Up-regulation of peroxiredoxin 1 in lung cancer and its implication as a prognostic and therapeutic target

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.

CHI3L1 as a Prognostic Biomarker and Therapeutic Target in Glioma

The role of Chitinase-3-like protein 1 (CHI3L1) in tumor progression has been gradually clarified in different kinds of solid tumors. Hence, we aim to elucidate its prognostic value for glioma. In this study, we analyzed RNA sequencing data combined with corresponding clinical information obtained from The Cancer Genome Atlas (TCGA) and the Chinese Glioma Genome Atlas (CGGA) databases. Differentially expressed genes (DEGs) were acquired based on CHI3L1 expression profiles and were used for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Cox regression, least absolute shrinkage and selection operator (LASSO) regression methods, along with a nomogram, were employed to establish a predictive model. Compared with the corresponding non-tumor tissues, CHI3L1 expression was significantly upregulated in various types of solid tumors, correlating with poor clinical outcomes including glioma. GO analysis identified oxidative stress-related genes (ORGs) that were differentially expressed and modulated by CHI3L1, with 11 genes subsequently identified as potential predictors, using Univariate-Cox regression and LASSO regression. In addition, an index of oxidative stress-related genes (ORGI) was established, demonstrating its prognostic value in conjunction with CHI3L1 expression. The aberrant expression of CHI3L1 was proved in glioma patients through immunohistochemistry (IHC). Meanwhile, the knockdown of CHI3L1 inhibited glioma growth in vitro, and real-time Quantitative PCR (qPCR) confirmed decreased ORG expression upon CHI3L1 knockdown, suggesting the potential prognostic value of CHI3L1 as a therapeutic target for glioma.

Identification of a necroptosis-related gene signature for making clinical predictions of the survival of patients with lung adenocarcinoma

Background

Lung adenocarcinoma (LUAD) is a major pathological subtype of malignant lung cancer with a poor prognosis. Necroptosis is a caspase-independent programmed cell death mode that plays a pivotal role in cancer oncogenesis and metastasis. Here, we explore the prognostic values of different necroptosis-related genes (NRGs) in LUAD.

Methods

mRNA expression data and related clinical information for LUAD samples were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus databases. NRGs were identified using the GeneCards database. Least absolute shrinkage and selection operator Cox regression and multivariate Cox analysis were used to construct a prognostic risk model. Time-dependent receiver-operating characteristic curves and a nomogram were constructed to validate the predictive values of the prognostic signatures. A necroptosis-related protein-protein interaction network was visualised using the STRING database and Cytoscape software. Functional analyses, including Gene Ontology, Kyoto Encyclopaedia of Genes and Genomes pathway enrichment, gene set enrichment, and gene set variation analyses, were conducted to explore the underlying molecular mechanisms. Finally, the mRNA expression of the prognostic signatures in LUAD cell lines was assessed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis.

Results

A prognostic model was established for eight NRGs (CALM1, DDX17, FPR1, OGT, PGLYRP1, PRDX1, TUFM, and CPSF3) based on TCGA-cohort data and validated with the GSE68465 cohort. Patients with low-risk scores had better survival outcomes than those with high-risk scores (p = 0.00013). The nomogram was used to predict the prognosis of patients with LUAD. The prediction curves for 1-, 3-, and 5-year OS showed good predictive performance and the accuracy of the nomograms increased over time. RT-qPCR results demonstrated that these eight genes, especially CALM1, PRDX1, and PGLYRP1, were differentially expressed in LUAD cells.

Conclusion

We constructed a reliable eight-NRG signature that provides new insights for guiding clinical practice in the prognosis and treatment of LUAD.

Dual role of PRDX1 in redox-regulation and tumorigenesis: Past and future

Tumour cells often display an active metabolic profile, leading to the intracellular accumulation of reactive oxygen species. As a member of the peroxidase family, peroxiredoxin 1 (PRDX1) functions generally in protecting against cell damage caused by H2O2. Additionally, PRDX1 plays a role as a molecular chaperone in various malignant tumours, exhibiting either tumour-promoting or tumour-suppressing effects. Currently, PRDX1-targeting drugs have demonstrated in vitro anticancer effects, indicating the potential of PRDX1 as a molecular target. Here we discussed the diverse functions of PRDX1 in tumour biology and provided a comprehensive analysis of the therapeutic potential of targeting PRDX1 signalling across various types of cancer.

CircZNF215 promotes tumor growth and metastasis through inactivation of the PTEN/AKT pathway in intrahepatic cholangiocarcinoma

BACKGROUND

Increasing evidence shows that circular RNAs (circRNAs), a novel class of noncoding RNAs, play a crucial role in the development of cancers, including intrahepatic cholangiocarcinoma (iCCA). Nevertheless, their functions and exact mechanisms in iCCA progression and metastasis are still unclear. Ipatasertib is a highly selective inhibitor of AKT that inhibits tumor growth by blocking the PI3K/AKT pathway. In addition, phosphatase and tensin homolog (PTEN) can also inhibit the activation of the PI3K/AKT pathway, but it is not clear whether the cZNF215-PRDX-PTEN axis plays a role in the antitumor activity of ipatasertib.

METHODS

We identified a new circRNA (circZNF215, termed cZNF215) through high-throughput circRNA sequencing (circRNA-seq). In addition, RT‒qPCR, immunoblot assay, RNA pull-down assay, RNA immunoprecipitation (RIP) assay, and fluorescence in situ hybridization assay (FISH) were used to investigate the interaction of cZNF215 with peroxiredoxin 1 (PRDX1). Coimmunoprecipitation (Co-IP) assays and duolink in situ proximity ligation assays (PLAs) were conducted to analyze the effects of cZNF215 on the interaction between PRDX1 and PTEN. Finally, we tested the potential effects of cZNF215 on the antitumor activity of ipatasertib with in vivo experiments.

RESULTS

We found that cZNF215 expression was obviously upregulated in iCCA tissues with postoperative metastases and was correlated with iCCA metastasis and poor outcome in patients with iCCA. We further revealed that overexpression of cZNF215 promoted iCCA cell growth and metastasis in vitro and in vivo, while cZNF215 knockdown had the opposite effect. Mechanistic studies suggested that cZNF215 competitively interacted with PRDX1, which blocked the association between PRDX1 and PTEN, subsequently leading to oxidation-induced inactivation of the PTEN/AKT pathway and finally contributing to iCCA progression and metastasis. Additionally, we also revealed that silencing cZNF215 in iCCA cells had the potential to enhance the antitumor effect of ipatasertib.

CONCLUSIONS

Our study demonstrates that cZNF215 facilitates iCCA progression and metastasis by regulating the PTEN/AKT pathway and may serve as a novel prognostic predictor in patients with iCCA.

The immunohistochemical detection of peroxiredoxin 1 and 2 in canine spontaneous vascular endothelial tumors

Peroxiredoxin (PRDX) is an antioxidant enzyme family with six isoforms (PRDX1-6). The main function of PRDXs is to decrease cellular oxidative stress by reducing reactive oxygen species, such as hydrogen peroxide, to H2O. Recently, it has been reported that PRDXs are overexpressed in various malignant tumors in humans, and are involved in the development, proliferation, and metastasis of tumors. However, studies on the expression of PRDXs in tumors of animals are limited. Therefore, in the present study, we immunohistochemically investigated the expression of PRDX1 and 2 in spontaneous canine hemangiosarcoma (HSA) and hemangioma (HA), as well as in selected normal tissue and granulation tissue, including newly formed blood vessels. Although there were some exceptions, immunolocalization of PRDX1 and 2 in normal canine tissues was similar to those in humans, rats, or mice. In granulation tissue, angiogenic endothelial cells were strongly positive for PRDX1 and 2, whereas quiescent endothelial cells in mature vessels were negative. Both PRDX1 and 2 were significantly highly expressed in HSA compared to HA. There were no significant differences in the expression of PRDX1 and 2 among the subtypes and primary sites of HSA. These results suggest that PRDX1 and 2 may be involved in the angiogenic phenotypes of endothelial cells in granulation tissue as well as in the behavior in the malignant endothelial tumors.

Near-Infrared Fluorescence Tumor-Targeted Imaging in Lung Cancer: A Systematic Review

Lung cancer is the most common cancer type worldwide, with non-small cell lung cancer (NSCLC) being the most common subtype. Non-disseminated NSCLC is mainly treated with surgical resection. The intraoperative detection of lung cancer can be challenging, since small and deeply located pulmonary nodules can be invisible under white light. Due to the increasing use of minimally invasive surgical techniques, tactile information is often reduced. Therefore, several intraoperative imaging techniques have been tested to localize pulmonary nodules, of which near-infrared (NIR) fluorescence is an emerging modality. In this systematic review, the available literature on fluorescence imaging of lung cancers is presented, which shows that NIR fluorescence-guided lung surgery has the potential to identify the tumor during surgery, detect additional lesions and prevent tumor-positive resection margins.

Epithelial-mesenchymal transition and H2O2 signaling - a driver of disease progression and a vulnerability in cancers

Mutation-selective drugs constitute a great advancement in personalized anticancer treatment with increased quality of life and overall survival in cancers. However, the high adaptability and evasiveness of cancers can lead to disease progression and the development of drug resistance, which cause recurrence and metastasis. A common characteristic in advanced neoplastic cancers is the epithelial-mesenchymal transition (EMT) which is strongly interconnected with H₂O₂ signaling, increased motility and invasiveness. H₂O₂ relays its signal through the installation of oxidative posttranslational modifications on cysteines. The increased H₂O₂ levels that are associated with an EMT confer a heightened sensitivity towards the induction of ferroptosis as a recently discovered vulnerability.

Membrane Bound Peroxiredoxin-1 Serves as a Biomarker for In Vivo Detection of Sessile Serrated Adenomas

Aim: Sessile serrated adenomas (SSAs) are premalignant lesions driven by the BRAF^V600E mutation to give rise to colorectal cancers (CRCs). They are often missed during white light colonoscopy because of their subtle appearance. Previously, a fluorescently labeled 7mer peptide KCCFPAQ was shown to detect SSAs in vivo. We aim to identify the target of this peptide. Results: Peroxiredoxin-1 (Prdx1) was identified as the binding partner of the peptide ligand. In vitro binding assays and immunofluorescence staining of human colon specimens ex vivo supported this result. Prdx1 was overexpressed on the membrane of cells with the BRAF^V600E mutation, and this effect was dependent on oxidative stress. RKO cells harboring the BRAF^V600E mutation and human SSA specimens showed higher oxidative stress as well as elevated levels of Prdx1 on the cell membrane. Innovation and Conclusion: These results suggest that Prdx1 is overexpressed on the cell surface in the presence of oxidative stress and can serve as an imaging biomarker for in vivo detection of SSAs. Antioxid. Redox Signal. 36, 39-56.

Comprehensive analysis of the expression levels and prognostic values of PRDX family genes in glioma

Gliomas are a histologically and molecularly heterogeneous group of neoplasms accounting for 80% of malignant primary brain tumors. Growing evidence suggests that production of reactive oxygen species (ROS) is linked to glioma pathogenesis, although it is still unclear whether it is a cause or an effect of this process. Peroxiredoxins (PRDXs), a family of six antioxidant proteins, may promote or inhibit carcinogenesis, depending on the tumor type and stage. The current knowledge on their expression, regulation and functions in glioma is scarce. In this study, a comprehensive analysis of PRDXs expression in distinct glioma subtypes and non-tumor brain tissues was conducted using gene expression data from The Cancer Genome Atlas (TCGA), REpository for Molecular BRAin NeoplasiaDaTa (REMBRANDT), The Chinese Glioma Atlas (CGGA) and Gene Expression Omnibus (GEO) datasets. The association between gene expression and patient survival was investigated. DNA methylation, mutations, copy number alterations of deregulated PRDXs as well as the correlation between gene expression and tumor-infiltrating immune cells were assessed. The analysis revealed overexpression of PRDX1, PRDX4, and PRDX6 in most histological glioma types compared to the non-tumor tissues, while PRDX2, PRDX3 and PRDX5 expression remained unaltered. The expression of PRDX4 and PRDX6 was higher in mesenchymal than proneural and classical glioma subtypes. Moreover, lower expression of PRDX1, PRDX4 and PRDX6 was observed in tumors with a glioma CpG island methylator phenotype (G-CIMP) compared to non-G-CIMP tumors, as well as in isocitrate dehydrogenase (IDH) mutant and 1p/19q co-deleted gliomas compared to the wild-type counterparts. High expression of PRDX1, PRDX4 or PRDX6 correlated with poor survival of glioma patients. PRDX1 and PRDX6 displayed a positive correlation with different immune cell population in low grade gliomas and, to a lesser extent, in glioblastoma. PRDX1 expression exhibited negative correlation with DNA methylation. These results indicate that high expression of PRDX1, PRDX4 and PRDX6 is associated with poor outcome in gliomas.

Prdx1 Interacts with ASK1 upon Exposure to H2O2 and Independently of a Scaffolding Protein

Hydrogen peroxide (H₂O₂) is a key redox signaling molecule that selectively oxidizes cysteines on proteins. It can accomplish this even in the presence of highly efficient and abundant H₂O₂ scavengers, peroxiredoxins (Prdxs), as it is the Prdxs themselves that transfer oxidative equivalents to specific protein thiols on target proteins via their redox-relay functionality. The first evidence of a mammalian cytosolic Prdx-mediated redox-relay—Prdx1 with the kinase ASK1—was presented a decade ago based on the outcome of a co-immunoprecipitation experiment. A second such redox-relay—Prdx2:STAT3—soon followed, for which further studies provided insights into its specificity, organization, and mechanism. The Prdx1:ASK1 redox-relay, however, has never undergone such a characterization. Here, we combine cellular and in vitro protein–protein interaction methods to investigate the Prdx1:ASK1 interaction more thoroughly. We show that, contrary to the Prdx2:STAT3 redox-relay, Prdx1 interacts with ASK1 at elevated H₂O₂ concentrations, and that this interaction can happen independently of a scaffolding protein. We also provide evidence of a Prdx2:ASK1 interaction, and demonstrate that it requires a facilitator that, however, is not annexin A2. Our results reveal that cytosolic Prdx redox-relays can be organized in different ways and yet again highlight the differentiated roles of Prdx1 and Prdx2.

PRDX2 Promotes the Proliferation and Metastasis of Non-Small Cell Lung Cancer In Vitro and In Vivo

Purpose

Previous studies have reported that the levels of PRDX2 were correlated with tumorigenicity, recurrence, and prognosis of patients with different cancers. We investigated the association between PRDX2 levels and the prognosis of lung cancer patients. We also measured PRDX2 expression of non-small cell lung cancer (NSCLC) cells and examined its roles in the proliferation and migration in vitro and in vivo.

Methods

We used the Kaplan–Meier plotter to analyze the survival of different levels of PRDX2 in lung cancer patients. The expression of PRDX2 in normal bronchial epithelial cell line and NSCLC cell lines was measured by qRT-PCR and western blot assays. Biological functions of NSCLC cells were detected by CCK8 and Transwell assays. We constructed tumor growth model using subcutaneously injection of nude mice and metastasis model by tail vein injection in vivo. The protein levels of proliferation related markers were measured by immunohistochemistry assay. Immunofluorescence method was used to detected EMT-related proteins.

Results

The high levels of PRDX2 were associated with bad prognosis in lung cancer patients, especially in patients with adenocarcinoma. The expression of PRDX2 in NSCLC cell lines was higher than normal bronchial epithelial cells. Knockdown of PRDX2 inhibited the proliferation, migration, and invasion in A549 cells, while overexpression of PRDX2 promoted the malignancy in NCI-H1299 cells in vitro. Silencing PRDX2 restrained tumor growth and repressed lung metastasis by EMT in vivo.

Conclusion

Our data indicates that PRDX2 functions as a protumor regulator and is involved in tumorigenesis and tumor progression of lung cancer.

Virtual screening of mutations in antioxidant genes and its putative association with HNSCC: An in silico approach

Abnormalities in the antioxidant pathway are usually associated with inflammatory conditions, followed by tissue damage. Cancer is one such disease where there is a build-up of reactive oxygen species leading to pathological consequences. The present study aims to identify the alteration in genes and proteins associated with the common antioxidant pathways among patients with head and neck squamous cell carcinoma (HNSCC). The study design follows a retrospective approach and employs computational tools to analyse the possible role of genes involved in the anti-oxidation pathways in patients with HNSCC. The TCGA PanCancer Atlas dataset was used for the analysis. The Oncoprint data were analysed further to obtain information on the type of gene alterations encountered in the HNSCC cases. Gene amplification and deletions were commonly observed in genes of the thiol reductase pathway, whereas substitutions leading to missense, frameshifts were found in the other pathways assessed. Gene encoding ceruloplasmin was found to harbor nucleotide variations in about 10 % of the patients with OSCC. An exhaustive knowledge of the molecular genetic mechanisms underlying the pathways identified can open new avenues in selecting candidate genes which can be used as therapeutic targets against HNSCC. The present work identifies and nominates crucial genes from the antioxidant system for further in vitro experiments.

Metabolic reprogramming and disease progression in cancer patients

Genomics has contributed to the treatment of a fraction of cancer patients. However, there is a need to profile the proteins that define the phenotype of cancer and its pathogenesis. The reprogramming of metabolism is a major trait of the cancer phenotype with great potential for prognosis and targeted therapy. This review overviews the major changes reported in the steady-state levels of proteins of metabolism in primary carcinomas, paying attention to those enzymes that correlate with patients' survival. The upregulation of enzymes of glycolysis, pentose phosphate pathway, lipogenesis, glutaminolysis and the antioxidant defense is concurrent with the downregulation of mitochondrial proteins involved in oxidative phosphorylation, emphasizing the potential of mitochondrial metabolism as a promising therapeutic target in cancer. We stress that high-throughput quantitative expression profiling of differentially expressed proteins in large cohorts of carcinomas paired with normal tissues will accelerate translation of metabolism to a successful personalized medicine in cancer.

Evaluation of a novel monoclonal antibody mAb109 by immuno-PET/fluorescent imaging for noninvasive lung adenocarcinoma diagnosis

Monoclonal antibodies are believed to be magic bullets and hold great potential for lots of biological process. About 100 μg of mAb109 was expressed in 5 × 10⁶ cells after 10 days' immunization. ⁶⁴Cu-NOTA-mAb109 was synthesized with the specific activity of 0.74 MBq/μg and high in vitro stability. The binding affinity of ⁶⁴Cu-NOTA-mAb109 in A549 cells was determined to be 29.64 nM. ⁶⁴Cu-NOTA-mAb109 displayed prominent tumor accumulation from 2 h to 60 h p.i. (9.34 ± 0.67 %ID/g). NIRF imaging of Cy5.5-mAb109 showed high accumulation till 9 days p.i., while tumors nearly can not be observed in negative groups, which was confirmed by autoradiography. Immunohistological study confirmed that mAb109 had strong and specific capacity to bind lung adenocarcinoma (concentration to 58 nM). Our study demonstrated mAb109 was a new platform for the development of novel agent for lung adenocarcinoma noninvasive imaging. The resulted ⁶⁴Cu-NOTA-mAb109/Cy5.5-mAb109 show favorable imaging properties/specificity for A549 tumor and high sensitivity to human lung adenocarcinoma tissues.

Peroxiredoxins and Beyond; Redox Systems Regulating Lung Physiology and Disease

Significance: The lung is a unique organ, as it is constantly exposed to air, and thus it requires a robust antioxidant defense system to prevent the potential damage from exposure to an array of environmental insults, including oxidants. The peroxiredoxin (PRDX) family plays an important role in scavenging peroxides and is critical to the cellular antioxidant defense system. Recent Advances: Exciting discoveries have been made to highlight the key features of PRDXs that regulate the redox tone. PRDXs do not act in isolation as they require the thioredoxin/thioredoxin reductase/NADPH, sulfiredoxin (SRXN1) redox system, and in some cases glutaredoxin/glutathione, for their reduction. Furthermore, the chaperone function of PRDXs, controlled by the oxidation state, demonstrates the versatility in redox regulation and control of cellular biology exerted by this class of proteins. Critical Issues: Despite the long-known observations that redox perturbations accompany a number of pulmonary diseases, surprisingly little is known about the role of PRDXs in the etiology of these diseases. In this perspective, we review the studies that have been conducted thus far to address the roles of PRDXs in lung disease, or experimental models used to study these diseases. Intriguing findings, such as the secretion of PRDXs and the formation of autoantibodies, raise a number of questions about the pathways that regulate secretion, redox status, and immune response to PRDXs. Future Directions: Further understanding of the mechanisms by which individual PRDXs control lung inflammation, injury, repair, chronic remodeling, and cancer, and the importance of PRDX oxidation state, configuration, and client proteins that govern these processes is needed.

Comprehensive analysis of peroxiredoxins expression profiles and prognostic values in breast cancer

BACKGROUND

The peroxiredoxins (PRDXs) gene family has been demonstrated to participate in carcinogenesis and development of numerous cancers and the prognostic values in several cancers have been evaluated already. Purpose of our research is to explore the expression profiles and prognostic values of PRDXs in breast cancer (BrCa).

METHODS

The transcriptional levels of PDRX family members in primary BrCa tissues and their association with intrinsic subclasses were analyzed using UALCAN database. Then, the genetic alterations of PDRXs were examined by cBioPortal database. Moreover, the prognostic values of PRDXs in BrCa patients were investigated via the Kaplan-Meier plotter.

RESULTS

The transcriptional levels of most PRDXs family members in BrCa tissues were significantly elevated compared with normal breast tissues. Meanwhile, dysregulated PRDXs expression was associated with intrinsic subclasses of BrCa. Besides, copy number alterations (CNA) of PRDXs positively regulated their mRNA expressions. Furthermore, high mRNA expression of PRDX4/6 was significantly associated with poor overall survival (OS) in BrCa patients, while high mRNA expression of PRDX3 was notably related to favorable OS. Simultaneously, high mRNA expression of PRDX1/2/4/5/6 was significantly associated with shorter relapse-free survival (RFS) in BrCa patients, while high mRNA expression of PRDX3 was notably related to favorable RFS. In addition, the prognostic value of PRDXs in the different clinicopathological features based on intrinsic subclasses and chemotherapeutic treatment of BrCa patients was further assessed in the KM plotter database.

CONCLUSION

Our findings systematically elucidate the expression profiles and distinct prognostic values of PRDXs in BrCa, which might provide novel therapeutic targets and potential prognostic biomarkers for BrCa patients.

Leprosy drug clofazimine activates peroxisome proliferator-activated receptor-γ and synergizes with imatinib to inhibit chronic myeloid leukemia cells

Leukemia stem cells contribute to drug-resistance and relapse in chronic myeloid leukemia (CML) and BCR-ABL1 inhibitor monotherapy fails to eliminate these cells, thereby necessitating alternate therapeutic strategies for patients CML. The peroxisome proliferator-activated receptor-γ (PPARγ) agonist pioglitazone downregulates signal transducer and activator of transcription 5 (STAT5) and in combination with imatinib induces complete molecular response in imatinib-refractory patients by eroding leukemia stem cells. Thiazolidinediones such as pioglitazone are, however, associated with severe side effects. To identify alternate therapeutic strategies for CML we screened Food and Drug Administration-approved drugs in K562 cells and identified the leprosy drug clofazimine as an inhibitor of viability of these cells. Here we show that clofazimine induced apoptosis of blood mononuclear cells derived from patients with CML, with a particularly robust effect in imatinib-resistant cells. Clofazimine also induced apoptosis of CD34⁺38^- progenitors and quiescent CD34⁺ cells from CML patients but not of hematopoietic progenitor cells from healthy donors. Mechanistic evaluation revealed that clofazimine, via physical interaction with PPARγ, induced nuclear factor kB-p65 proteasomal degradation, which led to sequential myeloblastoma oncoprotein and peroxiredoxin 1 downregulation and concomitant induction of reactive oxygen species-mediated apoptosis. Clofazimine also suppressed STAT5 expression and consequently downregulated stem cell maintenance factors hypoxia-inducible factor-1α and -2α and Cbp/P300 interacting transactivator with Glu/Asp-rich carboxy-terminal domain 2 (CITED2). Combining imatinib with clofazimine caused a far superior synergy than that with pioglitazone, with clofazimine reducing the half maximal inhibitory concentration (IC₅₀) of imatinib by >4 logs and remarkably eroding quiescent CD34⁺ cells. In a K562 xenograft study clofazimine and imatinib co-treatment showed more robust efficacy than the individual treatments. We propose clinical evaluation of clofazimine in imatinib-refractory CML.

The redox regulator sulfiredoxin forms a complex with thioredoxin domain-containing 5 protein in response to ER stress in lung cancer cells

Sulfiredoxin (Srx) reduces hyperoxidized 2-cysteine-containing peroxiredoxins (Prxs) and protects cells against oxidative stress. Previous studies have shown that Srx is highly expressed in primary specimens of lung cancer patients and plays a pivotal role in lung tumorigenesis and cancer progression. However, the oncogenic mechanisms of Srx in cancer are incompletely understood. In this study, we found that Srx knockdown sensitizes lung cancer cells to endoplasmic reticulum (ER) stress-induced cell death. Through MS analysis, we determined that Srx forms a complex with the ER-resident protein thioredoxin domain-containing protein 5 (TXNDC5). Using reciprocal co-immunoprecipitation, immunofluorescence imaging, subcellular fractionation, and domain-mapping assays with site-specific mutagenesis and purified recombinant proteins, we further characterized the Srx-TXNDC5 interaction. In response to ER stress but not to oxidative stress, Srx exhibits an increased association with TXNDC5, facilitating the retention of Srx in the ER. Of note, TXNDC5 knockdown in lung cancer cells inhibited cell proliferation and repressed anchorage-independent colony formation and migration, but increased cell invasion and activation of mitogen-activated protein kinases. Using immunohistochemical staining, we demonstrate that TXNDC5 is highly expressed in patient-derived lung cancer specimens. Bioinformatics analysis of publicly available data sets revealed that those with high Srx levels have significantly shorter survival and that those with high TXNDC5 levels have longer survival. We conclude that the cellular levels of Srx and TXNDC5 may be useful as biomarkers to predict the survival of individuals with lung cancer.

Neuroprotective activity of leukemia inhibitory factor is relayed through myeloid zinc finger-1 in a rat model of stroke

The aim of this study was to determine whether leukemia inhibitory factor (LIF) exerts its neuroprotective effects through signal transduction of the transcription factor myeloid zinc finger-1 (MZF-1). According to the hypothesis of this study, MZF-1 mediates LIF-induced neuroprotective signaling during ELVO through increased expression and transcriptional activity. To determine the in vivo role of MZF-1 in LIF-induced neuroprotection, we used Genomatix software was used to MZF-1 sites in the promoter region of the rat superoxide dismutase 3 (SOD3) gene. Stroke was induced via middle cerebral artery occlusion, and animals were administered PBS or 125 μg/kg LIF at 6, 24, and 48 h after the injury. MZF-1 binding activity was measured using electrophoretic mobility shift assay (EMSA) and its expression/localization were determined using western blot and immunohistochemical analysis. To determine whether MZF-1 relays LIF-induced neuroprotection in vitro, primary cultured neurons were subjected to oxygen-glucose deprivation (OGD) after treatment with PBS or LIF. MZF-1 expression was measured in vitro using real time PCR and immunohistochemical staining. Transfection with siRNA was used to determine whether LIF protected cultured neurons against OGD after silencing MZF-1 expression. Four MZF-1 binding sites were identified by Genomatix, and EMSA confirmed in vivo binding activity in brain after MCAO. LIF significantly increased MZF-1 protein levels compared to PBS treatment at 72 h post-MCAO. In vivo nuclear localization of MZF-1 as well as co-localization of SOD3 and MZF-1 was observed in the cortical neurons of LIF-treated rats. Primary cultured neurons treated with LIF had significantly higher levels of MZF-1 mRNA and protein after LIF treatment compared to neurons treated with PBS. Finally, knockdown MZF-1 using siRNA counteracted the neuroprotective effects of LIF in vitro. These data demonstrate that LIF-mediated neuroprotection is dependent upon MZF-1 activity. Furthermore, these findings identify a novel neuroprotective pathway that employs MZF-1, a transcription factor associated with hematopoietic gene expression.

Prognostic roles of mRNA expression of peroxiredoxins in lung cancer

Background

The peroxiredoxin (PRDX) protein family is involved in cancer cell invasion and metastasis, but its prognostic value in lung cancer remain elusive.

Methods

In this report, we accessed the overall survival (OS) of each individual PRDX mRNA expression through the Kaplan–Meier plotter (KM plotter) database, in which updated gene expression data and survival information include a total of 1,926 lung cancer patients.

Results

Our results indicated that PRDX1 and PRDX2 mRNA expressions were associated with improved OS in all lung cancer patients especially in lung adenocarcinoma patients, whereas PRDX5 and PRDX6 mRNA expressions were associated with poor OS in all lung cancer patients. In addition, the prognostic value of PRDXs in the different clinicopathological features according to smoking status, pathological grades, clinical stages, and chemotherapeutic treatment of lung cancer patients was further assessed in the KM plotter database by the multivariate cox regression analysis.

Conclusion

Our finding will elucidate the prognostic role of PRDXs in lung cancer and might promote development of PRDX-targeted inhibitors for the treatment of lung cancer.

The prognostic values of the peroxiredoxins family in ovarian cancer

Purpose: Peroxiredoxins (PRDXs) are a family of antioxidant enzymes with six identified mammalian isoforms (PRDX1–6). PRDX expression is up-regulated in various types of solid tumors; however, individual PRDX expression, and its impact on prognostic value in ovarian cancer patients, remains unclear.

Methods: PRDXs family protein expression profiles in normal ovarian tissues and ovarian cancer tissues were examined using the Human Protein Atlas database. Then, the prognostic roles of PRDX family members in several sets of clinical data (histology, pathological grades, clinical stages, and applied chemotherapy) in ovarian cancer patients were investigated using the Kaplan–Meier plotter.

Results: PRDXs family protein expression in ovarian cancer tissues was elevated compared with normal ovarian tissues. Meanwhile, elevated expression of PRDX3, PRDX5, and PRDX6 mRNAs showed poorer overall survival (OS); PRDX5 and PRDX6 also predicted poor progression-free survival (PFS) for ovarian cancer patients. Furthermore, PRDX3 played significant prognostic roles, particularly in poor differentiation and late-stage serous ovarian cancer patients. Additionally, PRDX5 predicted a lower PFS in all ovarian cancer patients treated with Platin, Taxol, and Taxol+Platin chemotherapy. PRDX3 and PRDX6 also showed poor PFS in patients treated with Platin chemotherapy. Furthermore, PRDX3 and PRDX5 indicated lower OS in patients treated with these three chemotherapeutic agents. PRDX6 predicted a poorer OS in patients treated with Taxol and Taxol+Platin chemotherapy.

Conclusion: These results suggest that there are distinct prognostic values of PRDX family members in patients with ovarian cancer, and that the expression of PRDX3, PRDX5, and PRDX6 mRNAs are a useful prognostic indicator in the effect of chemotherapy in ovarian cancer patients.

High Expression of Peroxiredoxin 1 Is Associated with Epithelial-Mesenchymal Transition Marker and Poor Prognosis in Gastric Cancer

Background

Recent studies show that peroxiredoxin 1 (Prdx1) contributes to the progression and poor prognosis of carcinoma through multiple mechanisms. However, there is little information on its expression and prognostic value in gastric cancer. This study investigated the expression of Prdx1 in gastric cancer, along with evaluating its clinical-pathological and prognostic importance.

Material/Methods

A total of 189 pairs of gastric cancer and paracarcinomatous tissues were assessed for Prdx1 expression and its association with clinical characteristics. The molecular mechanism was further investigated through in vitro experimentation.

Results

The mRNA and protein levels of Prdx1 in the GC tissues were higher than in the peri-tumor tissues. We also found that high Prdx1 expression was positively correlated with the lymph node invasion and poor prognosis. It also served as an autonomous prognostic factor for patients with gastric cancer. Moreover, Prdx1 regulates the invasion and metastasis of GC cell lines through inhibiting E-Ca expression.

Conclusions

Prdx1 can promote epithelial-mesenchymal transition and gastric cancer progression. Therefore, it might be a therapeutic target and prognostic indicator for gastric cancer patients.

Peroxiredoxin 1, restraining cell migration and invasion, is involved in hepatocellular carcinoma recurrence

OBJECTIVE

Hepatocellular carcinoma (HCC) is a high-burden disease. Peroxiredoxin 1 (PRDX1) is a member of the peroxiredoxin family of antioxidant enzymes. The aim of this study was to assess the value of PRDX1 for predicting HCC recurrence after curative resection and to explore the role of PRDX1 in HCC cell migration and invasion.

METHODS

Data of patients with HCC who had undergone complete resection between 2002 and 2006 were collected. Immunohistochemical detection of PRDX1 in HCC tissue and adjacent non-cancerous tissue was conducted. Kaplan-Meier survival estimate and log-rank test were used to assess the relationship between PRDX1 expression and prognostic significance. HCC cell migration and invasion together with the interaction between PRDX1 and ubiquitin C-terminal hydrolase 37 (UCH37) were studied in vitro.

RESULTS

PRDX1 was expressed at lower levels in HCC tissues than in adjacent non-cancerous tissues, and PRDX1 was found to be an independent risk factor for disease-free survival and overall survival. PRDX1 restrained cell migration and invasion in vitro. PRDX1 was found to interact with UCH37 to affect HCC cell migration and invasion.

CONCLUSION

PRDX1 restrains cell migration and invasion in HCC cell lines and that may be involved in a UCH37-relevant pathway, suggesting that PRDX1 may be a new marker for HCC recurrence after surgery.

Peroxiredoxin Involvement in the Initiation and Progression of Human Cancer

SIGNIFICANCE

It has been proposed that cancer cells are heavily dependent on their antioxidant defenses for survival and growth. Peroxiredoxins are a family of abundant thiol-dependent peroxidases that break down hydrogen peroxide, and they have a central role in the maintenance and response of cells to alterations in redox homeostasis. As such, they are potential targets for disrupting tumor growth. Recent Advances: Genetic disruption of peroxiredoxin expression in mice leads to an increased incidence of neoplastic disease, consistent with a role for peroxiredoxins in protecting genomic integrity. In contrast, many human tumors display increased levels of peroxiredoxin expression, suggesting that strengthened antioxidant defenses provide a survival advantage for tumor progression. Peroxiredoxin inhibitors are being developed and explored as therapeutic agents in different cancer models.

CRITICAL ISSUES

It is important to complement peroxiredoxin knockout and expression studies with an improved understanding of the biological function of the peroxiredoxins. Although current results can be interpreted within the context that peroxiredoxins scavenge hydroperoxides, some peroxiredoxin family members appear to have more complex roles in regulating the response of cells to oxidative stress through protein interactions with constituents of other signaling pathways.

FUTURE DIRECTIONS

Further mechanistic information is required for understanding the role of oxidative stress in cancer, the function of peroxiredoxins in normal versus cancer cells, and for the design and testing of specific peroxiredoxin inhibitors that display selectivity to malignant cells. Antioxid. Redox Signal. 28, 591-608.

Selenium targets resistance biomarkers enhancing efficacy while reducing toxicity of anti-cancer drugs: preclinical and clinical development

Selenium (Se)-containing molecules exert antioxidant properties and modulate targets associated with tumor growth, metastasis, angiogenesis, and drug resistance. Prevention clinical trials with low-dose supplementation of different types of Se molecules have yielded conflicting results. Utilizing several xenograft models, we earlier reported that the enhanced antitumor activity of various chemotherapeutic agents by selenomethione and Se-methylselenocysteine in several human tumor xenografts is highly dose- and schedule-dependent. Further, Se pretreament offered selective protection of normal tissues from drug-induced toxicity, thereby allowing higher dosing than maximum tolerated doses. These enhanced therapeutic effects were associated with inhibition of hypoxia-inducible factor 1- and 2-alpha (HIF1α, HIF2α) protein, nuclear factor (erythyroid-derived 2)-like 2 (Nrf2) and pair-related homeobox-1 (Prx1) transcription factors, downregulation of oncogenic- and upregulation of tumor suppressor miRNAs. This review provides: 1) a brief update of clinical prevention trials with Se; 2) advances in the use of specific types, doses, and schedules of Se that selectively modulate antitumor activity and toxicity of anti-cancer drugs; 3) identification of targets selectively modulated by Se; 4) plasma and tumor tissue Se levels achieved after oral administration of Se in xenograft models and cancer patients; 5) development of a phase 1 clinical trial with escalating doses of orally administered selenomethionine in sequential combination with axitinib to patients with advanced clear cell renal cell carcinoma; and 6) clinical prospects for future therapeutic use of Se in combination with anticancer drugs.

Peroxiredoxin 1 promotes invasion and migration by regulating epithelial-to-mesenchymal transition during oral carcinogenesis

Tobacco smoking is the major risk factor for oral squamous cell carcinoma (OSCC). Previously, we found that nicotine up-regulates peroxiredoxin 1 (Prx1), an important antioxidant enzyme, and nuclear factor kappa B (NFκB) in OSCC cells. However, the molecular mechanism of Prx1 in oral carcinogenesis remains obscure. To improve our understanding of the functional role of Prx1 during the cascade of tobacco-associated oral carcinogenesis, we characterized Prx1, NFκB, and epithelial-to-mesenchymal transition (EMT) markers including E-cadherin, vimentin and Snail in 30 primary oral tumors (15 from smokers with OSCC and 15 from non-smokers with OSCC) and 10 normal oral mucosa specimens from healthy individuals. The expression levels of Prx1, nuclear NFκB, vimentin and Snail were higher in the tumors from smokers with OSCC than in those from non-smokers with OSCC or the healthy controls. The expression levels of E-cadherin showed an opposite trend. Prx1 silencing suppressed the nicotine-induced EMT, cell invasion and migration in SCC15 cells in vitro. Furthermore, Prx1 activated the NFκB pathway in SCC15 cells. Prx1 might therefore play an oncogenic role in tobacco-related OSCC and thus serve as a target for chemopreventive and therapeutic interventions.

Clair DK, Kyprianou N. Profiles of Radioresistance Mechanisms in Prostate Cancer

Radiation therapy (RT) is commonly used for the treatment of localized prostate cancer (PCa). However, cancer cells often develop resistance to radiation through unknown mechanisms and pose an intractable challenge. Radiation resistance is highly unpredictable, rendering the treatment less effective in many patients and frequently causing metastasis and cancer recurrence. Understanding the molecular events that cause radioresistance in PCa will enable us to develop adjuvant treatments for enhancing the efficacy of RT. Radioresistant PCa depends on the elevated DNA repair system and the intracellular levels of reactive oxygen species (ROS) to proliferate, self-renew, and scavenge anti-cancer regimens, whereas the elevated heat shock protein 90 (HSP90) and the epithelial-mesenchymal transition (EMT) enable radioresistant PCa cells to metastasize after exposure to radiation. The up-regulation of the DNA repairing system, ROS, HSP90, and EMT effectors has been studied extensively, but not targeted by adjuvant therapy of radioresistant PCa. Here, we emphasize the effects of ionizing radiation and the mechanisms driving the emergence of radioresistant PCa. We also address the markers of radioresistance, the gene signatures for the predictive response to radiotherapy, and novel therapeutic platforms for targeting radioresistant PCa. This review provides significant insights into enhancing the current knowledge and the understanding toward optimization of these markers for the treatment of radioresistant PCa.

Anti-tumor Effect of Rhaponticum uniflorum Ethyl Acetate Extract by Regulation of Peroxiredoxin1 and Epithelial-to-Mesenchymal Transition in Oral Cancer

Objective: To explore whether Rhaponticum uniflorum (R. uniflorum) had anti-tumor effects in oral cancer and investigate the molecular mechanisms involved in these anti-tumor effects.

Methods: Chemical compositions of R. uniflorum ethyl acetate (RUEA) extracts were detected by ultra-performance liquid chromatography-Q/time-of-flight mass spectrometry (UPLC-Q/TOF-MS), followed by pharmacology-based network prediction analysis. The effects of RUEA extracts on proliferation, apoptosis, migration, and invasion ability of human oral squamous cell carcinoma (OSCC) cell line SCC15 were evaluated by CCK8 assay, Annexin V- fluorescein isothiocyanate/propidium iodide staining, wound healing assay, and Matrigel invasion assay, respectively. The mRNA and protein expression of peroxiredoxin1 (Prx1), the epithelial-to-mesenchymal transition (EMT) marker E-cadherin, vimentin, and Snail were determined by quantitative real-time reverse transcription polymerase chain reaction and western blotting. A mouse xenograft model of SCC15 cells was established to further evaluate the effect of RUEA extracts in vivo. Immunohistochemical assessment of Ki67 and terminal deoxynucleotidyl transferase dUTP nick end labeling staining of apoptotic cells were performed on the tumor tissues to assess the effects of RUEA extracts on proliferation and apoptosis.

Results: Fourteen compounds were identified from RUEA extracts by UPLC-Q/TOF-MS. The pharmacology-based network prediction analysis showed that Prx1 could be a potential binder of RUEA extracts. In SCC15 cells, RUEA extracts inhibited cell viability, induced apoptosis, and suppressed cell invasion and migration in a concentration-dependent manner. After treatment with RUEA extracts, the mRNA and protein expression of E-cadherin increased, whereas those of Prx1, vimentin, and Snail decreased. RUEA extracts also affected the EMT program and suppressed cell invasion and migration in Prx1 knockdown SCC15 cells. In an OSCC mouse xenograft model, RUEA extracts (25 and 250 mg/kg) significantly inhibited the growth of tumors. Compared with the control group, Ki67 expression was reduced and apoptosis rates were elevated in the transplanted tumors treated with RUEA extracts. RUEA extracts increased the expression of E-cadherin and decreased the expression of Prx1, vimentin, and Snail in vivo.

Conclusion: RUEA extracts inhibited tumor growth and invasion by reducing Prx1 expression and suppressing the EMT process in OSCC. RUEA extracts may be a potential candidate for OSCC treatment.

Peroxiredoxin1, a novel regulator of pronephros development, influences retinoic acid and Wnt signaling by controlling ROS levels

Peroxiredoxin1 (Prdx1) is an antioxidant enzyme belonging to the peroxiredoxin family of proteins. Prdx1 catalyzes the reduction of H₂O₂ and alkyl hydroperoxide and plays an important role in different biological processes. Prdx1 also participates in various age-related diseases and cancers. In this study, we investigated the role of Prdx1 in pronephros development during embryogenesis. Prdx1 knockdown markedly inhibited proximal tubule formation in the pronephros and significantly increased the cellular levels of reactive oxygen species (ROS), which impaired primary cilia formation. Additionally, treatment with ROS (H₂O₂) severely disrupted proximal tubule formation, whereas Prdx1 overexpression reversed the ROS-mediated inhibition in proximal tubule formation. Epistatic analysis revealed that Prdx1 has a crucial role in retinoic acid and Wnt signaling pathways during pronephrogenesis. In conclusion, Prdx1 facilitates proximal tubule formation during pronephrogenesis by regulating ROS levels.

Pro-Apoptotic Effects of JDA-202, a Novel Natural Diterpenoid, on Esophageal Cancer Through Targeting Peroxiredoxin I

AIMS

Esophageal cancer (EC) is an aggressive malignancy and the most common solid tumor of gastrointestinal tract all over the world, with high incidence in Asia. The current study was designed to investigate the anticancer efficacy and mechanism that is involved in the action of a natural ent-kaurene diterpenoid, JDA-202, targeting EC.

RESULTS

We found that an antioxidant protein peroxiredoxin I (Prx I) was upregulated in human EC tissues as well as in EC cell lines. JDA-202, a novel natural compound isolated from Isodon rubescens (Labiatae), was proved to possess strong anti-proliferative activities on those cell lines. Importantly, JDA-202 does not only bind to Prx I directly and markedly inhibit the activity of Prx I in vitro, but it also significantly induces hydrogen peroxide (H₂O₂)-related cell death. Furthermore, overexpression of Prx I significantly reversed EC109 cell apoptosis caused by JDA-202, whereas short interfering RNA (siRNA)-induced Prx I knockdown resulted in marked cell death even without JDA-202 pretreatment. On the other hand, the increased phosphorylation of mitogen-activated protein kinase (MAPK) proteins (c-Jun N-terminal kinase [JNK], p38, and extracellular signal-regulated kinase [ERK]) by JDA-202 was suppressed by N-acetylcysteine (NAC) or catalase, a known reactive oxygen species (ROS) or H₂O₂ scavenger. JDA-202 also significantly inhibited the growth of EC109 tumor xenograft, without significant body weight loss and multi-organ toxicities. Innovation and Conclusion: Our findings, for the first time, demonstrated that JDA-202 may serve as a lead compound, targeting the overexpressed Prx I in EC cell lines and ROS accumulation as well as inhibiting the activation of their downstream targets in MAPKs. Antioxid. Redox Signal. 27, 73-92.

Quantum-dot-based suspension microarray for multiplex detection of lung cancer markers: preclinical validation and comparison with the Luminex xMAP® system

A novel suspension multiplex immunoassay for the simultaneous specific detection of lung cancer markers in bronchoalveolar lavage fluid (BALF) clinical samples based on fluorescent microspheres having different size and spectrally encoded with quantum dots (QDEM) was developed. The designed suspension immunoassay was validated for the quantitative detection of three lung cancer markers in BALF samples from 42 lung cancer patients and 10 control subjects. Tumor markers were detected through simultaneous formation of specific immune complexes consisting of a capture molecule, the target antigen, and biotinylated recognition molecule on the surface of the different QDEM in a mixture. The immune complexes were visualized by fluorescently labeled streptavidin and simultaneously analyzed using a flow cytometer. Preclinical validation of the immunoassay was performed and results were compared with those obtained using an alternative 3-plex immunoassay based on Luminex xMAP^® technology, developed on classical organic fluorophores. The comparison showed that the QDEM and xMAP^® assays yielded almost identical results, with clear discrimination between control and clinical samples. Thus, developed QDEM technology can become a good alternative to xMAP^® assays permitting analysis of multiple protein biomarkers using conventional flow cytometers.

The role of peroxiredoxins in cancer

Peroxiredoxins (PRDXs) are a ubiquitously expressed family of small (22–27 kDa) non-seleno peroxidases that catalyze the peroxide reduction of H₂O₂, organic hydroperoxides and peroxynitrite. They are highly involved in the control of various physiological functions, including cell growth, differentiation, apoptosis, embryonic development, lipid metabolism, the immune response, as well as cellular homeostasis. Although the protective role of PRDXs in cardiovascular and neurological diseases is well established, their role in cancer remains controversial. Increasing evidence suggests the involvement of PRDXs in carcinogenesis and in the development of drug resistance. Numerous types of cancer cells, in fact, are characterized by an increase in reactive oxygen species (ROS) production, and often exhibit an altered redox environment compared with normal cells. The present review focuses on the complex association between oxidant balance and cancer, and it provides a brief account of the involvement of PRDXs in tumorigenesis and in the development of chemoresistance.

Peroxiredoxin 1 - an antioxidant enzyme in cancer

Peroxiredoxins (PRDXs), a ubiquitous family of redox‐regulating proteins, are reported of potential to eliminate various reactive oxygen species (ROS). As a major member of the antioxidant enzymes, PRDX1 can become easily over‐oxidized on its catalytically active cysteine induced by a variety of stimuli in vitro and in vivo. In nucleus, oligomeric PRDX1 directly associates with p53 or transcription factors such as c‐Myc, NF‐κB and AR, and thus affects their bioactivities upon gene regulation, which in turn induces or suppresses cell death. Additionally, PRDX1 in cytoplasm has anti‐apoptotic potential through direct or indirect interactions with several ROS‐dependent (redox regulation) effectors, including ASK1, p66^Shc, GSTpi/JNK and c‐Abl kinase. PRDX1 is proven to be a versatile molecule regulating cell growth, differentiation and apoptosis. Recent studies have found that PRDX1 and/or PRDX1‐regulated ROS‐dependent signalling pathways play an important role in the progression and metastasis of human tumours, particularly in breast, oesophageal and lung cancers. In this paper, we review the structure, effector functions of PRDX1, its role in cancer and the pivotal role of ROS in anticancer treatment.

SIRT2 Deacetylates and Inhibits the Peroxidase Activity of Peroxiredoxin-1 to Sensitize Breast Cancer Cells to Oxidant Stress-Inducing Agents

SIRT2 is a protein deacetylase with tumor suppressor activity in breast and liver tumors where it is mutated; however, the critical substrates mediating its antitumor activity are not fully defined. Here we demonstrate that SIRT2 binds, deacetylates, and inhibits the peroxidase activity of the antioxidant protein peroxiredoxin (Prdx-1) in breast cancer cells. Ectopic overexpression of SIRT2, but not its catalytically dead mutant, increased intracellular levels of reactive oxygen species (ROS) induced by hydrogen peroxide, which led to increased levels of an overoxidized and multimeric form of Prdx-1 with activity as a molecular chaperone. Elevated levels of SIRT2 sensitized breast cancer cells to intracellular DNA damage and cell death induced by oxidative stress, as associated with increased levels of nuclear FOXO3A and the proapoptotic BIM protein. In addition, elevated levels of SIRT2 sensitized breast cancer cells to arsenic trioxide, an approved therapeutic agent, along with other intracellular ROS-inducing agents. Conversely, antisense RNA-mediated attenuation of SIRT2 reversed ROS-induced toxicity as demonstrated in a zebrafish embryo model system. Collectively, our findings suggest that the tumor suppressor activity of SIRT2 requires its ability to restrict the antioxidant activity of Prdx-1, thereby sensitizing breast cancer cells to ROS-induced DNA damage and cell cytotoxicity. Cancer Res; 76(18); 5467-78. ©2016 AACR.

Aberrant expression of peroxiredoxin 1 and its clinical implications in liver cancer

AIM: To investigate the expression characteristics of peroxiredoxin 1 (PRDX1) mRNA and protein in liver cancer cell lines and tissues.

METHODS: The RNA sequencing data from 374 patients with liver cancer were obtained from The Cancer Genome Atlas. The expression and clinical characteristics of PRDX1 mRNA were analyzed in this dataset. The Kaplan-Meier and Cox regression survival analysis was performed to determine the relationship between PRDX1 levels and patient survival. Subcellular fractionation and Western blotting were used to demonstrate the expression of PRDX1 protein in six liver cancer cell lines and 29 paired fresh tissue specimens. After bioinformatics prediction, a putative post-translational modification form of PRDX1 was observed using immunofluorescence under confocal microscopy and immunoprecipitation analysis in liver cancer cells.

RESULTS: The mRNA of PRDX1 gene was upregulated about 1.3-fold in tumor tissue compared with the adjacent non-tumor control (P = 0.005). Its abundance was significantly higher in men than women (P < 0.001). High levels of PRDX1 mRNA were associated with a shorter overall survival time (P = 0.04) but not with recurrence-free survival. The Cox regression analysis demonstrated that patients with high PRDX1 mRNA showed about 1.9-fold increase of risk for death (P = 0.03). In liver cancer cells, PRDX1 protein was strongly expressed with multiple different bands. PRDX1 in the cytosol fraction existed near the theoretical molecular weight, whereas two higher molecular weight bands were present in the membrane/organelle and nuclear fractions. Importantly, the theoretical PRDX1 band was increased, whereas the high molecular weight form was decreased in tumor tissues. Subsequent experiments revealed that the high molecular weight bands of PRDX1 might result from the post-translational modification by small ubiquitin-like modifier-1 (SUMO1).

CONCLUSION: PRDX1 was overexpressed in the tumor tissues of liver cancer and served as an independent poor prognostic factor for overall survival. PRDX1 can be modified by SUMO to play specific roles in hepatocarcinogenesis.

Prognostic Significance of CREB-Binding Protein and CD81 Expression in Primary High Grade Non-Muscle Invasive Bladder Cancer: Identification of Novel Biomarkers for Bladder Cancer Using Antibody Microarray

High-grade (HG) bladder cancers (BCs) are genetically unstable and have an unpredictable course. The identification of prognostic factors in HG non-muscle invasive BC (NMIBC) is crucial for improving patients’ quality of life and preventing BC-specific mortality. Here, we used an antibody microarray (AbM) to identify novel candidate biomarkers in primary HG NMIBC and validated the prognostic significance of the candidate biomarkers. Three pairs of tissue samples from primary HG NMIBC and normal urothelium were analyzed using an AbM kit containing 656 antibodies, and differentially expressed proteins were identified. Among the 42 upregulated and 14 downregulated proteins with statistical significance in BC tissues, CREB-binding protein and CD81 were selected as representative upregulated and downregulated candidate biomarkers, respectively. We then validated the expression of these candidate biomarkers in primary human urothelial cells and BC cell lines by western blotting and immunofluorescence assays, and the results were consistent with the AbM expression profiles. Additionally, Kaplan-Meier survival using immunohistochemical data from an independent primary HG NMIBC cohort comprising 113 patients showed that expression of the 2 biomarkers was significantly associated with recurrence-free and progression-free survival. In multivariate analysis, the 2 biomarkers remained significant predictors for recurrence-free survival. Taken together, our findings suggest that expression of CREB-binding protein and CD81 in BC tissue specimens may have prognostic value in patients with primary HG NMIBC.

Cysteine specific targeting of the functionally distinct peroxiredoxin and glutaredoxin proteins by the investigational disulfide BNP7787

Glutaredoxin (Grx), peroxiredoxin (Prx), and thioredoxin (Trx) are redoxin family proteins that catalyze different types of chemical reactions that impact cell growth and survival through functionally distinct intracellular pathways. Much research is focused on understanding the roles of these redoxin proteins in the development and/or progression of human diseases. Grx and Prx are overexpressed in human cancers, including human lung cancers. BNP7787 is a novel investigational agent that has been evaluated in previous clinical studies, including non-small cell lung cancer (NSCLC) studies. Herein, data from activity assays, mass spectrometry analyses, and X-ray crystallographic studies indicate that BNP7787 forms mixed disulfides with select cysteine residues on Grx and Prx and modulates their function. Studies of interactions between BNP7787 and Trx have been conducted and reported separately. Despite the fact that Trx, Grx, and Prx are functionally distinct proteins that impact oxidative stress, cell proliferation and disease processes through different intracellular pathways, BNP7787 can modify each protein and appears to modulate function through mechanisms that are unique to each target protein. Tumor cells are often genomically heterogeneous containing subpopulations of cancer cells that often express different tumor-promoting proteins or that have multiple dysregulated signaling pathways modulating cell proliferation and drug resistance. A multi-targeted agent that simultaneously modulates activity of proteins important in mediating cell proliferation by functionally distinct intracellular pathways could have many potentially useful therapeutic applications.

Downregulation of peroxiredoxin-1 by β-elemene enhances the radiosensitivity of lung adenocarcinoma xenografts

β-elemene, the active component of elemene (1-methyl-1-vinyl-2,4-diisopropenyl-cyclohexane), is a naturally occurring compound isolated from the traditional Chinese medicinal herb Curcuma wenyujin. Studies have confirmed that β-elemene enhances the radiosensitivity of lung cancer cell lines such as A549, by multiple pathways; however, their underlying mechanisms and pathways are yet to be elucidated. In the present study, two-dimensional differential in-gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry were used to profile the different proteins in A549 cell xenograft models of both treatment groups. The protein/mRNA expression was assessed by reverse transcription-polymerase chain reaction and western blotting techniques in tumor samples from all treatment groups. As a critical player in redox regulation of cancer cells, inhibition of peroxiredoxin-1 (Prx-1) may be an effective option for enhancing the tumor response to radiation. We further verified Prx-1 expression at the transcription and translation levels. β-elemene at a dose of 45 mg/kg had little effect on the Prx-1 protein expression, which was correlated with a moderate antitumor effect. However, a 45 mg/kg dose of β-elemene significantly inhibited the Prx-1 mRNA expression, thereby suggesting a possible influence on the transcriptional process, and radiation significantly increased the Prx-1 mRNA/protein expression compared to the control group (p<0.01). Notably, Prx-1 mRNA/protein expression was significantly lower in the β-elemene/radiation co-treatment group compared to the baseline levels in the control group (p<0.01). These results suggest that radiation-induced Prx-1 expression is directly or indirectly suppressed by β-elemene, thus suggesting a new pathway by which to reverse radioresistance.

Peroxiredoxin 1 promotes tumorigenesis through regulating the activity of mTOR/p70S6K pathway in esophageal squamous cell carcinoma

The biological function of Peroxiredoxin 1 (Prdx1) in cancer is still ambiguous, and its mechanism has not been elucidated so far. Previous studies have shown that Prdx1 functions as tumor suppressor in several types of cancers, but other studies have indicated that it is overexpressed in some types of human cancers, and inhibition of Prdx1 by shRNA contributes to radiosensitivity and chemosensitivity. In this study, a suppression subtractive hybridization cDNA library between esophageal squamous cell carcinoma (ESCC) cell line EC9706 and noncancerous esophageal epithelial cell line Het-1A was constructed, and 11 tumorigenesis-associated genes including Prdx1 were isolated. In addition, we further confirmed that Prdx1 was overexpressed in ESCC cells at the level of protein compared with Het-1A (P < 0.05). Inhibition of Prdx1 by shRNA lentivirus decreased cell proliferation and invasion, and induced cell apoptosis, but did not affect cell cycle distribution of EC9706 cells (P > 0.05). Importantly, the total proteins of mTOR and p70S6K, as well as the activity of mTOR/p70S6K signaling pathway, were decreased in Prdx1-depletion EC9706 cells. Furthermore, the activity of mTOR/p70S6K signaling pathway was increased in Prdx1-overexpressing Het-1A cells. These findings mentioned above demonstrate that Prdx1 may be involved in tumorigenesis through regulation of mTOR/p70S6K pathway in ESCC.

Redox proteomics reveal stress responsive proteins linking peroxiredoxin-1 status in glioma to chemosensitivity and oxidative stress

The combined deletion of chromosomal arms 1p and 19q has been described as a prognostic marker for oligodendroglial tumors. These tumors show a better response to chemotherapy and radiotherapy. Recently, we found a lower abundance of peroxiredoxin 1 (PRDX1) in oligodendroglial tumors with 1p/19q deletion, suggesting a potential role of this enzyme in the clearance of therapy induced reactive oxygen species (ROS). Here, we confirmed the importance of PRDX1 in tumor cell survival by PRDX1 knockdown and overexpression in A-172 cells treated with the alkylating agent bis-chloroethyl nitrosourea (BCNU). Overexpression of PRDX1 resulted in a higher resistance of cells to BCNU treatment. In addition, BCNU challenged cells showed higher levels of ROS in PRDX1 knockdown cells. We applied a modified version of the redox two dimensional difference gel electrophoresis approach to analyze ROS mediated effects on protein thiols after BCNU treatment by labeling protein thiols with fluorescent dyes. Altogether eleven proteins were identified showing PRDX1 dependent altered labeling, many of them have been previously linked to stress response processes. Furthermore, 30 additional potentially redox active proteins were identified. The majority of them is involved in therapy associated processes like cellular stress response, DNA damage and regulation of cell death and therewith suggests that tumor cells maintain a network of redox sensitive proteins to escape chemotherapy. This article is part of a Special Issue entitled: Medical Proteomics.

Expression and clinical value of peroxiredoxin-1 in patients with pancreatic cancer

BACKGROUND

Peroxiredoxin-1 (Prx-1) is an important protector for redox damage and its abnormal expression is continually reported in various tumors. This study aims to investigate the expression status of Prx-1 and evaluate its clinical value in pancreatic cancer.

METHODOLOGY

Immunohistochemistry was used to detect Prx-1 expression in pancreatic cancer tissues and para-cancerous tissues. Enzyme-linked immunosorbent assay (ELISA) method was applied to detect the serum Prx-1 levels.

RESULTS

The immunohistochemical results indicated that positive rate of Prx-1 was (p < 0.05) higher in pancreatic cancer tissues (74.4%) than in para-cancerous tissues (37.2%). Prx-1 expression was positively correlated with vascular endothelial growth factor (VEGF) and microvessel density (MVD) in cancer tissues. The ELISA results showed that patients with pancreatic cancer had a higher serum Prx-1 level than healthy subjects (31.2 ± 13.5 vs. 13.2 ± 11.9 ng/ml, p < 0.001). Prx-1 expression was correlated with aggressive clinicopathological parameter. The combination of serum Prx-1 and CA19-9, the area under the curve (AUC) was significantly higher than Prx-1 separate. Positive Prx-1 expression was correlated with disappointing overall survival (OS) (p = 0.002) and disease-free survival (DFS) (p < 0.001). Multivariate analysis showed that Prx-1 staining as an independent biomarker of poor OS (p = 0.035) and DFS (p < 0.001).

CONCLUSION

These findings suggest that the levels of Prx-1 expression are significantly increased in pancreatic cancer. The up-regulated Prx-1 is closely related to tumor angiogenesis and acts as a promising tumor marker for diagnosis and prognosis of pancreatic cancer.

Prognostic significance of heme oxygenase-1, S100 calcium-binding protein A4, and syndecan-1 expression in primary non-muscle-invasive bladder cancer

We investigated the prognostic significance of heme oxygenase-1 (HO-1), S100 calcium-binding protein A4 (S100A4), and syndecan-1 (SYND1) expression in patients with primary non-muscle-invasive bladder cancer (NMIBC). Immunohistochemical studies were performed on tissue specimens from 109 patients diagnosed with primary NMIBC following complete transurethral resection, with the expression dichotomized as negative/mild ("low") versus moderate/strong ("high") according to scores based on staining area and intensity. The effect of each biomarker on recurrence-free survival (RFS) and progression-free survival (PFS) was analyzed. The predictive accuracy for RFS and PFS in multivariate Cox regression models with or without (the baseline model) biomarkers was estimated using the Harrell concordance index. High HO-1, S100A4, and SYND1 expressions were observed in 33.0%, 36.7%, and 63.3% cases, respectively. High HO-1 and S100A4 expressions were significantly associated with various adverse pathological characteristics (high T stage and grade); SYND1 expression was inversely correlated with these characteristics (all, P < .05). In the baseline multivariate model, multifocality, intravesical therapy, and T stage were significant predictors for RFS, whereas intravesical therapy and T stage had marginal statistical significance in predicting PFS. In the multivariate model with the biomarkers, the 3 biomarkers were significant predictors for RFS; and HO-1 expression was a significant predictor for PFS. Addition of the 3 biomarkers to the baseline model significantly increased the predictive accuracy for RFS from 0.754 to 0.828 (P = .043). Our findings suggest that HO-1, S100A4, and SYND1 expressions have prognostic value in primary NMIBC; thus, their evaluation might be useful for determining treatment strategies.

Oral cancer secretome: identification of cancer-associated proteins

This study aims to identify cancer-associated proteins in the secretome of oral cancer cell lines. We have successfully established four primary cell cultures of normal cells with a limited lifespan without human telomerase reverse transcriptase (hTERT) immortalization. The secretome of these primary cell cultures were compared with that of oral cancer cell lines using 2DE. Thirty five protein spots were found to have changed in abundance. Unambiguous identification of these proteins was achieved by MALDI TOF/TOF. In silico analysis predicted that 24 of these proteins were secreted via classical or nonclassical mechanisms. The mRNA expression of six genes was found to correlate with the corresponding protein abundance. Ingenuity Pathway Analysis (IPA) core analysis revealed that the identified proteins were relevant in, and related to, cancer development with likely involvements in tumor growth, metastasis, hyperproliferation, tumorigenesis, neoplasia, hyperplasia, and cell transformation. In conclusion, we have demonstrated that a comparative study of the secretome of cancer versus normal cell lines can be used to identify cancer-associated proteins.

Towards scarless wound healing: a comparison of protein expression between human, adult and foetal fibroblasts

Proteins from human adult and foetal fibroblast cell lines were compared, focusing on those involved in wound healing. Proteins were separated through two-dimensional gel electrophoresis (2DE). Differences in protein spot intensity between the lineages were quantified through 3D gel scanning densitometry. Selected protein spots were excised, subjected to tryptic digests, prior to separation using HPLC with a linear ion trap mass spectrometer, and identified. Protein maps representing the proteomes from adult and foetal fibroblasts showed similar distributions but revealed differences in expression levels. Heat shock cognate 71 kDA protein, Tubulin alpha-1A chain, actin cytoplasmic-1, and neuron cytoplasmic protein were all expressed in significantly higher concentrations by foetal fibroblasts, nearly double those observed for their adult counterparts. Fructose bisphosphate aldolase A, Cofilin-1, Peroxiredoxin-1, Lactotransferrin Galectin-1, Profilin-1, and Calreticulin were expressed at comparatively higher concentrations by the adult fibroblasts. Significant differences in the expression levels of some proteins in human adult and foetal fibroblasts correlated with known differences in wound healing behaviour. This data may assist in the development of technologies to promote scarless wound healing and better functional tissue repair and regeneration.

Peroxiredoxin 1 is involved in disassembly of flagella and cilia

Cilia/flagella are evolutionarily conserved cellular organelles. In this study, we demonstrated that Dunaliella salina Peroxiredoxin 1 (DsPrdx1) localized to the flagella and basal bodies, and was involved in flagellar disassembly. The link between DsPrdx1 and flagella of Dunaliella salina (D. salina) encouraged us to explore the function of its human homologue, Homo sapiens Peroxiredoxin 1 (HsPrdx1) in development and physiology. Our results showed that HsPrdx1 was overexpressed, and cilia were lost in esophageal squamous cell carcinoma (ESCC) cells compared with the non-cancerous esophageal epithelial cells Het-1A. Furthermore, when HsPrdx1 was knocked down by short hairpin RNA (shRNA) lentivirus in ESCC cells, the phenotype of cilia lost can be reversed, and the expression levels of tumor suppressor genes LKB1 and p-AMPK were increased, and the activity of the oncogene Aurora A was inhibited compared with those in cells transfected with scrambe-shRNA lentivirus. These findings firstly showed that Prdx1 is involved in disassembly of flagella and cilia, and suggested that the abnormal expression of the cilia-related gene including Prdx1 may affect both ciliogenesis and cancernogenesis.

PRDX1 and PRDX6 are repressed in papillary thyroid carcinomas via BRAF V600E-dependent and -independent mechanisms

Many clinical studies highlight the dichotomous role of PRDXs in human cancers, where they can exhibit strong tumor-suppressive or tumor-promoting functions. Recent evidence suggests that lower expression of PRDXs correlates with cancer progression in colorectal cancer (CRC) or in esophageal squamous carcinoma. In the thyroid, increased levels of PRDX1 has been described in follicular adenomas and carcinomas, as well as in thyroiditis, while reduced levels of PRDX6 has been found in follicular adenomas. We studied the expression of PRDX1 and PRDX6, in a series of thyroid tissue samples, covering different thyroid diseases, including 13 papillary thyroid carcinomas (PTCs). Our results show that PRDX1 and PRDX6 are significantly reduced in all PTCs compared to normal tissues, to non-neoplastic tissue (MNG) or follicular neoplasms. This reduction is strongly evident in PTCs harboring BRAF V600E (31% of our cases). Using TPC-1 and BCPAP and FRTL-5 cell lines, we demonstrate for the first time that the presence of BRAF V600E is responsible of the hypoexpression of PRDX1 and PRDX6 both at mRNA and protein levels. Finally, independently of BRAF status, we observe an interesting correlation between the tumor size, the presence of lymph node metastasis and the lowest PRDX1 and PRDX6 levels. Therefore, these data indicate that PRDX1 and PRDX6 expression not only may play a key role in papillary thyroid carcinogenesis via a BRAF V600E-dependent mechanism, but their determination could be considered as potential tumor marker for indicating tumor progression in PTCs, independently of BRAF status.

Diagnostic and prognostic significance of peroxiredoxin 1 expression in human hepatocellular carcinoma

Peroxiredoxin 1 (Prdx1) is a member of the peroxiredoxin family of antioxidant enzymes and implicated in cell differentiation, proliferation, and apoptosis. The aim of the present study was to determine the expression and diagnostic and prognostic significance of Prdx1 in human hepatocellular carcinoma (HCC). Prdx1 expression was examined in 76 HCC patients and 20 healthy volunteers. The relationships between Prdx1 expression and clinicopathological features were analyzed. Receiver operating characteristics analysis was used to calculate the diagnostic accuracy of serum Prdx1, serum alpha-fetoprotein (AFP), and their combination. The prognostic impact of Prdx1 on overall survival (OS) and disease-free survival (DFS) of HCC patients was investigated. Prdx1-positive rate was significantly (p < 0.05) higher in HCC (77.1 %) than in adjacent non-tumorous liver tissues (18.4 %). Prdx1 immunoreactivity was positively correlated with tumor vascular endothelial growth factor expression and microvessel density. Prdx1 expression was significantly associated with tumor size, microvascular invasion, Edmondson grade, tumor capsula status, serum AFP, and tumor-node-metastasis stage. The combination of serum Prdx1 and AFP had a markedly higher area under the curve than serum Prdx1 alone. Positive Prdx1 expression was associated with unfavorable OS (p = 0.004) and DFS (p = 0.001). Multivariate analysis revealed intra-tumoral Prdx1 staining as an independent poor prognostic marker for OS (p = 0.006) and DFS (p = 0.002). Taken together, our data suggest that increased Prdx1 expression is associated with tumor angiogenesis and progression in HCC and serves as a promising biomarker for detection and prognosis of this malignancy.

Peroxiredoxin 1 is a tumor-associated antigen in esophageal squamous cell carcinoma

Peroxiredoxin 1 (Prdx1) is an antioxidant and plays an important role in H2O2-mediated cell signaling. We previously found that the expression level of Prdx1 was elevated in esophagus squamous cell carcinoma (ESCC) tissue using a proteomics approach. Since overexpressed protein can induce an autoimmune response, to further examine whether serum from ESCC patients exhibits immunoreactivity against Prdx1, autoantibody responses to Prdx1 were evaluated by ELISA, western blotting and indirect immunofluorescence assay in sera from patients with ESCC and normal individuals. Immunohistochemical study with tissue array slides and western blot analysis with cancer cell lines were also performed to analyze the protein expression profiles of Prdx1 in ESCC tissues and cancer cell lines. The results demonstrated that the positive rate of autoantibody against Prdx1 in ESCC sera was 13.2% (9/68), whereas this rate was 0% (0/89) in normal individuals. Data also showed that expression of Prdx1 was significantly increased in ESCC tissues when compared to expression in paired adjacent normal tissues (P<0.05). The data indicate that Prdx1 may contribute to malignant transformation of the esophagus, and may be used as a biomarker in the immunodiagnosis of ESCC.