inhibitor (AZD0530), progression of TGF-β1 induced EMT related cellular remodeling, extra cellular matrix (ECM) production, cell migration and invasion, got significantly reverted. Together, these results indicate that NOX2 and NOX4 play important, albeit distinct, roles in the activation of cytokine mediated EMT and its associated processes via tyrosine phosphorylation of the FAK/SRC pathway.

Mutant p53-Associated Molecular Mechanisms of ROS Regulation in Cancer Cells

The TP53 tumor suppressor gene is the most frequently altered gene in tumors and an increasing number of studies highlight that mutant p53 proteins can acquire oncogenic properties, referred to as gain-of-function (GOF). Reactive oxygen species (ROS) play critical roles as intracellular messengers, regulating numerous signaling pathways linked to metabolism and cell growth. Tumor cells frequently display higher ROS levels compared to healthy cells as a result of their increased metabolism as well as serving as an oncogenic agent because of its damaging and mutational properties. Several studies reported that in contrast with the wild type protein, mutant p53 isoforms fail to exert antioxidant activities and rather increase intracellular ROS, driving a pro-tumorigenic survival. These pro-oxidant oncogenic abilities of GOF mutant p53 include signaling and metabolic rewiring, as well as the modulation of critical ROS-related transcription factors and antioxidant systems, which lead ROS unbalance linked to tumor progression. The studies summarized here highlight that GOF mutant p53 isoforms might constitute major targets for selective therapeutic intervention against several types of tumors and that ROS enhancement driven by mutant p53 might represent an “Achilles heel” of cancer cells, suggesting pro-oxidant drugs as a therapeutic approach for cancer patients bearing the mutant TP53 gene.

TGF-β3 Induces Autophagic Activity by Increasing ROS Generation in a NOX4-Dependent Pathway

Higher concentrations of reactive oxygen species (ROS) have been associated with epithelial cell damage, cell shedding, and airway hyperresponsiveness. Previous studies have indicated that transforming growth factor-beta (TGF-β) mediates ROS production and NADPH oxidase (NOX) activity. In our previous study, we also observed that TGF-β3 increases mucus secretion in airway epithelial cells in an autophagy-dependent fashion. Although it is well known that the relationship between ROS and autophagy is cell context-dependent, the exact mechanism of action remains unclear. The following study examined whether ROS act as upstream of autophagy activation in response to TGF-β3 induction. Using an allergic inflammation mouse model induced by house dust mite (HDM), we observed elevated lung amounts of TGF-β3 accompanied by increased ROS levels. And we found that ROS levels were elevated and NOX4 expression was increased in TGF-β3-induced epithelial cells, while the lack of NOX4 in the epithelial cells could reduce ROS generation and autophagy-dependent MUC5AC expression treated with TGF-β3. Furthermore, our studies demonstrated that the Smad2/3 pathway was involved in TGF-β3-induced ROS generation by promoting NOX4 expression. The inhibition of ROS generation by N-Acetyl-L-cysteine (NAC) resulted in a decrease in mucus expression and autophagy activity in vivo as well as in vitro. Finally, TGF-β3-neutralizing antibody significantly reduced the ROS generation, mucus expression, and autophagy activity and also decreased the phosphorylation of Smad2 and Smad3. Taken together, the obtained results revealed that persistent TGF-β3 activation increased ROS levels in a NOX4-dependent pathway and subsequently induced autophagy as well as MUC5AC expression in the epithelial cells.

Mutant p53 induces SIRT3/MnSOD axis to moderate ROS production in melanoma cells

The TP53 tumor suppressor gene is the most frequently altered gene in tumors and mutant p53 isoforms can acquire oncogenic properties referred to as gain-of-function (GOF). In this study, we used wild-type (A375) and mutant p53 (MeWo) melanoma cell lines to assess the regulation of the mitochondrial antioxidant manganese superoxide dismutase (MnSOD) by mutant p53. The effects of mutant p53 were evaluated by qPCR, immunoblotting, enzyme activity assay, cell proliferation assay, reactive oxygen species (ROS) assay after cellular transfection. We demonstrate that mutant p53 induces MnSOD expression, which is recovered by the ROS scavenger N-acetyl-l-cysteine. This suggests MnSOD induction as a defense mechanism of melanoma cells to counterbalance the pro-oxidant conditions induced by mutant p53. We also demonstrate that mutant p53 induces the expression of Sirtuin3 (SIRT3), a major mitochondrial NAD⁺-dependent deacetylase, stimulating MnSOD deacetylation and enzymatic activity. Indeed, the restoration of SIRT3 reverses MnSOD activity decrease by mutant p53 knock-down. Finally, MnSOD knock-down further enhances mutant p53-mediated ROS increase, counteracting mutp53-dependent cell hyperproliferation. This indicates that SIRT3 and MnSOD act to maintain ROS levels controlled to promote cell proliferation and survival, providing new therapeutic opportunities to be further considered for clinical studies in cancer patients bearing mutant TP53 gene.

Morphologic and genomic characterization of urothelial to sarcomatoid transition in muscle-invasive bladder cancer

INTRODUCTION

The sarcomatoid morphology of muscle-invasive bladder cancer (MIBC) is associated with unfavorable prognosis. However, the genomic, transcriptomic, and proteomic relationship between conventional urothelial and synchronous sarcomatoid morphology is poorly defined.

METHODS

We compiled a cohort of 21 MIBC patients with components of conventional urothelial and adjacent sarcomatoid morphology within the same tumor focus. We performed comprehensive pathologic and immunohistochemical characterization and in 4 selected cases, subjected both morphologic components to targeted DNA sequencing and whole transcriptome analysis.

RESULTS

Synchronous sarcomatoid and urothelial morphology from the same MIBC foci shared truncal somatic mutations, indicating a common ancestral clone. However, additional mutations or copy number alterations restricted to the either component suggested divergent evolution at the genomic level. This was confirmed at the transcriptome level since while the urothelial component exhibited a basal-like subtype (TCGA2014: cluster III, LundTax: basal/squamous-like), the sarcomatoid morphology was predominantly cluster IV (claudin-low). Protein expression was consistent with a basal-like phenotype in both morphologies in 18/21 of cases. However, most cases had evidence of active epithelial-to-mesenchymal transition (E-Cad ↓ and Zeb1 or TWIST1 ↑) from urothelial toward the sarcomatoid morphology. Drug response signatures nominated different targets for each morphology and proposed agents under clinical investigation in liposarcoma or other sarcoma. PD-L1 expression was higher in the sarcomatoid than the urothelial component.

CONCLUSIONS

Conventional urothelial and adjacent sarcomatoid morphologies of MIBC arise from the same common ancestor and share a basal-like phenotype. However, divergence between the morphologies at the genome, transcriptome, and proteome level suggests differential sensitivity to therapy.

PAC1 regulates receptor tyrosine kinase transactivation in a reactive oxygen species-dependent manner

Pituitary adenylate cyclase activating polypeptide (PACAP) is a growth factor for lung cancer cells. PACAP-27 or PACAP-38 binds with high affinity to non-small cell lung cancer (NSCLC) cells, causing elevated cytosolic Ca²⁺, increased proliferation and increased phosphorylation of extracellular regulated kinase (ERK) and the epidermal growth factor receptor (EGFR). The role of reactive oxygen species (ROS) was investigated in these processes. Addition of PACAP-38 to NCI-H838 or A549 cells increased the tyrosine phosphorylation of the EGFR, HER2 and ERK significantly by 4-, 3-, and 2-fold, respectively. The transactivation of the EGFR and HER2 was inhibited by gefitinib or lapatinib (tyrosine kinase inhibitors), PACAP (6-38) (PAC1 antagonist), N-acetylcysteine (NAC is an anti-oxidant) or dipheyleneiodonium (DPI is an inhibitor of Nox and Duox enzymes). PACAP-38 addition to NSCLC cells increased ROS which was inhibited by PACAP (6-38), NAC or DPI. Nox1, Nox2, Nox3, Nox4, Nox5, Duox1 and Duox2 mRNA was present in many NSCLC cell lines. PACAP-38 stimulated the growth of NSCLC cells whereas PACAP (6-38), gefitinib or DPI inhibited proliferation. The results show that ROS are essential for PAC1 to regulate EGFR and HER2 transactivation as well as proliferation of NSCLC cells.

Morphologic and genomic characterization of urothelial to sarcomatoid transition in muscle-invasive bladder cancer

INTRODUCTION

The sarcomatoid morphology of muscle-invasive bladder cancer (MIBC) is associated with unfavorable prognosis. However, the genomic, transcriptomic, and proteomic relationship between conventional urothelial and synchronous sarcomatoid morphology is poorly defined.

METHODS

We compiled a cohort of 21 MIBC patients with components of conventional urothelial and adjacent sarcomatoid morphology within the same tumor focus. We performed comprehensive pathologic and immunohistochemical characterization and in 4 selected cases, subjected both morphologic components to targeted DNA sequencing and whole transcriptome analysis.

RESULTS

Synchronous sarcomatoid and urothelial morphology from the same MIBC foci shared truncal somatic mutations, indicating a common ancestral clone. However, additional mutations or copy number alterations restricted to the either component suggested divergent evolution at the genomic level. This was confirmed at the transcriptome level since while the urothelial component exhibited a basal-like subtype (TCGA2014: cluster III, LundTax: basal/squamous-like), the sarcomatoid morphology was predominantly cluster IV (claudin-low). Protein expression was consistent with a basal-like phenotype in both morphologies in 18/21 of cases. However, most cases had evidence of active epithelial-to-mesenchymal transition (E-Cad ↓ and Zeb1 or TWIST1 ↑) from urothelial toward the sarcomatoid morphology. Drug response signatures nominated different targets for each morphology and proposed agents under clinical investigation in liposarcoma or other sarcoma. PD-L1 expression was higher in the sarcomatoid than the urothelial component.

CONCLUSIONS

Conventional urothelial and adjacent sarcomatoid morphologies of MIBC arise from the same common ancestor and share a basal-like phenotype. However, divergence between the morphologies at the genome, transcriptome, and proteome level suggests differential sensitivity to therapy.

NADPH oxidase 4 is correlated with gastric cancer progression and predicts a poor prognosis

NADPH oxidase 4 (NOX4) is one of the main sources of reactive oxygen species, and plays a crucial role in the occurrence and development of tumors. However, there is currently little evidence demonstrating that NOX4 expression is associated with gastric cancer. To establish whether NOX4 plays a role in gastric cancer progression and prognosis, we performed immunohistochemistry on gastric cancer tissues and paired adjacent normal tissues from 90 gastric cancer patients to detect and compare NOX4 expression. Next, we analyzed the association between NOX4 expression and clinicopathological characteristics. Survival analysis was performed to explore the association between NOX4 expression and the prognosis of gastric cancer patients. Furtherly, we investigated the effect of NOX4-knockdown using siRNA on gastric cancer progression in vitro and in vivo. Our results revealed that NOX4 expression in gastric cancer tissues is higher than in paired adjacent normal tissues (P = 0.0009). NOX4 expression is significantly correlated with tumor size (P = 0.0321), lymphatic metastasis (P = 0.0125) and vascular invasion (P = 0.0017) and a poor prognosis (P = 0.0000) in gastric cancer patients. NOX4 depletion could significantly inhibit the invasion, proliferation, EMT and MMP7 expression of gastric cancer cells and suppress the progression of gastric cancer in vivo. In conclusion, NOX4 is related to gastric cancer development and predicts a poor prognosis. NOX4 may play an essential role in the progression of gastric cancer, and is a promising target for the prevention and treatment of gastric cancer.

H2O2 Metabolism in Normal Thyroid Cells and in Thyroid Tumorigenesis: Focus on NADPH Oxidases

Thyroid hormone synthesis requires adequate hydrogen peroxide (H₂O₂) production that is utilized as an oxidative agent during the synthesis of thyroxin (T4) and triiodothyronine (T3). Thyroid H₂O₂ is generated by a member of the family of NADPH oxidase enzymes (NOX-es), termed dual oxidase 2 (DUOX2). NOX/DUOX enzymes produce reactive oxygen species (ROS) as their unique enzymatic activity in a timely and spatially regulated manner and therefore, are important regulators of diverse physiological processes. By contrast, dysfunctional NOX/DUOX-derived ROS production is associated with pathological conditions. Inappropriate DUOX2-generated H₂O₂ production results in thyroid hypofunction in rodent models. Recent studies also indicate that ROS improperly released by NOX4, another member of the NOX family, are involved in thyroid carcinogenesis. This review focuses on the current knowledge concerning the redox regulation of thyroid hormonogenesis and cancer development with a specific emphasis on the NOX and DUOX enzymes in these processes.

Oxidative stress in thyroid carcinomas: biological and clinical significance

At physiological concentrations, reactive oxygen species (ROS), including superoxide anions and H2O2, are considered as second messengers that play key roles in cellular functions, such as proliferation, gene expression, host defence and hormone synthesis. However, when they are at supraphysiological levels, ROS are considered potent DNA-damaging agents. Their increase induces oxidative stress, which can initiate and maintain genomic instability. The thyroid gland represents a good model for studying the impact of oxidative stress on genomic instability. Indeed, one particularity of this organ is that follicular thyroid cells synthesise thyroid hormones through a complex mechanism that requires H2O2. Because of their detection in thyroid adenomas and in early cell transformation, both oxidative stress and DNA damage are believed to be neoplasia-preceding events in thyroid cells. Oxidative DNA damage is, in addition, detected in the advanced stages of thyroid cancer, suggesting that oxidative lesions of DNA also contribute to the maintenance of genomic instability during the subsequent phases of tumourigenesis. Finally, ionizing radiation and the mutation of oncogenes, such as RAS and BRAF, play a key role in thyroid carcinogenesis through separate and unique mechanisms: they upregulate the expression of two distinct 'professional' ROS-generating systems, the NADPH oxidases DUOX1 and NOX4, which cause DNA damage that may promote chromosomal instability, tumourigenesis and dedifferentiation.

Carcinogenesis and Reactive Oxygen Species Signaling: Interaction of the NADPH Oxidase NOX1-5 and Superoxide Dismutase 1-3 Signal Transduction Pathways

SIGNIFICANCE

Reduction/oxidation (redox) balance could be defined as an even distribution of reduction and oxidation complementary processes and their reaction end products. There is a consensus that aberrant levels of reactive oxygen species (ROS), commonly observed in cancer, stimulate primary cell immortalization and progression of carcinogenesis. However, the mechanism how different ROS regulate redox balance is not completely understood. Recent Advances: In the current review, we have summarized the main signaling cascades inducing NADPH oxidase NOX1-5 and superoxide dismutase (SOD) 1-3 expression and their connection to cell proliferation, immortalization, transformation, and CD34+ cell differentiation in thyroid, colon, lung, breast, and hematological cancers.

CRITICAL ISSUES

Interestingly, many of the signaling pathways activating redox enzymes or mediating the effect of ROS are common, such as pathways initiated from G protein-coupled receptors and tyrosine kinase receptors involving protein kinase A, phospholipase C, calcium, and small GTPase signaling molecules.

FUTURE DIRECTIONS

The clarification of interaction of signal transduction pathways could explain how cells regulate redox balance and may even provide means to inhibit the accumulation of harmful levels of ROS in human pathologies.

Model Systems to Investigate NOX-Dependent Cell Migration and Invasiveness

There is mounting evidence indicating that reactive oxygen species (ROS) play a crucial role in cell migration and invasion. Our previous studies have demonstrated the NADPH oxidase (NOX) family of enzymes are a source of ROS in different cell types undergoing migration. Several NOX enzymes are induced or activated in processes including wound repair and maintenance of epithelial barriers, as well as in promoting metastatic cell migration and invasiveness. This chapter outlines three different in vitro assays used to examine how NOX enzymes are involved in cell motility: scratch-wound repair, Matrigel invasion, and migration from confluent cell monolayer boundaries created by cell culture inserts. The three methods provide a range of experimental approaches for delineating roles of NOX enzymes in cell migration through manipulation of the expression or activities of the endogenous or overexpressed oxidases.

Mutant p53 blocks SESN1/AMPK/PGC-1α/UCP2 axis increasing mitochondrial O2-· production in cancer cells

BACKGROUND

The TP53 tumor suppressor gene is the most frequently altered gene in tumors and mutant p53 gain-of-function isoforms actively promote cancer malignancy.

METHODS

A panel of wild-type and mutant p53 cancer cell lines of different tissues, including pancreas, breast, skin, and lung were used, as well as chronic lymphocytic leukemia (CLL) patients with different TP53 gene status. The effects of mutant p53 were evaluated by confocal microscopy, reactive oxygen species production assay, immunoblotting, and quantitative reverse transcription polymerase chain reaction after cellular transfection.

RESULTS

We demonstrate that oncogenic mutant p53 isoforms are able to inhibit SESN1 expression and consequently the amount of SESN1/AMPK complex, resulting in the downregulation of the AMPK/PGC-1α/UCP2 axis and mitochondrial O₂-· production. We also show a correlation between the decrease of reduced thiols with a poorer clinical outcome of CLL patients bearing mutant TP53 gene. The restoration of the mitochondrial uncoupling protein 2 (UCP2) expression, as well as the addition of the radical scavenger N-acetyl-L-cysteine, reversed the oncogenic effects of mutant p53 as cellular hyper-proliferation, antiapoptotic effect, and resistance to drugs.

CONCLUSIONS

The inhibition of the SESN1/AMPK/PGC-1α/UCP2 axis contributes to the pro-oxidant and oncogenic effects of mutant p53, suggesting pro-oxidant drugs as a therapeutic approach for cancer patients bearing mutant TP53 gene.

NOX4, a new genetic target for anti-cancer therapy in digestive system cancer

Oxidative stress has been implicated as an important factor in tumorigenesis and tumor progression. The nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit 4 (NOX4), a substrate of NADPH that can generate H₂ O₂ reactive oxygen species, has been reported to be highly expressed in gastrointestinal tumors. In this review we summarize the available evidence on the biological function of NOX4 in digestive system tumors by focusing on its correlation with classical cell signaling pathways, including VEGF, MAPK and PI3K/AKT, and with biochemical mediators, such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), activator protein (AP)-1 and transforming growth factor (TGF)-β. According to the clinical and database studies on tumors of the digestive system, such as colorectal, gastric and pancreatic cancer, there are significant associations between NOX4 expression and tumor prognosis as well as patient's survival. Animal studies using NOX4 inhibitors such as diphenylene iodonium and GKT137831, which selectively block NOX4, indicate their potential as therapeutic agents for targeting cancer cells.

NADPH oxidase 4 regulates anoikis resistance of gastric cancer cells through the generation of reactive oxygen species and the induction of EGFR

Anoikis is a type of programmed cell death induced by detachment from the extracellular matrix. In cancer cells, anoikis resistance is essential for cancer cell survival in blood circulation and distant metastasis. However, the mechanisms behind anoikis resistance of gastric cancer remain largely unknown. Herein, we demonstrate that NADPH oxidase 4 (NOX4) expression and reactive oxygen species (ROS) generation are upregulated in suspension gastric cell cultures compared with adherent cultures. Silencing of NOX4 decreases ROS generation and downregulates EGFR, sensitizing cells to anoikis. NOX4 overexpression upregulates ROS and EGFR levels and promotes anoikis resistance. NOX4 depletion inhibits gastric cancer survival in blood circulation and attenuates distant metastasis. NOX4 expression is correlated with EGFR expression in patients. In conclusion, induction of NOX4 expression by detachment promotes anoikis resistance of gastric cancer through ROS generation and downstream upregulation of EGFR, which is critical for the metastatic progression of gastric cancer.

ROS modifiers and NOX4 affect the expression of the survivin-associated radio-adaptive response

The survivin-associated radio-adaptive response can be induced following exposure to ionizing radiation in the dose range from 5 to 100 mGy, and its magnitude of expression is dependent upon the TP53 mutational status of cells and ROS signaling. The purpose of the study was to investigate the potential role of ROS in the development of the survivin-associated adaptive response. Utilizing human colon carcinoma HCT116 TP53 wild type (WT) and HCT116 isogenic TP53 null mutant (Mut) cell cultures, the roles of inter- and intracellular ROS signaling on expression of the adaptive response as evidenced by changes in intracellular translocation of survivin measured by ELISA, and cell survival determined by a standard colony forming assay were investigated using ROS modifying agents that include emodin, N-acetyl-L-cysteine (NAC), fulvene-5, honokiol, metformin and rotenone. The role of NADPH oxidase 4 (NOX4) in the survivin-associated adaptive response was investigated by transfecting HCT116 cells, both WT and Mut, with two different NOX4 siRNA oligomers and Western blotting. A dose of 5 mGy or a 15 min exposure to 50 µM of the ROS producing drug emodin were equally effective in inducing a pro-survival adaptive response in TP53 WT and a radio-sensitization adaptive response in TP53 Mut HCT116 cells. Each response was associated with a corresponding translocation of survivin into the cytoplasm or nucleus, respectively. Exposure to 10 mM NAC completely inhibited both responses. Exposure to 10 µM honokiol induced responses similar to those observed following NAC exposure in TP53 WT and Mut cells. The mitochondrial complex 1 inhibitor rotenone was effective in reducing both cytoplasmic and nuclear survivin levels, but was ineffective in altering the expression of the adaptive response in either TP53 WT or Mut cells. In contrast, both metformin and fulvene-5, inhibitors of NOX4, facilitated the reversal of TP53 WT and Mut adaptive responses from pro-survival to radio-sensitization and vice versa, respectively. These changes were accompanied by corresponding reversals in the translocation of survivin to the nuclei of TP53 WT and to the cytoplasm of TP53 Mut cells. The potential role of NOX4 in the expression of the survivin-associated adaptive response was investigated by transfecting HCT116 cells with NOX4 siRNA oligomers to inhibit NOX4 expression. Under these conditions NOX4 expression was inhibited by about 50%, resulting in a reversal in the expression of the TP53 WT and Mut survivin-associated adaptive responses as was observed following metformin and fulvene-5 treatment. Exposure to 5 mGy resulted in enhanced NOX4 expression by about 40% in both TP53 WT and Mut cells, in contrast to only a 1-2% increase following a 2 Gy only exposure. Utilizing mixed cultures of HCT116 TP53 WT and isogenic null Mut cells, as few as 10% TP53 Mut cells were sufficient to control the expression of the remaining 90% WT cells and resulted in an overall radio-sensitization response accompanied by the nuclear translocation of survivin characteristic of homogeneous TP53 Mut populations.

Immune Cell Induced Migration of Osteoprogenitor Cells Is Mediated by TGF-β Dependent Upregulation of NOX4 and Activation of Focal Adhesion Kinase

The cytokines secreted by immune cells have a large impact on the tissue, surrounding a fracture, e.g., by attraction of osteoprogenitor cells. However, the underlying mechanisms are not yet fully understood. Thus, this study aims at investigating molecular mechanisms of the immune cell-mediated migration of immature primary human osteoblasts (phOBs), with transforming growth factor beta (TGF-β), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (NOX4) and focal adhesion kinase (FAK) as possible regulators. Monocyte- and macrophage (THP-1 cells ± phorbol 12-myristate 13-acetate (PMA) treatment)-conditioned media, other than the granulocyte-conditioned medium (HL-60 cells + dimethyl sulfoxide (DMSO) treatment), induce migration of phOBs. Monocyte- and macrophage (THP-1 cells)-conditioned media activate Smad3-dependent TGF-β signaling in the phOBs. Stimulation with TGF-β promotes migration of phOBs. Furthermore, TGF-β treatment strongly induces NOX4 expression on both mRNA and protein levels. The associated reactive oxygen species (ROS) accumulation results in phosphorylation (Y397) of FAK. Blocking TGF-β signaling, NOX4 activity and FAK signaling effectively inhibits the migration of phOBs towards TGF-β. In summary, our data suggest that monocytic- and macrophage-like cells induce migration of phOBs in a TGF-β-dependent manner, with TGF-β-dependent induction of NOX4, associated production of ROS and resulting activation of FAK as key mediators.

Hearing vulnerability after noise exposure in a mouse model of reactive oxygen species overproduction

Previous studies have convincingly argued that reactive oxygen species (ROS) contribute to the development of several major types of sensorineural hearing loss, such as noise-induced hearing loss (NIHL), drug-induced hearing loss, and age-related hearing loss. However, the underlying molecular mechanisms induced by ROS in these pathologies remain unclear. To resolve this issue, we established an in vivo model of ROS overproduction by generating a transgenic (TG) mouse line expressing the human NADPH oxidase 4 (NOX4, NOX4-TG mice), which is a constitutively active ROS-producing enzyme that does not require stimulation or an activator. Overproduction of ROS was detected at the cochlea of the inner ear in NOX4-TG mice, but they showed normal hearing function under baseline conditions. However, they demonstrated hearing function vulnerability, especially at high-frequency sounds, upon exposure to intense noise, which was accompanied by loss of cochlear outer hair cells (OHCs). The vulnerability to loss of hearing function and OHCs was rescued by treatment with the antioxidant Tempol. Additionally, we found increased protein levels of the heat-shock protein 47 (HSP47) in models using HEK293 cells, including H₂ O₂ treatment and cells with stable and transient expression of NOX4. Furthermore, the up-regulated levels of Hsp47 were observed in both the cochlea and heart of NOX4-TG mice. Thus, antioxidant therapy is a promising approach for the treatment of NIHL. Hsp47 may be an endogenous antioxidant factor, compensating for the chronic ROS overexposure in vivo, and counteracting ROS-related hearing loss.

Neuropeptide G Protein-Coupled Receptors as Oncotargets

Neuropeptide G protein-coupled receptors (GPCRs) are overexpressed on numerous cancer cells. In a number of tumors, such as small cell lung cancer (SCLC), bombesin (BB) like peptides and neurotensin (NTS) function as autocrine growth factors whereby they are secreted from tumor cells, bind to cell surface receptors and stimulate growth. BB-drug conjugates and BB receptor antagonists inhibit the growth of a number of cancers. Vasoactive intestinal peptide (VIP) increases the secretion rate of BB-like peptide and NTS from SCLC leading to increased proliferation. In contrast, somatostatin (SST) inhibits the secretion of autocrine growth factors from neuroendocrine tumors (NETs) and decreases proliferation. SST analogs such as radiolabeled octreotide can be used to localize tumors, is therapeutic for certain cancer patients and has been approved for four different indications in the diagnosis/treatment of NETs. The review will focus on how BB, NTS, VIP, and SST receptors can facilitate the early detection and treatment of cancer.

Plakoglobin restores tumor suppressor activity of p53R175H mutant by sequestering the oncogenic potential of β-catenin

Tumor suppressor/transcription factor p53 is mutated in over 50% of all cancers. Some mutant p53 proteins have not only lost tumor suppressor activities but they also gain oncogenic functions (GOF). One of the most frequently expressed GOF p53 mutants is Arg175His (p53R175H ) with well-documented roles in cancer development and progression. Plakoglobin is a cell adhesion and signaling protein and a paralog of β-catenin. Unlike β-catenin that has oncogenic function through its role in the Wnt pathway, plakoglobin generally acts as a tumor/metastasis suppressor. We have shown that plakoglobin interacted with wild type and a number of p53 mutants in various carcinoma cell lines. Plakoglobin and mutant p53 interacted with the promoter and regulated the expression of several p53 target genes. Furthermore, plakoglobin interactions with p53 mutants restored their tumor suppressor/metastasis activities in vitro. GOF p53 mutants induce accumulation and oncogenic activation of β-catenin. Previously, we showed that one mechanism by which plakoglobin may suppress tumorigenesis is by sequestering β-catenin's oncogenic activity. Here, we examined the effects of p53R175H expression on β-catenin accumulation and transcriptional activation and their modifications by plakoglobin coexpression. We showed that p53R175H expression in plakoglobin null cells increased total and nuclear levels of β-catenin and its transcriptional activity. Coexpression of plakoglobin in these cells promoted β-catenin's proteasomal degradation, and decreased its nuclear levels and transactivation. Wnt/β-catenin targets, c-MYC and S100A4 were upregulated in p53R175H cells and were downregulated when plakoglobin was coexpressed. Plakoglobin-p53R175H cells also showed significant reduction in their migration and invasion in vitro.

Histone modifications affect differential regulation of TGFβ- induced NADPH oxidase 4 (NOX4) by wild-type and mutant p53

Previously, we showed wild-type (WT) and mutant (mut) p53 differentially regulate reactive oxygen species (ROS) generation by NADPH oxidase-4 (NOX4): p53-WT suppresses TGFβ-induced NOX4, ROS and cell migration, whereas tumor-associated mut-p53 proteins enhance NOX4 expression and cell migration. Here, we extended our findings on the effects of p53 on NOX4 in several tumors and examined the basis of NOX4 transcriptional regulation by p53 and SMAD3. Statistical analysis of expression data from primary tumors available from The Cancer Genome Atlas (TCGA) detected correlations between mut-p53 and increased NOX4 expression. Furthermore, by altering p53 levels in cell culture models we showed several common tumor-associated mutant forms support TGFβ/SMAD3-dependent NOX4 expression. Deletion analysis revealed two critical SMAD3 binding elements (SBE) required for mut-p53-dependent NOX4 induction, whereas p53-WT caused dose-dependent suppression of NOX4 transcription. ChIP analysis revealed SMAD3 and p53-WT or mut-p53 associate with SBEs and p53 response elements in a TGFβ-dependent manner. Interestingly, the repressive effects of p53-WT on NOX4 were relieved by mutation of its transactivation domain or histone deacetylase (HDAC) inhibitor treatment. Overexpression of p300, a transcriptional co-regulator and histone acetyltransferase (HAT), enhanced p53-mediated NOX4 induction, whereas HAT-inactive p300 reduced NOX4 expression. Mut-p53 augmented TGFβ-stimulated histone acetylation within the NOX4 promoter. Finally, wound assays demonstrated NOX4 and p300 promote TGFβ/mut-p53-mediated cell migration. Our studies provide new insight into TGFβ/SMAD3 and mut-p53-mediated NOX4 induction involving epigenetic control of NOX4 in tumor cell migration, suggesting NOX4 is a potential therapeutic target to combat tumor progression and metastasis.

Novel NADPH oxidase inhibitor VAS2870 suppresses TGF‑β‑dependent epithelial‑to‑mesenchymal transition in retinal pigment epithelial cells

NADPH oxidases (NOXs) are important in the pathophysiology of fibrotic diseases. The expression and activity of NOXs are regulated by growth factors, including transforming growth factor (TGF-β). The proliferation of retinal pigment epithelial (RPE) cells following epithelial- to-mesenchymal transition (EMT) is a major pathological change involved in proliferative vitreoretinopathy (PVR). The aim of the present study was to determine the effects of the novel NOX inhibitor VAS2870 on the TGF-β-dependent expression of NOX4 and associated cellular events in RPE cells. Cell viability was examined using a Cell Counting Kit-8 assay and cell cycle progression was detected by flow cytometric analysis. Immunofluorescence analysis and western blot analysis were performed to assess EMT. It was found that TGF-β increased the expression of NOX4 and that pre-incubation with VAS2870 eliminated this effect. Additionally, TGF-β promoted RPE migration and increased EMT. Pre-incubation with VAS2870 significantly prevented TGF-β2-induced EMT by decreasing the levels of α-smooth muscle actin and E-cadherin, and also inhibited the migratory ability of the RPE cells, as demonstrated by scratch assays. Finally, VAS2870 suppressed the proliferation of RPE cells, and led to G₁-phase cell cycle arrest and a significant downregulation of the expression of cyclin D1. In conclusion, the pharmacological inhibition of NOX may be a promising tool for the treatment of PVR.

Functional Precision Medicine Identifies Novel Druggable Targets and Therapeutic Options in Head and Neck Cancer

Purpose: Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide, with high mortality and a lack of targeted therapies. To identify and prioritize druggable targets, we performed genome analysis together with genome-scale siRNA and oncology drug profiling using low-passage tumor cells derived from a patient with treatment-resistant HPV-negative HNSCC.Experimental Design: A tumor cell culture was established and subjected to whole-exome sequencing, RNA sequencing, comparative genome hybridization, and high-throughput phenotyping with a siRNA library covering the druggable genome and an oncology drug library. Secondary screens of candidate target genes were performed on the primary tumor cells and two nontumorigenic keratinocyte cell cultures for validation and to assess cancer specificity. siRNA screens of the kinome on two isogenic pairs of p53-mutated HNSCC cell lines were used to determine generalizability. Clinical utility was addressed by performing drug screens on two additional HNSCC cell cultures derived from patients enrolled in a clinical trial.Results: Many of the identified copy number aberrations and somatic mutations in the primary tumor were typical of HPV(-) HNSCC, but none pointed to obvious therapeutic choices. In contrast, siRNA profiling identified 391 candidate target genes, 35 of which were preferentially lethal to cancer cells, most of which were not genomically altered. Chemotherapies and targeted agents with strong tumor-specific activities corroborated the siRNA profiling results and included drugs that targeted the mitotic spindle, the proteasome, and G₂-M kinases WEE1 and CHK1 We also show the feasibility of ex vivo drug profiling for patients enrolled in a clinical trial.Conclusions: High-throughput phenotyping with siRNA and drug libraries using patient-derived tumor cells prioritizes mutated driver genes and identifies novel drug targets not revealed by genomic profiling. Functional profiling is a promising adjunct to DNA sequencing for precision oncology. Clin Cancer Res; 24(12); 2828-43. ©2018 AACR.

Senescence-associated secretory factors induced by cisplatin in melanoma cells promote non-senescent melanoma cell growth through activation of the ERK1/2-RSK1 pathway

Although targeted therapy and immunotherapy greatly improve the outcome of melanoma, drug resistance and low response rates still maintain the unsubstitutability of traditional chemotherapy. Cisplatin (CDDP) is widely used in different types of tumours with high response rates, but it generally has low efficiency in melanoma. The mechanisms underpinning the phenomena are not sufficiently understood. Here we demonstrated that various melanoma cell lines adopted senescence phenotype after CDDP treatment in contrast to the other types of tumour cells. CDDP treatment induced melanoma A375 cells into senescence through the sequential activation of the DNA damage response and the P53/P21 pathway. All the senescent melanoma cells induced by CDDP alone or the combination of CDDP and dacarbazine developed robust senescence-associated secretory phenotype (SASP), that is, the secretion of multiple cytokines. IL-1α was an early component and an upstream regulator of SASP. Similarly, CDDP either alone or combined with dacarbazine could induce melanoma cell senescence and SASP in either A375 or B16F10 melanoma xenograft mice. The supernatant of senescent A375 cells promoted the growth of normal non-senescent A375 cells and enhanced their expression and secretion of IL-8 through the activation of the ERK1/2-RSK1 pathway. The transplantation of non-senescent and senescent A375 cells together into nude mice showed accelerated tumour growth compared with transplanting non-senescent cells alone; no tumours developed when transplanting senescent cells alone. Following CDDP administration in A375-bearing mice, the intratumour injection of neutralisation antibodies targeting the SASP factors IL-1α or IL-8 evidently delayed tumour growth. The results suggest that the CDDP-induced senescent melanoma cells promote non-senescent cells proliferation through the activation of ERK1/2-RSK1 pathway by the SASP factors. Cell senescence and concomitant SASP may be the particular mechanisms for melanoma to resist chemotherapeutics.

Metabolic pathways regulated by TAp73 in response to oxidative stress

Reactive oxygen species are involved in both physiological and pathological processes including neurodegeneration and cancer. Therefore, cells have developed scavenging mechanisms to maintain redox homeostasis under control. Tumor suppressor genes play a critical role in the regulation of antioxidant genes. Here, we investigated whether the tumor suppressor gene TAp73 is involved in the regulation of metabolic adaptations triggered in response to oxidative stress. H₂O₂ treatment resulted in numerous biochemical changes in both control and TAp73 knockout (TAp73−/−) mouse embryonic fibroblasts, however the extent of these changes was more pronounced in TAp73−/− cells when compared to control cells. In particular, loss of TAp73 led to alterations in glucose, nucleotide and amino acid metabolism. In addition, H₂O₂ treatment resulted in increased pentose phosphate pathway (PPP) activity in null mouse embryonic fibroblasts. Overall, our results suggest that in the absence of TAp73, H₂O₂ treatment results in an enhanced oxidative environment, and at the same time in an increased pro-anabolic phenotype. In conclusion, the metabolic profile observed reinforces the role of TAp73 as tumor suppressor and indicates that TAp73 exerts this function, at least partially, by regulation of cellular metabolism.

Bioenergetics of acquired cisplatin resistant H1299 non-small cell lung cancer and P31 mesothelioma cells

Acquired cisplatin resistance is a common feature of tumours following cancer treatment with cisplatin and also of non-small cell lung cancer (H1299) and mesothelioma (P31) cell lines exposed to cisplatin. To elucidate the cellular basis of acquired cisplatin resistance, a comprehensive bioenergetic analysis was undertaken. We demonstrate that cellular oxygen consumption was significantly decreased in cisplatin resistant cells and that the reduction was primarily due to reduced mitochondrial activity as a result of reduced mitochondrial abundance. The differential mitochondrial abundance was supported by data showing reduced sirtuin 1 (SIRT1), peroxisome-proliferator activator receptor-γ co-activator 1-alpha (PGC1α), sirtuin 3 (SIRT3) and mitochondrial transcription factor A (TFAM) protein expression in resistant cells. Consistent with these data we observed increased reactive oxygen species (ROS) production and increased hypoxia inducible factor 1-alpha (HIF1α) stabilization in cisplatin resistant cells when compared to cisplatin sensitive controls. We also observed an increase in AMP kinase subunit α2 (AMPKα2) transcripts and protein expression in resistant H1299 cells. mRNA expression was also reduced for cisplatin resistant H1299 cells in these genes, however the pattern was not consistent in resistant P31 cells. There was very little change in DNA methylation of these genes, suggesting that the cells are not stably reprogrammed epigenetically. Taken together, our data demonstrate reduced oxidative metabolism, reduced mitochondrial abundance, potential for increased glycolytic flux and increased ROS production in acquired cisplatin resistant cells. This suggests that the metabolic changes are a result of reduced SIRT3 expression and increased HIF-1α stabilization.