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

Role of Glutathione Peroxidases and Peroxiredoxins in Free Radical-Induced Pathologies

In this review, we discuss the pathogenesis of some socially significant diseases associated with the development of oxidative stress, such as atherosclerosis, diabetes, and radiation sickness, as well as the possibilities of the therapeutic application of low-molecular-weight natural and synthetic antioxidants for the correction of free radical-induced pathologies. The main focus of this review is the role of two phylogenetically close families of hydroperoxide-reducing antioxidant enzymes peroxiredoxins and glutathione peroxidases - in counteracting oxidative stress. We also present examples of the application of exogenous recombinant antioxidant enzymes as therapeutic agents in the treatment of pathologies associated with free-radical processes and discuss the prospects of the therapeutic use of exogenous antioxidant enzymes, as well as the ways to improve their therapeutic properties.

A Comprehensive Mini-Review of Curcumae Radix: Ethnopharmacology, Phytochemistry, and Pharmacology

Curcumae Radix is an efficacious ingredient with various medicinal properties empirically used in traditional Chinese medicine (TCM) formula for the treatment of cancer, depression, chest pain, dysmenorrhea, epilepsy, and jaundice. However, either phytochemical or pharmacological information of Curcumae Radix underlying its traditionally medicinal uses is rarely summarized and systematically analyzed. To provide evidence for clinical trials, a comprehensive literature review has been prepared of the phytochemicals, and ethnopharmacological and pharmacological mechanisms of this herb. The review approach consisted of searching several web-based scientific databases, including PubMed, Web of Science, and Elsevier. The keywords included “Curcumae Radix,” “ Curcuma wenyujin,” “ Curcuma longa,” “ Curcuma kwangsiensis,” and “ Curcuma phaeocaulis.” Based on the proposed criteria, 57 articles were evaluated in detail. The accumulated data indicate that Curcumae Radix contains a number of bioactive phytochemicals, mainly sesquiterpenes, diarylheptanoids, and diarylpentanoids, which account for a variety of medicinal values, such as anticancer, anti-inflammation, anti-hepatic fibrosis, and antioxidant. A wide range of apoptotic proteins, cell adhesion molecules, inflammatory cytokines, and enzymic and nonenzymic antioxidants could be modulated by either Curcumae Radix or its bioactive compounds, thus underpinning a fundamental understanding for the pharmacological effects of this herb. This review highlights the therapeutic potential of Curcumae Radix to progress the development of versatile adjuvants or therapeutic agents in the future.

The role of TLR4/NF-κB signaling in the radioprotective effects of exogenous Prdx6

Peroxiredoxin 6 (Prdx6) is a bifunctional enzyme with multi-substrate peroxidase and phospholipase activities that is involved in cell redox homeostasis and regulates intracellular processes. Previously, recombinant Prdx6 was shown to exert a radioprotective effect during whole-body exposure to a lethal dose of X-ray radiation. Moreover, a mutant form Prdx6-C47S, which lacks peroxidase activity, also had a radioprotective effect, and this indicates that the mechanism of radioprotection is unknown. The present study was aimed to test the hypothesis that the radioprotective effect of Prdx6 and Prdx6-C47S may be mediated through the TLR4/NF-κB signaling pathway. It was demonstrated that exogenously applied Prdx6 protected 3T3 fibroblast cells against LD50 X-ray radiation in vitro. Pretreatment with Prdx6 increased cell survival, stimulated proliferation, normalized the level of reactive oxygen species in culture, and suppressed apoptosis and necrosis. Wild-type Prdx6 and, to a lesser degree, the Prdx6-C47S mutant proteins promoted a significant increase in NF-κB activation in irradiated cells, which likely contributes to the antiapoptotic effect. Pretreatment with TLR4 inhibitors, especially those directed to the extracellular part of the receptor, significantly reduced the radioprotective effect, and this supports the role of TLR4 signaling in the protective effects of Prdx6. Therefore, the radioprotective effect of Prdx6 was related not only to its antioxidant properties, but also to its ability to trigger cellular defense mechanisms through interaction with the TLR4 receptor and subsequent activation of the NF-κB pathway. Recombinant Prdx6 may be useful for the development of a new class of safe radioprotective compounds that have a combination of antioxidant and immunomodulatory properties.

Anti-Tumor Drug Discovery Based on Natural Product β-Elemene: Anti-Tumor Mechanisms and Structural Modification

Natural products are important sources for drug discovery, especially anti-tumor drugs. β-Elemene, the prominent active ingredient extract from the rhizome of Curcuma wenyujin, is a representative natural product with broad anti-tumor activities. The main molecular mechanism of β-elemene is to inhibit tumor growth and proliferation, induce apoptosis, inhibit tumor cell invasion and metastasis, enhance the sensitivity of chemoradiotherapy, regulate the immune system, and reverse multidrug resistance (MDR). Elemene oral emulsion and elemene injection were approved by the China Food and Drug Administration (CFDA) for the treatment of various cancers and bone metastasis in 1994. However, the lipophilicity and low bioavailability limit its application. To discover better β-elemene-derived anti-tumor drugs with satisfying drug-like properties, researchers have modified its structure under the premise of not damaging the basic scaffold structure. In this review, we comprehensively discuss and summarize the potential anti-tumor mechanisms and the progress of structural modifications of β-elemene.

Antioxidative Stress: Inhibiting Reactive Oxygen Species Production as a Cause of Radioresistance and Chemoresistance

Radiotherapy and chemotherapy are the most effective nonsurgical treatments for cancer treatment. They usually induce regulated cell death by increasing the level of reactive oxygen species (ROS) in tumour cells. However, as intracellular ROS concentration increases, many antioxidant pathways are concurrently upregulated by cancer cells to inhibit ROS production, ultimately leading to drug resistance. Understanding the mechanism of antioxidant stress in tumour cells provides a new research direction for overcoming therapeutic resistance. In this review, we address (1) how radiotherapy and chemotherapy kill tumour cells by increasing the level of ROS, (2) the mechanism by which ROS activate antioxidant pathways and the subsequent cellular mitigation of ROS in radiotherapy and chemotherapy treatments, and (3) the potential research direction for targeted treatment to overcome therapeutic resistance.

β-Elemene enhances radiosensitivity in non-small-cell lung cancer by inhibiting epithelial-mesenchymal transition and cancer stem cell traits via Prx-1/NF-kB/iNOS signaling pathway

Radiation therapy is widely used to treat a variety of malignant tumors, including non-small-cell lung cancer (NSCLC). However, ionizing radiation (IR) paradoxically promotes radioresistance, metastasis and recurrence by inducing epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs). Here, we developed two NSCLC radioresistant (RR) cell lines (A549-RR and H1299-RR) and characterized their motility, cell cycle distribution, DNA damage, and CSC production using migration/invasion assays, flow cytometry, comet assays, and sphere formation, respectively. We also evaluated their tumorigenicity in vivo using a mouse xenograft model. We found that invasion and spheroid formation by A549-RR and H1299-RR cells were increased as compared to their parental cells. Furthermore, as compared to radiation alone, the combination of β-elemene administration with radiation increased the radiosensitivity of A549 cells and reduced expression of EMT/CSC markers while inhibiting the Prx-1/NF-kB /iNOS signaling pathway. Our findings suggest that NSCLC radioresistance is associated with EMT, enhanced CSC phenotypes, and activation of the Prx-1/NF-kB/iNOS signaling pathway. They also suggest that combining β-elemene with radiation may be an effective means of overcoming radioresistance in NSCLC.

Down-Regulation of Hypoxia-Inducible Factor-1α and Downstream Glucose Transporter Protein-1 Gene by β-elemene Enhancing the Radiosensitivity of Lung Adenocarcinoma Transplanted Tumor

Purpose

To study the effect of β-elemene on the radiosensitivity of A549 cell xenograft tumor and potential mechanisms by which β-elemene regulates the expression of hypoxia-inducible factor-1α (HIF-1α) and glucose transporter protein-1 (GLUT-1).

Methods

Using an A549 cell transplantation tumor model with male nude mice, we studied the effect of β-elemene on the radiosensitivity of non-small cell lung cancer (NSCLC). The expression of HIF-1α and GLUT-1 was detected by real-time PCR, Western blotting and immunohistochemistry. The relationship between the radiosensitivity of β-elemene and the expression of HIF-1α and GLUT-1 was analyzed.

Results

β-elemene and radiotherapy intervened in the growth of transplanted tumors in varying degrees. The enhancement factor (EF=2.44>1) was calculated; β-elemene at 45 mg/kg had the most significant enhanced effect on radiosensitivity. When β-elemene was used in combination with radiation, the expression of HIF-1α and GLUT-1 was significantly decreased, and there was a positive correlation between the two genes.

Conclusion

β-elemene exhibits a radiosensitizing effect on A549 cell xenograft tumor. The underlying molecular mechanism is probably associated with the down-regulation of HIF-1α and GLUT-1 expression, suggesting that β-elemene may directly or indirectly inhibit the expression of HIF-1α and GLUT-1. There is a positive significant correlation between expression of HIF-1α and GLUT-1. HIF-1α and downstream GLUT-1 could be used as a new target for the radiosensitization of NSCLC.

Sesquiterpenes and their derivatives-natural anticancer compounds: An update

Sesquiterpenes belong to the largest group of plant secondary metabolites, which consist of three isoprene building units. These compounds are widely distributed in various angiosperms, a few gymnosperms and bryophytes. Sesquiterpenes and their allied derivatives are bio-synthesized in various plant parts including leaves, fruits and roots. These plant-based metabolites are predominantly identified in the Asteraceae family, wherein up to 5000 complexes have been documented to date. Sesquiterpenes and their derivatives are characteristically associated with plant defence mechanisms owing to their antifungal, antibacterial and antiviral activities. Over the last two decades, these compounds have been reportedly demonstrated health promoting perspectives against a wide range of metabolic syndromes i.e. hyperglycemia, hyperlipidemia, cardiovascular complications, neural disorders, diabetes, and cancer. The high potential of sesquiterpenes and their derivatives against various cancers like breast, colon, bladder, pancreatic, prostate, cervical, brain, liver, blood, ovarium, bone, endometrial, oral, lung, eye, stomach and kidney are the object of this review. Predominantly, it recapitulates the literature elucidating sesquiterpenes and their derivatives while highlighting the mechanistic approaches associated with their potent anticancer activities such as modulating nuclear factor kappa (NF-kB) activity, inhibitory action against lipid peroxidation and retarding the production of reactive oxygen & nitrogen species (ROS&RNS).

The Use of ß-Elemene to Enhance Radio Sensitization of A375 Human Melanoma Cells

Objective

Melanoma is the most malignant and severe type of skin cancer. It is a tumor with a high risk of metastasis and resistant to conventional treatment methods (surgery, radiotherapy, and chemotherapy). β-elemene is the most active constituent of Curcuma wenyujin which is a non-cytotoxic antitumor drug, proved to be effective in different types of cancers. The study aimed to investigate the therapeutic effects of β-elemene in combination with radiotherapy on A375 human melanoma.

Materials and Methods

In this experimental study, human melanoma cells were grown in the monolayer culture model. The procedure of the treatment was performed by the addition of different concentrations of β-elemene to the cells. Then, the cells were exposed to 2 and 4 Gy X-ray in different incubation times (24, 48, and 72 hours). The MTT assay was used for the determination of the cell viability. To study the rate of apoptosis response to treatments, the Annexin V/PI assay was carried out.

Results

The results of the MTT assay showed β-elemene reduced the cell proliferation in dose- and time-dependent manners in cells exposed to radiation. Flow cytometry analysis indicated that β-elemene was effective in the induction of apoptosis. Furthermore, the combination treatment with radiation remarkably decreased the cells proliferation ability and also enhanced apoptosis. For example, cell viability in a group exposed to 40 µg/ml of β-elemene was 80%, but combination treatment with 6 MV X beam at a dose of 2 Gy reduced the viability to 61%.

Conclusion

Our results showed that β-elemene reduced the proliferation of human melanoma cancer cell through apoptosis. Also, the results demonstrated that the radio sensitivity of A375 cell line was significantly enhanced by β-elemene. The findings of this study indicated the efficiency of β-elemene in treating melanoma cells and the necessity for further research in this field.

Molecular targets of β-elemene, a herbal extract used in traditional Chinese medicine, and its potential role in cancer therapy: A review

β-Elemene is a sesquiterpene compound extracted from the herb Curcuma Rhizoma and is used in traditional Chinese medicine (TCM) to treat several types of cancer, with no reported severe adverse effects. Recent studies, using in vitro and in vivo studies combined with molecular methods, have shown that β-elemene can inhibit cell proliferation, arrest the cell cycle, and induce cell apoptosis. Recent studies have identified the molecular targets of β-elemene that may have a role in cancer therapy. This review aims to discuss the anticancer potential of β-elemene through its actions on several molecular targets including kinase enzymes, transcription factors, growth factors and their receptors, and proteins. β-Elemene also regulates the expression of several key molecules that are involved in tumor angiogenesis and metastasis including vascular endothelial growth factor (VEGF), matrix metalloproteinases (MMPs), E-cadherin, N-cadherin, and vimentin. Also, β-elemene has been shown to have regulatory effects on the immune response and increases the sensitivity of cancer cells to chemoradiotherapy and has shown effects on multidrug resistance (MDR) in malignancy. Recent studies have shown that β-elemene can induce autophagy, which prevents cancer cells from undergoing apoptosis. Therefore, the molecular mechanisms for the treatment effects on cancer of the herbal extract, β-elemene, which has been used for centuries in traditional Chinese medicine, are now being studied and identified.

Differential proteomics for studying action mechanisms of traditional Chinese medicines

Differential proteomics, which has been widely used in studying of traditional Chinese medicines (TCMs) during the past 10 years, is a powerful tool to visualize differentially expressed proteins and analyzes their functions. In this paper, the applications of differential proteomics in exploring the action mechanisms of TCMs on various diseases including cancers, cardiovascular diseases, diabetes, liver diseases, kidney disorders and obesity, etc. were reviewed. Furthermore, differential proteomics in studying of TCMs identification, toxicity, processing and compatibility mechanisms were also included. This review will provide information for the further applications of differential proteomics in TCMs studies.

Radioprotective Role of Peroxiredoxin 6

Peroxiredoxin 6 (Prdx6) is a member of an evolutionary ancient family of peroxidase enzymes with diverse functions in the cell. Prdx6 is an important enzymatic antioxidant. It reduces a wide range of peroxide substrates in the cell, thus playing a leading role in the maintenance of the redox homeostasis in mammalian cells. Beside peroxidase activity, Prdx6 has been shown to possess an activity of phospholipase A2, an enzyme playing an important role in membrane phospholipid metabolism. Moreover, Prdx6 takes part in intercellular and intracellular signal transduction due to its peroxidase and phospholipase activity, thus facilitating the initiation of regenerative processes in the cell, suppression of apoptosis, and activation of cell proliferation. Being an effective and important antioxidant enzyme, Prdx6 plays an essential role in neutralizing oxidative stress caused by various factors, including action of ionizing radiation. Endogenous Prdx6 has been shown to possess a significant radioprotective potential in cellular and animal models. Moreover, intravenous infusion of recombinant Prdx6 to animals before irradiation at lethal or sublethal doses has shown its high radioprotective effect. Exogenous Prdx6 effectively alleviates the severeness of radiation lesions, providing normalization of the functional state of radiosensitive organs and tissues, and leads to a significant elevation of the survival rate of animals. Prdx6 can be considered as a potent and promising radioprotective agent for reducing the pathological effect of ionizing radiation on mammalian organisms. The radioprotective properties and mechanisms of radioprotective action of Prdx6 are discussed in the current review.

Drug delivery systems for elemene, its main active ingredient β-elemene, and its derivatives in cancer therapy

β-elemene is a noncytotoxic Class II antitumor drug extracted from the traditional Chinese medicine Curcuma wenyujin Y. H. Chen et C. Ling. β-elemene exerts its effects by inhibiting cell proliferation, arresting the cell cycle, inducing cell apoptosis, exerting antiangiogenesis and antimetastasis effects, reversing multiple-drug resistance (MDR), and enhancing the immune system. Elemene injection and oral emulsion have been used to treat various tumors, including cancer of the lung, liver, brain, breast, ovary, gastric, prostate, and other tissues, for >20 years. The safety of both elemene injection and oral emulsion in the clinic has been discussed. Recently, the secondary development of β-elemene has attracted the attention of researchers and made great progress. On the one hand, studies have been carried out on liposome-based systems (including solid lipid nanoparticles [SLNs], nanostructured lipid carriers [NLCs], long-circulating liposomes, active targeting liposomes, and multidrug-loaded liposomes) and emulsion systems (including microemulsions, self-emulsion drug delivery systems [SEDDSs], and active targeting microemulsion) to solve the issues of poor solubility in water, low bioavailability, and severe phlebitis, as well as to improve antitumor efficacy. The pharmacokinetics of different drug delivery systems of β-elemene are also summarized. On the other hand, a number of highly active anticancer β-elemene derivatives have been obtained through modification of the structure of β-elemene. This review focuses on the two drug delivery systems and derivatives of β-elemene for cancer therapy.

β-elemene regulates endoplasmic reticulum stress to induce the apoptosis of NSCLC cells through PERK/IRE1α/ATF6 pathway

Endoplasmic reticulum stress (ERs) has been regarded as an important cause for the pathogenesis of non-small-cell lung cancer (NSCLC). β-elemene is an active component in the essential oil extracted from a medicinal herb, Curcuma wenyujin, and has been reported to be effective against non-small-cell lung cancer (NSCLC). However, the potential effect and underlying mechanisms of β-elemene on regulating ERs to inhibit NSCLC are still unclear. In the present study, A549 cells and Lewis tumor-bearing C57BL/6J mice were established to evaluate this effect. Visualsonics Vevo 2100 Small Animal Dedicated High-frequency Color Ultrasound was performed to observe tumor volume in vivo. 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) was used to evaluate cell vitality of A549 cells. Furthermore, western blotting (WB), immunohistochemistry (IHC) and quantitative reverse transcription polymerase chain reaction (q-PCR) were applied to detect the ERs-related proteins. Flow cytometry was also applied to detect cell apoptosis and assay kit for reactive oxygen species (ROS) generation. Our results showed that β-elemene inhibited lung cancer tumor growth and cell vitality in a dose- and time-dependent manner. Not only that, β-elemene could up-regulate ERs-related proteins like PERK, IRE1α, ATF6, ATF4, CHOP and down-regulate the Bcl-2 expression. More importantly, ERs inhibitor 4-PBA, IRE1α inhibitor STF-083010, ATF6 inhibitor Anti-ATF6 and PERK inhibitor GSK2656157 can all reduce the amplitude of protein expression changes and apoptosis rates, then weaken the anti-tumor effect of β-elemene. Therefore, the present in vivo and in vitro study revealed that the anti-NSCLC effect of β-elemene is closely related to the activation of ERs through PERK/IRE1α/ATF6 pathway, and this might be beneficial for clinical therapy of NSCLC.

Chinese Herbal Extractions for Relieving Radiation Induced Lung Injury: A Systematic Review and Meta-Analysis

Background. Radiation induced lung injury (RILI) is one of the most common and severe side effects of thoracic radiotherapy. In this meta-analysis, the effects of Chinese herbal extractions (CHE) for preventing and treating RILI are evaluated. Methods. Randomized Controlled Trials (RCTs) from five databases were identified. Studies were evaluated and the relevant data were extracted by two authors independently. Differences were resolved by a third party. Meta-analysis was conducted using RevMan 5.0. Results. In total, 2734 participants receiving thoracic radiotherapy were included in 28 RCTs, and 16 CHE were evaluated. Meta-analysis showed that CHE intervention significantly reduced the incidence of acute radiation pneumonitis (RP) and radiation induced pulmonary fibrosis (RIPF). In CHE group, total effective rate and remission rate of RILI patients were significantly higher. Patient's quality of life (Qol) and clinical symptoms and signs were improved significantly. Inflammatory cytokines decreased, and thymus dependent lymphocytes subgroups were improved. Conclusion. CHE intervention may have clinical effectiveness for relieving RILI and related symptoms and signs and lead to improvement of Qol. However, more double-blind, multicenter, large-scale RCTs are needed to support this theory. Trial Registration. PROSPERO International prospective register of systematic reviews has registration number CRD42016043538.

Anticancer effects of β-elemene with hyperthermia in lung cancer cells

β-elemene is a novel, plant-derived anticancer drug, which has been used to target multiple solid tumor types. Hyperthermia is an adjuvant therapeutic modality to treat cancer. However, the underlying mechanisms associated with the efficacy of these two treatments are largely unknown. The aim of the present study was to evaluate the effects of β-elemene combined with hyperthermia in lung cancer cell lines. An MTT assay was used to determine cell viability. The cell cycle and apoptosis were analyzed using flow cytometry. The morphology of cells during apoptosis was determined using a transmission electron microscope. The expression levels of P21, survivin, caspase-9, B-cell lymphoma 2 (Bcl-2) and Bcl-2-like protein 4 (Bax) mRNA were detected using quantitative polymerase chain reaction. β-elemene with hyperthermia treatment significantly inhibited the viability and increased the apoptosis rate of A549 cells compared with β-elemene treatment alone (P<0.01), and significantly decreased the proportion of cells in S phase compared with the control (P<0.01). Morphological observation using transmission electron microscopy indicated cross-sectional features of apoptosis: Chromatin condensation, reduced integrity of the plasma membrane, increased cellular granularity, nuclear collapse and the formation of apoptotic bodies. β-elemene with hyperthermia treatment significantly promoted P21 and Bax mRNA expression (P<0.01) and significantly decreased caspase-9, Bcl-2 and survivin mRNA expression (P<0.01) in A549 cells. In conclusion, β-elemene with hyperthermia has a significant inhibitory effect on A549 cells. This occurs through reducing S phase and inducing apoptosis, via an increase in P21 and Bax expression and a decrease in caspase-9, Bcl-2 and survivin expression.

Interplay of DNA methyltransferase 1 and EZH2 through inactivation of Stat3 contributes to β-elemene-inhibited growth of nasopharyngeal carcinoma cells

β-elemene, a compound extracted from Curcuma wenyujin plant, exhibits anticancer activity in many cancer types. However, the detailed mechanism by which β-elemene inhibits growth of nasopharyngeal carcinoma (NPC) cells remains unknown. We showed that β-elemene reduced phosphorylation of signal transducer and activator of transcription 3 (Stat3), and protein expressions of DNA methyltransferase 1 (DNMT1) and enhancer of zeste homolog 2 (EZH2). Exogenously expressed Stat3 antagonized the effect of β-elemene on DNMT1 and EZH2 expressions. Furthermore, overexpressions of DNMT1 and EZH2 reversed the effect of β-elemene on phosphorylation of Stat3 and cell growth inhibition. Intriguingly, exogenously expressed DNMT1 overcame β-elemene-inhibited EZH2 protein expression and promoter activity. On the contrary, silencing of EZH2 and DNMT1 genes feedback strengthened the effect of β-elemene on phosphorylation of Stat3. Consistent with this, β-elemene inhibited tumor growth, phosphorylation of Stat3, expressions of DNMT1 and EZH2 in a mouse xenograft model. Collectively, this study shows that β-elemene inhibits NPC cell growth via inactivation of Stat3, and reduces DNMT1 and EZH2 expressions. The interplay of DNMT1 and EZH2, and the mutual regulations among Stat3, EZH2 and DNMT1 contribute to the overall responses of β-elemene. This study uncovers a novel mechanism by which β-elemene inhibits growth of NPC cells.

β-Elemene Selectively Inhibits the Proliferation of Glioma Stem-Like Cells Through the Downregulation of Notch1

Glioma is the most frequent primary central nervous system tumor. Although the current first-line medicine, temozolomide (TMZ), promotes patient survival, drug resistance develops easily. Thus, it is important to investigate novel therapeutic reagents to solidify the treatment effect. β-Elemene (bELE) is a compound from a Chinese herb whose anticancer effect has been shown in various types of cancer. However, its role in the inhibition of glioma stem-like cells (GSLCs) has not yet been reported. We studied both the in vitro and the in vivo inhibitory effect of bELE and TMZ in GSLCs and parental cells and their combined effects. The molecular mechanisms were also investigated. We also optimized the delivery methods of bELE. We found that bELE selectively inhibits the proliferation and sphere formation of GSLCs, other than parental glioma cells, and TMZ exerts its effects on parental cells instead of GSLCs. The in vivo data confirmed that the combination of bELE and TMZ worked better in the xenografts of GSLCs, mimicking the situation of tumorigenesis of human cancer. Notch1 was downregulated with bELE treatment. Our data also demonstrated that the continuous administration of bELE produces an ideal effect to control tumor progression. Our findings have demonstrated, for the first time, that bELE could compensate for TMZ to kill both GSLCs and nonstem-like cancer cells, probably improving the prognosis of glioma patients tremendously. Notch1 might be a downstream target of bELE. Therefore, our data shed light on improving the outcomes of glioma patients by combining bELE and TMZ. Stem Cells Translational Medicine 2017;6:830-839.

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.

Peroxiredoxins and the Regulation of Cell Death

Cell death pathways such as apoptosis can be activated in response to oxidative stress, enabling the disposal of damaged cells. In contrast, controlled intracellular redox events are proposed to be a significant event during apoptosis signaling, regardless of the initiating stimulus. In this scenario oxidants act as second messengers, mediating the post-translational modification of specific regulatory proteins. The exact mechanism of this signaling is unclear, but increased understanding offers the potential to promote or inhibit apoptosis through modulating the redox environment of cells. Peroxiredoxins are thiol peroxidases that remove hydroperoxides, and are also emerging as important players in cellular redox signaling. This review discusses the potential role of peroxiredoxins in the regulation of apoptosis, and also their ability to act as biomarkers of redox changes during the initiation and progression of cell death.

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.

The reversal of antineoplastic drug resistance in cancer cells by β-elemene

Multidrug resistance (MDR), defined as the resistance of cancer cells to compounds with diverse structures and mechanisms of actions, significantly limits the efficacy of antitumor drugs. A major mechanism that mediates MDR in cancer is the overexpression of adenosine triphosphate (ATP)-binding cassette transporters. These transporters bind to their respective substrates and catalyze their efflux from cancer cells, thereby lowering the intracellular concentrations of the substrates and thus attenuating or even abolishing their efficacy. In addition, cancer cells can become resistant to drugs via mechanisms that attenuate apoptosis and cell cycle arrest such as alterations in the p53, check point kinase, nuclear factor kappa B, and the p38 mitogen-activated protein kinase pathway. In this review, we discuss the mechanisms by which β-elemene, a compound extracted from Rhizoma zedoariae that has clinical antitumor efficacy, overcomes drug resistance in cancer.