Review Article Molecular and Cellular Effects of …downloads.hindawi.com/journals/omcl/2016/1908164.pdfReview Article Molecular and Cellular Effects of Hydrogen Peroxide on Human

Review ArticleMolecular and Cellular Effects of Hydrogen Peroxide onHuman Lung Cancer Cells Potential Therapeutic Implications

Gabriela Vilema-Enriacutequez123 Aurora Arroyo4 Marcelo Grijalva12

Ricardo Israel Amador-Zafra5 and Javier Camacho14

1Departamento de Ciencias de la Vida Universidad de las Fuerzas Armadas (ESPE) Avenida General RuminahuiSN PO Box 171-5-231B Sangolquı Ecuador2Centro de Nanociencia y Nanotecnologıa Universidad de las Fuerzas Armadas (ESPE) Avenida General RuminahuiSN PO Box 171-5-231B Sangolquı Ecuador3Department of Physiology Anatomy and Genetics University of Oxford Le Gros Clark Building South Parks RoadOxford OX1 3QX UK4Department of Pharmacology Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico NacionalAvenida Instituto Politecnico Nacional 2508 07360 Mexico City DF Mexico5Department of Genetics and Molecular Biology Centro de Investigacion y de Estudios Avanzados delInstituto Politecnico Nacional Avenida Instituto Politecnico Nacional 2508 07360 Mexico City DF Mexico

Correspondence should be addressed to Javier Camacho fcamachocinvestavmx

Received 15 March 2016 Accepted 10 May 2016

Academic Editor Alexandr V Bazhin

Copyright copy 2016 Gabriela Vilema-Enrıquez et al This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

Lung cancer has a very high mortality-to-incidence ratio representing one of the main causes of cancer mortality worldwideTherefore new treatment strategies are urgently needed Several diseases including lung cancer have been associated with theaction of reactive oxygen species (ROS) from which hydrogen peroxide (H

2O2) is one of the most studied Despite the fact

that H2O2may have opposite effects on cell proliferation depending on the concentration and cell type it triggers several

antiproliferative responses H2O2produces both nuclear and mitochondrial DNA lesions increases the expression of cell adhesion

molecules and increases p53 activity and other transcription factors orchestrating cancer cell death In addition H2O2facilitates

the endocytosis of oligonucleotides affects membrane proteins induces calcium release and decreases cancer cell migration andinvasion Furthermore the MAPK pathway and the expression of genes related to inflammation including interleukins TNF-120572and NF-120581B are also affected by H

2O2 Herein we will summarize the main effects of hydrogen peroxide on human lung cancer

leading to suggesting it as a potential therapeutic tool to fight this disease Because of the multimechanistic nature of this moleculenovel therapeutic approaches for lung cancer based on the use of H

2O2may help to decrease the mortality from this malignancy

1 Introduction

Lung cancer is one of themain causes of cancer deaths world-wide [1] Lung cancer can be divided into two major groupsaccording to the pathological classification small-cell lungcancer (SCLC) and non-small-cell lung cancer (NSCLC)NSCLC is a cancer of epithelial origin that comprises severalhistological subtypes that differ in their cytology embryonicorigin anatomical location and oncogene expression [2]Themost common subtypes of NSCLC are adenocarcinoma (40

of all forms of lung cancer) squamous cell carcinoma (25 to30) and large-cell carcinoma (10 to 15) [3]More than 80of NSCLC display in many cases high metastatic potentialand drug resistance resulting in poor prognosis even withan early diagnosis [4]Therefore new treatment strategies areurgently needed

Reactive oxygen species (ROS) are radicals molecules orions with a sole unpaired electron in the outermost shell ofelectrons [5] They are well known cytotoxic agents involvedin the etiology of several human diseases including cancer

Hindawi Publishing CorporationOxidative Medicine and Cellular LongevityVolume 2016 Article ID 1908164 12 pageshttpdxdoiorg10115520161908164

2 Oxidative Medicine and Cellular Longevity

Accordingly the expression of ROS detoxifying antioxidantproteins is altered in cancer cells in comparison to normalcells For instance thioredoxin reductase thioredoxin per-oxiredoxin glutathione S-transferase pi 1 glucose-6-phos-phate dehydrogenase and apurinicapyrimidinic endonucle-ase 1ref-1 (APE1ref-1) have been found to be increasedwhile glutamate-cysteine ligase and 120574-glutamyltransferasehave been found to be decreased in lung cancer cells [67] APE1ref-1 is a key enzyme in base excision repair andin the transcriptional modulation against oxidative stressAPE1ref-1 is mainly localized in the nucleus of nontumorregions of the lung cancer tissue samples However nuclearand cytoplasmic expression of APE1ref-1 is markedly upreg-ulated inNSCLC and the treatment ofH460 lung cancer cellswith hydrogen peroxide increases APE1ref-1 expression [7]

ROS are considered potential carcinogens since they playa role inmutagenesis cancer promotion and progression [8]However ROS also have anticancer properties by decreasingcell proliferation damaging DNA and inducing apoptosisamong other mechanisms One of the most studied ROS ishydrogen peroxide (H

2O2)

2 Hydrogen Peroxide

H2O2is a protonated form of O

2

2minus and is produced inbiological systems by the dismutation of superoxide anion ina reaction carried out by the enzyme superoxide dismutase(SOD) in the following manner [9]

M(119899+1)+-SOD +O2

minus997888rarr M119899+-SOD +O

2

M119899+-SOD +O2

minus+ 2H+ 997888rarr M(119899+1)+-SOD +H

2O2

(1)

where M = Cu(119899 = 1) Mn(119899 = 2) Fe(119899 = 2) Ni(119899 = 2)H2O2is also a soluble lipid and strong oxidizing agent that

has been suggested to diffuse throughout the cell membranevia some aquaporins like aquaporin-8 AtTIP11 andAtTIP12[10 11] H

2O2is also a hypochlorous acid precursor [9 12]

This ROS reacts in the presence of transition metals likecupper or iron and produces the hydroxyl radical a powerfulreactive and toxic compound

One of the preferred targets for H2O2is the DNA it

produces single- or double-stranded DNA breaks as wellas DNA cross links in addition to purine pyrimidine ordeoxyribose modifications [13] Changes in DNA are usuallyrepaired by the cell but when persistent DNAdamage occursthen replication errors genomic instability activation ofoncogenes and inactivation of tumor suppressor genesmightemerge [14] All of these processes have been associated withthe development of a variety of cancers However increasingevidence shows that H

2O2has contrasting effects on cancer

cell proliferation depending on its concentration it generatesseveral antiproliferative responses induces apoptosis andinhibits cancer cell migration and invasion

3 Effects of H2O2 on Plasma Membrane andCalcium Mobilization

Ion channels play important roles in health and diseaseand Ca2+ signaling is an important second messenger that

participates in many processes including proliferation andapoptosis H

2O2increases intracellular Ca2+ concentration

and decreases electrical resistance in human lung microvas-cular endothelial cells via activation of TRPV4 ion chan-nels through a mechanism that requires the Src tyrosinekinase Fyn [15] In addition exposure to H

2O2increases

intracellular Ca2+ concentration in rat alveolar type IIepithelial cells [16] and induces calcium release from theendoplasmic reticulum in endothelial cells [17] Ma andcollaborators observed that A549 lung cancer cells treatedwith H

2O2(500120583M) showed an intracellular Ca2+ ele-

vation due to Ca2+ influx and Ca2+ mobilization fromintracellular stores They also describe that H

2O2increases

polyethylenimineoligonucleotide endocytosis by activat-ing the calciumcalmodulin-dependent protein kinase II(CaMKII) This study suggests that H

2O2may be useful

to improving aerosol oligonucleotide therapy in pulmonarydiseases [18] Zhang et al also observed that H

2O2increases

the cytoplasmic Ca2+ concentration in A549 cells [19] thischange in calcium concentration might be a critical regulatorof apoptosis Another plasma membrane effect of H

2O2is

on adhesion molecules that are important for permeabilityand signaling transduction in lung epithelium [20] WhenA549 cells were stimulated byH

2O2the levels of the adhesion

molecules CD49f CD49b CD29 and CD44 were increasedThe expression of these molecules is closely associated withthe stress response [21] The effect of H

2O2on the plasma

membrane and intracellular calcium concentration may bealready involved in triggering cell death (Figure 1)

4 H2O2 Induces Nuclear andMitochondrial DNA Damage

Cells are constantly exposed to reactive oxygen speciesincluding those metabolically generated as products of aer-obic respiration [32 33] and those originated from environ-mental pollutants [34] It has been observed that hydrogenperoxide concentrations above 100120583M are cytotoxic andgenotoxic in A549 cells [35] causing DNA damage [36]and inducing the catalytic activities of DNA topoisomerasecomplexes [37ndash39] Furthermore the H

2O2-induced damage

could be also revealed by the oxidation of DNA bases forinstance guanine adducts like 8-oxo-78-dihydro-21015840-deoxy-guanosine (8-oxo-dG) [40] H

2O2DNA damage triggers a

complex network of DNA damage response (DDR) pathwaysthatmay initiateDNArepair arrest cell cycle progression andtrigger apoptosis In A549 cells H

2O2activates DDR through

the Mre11 (MRN) complex of proteins (Mre11 Rad50 andNbs1) which are essential for activation of telangiectasiamutated protein kinase (ATM) checkpoint kinase 2 (Chk2)and H2AX (120574H2AX) After Chk2 activation the cells becomearrested at either the G2-M or G1-S transition [41] Moreovertotal p53 and p21Cip1Waf1 levels were increased after exposureof A549 cells to H

2O2[42] These DNA damage response

events induce the formation of DNA damage foci thatprobably will be activated by stalled replication forks as wellas by the induction of DNA double-strand breaks (DSBs)at the primary DNA lesion sites [43] It has been described

Oxidative Medicine and Cellular Longevity 3

H2O2

H2O2

H 2O2

H2 O

2

H2 O

2H2O2

H2 O

2

Calciumrelease

adhesionmolecules

PARP-1

PARG

Strandbreaks

8-oxo-dG

[Ca2+]

TRPcalciumchannels

Nbs1 Mre11

Rad50

ATM

P

P

P

Chk2

H2AX

p53 p21

caspases 37

Cyt C

BAX

Bcl-2

Bcl-2

ΔΨm

aco-2 hOgg1

mtAPE1

Protectsagainst

mtDNAmutations

Figure 1 Effects of H2O2that may lead to cell death H

2O2affects several compartments and proteins potentially leading to cell death

Oxidation of DNA bases enriched with guanine adducts like oxo8dG base ring fragmentation sugar modification covalent cross linkingof DNA and protein and induction of DNA strand breaks may occur as a result of oxidative DNA damage induced by H

2O2[22] Chk2

plays a major role in arresting the cell cycle progression in response to DNA damage [23] Phosphorylation of Cdc25C and Cdc25A by Chk2prevents cell cycle progression [24] DDR involves the activation of the kinases ATM and Chk2 and their downstream effector p53 and itstarget p21Cip1Waf1 axis [25 26] Overexpression of Aco-2 reduced oxidant-induced mtDNA lesions mitochondrial p53 translocation andapoptosis Bcl-2 family proteins control the relocalization and actions of cytochrome C a relevant step of apoptotic cell death [27] H

2O2also

increases caspase-3caspase-7 activity [28] and upregulates the cleaved-caspase-9 [27] modifying the ΔΨm [28] Apoptosis is also relatedwith increased Ca2+ concentration that may be increased by influx via TRP ion channels or released from intracellular stores [29ndash31]

that H2O2activates poly(ADP-ribose) polymerase (PARP)

enzymes whenDNA strand breaks have been paired with theactivation of PARP-1 and poly(ADP-ribose) glycohydrolase(PARG) suggesting that this activation process is a survivalmechanism Three members of the 17-member PARP family(PARP-1 to PARP-3) have been shown to be activated byDNA damage Activated PARP enzymes cleave NAD+ intonicotinamide and ADP-ribose from which protein-bound(ADP-ribose)n polymers are synthesized these polymerslabel the site of DNA damage enhancing DNA repair andconsequently cell survival [44 45] Even though PARP acti-vation has a central role inDNA single-strand break repair itsoveractivation can cause cell death if excessive oxidative stressexists (in which DNA damage is severe and irreversible) [44]On the other hand repair of some DSBs can be error-prone

resulting in deletion of base pairs and other defects thatcan result in translocations and chromosomal instability[46ndash49] The association between DNA oxidation and DNAmethylation inA549 cells exposed toH

2O2has been reported

by Ke et al Hydrogen peroxide induced the formation of 5-methylcytosine (5-mC) which is a cytosine variant producedby the transfer of a methyl group to the carbon located in thefifth position of cytosine These authors showed that H

2O2

induced decreased levels of DNA methylation in a dose-dependent manner although significant changes in the levelof DNA methylation required at least 10 days of exposureto the oxidant This negative correlation suggests that DNAoxidation may take place before DNA methylation [40]

Not only nuclear DNA (nDNA) but also mitochondrialDNA (mtDNA) can be damaged by hydrogen peroxide


The rate of mtDNA mutations may actually be more thantwo orders of magnitude higher than that of nDNA Somaticmutations of mtDNA are potentially more harmful for cellphysiology compared to somatic damage of nDNA conse-quently the DNA repair systems may play a more importantrole in themitochondria than in the nuclei especially in non-dividing cells [50] This could be explained because mtDNAis in close proximity to the electron transport chain and dueto the lack of protective histones [51 52] Even though themechanisms that modulate mtDNA damage are still unclearKim et al suggest that human 8-oxoguanineDNAglycosylase(hOgg1) and aconitase-2 (aco-2) are important factors inlimiting oxidant-inducedmitochondrial DNA damageThusH2O2induces nuclear and mitochondrial DNA damage by

severalmechanisms [53] HumanAPE1 is amajor componentof the base excision repair in both nDNA and mtDNA [54]in various types of cells including lung cancer cells [7 55] Ithas been shown that Bcl-2 suppresses mtDNA repair throughdirect interaction with APE1 in mitochondria via its BHdomains and inhibition of mtAPE1 endonuclease activity[56] This led to increased frequency of mtDNA mutationsfollowing H

2O2or nitrosamine 4-(methylnitrosamino)-1-(3-

pyridyl)-1-butanone (a carcinogen in cigarette smoke) expo-sure in H1299 human lung cells [56] Moreover increasedmitochondrial DNA (mtDNA) lesions in A549 cells havebeen reported after exposure to H

2O2in a dose-dependent

manner the effect also included a slight reduction inmtDNAcopy number [53] Figure 1 summarizes the effects ofH

2O2on

DNA damage

5 Paradoxical Effects of H2O2 on Cancer CellProliferation and Migration

ROShave been proposed to have contrasting effects on cancermodels On one hand ROS may promote cancer initiationhowever they can also inhibit metastasis of melanoma cells[57 58] Opposite or dual effects for H

2O2on cancer cell

proliferation have also been described For instance H2O2

(50ndash200120583M) inhibits the proliferation of human breastcancer MCF-7 cells [59] but at 1ndash10 120583M it increases theproliferation of hepatoma 7721 cells [60] Interestingly theproliferation of HT-29 colon cancer cells is enhanced at10 120583M whereas a higher concentration (1000120583M) leads toapoptosis [61] H

2O2(50 120583M) also produced cell cycle arrest

in A549 lung cancer cells this effect correlated with thedownregulation of cyclins D1 and E [62] Cell migrationand invasion are very relevant in cancer progression andmalignancy Opposite effects of H

2O2on these phenomena

have also been observed The migration of H460 large lungcancer cells was inhibited by 100 120583M H

2O2 the superoxide

anion and hydrogen peroxide downregulated Cav-1 expres-sion and inhibited cell migration and invasion whereasthe hydroxyl radical upregulated Cav-1 expression and pro-moted cell migration and invasion The downregulatingeffect of superoxide anion and hydrogen peroxide on Cav-1 was mediated through a transcription-independent mech-anism that involved protein degradation via the ubiquitin-proteasome pathway [63] In H1299 non-small lung can-cer cells 100 120583M of H

2O2inhibited migration upregulated

Deleted in Liver Cancer 1 (DLC1) protein expression andreduced the activity of RhoA [64] Thus H

2O2may be used

as an inhibitor of cancer cell proliferation migration andinvasion if used at particular concentrations and cancer celltypes The potential use of this ROS as an anticancer agent isalso supported by its proapoptotic properties as the followingdiscussed

6 Hydrogen Peroxide Leads toCell DeathApoptosis

DNA damage responses usually end up with the decrease ofcell viability and activation of apoptosis pathways dependingon the stimulus intensity H

2O2induces cell deathapoptosis

[65ndash67] and attenuates cell viability of A549 cells in aconcentration- and time-dependent manner [68] One ofthe first damage mechanisms induced by oxidative stress iscarbonylation of lipids proteins and DNA as it has beenobserved in A549 lung cancer cells [69] Moreover H

2O2

decreases intracellular ATP levels and stimulates caspase-3caspase-7 activity [28] and upregulates the expression ofcleaved-caspase-9 [27] This nonradical ROS also affects themitochondrial membrane potential closely related to mito-chondrial-mediated apoptosis [28] Cui et al showed thatH2O2downregulates the antiapoptotic protein Bcl-2 upreg-

ulates the proapoptotic protein BAX and increases cyto-chrome C (Cyt C) release from the mitochondria (Figure 1)[27] It is well known that translocation of BAX from thecytosol to the mitochondria plays a role in the releaseof mitochondrial proteins [70] Prolonged dissipation ofmitochondrial membrane potential (ΔΨm)might result frommitochondrial DNA damage Therefore the upregulation ofBAX and the loss of the ΔΨm produced by H

2O2may be

responsible for the effect of BAX in the mitochondrial releaseof Cyt C inA549 cells Indeed the apoptotic intrinsic pathwayis activated by several mitochondrial proteins released intothe cytosol including Cyt C [71] In addition to its effects onapoptosis H

2O2(100120583M 6ndash24 hours) induced necrosis in

A549 cells [72] Thus H2O2leads to cell death in different

manners Additionally this ROS has effects on inflammationas reviewed in the next section

7 Inflammation ROS and H2O2 inLung Cancer

Chronic inflammation has been proposed to play a centralrole in cancer development Cancer-related inflammation isassociated with the proliferation and survival of malignantcells angiogenesis tumor metastasis and tumor response tochemotherapeutic drugs and hormones [73] Thus inflam-mation is a potential target for lung cancer prevention andtreatment Inflammatory cells release a variety of cytokineschemokines cytotoxicmediators including ROSmetallopro-teinases (MMPs) andmembrane-perforating agents and sol-uble mediators of cell death such as TNF-120572 (Tumor NecrosisFactor-120572) interleukins (IL) and interferons (IFNs) [74] Thetumor stroma of NSCLC is characterized by active angiogen-esis and abundant inflammatory infiltrate which is mainly


composed of tumor-associatedmacrophages (TAM) It is alsocharacterized by the presence of tumor infiltrating lympho-cytes (TIL) including T B and natural killer (NK) cells andtumor-associated neutrophils (TAN) [75 76] Several impor-tant molecules involved in the inflammatory response areregulated by or have been associated with ROS and H

2O2

71 TGF120573 Transforming growth factor-120573 (TGF120573) is animmunosuppressive cytokine [77] that has a pleiotropic rolein tumor biology and is frequently overexpressed in manycancers including NSCLC [78ndash80] TGF120573 affects cell growthproliferation differentiation and apoptosis [81] High expres-sion of TGF120573 is a poor survival predictor in NSCLC [79]Treatment of human malignant mesothelioma cells (HMM)with H

2O2promoted the epithelial-mesenchymal transition

as indicated by increased expression levels of vimentinSLUG and TWIST1 and decreased E-cadherin Expressionof stemness genes such as OCT4 SOX2 and NANOG wasalso significantly increased in HMM cells treated with H

2O2

These gene expression changes were mediated via activationof hypoxia inducible factor 1 alpha (HIF-1120572) and TGF-1205731 [82]

72 Interleukins Interleukin-10 (IL-10) is a multifunctionalcytokine with both immunosuppressive and antiangiogenicfunctions thus it has both tumor-promoting and tumor-inhibiting properties [83] Increased serum and peritumoralIL-10 levels have been reported in several malignancies [84]including lung cancer [83] suggesting a role for IL-10 in thetumor escape from the immune response High IL-10 expres-sion and increased serum concentrations of IL-10 in NSCLCpatients have been shown to correlate with reduced survival[83] IL-10 serum levels are higher in patients with metastaticdisease in contrast to patients with localized tumors [85] IL-10 favors tumor malignancy by promoting T cell apoptosisand tumor cell survival [86] In lung carcinomas IL-10inhibits tumor cell susceptibility to cytotoxic T-lymphocyte-mediated killing [87] Transgenic mice overexpressing IL-10developed larger tumors than control mice when injectedwith Lewis lung carcinoma cells suggesting that the produc-tion of IL-10 prevents a full immune response against thetumor cells [88] IL-6 is of particular interest because it isexpressed in malignant epithelial cells and their expressionis associated with a poor prognosis in lung cancer patients[89]This interleukin has been detected in primary squamouscell carcinomas adenocarcinomas and several tumor celllines [90 91] In a study with lung cancer patients increasedserum levels of IL-6 were found in 39 of the patientswhereas it was not detected in the serum of healthy controlsor in patients with benign lung diseases [90 92] Bihl andcoworkers demonstrated that IL-6 may be required for theproper control of cell proliferation in a subset of NSCLC celllines Two cell subgroups were reported in this study NSCLCIL-6-dependent and IL-6-independent cells this findingmayhave interesting clinical implications [93] Paradoxicallyantitumor effects of IL-6 have been demonstrated in vitroand in vivo as well as in human biopsies from NSCLC andbreast cancer [90] TNF-120572 induced IL-8 gene expression inH441 lung epithelial cells by activating the IL-8 promoter viarecruitment of NF-120581B to a TNF-120572 response element [94]

Similar results were obtained with lung adenocarcinomaGLC-82 cells treated with H

2O2(05mM) [95] In addition

Hsu et al described that A549 lung cancer cells treated withH2O2showed reduced I-120581120573 expression with a concomitant

increase in NF-120581B and IL-8 expression [21]

73 NF-120581B NF-120581B is a positive mediator of cell growth andproliferation as well as a critical signaling molecule in H

2O2-

induced inflammation NF-120581B increases the expression ofseveral components involved in cell cycle progression includ-ing cyclins D and E However the contributions of NF-120581Bto lung cancer development are complex and the underlyingmechanisms are not fully understood [96] Tumor biopsiesfrom lung cancer patients showed high levels of NF-120581Bactivation in both SCLC and NSCLC and were significantlyassociated with TNM (tumor size node status and metasta-sis) stages and poor prognosis [96] Interestingly inhibitingNF-120581Bwith either siRNA IKK inhibitors or IKK suppressorsinhibited lung cancer cell survival and proliferation [96 97]H2O2activates cytosolic phosphorylation of NF-120581B p65 and

ERK12 and induces nuclear translocation of pNF-120581B p65producing inflammatory damage in A549 lung cancer cellsThe genes involved in this response of the NF-120581B andMAPKsignaling pathways included IL-1120573 IL-6 IL-8 TNF-120572 MCP-1 IP-10 and MIP [98]

74 MMPs MMPs are a family of proteolytic enzymes thatare capable of degrading various components of the extracel-lularmatrix [99]They are involved in all stages of cancer pro-gression not only in the process of tumor invasion andmetas-tasis [100] but also in the proliferation adhesion migrationdifferentiation angiogenesis senescence autophagy apop-tosis and evasion of the immune system [101 102] Severalstudies have reported that plasma andor serum levels ofMMP-9 and TIMP-1 are elevated in stage IIIIV lung cancerpatients when compared with patients with nonmalignantlung diseases [103 104] Retrospective studies of NSCLCtissue found that MMP-7 expression was higher in squamouscell carcinomas than in adenocarcinomas and correlated withsignificantly lower overall survival in patients [105] MMP-9 is not produced by resident cells in the normal lung butbronchial epithelial cells alveolar type II cells fibroblastssmoothmuscle cells and endothelial cells produceMMP-9 inresponse to diverse stimuli [106] Leukocytes in the lung canalso be a source of MMP-9 Macrophages eosinophils mastcells lymphocytes NK cells and dendritic cells all are ableto produce MMP-9 [106] Lung cancer cells both primaryandmetastatic can expressMMP-9 constitutively whichmaycorrelate with metastatic potential [106ndash108]

The transcription factor Ets-1 was found to be associatedwith the progression of several human cancers includingNSCL [109] Ets-1 may upregulate MMP-9 expression trig-gered by TGF-beta1 and TPA via MAPK signaling [110]H2O2upregulates Ets-1 via an antioxidant response element

in the promoter suggesting its potential role inROS-triggeredtumor progression [111] Interestingly H

2O2inducedMMP-2

and MMP-9 expression in the lung adenocarcinoma cell lineGLC-82 as well as of several components activated by theinnate immune response including MyD88 TRAF2 TRAF6


and TRADD [95]The association of ROS with inflammationmight be used to suggest combined treatments of H

2O2with

anti-inflammatory drugs in cancer therapy

8 Potential H2O2-Based TherapeuticStrategies and Implications

Herein we described that hydrogen peroxide has severaleffects on lung cancer cells including DNA damage cellcycle arrest apoptosis migration and inflammation Becausemany of these mechanisms end up with cell death cautiousdelivery of H

2O2may be used as a potential therapeutic tool

to treat some disorders including lung cancer Actually oppo-site effects of H

2O2may be also used in favor of some con-

ditions For instance H2O2(30 120583M) induced the migration

of A549 cells showing that the exposure to low concentra-tions of hydrogen peroxide may benefit tissue repair duringacute lung injury [112] Furthermore H

2O2has been used

to enhance the adhesion of hematopoietic stemprogenitorcells when systemically administered in inflammatory boweldisorders [113]

A few years ago a hydrogen peroxide-generating systememerged as an interesting anticancer alternative strategy toselectively kill cancer cells As cancer cells generate highconcentrations of ROS and are under increased intrinsicoxidative stress they might be more vulnerable to furtheroxidative insults produced by ROS-generating agents [114] Inmalignant cells prooxidant changes induce a redox shift thatturns the cancer cell proliferative machinery on leading tofunctional impairment cell cycle arrest and finally cell deathEven if the direct administration ofH

2O2to cancer patients is

not an accepted therapeutic strategy there is now convincingevidence that H

2O2-generating systems might be an efficient

way of killing cancer cells [115] For instance H2O2can

selectively induce apoptosis in cancer cells and mediate atleast in part the activity of several anticancer drugs includingpaclitaxel doxorubicin cisplatin casiopeınas and arsenic tri-oxide since these drugs generate ROS as a potential mode ofaction increasing the rate of cancer cell death [116] ActuallyH2O2seems to play an important role in oxidative stress-

induced cancer cell death [115 117] H2O2produced in

the mitochondria is able to induce cell cycle arrest andsenescence a combination thatmight suppress tumor growthwhen sublethal concentrations of ROS are generated inresponse to therapy [118] Not only synthetic products butalso natural compounds have been described as promisingcandidates to potentially increase ROS levels and attack awide variety of cancer cells For instance the codrug Bet-CA (a chemical combination of dichloroacetate and betulinicacid) increases ROS production and significantly alters mito-chondrial membrane potential gradient (ΔΨm) followed bythe release of Cyt C which prompts cells to undergo mito-chondria mediated apoptosis [119]

Recently cold atmospheric or nonthermal plasma hasbeen suggested as an alternative therapy for different types ofcancers with promising results obtained in vitro [120 121] aswell as in vivo [122 123] Nonthermal plasma can be producedby ionizing neutral gas moleculesatoms which leads to ahighly reactive gas at room temperature This gas contains

excited molecules and reactive species among its mostimportant constituents [123] The therapeutic effects of non-thermal plasma result from the generation of ROSwhich leadto ΔΨm mitochondrial ROS accumulation changes in thecell cycle expression of DNA damage markers like 120574H2AXand finally induction of apoptosis [120 121 123] Nonthermalplasma decreases the intracellular ATP concentration and theviability of A549 cells It also increases the number of apop-totic cells due to caspase activation In addition plasma altersthe mitochondrial membrane potential regulates the mRNAlevels of BAX BAX1 H2AX and Bcl-2 and modifies phos-phorylated ERK12MAPK protein levels [28]

Panieri et al demonstrated that NSCLC cells resistantto conventional anticancer treatment can be sensitized inthe presence of either high levels of H

2O2(48120583M) resulting

in DNA damage and irreversible ATP depletion (caspase-independent) or lower H

2O2concentrations (65 120583M) which

induces inhibition of glycolysis and abrogation of ATPrestoring mechanisms Thus cancers not responding toconventional therapies may be evaluated for their responseto different H

2O2concentrations Despite the fact that H

2O2

may activate the inflammatory response potentially leadingto cancer the combined use of H

2O2with anti-inflammatory

drugs may preserve the anticancer effect of this ROS andoverwhelm the potential inflammatory response improvingthe anticancer treatment

Recently several drugs indicated for other diseases havebeen shown to have antiproliferative properties andhave beensuggested as an alternative therapy for different malignanciesincluding lung cancer [124] Thus the novel combination ofH2O2with such repositioned drugs represents a new research

area in cancer therapy

9 Conclusions

Because of the multimechanistic and multitarget anticancerproperties of H

2O2 this molecule is a very interesting poten-

tial therapeutic tool to fight cancer (Figure 2) The properand cautious use of H

2O2in combination with commonly

used chemotherapeutic drugs may have synergistic effectsincreasing lung cancer cell death Particularly novel thera-peutic approaches combining H

2O2with repositioned drugs

may help to decrease the mortality from this malignancy

Abbreviations

aco-2 Aconitase-2APE1ref-1 Apurinicapyrimidinic endonuclease 1ref-1APE1 Purinicapyrimidinic (AP) endonuclease 1ATM Activation of telangiectasia mutated protein

kinaseATP Adenosine triphosphateBcl-2 B cell lymphoma 2CaMKII Calciumcalmodulin-dependent protein

kinase IICav-1 Caveolin-1CD49f Cluster of differentiationCDKs Cyclin dependent kinasesChk2 Checkpoint kinase 2


H2O2

H2O2

H+

2 O2

H2O2

H2O2 ROS

Proliferation

Cancer cells

uarr apoptosis

darr proliferation

Migration and invasion

Normal tissue

Therapeutic ROS productionArtificial

ROS-generating system

Cell death

Synergic effect with anticanceror repositioned drugs

Anticancerdrugs

Anticancerdrugs

Anticancerdrugs

Anticancer

drugsRepositioned drugs

Repositioned drugs

Cell death

uarruarruarr cell death

Anticancer drug response

Resistant

Sensitive+

Figure 2 Potential therapeutic use of H2O2to fight lung cancer H

2O2can decrease the proliferation and increase the apoptosis of lung cancer

cells In addition metastasis may be prevented because of the inhibitory effects of H2O2in cell migration and invasion Artificial ROS-H

2O2

production directed to cancer cells in an excessive manner may lead also to cell death H2O2may also increase the cytotoxicity of anticancer

drugs and revert drug resistance as well as potentiating the effect of repositioned drugs with anticancer effects

Cyt C Cytochrome CDDR DNA damage responseDLC1 Deleted in Liver Cancer 1DSBs DNA double-strand breaksERK12 Extracellular-signal-regulated kinasesFyn Nonreceptor tyrosine kinaseH2AX Histone family member XH2O2 Hydrogen peroxide

HIF-1120572 Hypoxia inducible factor 1 alphaHMM Human malignant mesothelioma cellshOgg1 Human 8-oxoguanine DNA glycosylaseIFNs InterferonsIKK IkB kinaseIL InterleukinsIP-10 Interferon gamma-induced protein 10MCP-1 Monocyte chemotactic protein 1MIP Macrophage Inflammatory ProteinsMMPs MetalloproteinasesMRN Complex of Mre11 Rad50 and Nbs1 proteinsmtDNA Mitochondrial DNA

nDNA Nuclear DNANbs1 NibrinNF-120581B Nuclear factor kappa-light-chain-enhancer of

activated B cellsNK Natural killerNSCLC Non-small-cell lung cancerOCT4 Octamer-binding transcription factor 4PARG Poly(ADP-ribose) glycohydrolasePARP Poly(ADP-ribose) polymeraseRad50 Double-strand break repair proteinROS Reactive oxygen speciesSCLC Small-cell lung cancersiRNA Small interfering RNSOD Superoxide dismutaseSOX2 Sex determining region Y-box 2Src Nonreceptor tyrosine kinaseTAM Tumor-associated macrophagesTAN Tumor-associated neutrophilsTGF120573 Transforming growth factor-120573TIL Tumor infiltrating lymphocytes


TIMP-1 Tissue metallopeptidase inhibitorTNF-120572 Tumor Necrosis Factor-120572TRPV4 Transient receptor potential cation channel

subfamily V member 4ΔΨm Mitochondrial membrane potential

Disclosure

Gabriela Vilema-Enrıquez is a recipient of a doctoral schol-arship from the Ecuadorian government through the Secre-tariat for Higher Education Science Technology and Inno-vation (SENESCYT)

Competing Interests

The authors declare that they have no competing interests

Authorsrsquo Contributions

Gabriela Vilema-Enrıquez and Aurora Arroyo contributedequally to this work

References

[1] World Health OrganizationThe Top 10 Causes of Death WorldHealth Organization Geneva Switzerland 2014 httpwwwwhointmediacentrefactsheetsfs310en

[2] W D Travis ldquoPathology of lung cancerrdquo Clinics in ChestMedicine vol 23 no 1 pp 65ndash81 2002

[3] J R Molina P Yang S D Cassivi S E Schild and A A AdjeildquoNon-small cell lung cancer epidemiology risk factors treat-ment and survivorshiprdquoMayo Clinic Proceedings vol 83 no 5pp 584ndash594 2008

[4] G Zalcman E Bergot and E Lechapt ldquoUpdate on nonsmallcell lung cancerrdquo European Respiratory Review vol 19 no 117pp 173ndash185 2010

[5] G-Y Liou and P Storz ldquoReactive oxygen species in cancerrdquo FreeRadical Research vol 44 no 5 pp 479ndash496 2010

[6] R Tobe B Carlson P Tsuji B Lee V Gladyshev and D Hat-field ldquoDifferences in redox regulatory systems in human lungand liver tumors suggest different avenues for therapyrdquoCancersvol 7 no 4 pp 2262ndash2276 2015

[7] D G Yoo Y J Song E J Cho et al ldquoAlteration of APE1ref-1 expression in non-small cell lung cancer the implicationsof impaired extracellular superoxide dismutase and catalaseantioxidant systemsrdquo Lung Cancer vol 60 no 2 pp 277ndash2842008

[8] G Waris and H Ahsan ldquoReactive oxygen species role in thedevelopment of cancer and various chronic conditionsrdquo Journalof Carcinogenesis vol 5 article 14 2006

[9] G Manda M T Nechifor and T-M Neagu ldquoReactive oxygenspecies cancer and anti-cancer therapiesrdquo Current ChemicalBiology vol 3 no 1 pp 22ndash46 2009

[10] G P Bienert A L B Moslashller K A Kristiansen et al ldquoSpecificaquaporins facilitate the diffusion of hydrogen peroxide acrossmembranesrdquoThe Journal of Biological Chemistry vol 282 no 2pp 1183ndash1192 2007

[11] A CMontezano andRM Touyz ldquoInformation of the Editorialis now providedrdquo in Reactive Oxygen Species and theCardiovas-cular System Morgan and Claypool Life Sciences San RafaelCalif USA 2012

[12] V J Thannickal and B L Fanburg ldquoReactive oxygen species incell signalingrdquo American Journal of PhysiologymdashLung CellularandMolecular Physiology vol 279 no 6 pp L1005ndashL1028 2000

[13] B Halliwell and J Gutteridge Free Radicals in Biology andMedicine Oxford University Press Oxford UK 2015

[14] S Negrini V G Gorgoulis and T D Halazonetis ldquoGenomicinstability an evolving hallmark of cancerrdquo Nature ReviewsMolecular Cell Biology vol 11 no 3 pp 220ndash228 2010

[15] K Suresh L Servinsky J Reyes et al ldquoHydrogen peroxide-induced calcium influx in lung microvascular endothelial cellsinvolves TRPV4rdquo American Journal of PhysiologymdashLung Cellu-lar and Molecular Physiology vol 309 no 12 pp L1467ndashL14772015

[16] K L Rice P G Duane S L Archer D P Gilboe and D ENiewoehner ldquoH

2O2injury causes Ca2+-dependent and inde-

pendent hydrolysis of phosphatidylcholine in alveolar epithe-lial cellsrdquo American Journal of PhysiologymdashLung Cellular andMolecular Physiology vol 263 no 4 pp L430ndashL438 1992

[17] T Volk M Hensel and W J Kox ldquoTransient Ca2+ changesin endothelial cells induced by low doses of reactive oxygenspecies role of hydrogen peroxiderdquo Molecular and CellularBiochemistry vol 171 no 1-2 pp 11ndash21 1997

[18] Z Ma W W Sun and X Wang ldquoHydrogen peroxide enhancesthe uptake of polyethylenimineoligonucleotide complexes inA549 cells by activating CaMKII independent of [ca2+]c eleva-tionrdquo Genetics and Molecular Research vol 13 no 2 pp 2914ndash2921 2014

[19] S Zhang C Li J Gao X Qiu and Z Cui ldquo[Application of theCa2+ indicator fluo-3 and fluo-4 in the process of H

2O2induced

apoptosis of A549 cell]rdquo Chinese Journal of Lung Cancer vol 17no 3 pp 197ndash202 2014

[20] A Laitinen and L A Laitinen ldquoAirway morphology epithe-liumbasement membranerdquo American Journal of Respiratoryand Critical Care Medicine vol 150 no 5 pp S14ndashS17 1994

[21] J-Y Hsu J-J Chu M-C Chou and Y-W Chen ldquoDioscorinpre-treatment protects A549 human airway epithelial cells fromhydrogen peroxide-induced oxidative stressrdquo Inflammationvol 36 no 5 pp 1013ndash1019 2013

[22] K B Beckman and B N Ames ldquoOxidative decay of DNArdquoJournal of Biological Chemistry vol 272 no 32 pp 19633ndash196361997

[23] B-B S Zhou and S J Elledge ldquoThe DNA damage responseputting checkpoints in perspectiverdquo Nature vol 408 no 6811pp 433ndash439 2000

[24] C-Y Peng P R Graves R S Thoma Z Wu A S Shaw andH Piwnica-Worms ldquoMitotic and G2 checkpoint control regu-lation of 14-3-3 protein binding by phosphorylation of Cdc25con serine-216rdquo Science vol 277 no 5331 pp 1501ndash1505 1997

[25] J Bartkova N Rezaei M Liontos et al ldquoOncogene-inducedsenescence is part of the tumorigenesis barrier imposed byDNAdamage checkpointsrdquo Nature vol 444 no 7119 pp 633ndash6372006

[26] J Campisi and F D A di Fagagna ldquoCellular senescence whenbad things happen to good cellsrdquoNature ReviewsMolecular CellBiology vol 8 no 9 pp 729ndash740 2007

[27] J Cui H Zhao C Wang J J Sun K Lu and D Ma ldquoDexme-detomidine attenuates oxidative stress induced lung alveolarepithelial cell apoptosis in vitrordquo Oxidative Medicine and Cel-lular Longevity vol 2015 Article ID 358396 11 pages 2015


[28] NKaushikNUddinG B Sim et al ldquoResponses of solid tumorcells in DMEM to reactive oxygen species generated by non-thermal plasma and chemically inducedROS systemsrdquo ScientificReports vol 5 article 8587 2015

[29] I Kruman Q Guo and M P Mattson ldquoCalcium and reactiveoxygen species mediate staurosporine-induced mitochondrialdysfunction and apoptosis in PC12 cellsrdquo Journal of Neuro-science Research vol 51 no 3 pp 293ndash308 1998

[30] B Tombal S R Denmeade and J T Isaacs ldquoAssessmentand validation of a microinjection method for kinetic analysisof [Ca2+](i) in individual cells undergoing apoptosisrdquo CellCalcium vol 25 no 1 pp 19ndash28 1999

[31] K Lynch G Fernandez A Pappalardo and J J Peluso ldquoBasicfibroblast growth factor inhibits apoptosis of spontaneouslyimmortalized granulosa cells by regulating intracellular free cal-cium levels through a protein kinase C120575-dependent pathwayrdquoEndocrinology vol 141 no 11 pp 4209ndash4217 2000

[32] M M Vilenchik and A G Knudson ldquoEndogenous DNAdouble-strand breaks production fidelity of repair and induc-tion of cancerrdquo Proceedings of the National Academy of Sciencesof the United States of America vol 100 no 22 pp 12871ndash128762003

[33] H Zhao T Tanaka H DHalicka et al ldquoCytometric assessmentofDNAdamage by exogenous and endogenous oxidants reportsaging-related processesrdquo Cytometry Part A vol 71 no 11 pp905ndash914 2007

[34] E Taioli R J Sram S Garte I Kalina T A Popov and P BFarmer ldquoEffects of polycyclic aromatic hydrocarbons (PAHs)in environmental pollution on exogenous and oxidative DNAdamage (EXPAH project) description of the population understudyrdquoMutation ResearchmdashFundamental and Molecular Mech-anisms of Mutagenesis vol 620 no 1-2 pp 1ndash6 2007

[35] S Sharma V Venkatesan B M Prakhya and R BhondeldquoHumanmesenchymal stem cells as a novel platform for simul-taneous evaluation of cytotoxicity and genotoxicity of pharma-ceuticalsrdquo Mutagenesis vol 30 no 3 Article ID geu086 pp391ndash399 2015

[36] L Marabini R Calo and P C Braga ldquoProtective effect oferdosteine metabolite I against hydrogen peroxide-inducedoxidative DNA-damage in lung epithelial cellsrdquo Arzneimittel-Forschung vol 61 no 12 pp 700ndash706 2011

[37] T-K Li A Y Chen C Yu YMao HWang and L F Liu ldquoActi-vation of topoisomerase II-mediated excision of chromosomalDNA loops during oxidative stressrdquo Genes amp Development vol13 no 12 pp 1553ndash1560 1999

[38] P Daroui S D Desai T-K Li A A Liu and L F Liu ldquoHydro-gen peroxide induces topoisomerase I-mediated DNA damageand cell deathrdquoThe Journal of Biological Chemistry vol 279 no15 pp 14587ndash14594 2004

[39] M Lopez-Lazaro J M Calderon-Montano E Burgos-Moronand C A Austin ldquoGreen tea constituents (minus)-epigallocatechin-3-gallate (EGCG) and gallic acid induce topoisomerase I- andtopoisomerase II-DNA complexes in cells mediated by pyro-gallol-induced hydrogen peroxiderdquo Mutagenesis vol 26 no 4pp 489ndash498 2011

[40] Y Ke X Xu SMei X Xie andG Tao ldquoThe association of DNAmethylation and DNA oxidation induced by H

2O2rdquo Chinese

Journal of Industrial Hygiene and Occupational Diseases vol 32no 1 pp 50ndash54 2014

[41] H Zhao F Traganos A P Albino and Z DarzynkiewiczldquoOxidative stress induces cell cycle-dependent Mre11 recruit-ment ATM and Chk2 activation and histone H2AX phospho-rylationrdquo Cell Cycle vol 7 no 10 pp 1490ndash1495 2008

[42] A Sfikas C Batsi E Tselikou et al ldquoThe canonical NF-120581Bpath-way differentially protects normal and human tumor cells fromROS-induced DNA damagerdquo Cellular Signalling vol 24 no 11pp 2007ndash2023 2012

[43] H Zhao J Dobrucki P Rybak F Traganos H Dorota Halickaand Z Darzynkiewicz ldquoInduction of DNA damage signaling byoxidative stress in relation to DNA replication as detected usinglsquoclick chemistryrsquordquo Cytometry Part A vol 79 no 11 pp 897ndash9022011

[44] K Kovacs K Erdelyi C Hegeds et al ldquoPoly(ADP-ribosyl)ationis a survival mechanism in cigarette smoke-induced and hydro-gen peroxide-mediated cell deathrdquo Free Radical Biology andMedicine vol 53 no 9 pp 1680ndash1688 2012

[45] K Erdelyi P Pacher L Virag and C Szabo ldquoRole of poly(ADP-ribosyl)ation in a lsquotwo-hitrsquomodel of hypoxia and oxidative stressin human A549 epithelial cells in vitrordquo International Journal ofMolecular Medicine vol 32 no 2 pp 339ndash346 2013

[46] V Gorbunova and A Seluanov ldquoMaking ends meet in old ageDSB repair and agingrdquoMechanisms of Ageing and Developmentvol 126 no 6-7 pp 621ndash628 2005

[47] Z E Karanjawala and M R Lieber ldquoDNA damage and agingrdquoMechanisms of Ageing and Development vol 125 no 6 pp 405ndash416 2004

[48] E Pastwa and J Błasiak ldquoNon-homologous DNA end joiningrdquoActa Biochimica Polonica vol 50 no 4 pp 891ndash908 2003

[49] P A Jeggo and M Lobrich ldquoArtemis links ATM to doublestrand break rejoiningrdquo Cell Cycle vol 4 no 3 pp 359ndash3622005

[50] I N Todorov and G I Todorov ldquoMultifactorial nature of highfrequency of mitochondrial DNA mutations in somatic mam-malian cellsrdquo Biochemistry vol 74 no 9 pp 962ndash970 2009

[51] BVanHoutenVWoshner and JH Santos ldquoRole ofmitochon-drial DNA in toxic responses to oxidative stressrdquo DNA Repairvol 5 no 2 pp 145ndash152 2006

[52] T R Figueira M H Barros A A Camargo et al ldquoMitochon-dria as a source of reactive oxygen and nitrogen species frommolecular mechanisms to human healthrdquo Antioxidants andRedox Signaling vol 18 no 16 pp 2029ndash2074 2013

[53] S-J Kim P Cheresh DWilliams et al ldquoMitochondria-targetedOgg1 and aconitase-2 prevent oxidant-induced mitochondrialDNA damage in alveolar epithelial cellsrdquoThe Journal of Biolog-ical Chemistry vol 289 no 9 pp 6165ndash6176 2014

[54] B Karahalil B A Hogue N C De Souza-Pinto and V ABohr ldquoBase excision repair capacity inmitochondria andnucleitissue-specific variationsrdquoThe FASEB Journal vol 16 no 14 pp1895ndash1902 2002

[55] G Tell G Damante D Caldwell and M R Kelley ldquoTheintracellular localization of APE1Ref-1 more than a passivephenomenonrdquo Antioxidants amp Redox Signaling vol 7 no 3-4pp 367ndash384 2005

[56] M Xie P W Doetsch and X Deng ldquoBcl2 inhibition ofmitochondrial DNA repairrdquo BMCCancer vol 15 no 1 pp 1ndash122015

[57] E Piskounova M Agathocleous M M Murphy et al ldquoOxida-tive stress inhibits distantmetastasis by humanmelanoma cellsrdquoNature vol 527 no 7577 pp 186ndash191 2015


[58] I S Harris and J S Brugge ldquoCancer the enemy of my enemy ismy friendrdquo Nature vol 527 no 7577 pp 170ndash171 2015

[59] P-J Chua G W-C Yip and B-H Bay ldquoCell cycle arrestinduced by hydrogen peroxide is associated with modulation ofoxidative stress related genes in breast cancer cellsrdquo Experimen-tal Biology and Medicine vol 234 no 9 pp 1086ndash1094 2009

[60] S-L Liu X Lin D-Y Shi J Cheng C-Q Wu and Y-DZhang ldquoReactive oxygen species stimulated human hepatomacell proliferation via cross-talk between PI3-KPKB and JNKsignaling pathwaysrdquo Archives of Biochemistry and Biophysicsvol 406 no 2 pp 173ndash182 2002

[61] I-J Park J-T Hwang M K Young J Ha and J P Ock ldquoDif-ferential modulation of AMPK signaling pathways by low orhigh levels of exogenous reactive oxygen species in colon cancercellsrdquo Annals of the New York Academy of Sciences vol 1091 no1 pp 102ndash109 2006

[62] D Upadhyay W Chang K Wei M Gao and G D RosenldquoFibroblast growth factor-10 prevents H

2O2-induced cell cycle

arrest by regulation of G1 cyclins and cyclin dependent kinasesrdquoFEBS Letters vol 581 no 2 pp 248ndash252 2007

[63] S Luanpitpong S J Talbott Y Rojanasakul et al ldquoRegulationof lung cancer cell migration and invasion by reactive oxygenspecies and caveolin-1rdquoThe Journal of Biological Chemistry vol285 no 50 pp 38832ndash38840 2010

[64] L Ma W-Z Zhu T-T Liu et al ldquoH2O2inhibits proliferation

and mediates suppression of migration via DLC1RhoA signal-ing in cancer cellsrdquo Asian Pacific Journal of Cancer Preventionvol 16 no 4 pp 1637ndash1642 2015

[65] J-P Chen D-G Xu X-Y Yu et al ldquoDiscrepancy between theeffects of morronside on apoptosis in human embryonic lungfibroblast cells and lung cancer A549 cellsrdquo Oncology Lettersvol 7 no 4 pp 927ndash932 2014

[66] H Su D-D Liu M Zhao et al ldquoDual-enzyme characteris-tics of polyvinylpyrrolidone-capped iridium nanoparticles andtheir cellular protective effect against H

2O2-induced oxidative

damagerdquoACS Applied Materials and Interfaces vol 7 no 15 pp8233ndash8242 2015

[67] Y I Chirino Y Sanchez-Perez A R Osornio-Vargas et alldquoPM10impairs the antioxidant defense system and exacerbates

oxidative stress driven cell deathrdquo Toxicology Letters vol 193no 3 pp 209ndash216 2010

[68] L Lanceta C Li A M Choi and J W Eaton ldquoHaem oxy-genase-1 overexpression alters intracellular iron distributionrdquoBiochemical Journal vol 449 no 1 pp 189ndash194 2013

[69] K Mukherjee T I Chio D L Sackett and S L BaneldquoDetection of oxidative stress-induced carbonylation in livemammalian cellsrdquo Free Radical Biology and Medicine vol 84pp 11ndash21 2015

[70] K Kandasamy S M Srinivasula E S Alnemri et al ldquoInvolve-ment of proapoptotic molecules Bax and Bak in tumor necro-sis factor-related apoptosis-inducing ligand (TRAIL)-inducedmitochondrial disruption and apoptosis differential regulationof cytochrome c and SmacDIABLO releaserdquo Cancer Researchvol 63 no 7 pp 1712ndash1721 2003

[71] C Garrido L Galluzzi M Brunet P E Puig C Didelot andG Kroemer ldquoMechanisms of cytochrome c release from mito-chondriardquo Cell Death amp Differentiation vol 13 no 9 pp 1423ndash1433 2006

[72] S-Y Chiou Y-S Lee M-J Jeng P-C Tsao and W-J SoongldquoModerate hypothermia attenuates oxidative stress injuries inalveolar epithelial A549 cellsrdquo Experimental Lung Research vol39 no 6 pp 217ndash228 2013

[73] A Mantovani P Allavena A Sica and F Balkwill ldquoCancer-related inflammationrdquo Nature vol 454 no 7203 pp 436ndash4442008

[74] L M Coussens and Z Werb ldquoInflammation and cancerrdquoNature vol 420 no 6917 pp 860ndash867 2002

[75] A Kataki P Scheid M Piet et al ldquoTumor infiltrating lympho-cytes andmacrophages have a potential dual role in lung cancerby supporting both host-defense and tumor progressionrdquo Jour-nal of Laboratory and Clinical Medicine vol 140 no 5 pp 320ndash328 2002

[76] A Carus M Ladekarl H Hager H Pilegaard P S Nielsen andF Donskov ldquoTumor-associated neutrophils and macrophagesin non-small cell lung cancer no immediate impact on patientoutcomerdquo Lung Cancer vol 81 no 1 pp 130ndash137 2013

[77] R A Flavell S Sanjabi S H Wrzesinski and P Licona-LimonldquoThe polarization of immune cells in the tumour environmentby TGF120573rdquo Nature Reviews Immunology vol 10 no 8 pp 554ndash567 2010

[78] A Bruno C Focaccetti A Pagani et al ldquoThe proangiogenicphenotype of natural killer cells in patients with non-small celllung cancerrdquo Neoplasia vol 15 no 2 pp 133ndash142 2013

[79] A L Teixeira A Araujo A Coelho et al ldquoInfluence ofTGFB1+869TgtC functional polymorphism in non-small celllung cancer (NSCLC) riskrdquo Journal of Cancer Research andClinical Oncology vol 137 no 3 pp 435ndash439 2011

[80] P M Siegel and J Massague ldquoCytostatic and apoptotic actionsof TGF-120573 in homeostasis and cancerrdquo Nature Reviews Cancervol 3 no 11 pp 807ndash820 2003

[81] X Luo Q Ding M Wang et al ldquoIn vivo disruption of TGF-120573 signaling by Smad7 in airway epithelium alleviates allergicasthma but aggravates lung carcinogenesis in mouserdquo PLoSONE vol 5 no 4 Article ID e10149 2010

[82] M-C Kim F-J Cui and Y Kim ldquoHydrogen peroxide promotesepithelial to mesenchymal transition and stemness in humanmalignant mesothelioma cellsrdquo Asian Pacific Journal of CancerPrevention vol 14 no 6 pp 3625ndash3630 2013

[83] C-M Shih Y-L Lee H-L Chiou et al ldquoThe involvement ofgenetic polymorphism of IL-10 promoter in non-small cell lungcancerrdquo Lung Cancer vol 50 no 3 pp 291ndash297 2005

[84] W Dummer J C Becker A Schwaaf M Leverkus T Molland E B Brocker ldquoElevated serum levels of interleukin-10in patients with metastatic malignant melanomardquo MelanomaResearch vol 5 no 1 pp 67ndash68 1995

[85] F De Vita M Orditura G Galizia et al ldquoSerum interleukin-10 levels as a prognostic factor in advanced non-small cell lungcancer patientsrdquo Chest vol 117 no 2 pp 365ndash373 2000

[86] Y-C Wang W-W Sung T-C Wu et al ldquoInterleukin-10 hap-lotype may predict survival and relapse in resected non-smallcell lung cancerrdquoPLoSONE vol 7 no 7 Article ID e39525 2012

[87] C Asselin-Paturel S Megherat I Vergnon et al ldquoDifferentialeffect of high doses versus low doses of interleukin-12 on theadoptive transfer of human specific cytotoxic T lymphocytein autologous lung tumors engrafted into severe combinedimmunodeficiency disease-nonobese diabetic mice relationwith interleukin-10 inductionrdquoCancer vol 91 no 1 pp 113ndash1222001

[88] LMMontuenga and R Pio ldquoTumour-associatedmacrophagesin nonsmall cell lung cancer the role of interleukin-10rdquo Euro-pean Respiratory Journal vol 30 no 4 pp 608ndash610 2007

[89] S R Pine L E Mechanic L Enewold et al ldquoIncreased levels ofcirculating interleukin 6 interleukin 8 C-reactive protein and


risk of lung cancerrdquo Journal of the National Cancer Institute vol103 no 14 pp 1112ndash1122 2011

[90] K-T Chang C-Y F Huang C-M Tsai C-H Chiu and Y-YLok ldquoRole of IL-6 in neuroendocrine differentiation andchemosensitivity of non-small cell lung cancerrdquo American Jour-nal of PhysiologymdashLung Cellular and Molecular Physiology vol289 no 3 pp L438ndashL445 2005

[91] A Azevedo V Cunha A L Teixeira and R Medeiros ldquoIL-6IL-6R as a potential key signaling pathway in prostate cancerdevelopmentrdquoWorld Journal of Clinical Oncology vol 2 no 12pp 384ndash396 2011

[92] H Yanagawa S Sone Y Takahashi et al ldquoSerum levels ofinterleukin 6 in patients with lung cancerrdquo British Journal ofCancer vol 71 no 5 pp 1095ndash1098 1995

[93] M Bihl M Tamm M Nauck H Wieland A P Perruchoudand M Roth ldquoProliferation of human non-small-cell lungcancer cell lines role of interleukin-6rdquoAmerican Journal of Res-piratory Cell and Molecular Biology vol 19 no 4 pp 606ndash6121998

[94] H Chandru and V Boggaram ldquoThe role of sphingosine 1-phosphate in the TNF-120572 induction of IL-8 gene expression inlung epithelial cellsrdquo Gene vol 391 no 1-2 pp 150ndash160 2007

[95] L Gallelli D Falcone M Scaramuzzino et al ldquoEffects ofsimvastatin on cell viability and proinflammatory pathwaysin lung adenocarcinoma cells exposed to hydrogen peroxiderdquoBMC Pharmacology and Toxicology vol 15 article 67 2014

[96] W Chen Z Li L Bai and Y Lin ldquoNF-kappaB in lung cancer acarcinogenesis mediator and a prevention and therapy targetrdquoFrontiers in Bioscience vol 16 no 3 pp 1172ndash1185 2011

[97] M Karin ldquoThe IkB kinase-a bridge between inflammation andcancerrdquo Cell Research vol 18 no 3 pp 334ndash342 2008

[98] WWang J-P Zheng S-X ZhuW-J GuanM Chen andN-SZhong ldquoCarbocisteine attenuates hydrogen peroxide-inducedinflammatory injury in A549 cells via NF-120581B and ERK12MAPK pathwaysrdquo International Immunopharmacology vol 24no 2 pp 306ndash313 2015

[99] D Liu H Guo Y Li X Xu K Yang and Y Bai ldquoAssociationbetween polymorphisms in the promoter regions of matrixmetalloproteinases (MMPs) and risk of cancer metastasis ameta-analysisrdquo PLoS ONE vol 7 no 2 Article ID e31251 2012

[100] Z Hu X Huo D Lu et al ldquoFunctional polymorphisms ofMatrix metalloproteinase-9 are associated with risk of occur-rence and metastasis of lung cancerrdquo Clinical Cancer Researchvol 11 no 15 pp 5433ndash5439 2005

[101] P Gonzalez-Arriaga T Pascual A Garcıa-Alvarez AFernandez-Somoano M F Lopez-Cima and A TardonldquoGenetic polymorphisms inMMP 2 9 and 3 genes modify lungcancer risk and survivalrdquo BMC Cancer vol 12 article 121 2012

[102] E I Deryugina and J P Quigley ldquoMatrix metalloproteinasesand tumor metastasisrdquo Cancer and Metastasis Reviews vol 25no 1 pp 9ndash34 2006

[103] C Jumper E Cobos and C Lox ldquoDetermination of the serummatrix metalloproteinase-9 (MMP-9) and tissue inhibitor ofmatrix metalloproteinase-1 (TIMP-1) in patients with eitheradvanced small-cell lung cancer or non-small-cell lung cancerprior to treatmentrdquo Respiratory Medicine vol 98 no 2 pp 173ndash177 2004

[104] M Koc D Ediger F Budak et al ldquoMatrix metalloproteinase-9 (MMP-9) elevated in serum but not in bronchial lavage inlung cancer patientsrdquo European Respiratory Journal vol 42supplement 57 Article ID P2898 2013

[105] D Liu J Nakano S Ishikawa et al ldquoOverexpression of matrixmetalloproteinase-7 (MMP-7) correlates with tumor prolifera-tion and a poor prognosis in non-small cell lung cancerrdquo LungCancer vol 58 no 3 pp 384ndash391 2007

[106] J J Atkinson and R M Senior ldquoMatrix metalloproteinase-9in lung remodelingrdquo American Journal of Respiratory Cell andMolecular Biology vol 28 no 1 pp 12ndash24 2003

[107] S Zucker R M Lysik M Malik B A Bauer J Caamanoand A J P Klein-Szanto ldquoSecretion of gelatinases and tissueinhibitors of metalloproteinases by human lung cancer celllines and revertant cell lines not an invariant correlation withmetastasisrdquo International Journal of Cancer vol 52 no 3 pp366ndash371 1992

[108] R R Baruch H Melinscak J Lo Y Liu O Yeung and R AR Hurta ldquoAltered matrix metalloproteinase expression asso-ciated with oncogene-mediated cellular transformation andmetastasis formationrdquo Cell Biology International vol 25 no 5pp 411ndash420 2001

[109] J Phuchareon FMcCormickDW Eisele andO Tetsu ldquoEGFRinhibition evokes innate drug resistance in lung cancer cells bypreventing Akt activity and thus inactivating Ets-1 functionrdquoProceedings of the National Academy of Sciences of the UnitedStates of America vol 112 no 29 pp E3855ndashE3863 2015

[110] H-C Huang S-Y Liu Y Liang Y Liu J-Z Li and H-YWang ldquoTransforming growth factor-1205731 stimulates matrix met-alloproteinase-9 production through ERK activation pathwayand upregulation of Ets-1 proteinrdquo Zhonghua Yi Xue Za Zhi vol85 no 5 pp 328ndash331 2005

[111] L AWilson A Gemin R Espiritu and G Singh ldquoets-1 is tran-scriptionally up-regulated by H

2O2via an antioxidant response

elementrdquo The FASEB Journal vol 19 no 14 pp 2085ndash20872005

[112] Z-R Shao Q Wang X-F Xu et al ldquoPhospholipase D partici-pates in H

2O2-induced A549 alveolar epithelial cell migrationrdquo

Experimental Lung Research vol 38 no 8 pp 427ndash433 2012[113] A Yemm D Adams and N Kalia ldquoTargeting the delivery

of systemically administered haematopoietic stemprogenitorcells to the inflamed colon using hydrogen peroxide and plateletmicroparticle pre-treatment strategiesrdquo Stem Cell Research vol15 no 3 pp 569ndash580 2015

[114] D Trachootham J Alexandre and P Huang ldquoTargeting can-cer cells by ROS-mediated mechanisms a radical therapeuticapproachrdquo Nature Reviews Drug Discovery vol 8 no 7 pp579ndash591 2009

[115] M Lopez-Lazaro ldquoDual role of hydrogen peroxide in cancerpossible relevance to cancer chemoprevention and therapyrdquoCancer Letters vol 252 no 1 pp 1ndash8 2007

[116] R Kachadourian H M Brechbuhl L Ruiz-Azuara I Gracia-Mora and B J Day ldquoCasiopeına IIgly-induced oxidative stressandmitochondrial dysfunction in human lung cancerA549 andH157 cellsrdquo Toxicology vol 268 no 3 pp 176ndash183 2010

[117] M Lopez-Lazaro ldquoA new view of carcinogenesis and an alter-native approach to cancer therapyrdquoMolecular Medicine vol 16no 3-4 pp 144ndash153 2010

[118] E Panieri V Gogvadze E Norberg R Venkatesh S Orreniusand B Zhivotovsky ldquoReactive oxygen species generated in dif-ferent compartments induce cell death survival or senescencerdquoFree Radical Biology and Medicine vol 57 pp 176ndash187 2013

[119] S Saha M Ghosh and S K Dutta ldquoA potent tumoricidalco-drug lsquoBet-CArsquomdashan ester derivative of betulinic acid anddichloroacetate selectively and synergistically kills cancer cellsrdquoScientific Reports vol 5 article 7762 2015


[120] O Volotskova T S Hawley M A Stepp and M KeidarldquoTargeting the cancer cell cycle by cold atmospheric plasmardquoScientific Reports vol 2 article 636 2012

[121] H J Ahn K I Kim N N Hoan et al ldquoTargeting cancer cellswith reactive oxygen and nitrogen species generated by atmos-pheric-pressure air plasmardquo PLoS ONE vol 9 no 1 Article IDe86173 2014

[122] M Keidar RWalk A Shashurin et al ldquoCold plasma selectivityand the possibility of a paradigm shift in cancer therapyrdquo BritishJournal of Cancer vol 105 no 9 pp 1295ndash1301 2011

[123] M Vandamme E Robert S Lerondel et al ldquoROS implicationin a new antitumor strategy based on non-thermal plasmardquoInternational Journal of Cancer vol 130 no 9 pp 2185ndash21942012

[124] H Lee S KangWKim and EHernandez-Lemus ldquoDrug repo-sitioning for cancer therapy based on large-scale drug-inducedtranscriptional signaturesrdquo PLoS ONE vol 11 no 3 Article IDe0150460 2016

Submit your manuscripts athttpwwwhindawicom

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


MEDIATORSINFLAMMATION

of


Behavioural Neurology

EndocrinologyInternational Journal of



Disease Markers


BioMed Research International

OncologyJournal of



Oxidative Medicine and Cellular Longevity


PPAR Research

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Immunology ResearchHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

ObesityJournal of



Computational and Mathematical Methods in Medicine

OphthalmologyJournal of


Diabetes ResearchJournal of



Research and TreatmentAIDS


Gastroenterology Research and Practice


Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom


Accordingly the expression of ROS detoxifying antioxidantproteins is altered in cancer cells in comparison to normalcells For instance thioredoxin reductase thioredoxin per-oxiredoxin glutathione S-transferase pi 1 glucose-6-phos-phate dehydrogenase and apurinicapyrimidinic endonucle-ase 1ref-1 (APE1ref-1) have been found to be increasedwhile glutamate-cysteine ligase and 120574-glutamyltransferasehave been found to be decreased in lung cancer cells [67] APE1ref-1 is a key enzyme in base excision repair andin the transcriptional modulation against oxidative stressAPE1ref-1 is mainly localized in the nucleus of nontumorregions of the lung cancer tissue samples However nuclearand cytoplasmic expression of APE1ref-1 is markedly upreg-ulated inNSCLC and the treatment ofH460 lung cancer cellswith hydrogen peroxide increases APE1ref-1 expression [7]

ROS are considered potential carcinogens since they playa role inmutagenesis cancer promotion and progression [8]However ROS also have anticancer properties by decreasingcell proliferation damaging DNA and inducing apoptosisamong other mechanisms One of the most studied ROS ishydrogen peroxide (H

2O2)

2 Hydrogen Peroxide

H2O2is a protonated form of O

2

2minus and is produced inbiological systems by the dismutation of superoxide anion ina reaction carried out by the enzyme superoxide dismutase(SOD) in the following manner [9]

M(119899+1)+-SOD +O2

minus997888rarr M119899+-SOD +O

2

M119899+-SOD +O2

minus+ 2H+ 997888rarr M(119899+1)+-SOD +H

2O2

(1)

where M = Cu(119899 = 1) Mn(119899 = 2) Fe(119899 = 2) Ni(119899 = 2)H2O2is also a soluble lipid and strong oxidizing agent that

has been suggested to diffuse throughout the cell membranevia some aquaporins like aquaporin-8 AtTIP11 andAtTIP12[10 11] H

2O2is also a hypochlorous acid precursor [9 12]

This ROS reacts in the presence of transition metals likecupper or iron and produces the hydroxyl radical a powerfulreactive and toxic compound

One of the preferred targets for H2O2is the DNA it

produces single- or double-stranded DNA breaks as wellas DNA cross links in addition to purine pyrimidine ordeoxyribose modifications [13] Changes in DNA are usuallyrepaired by the cell but when persistent DNAdamage occursthen replication errors genomic instability activation ofoncogenes and inactivation of tumor suppressor genesmightemerge [14] All of these processes have been associated withthe development of a variety of cancers However increasingevidence shows that H

2O2has contrasting effects on cancer

cell proliferation depending on its concentration it generatesseveral antiproliferative responses induces apoptosis andinhibits cancer cell migration and invasion

3 Effects of H2O2 on Plasma Membrane andCalcium Mobilization

Ion channels play important roles in health and diseaseand Ca2+ signaling is an important second messenger that

participates in many processes including proliferation andapoptosis H

2O2increases intracellular Ca2+ concentration

and decreases electrical resistance in human lung microvas-cular endothelial cells via activation of TRPV4 ion chan-nels through a mechanism that requires the Src tyrosinekinase Fyn [15] In addition exposure to H

2O2increases

intracellular Ca2+ concentration in rat alveolar type IIepithelial cells [16] and induces calcium release from theendoplasmic reticulum in endothelial cells [17] Ma andcollaborators observed that A549 lung cancer cells treatedwith H

2O2(500120583M) showed an intracellular Ca2+ ele-

vation due to Ca2+ influx and Ca2+ mobilization fromintracellular stores They also describe that H

2O2increases

polyethylenimineoligonucleotide endocytosis by activat-ing the calciumcalmodulin-dependent protein kinase II(CaMKII) This study suggests that H

2O2may be useful

to improving aerosol oligonucleotide therapy in pulmonarydiseases [18] Zhang et al also observed that H

2O2increases

the cytoplasmic Ca2+ concentration in A549 cells [19] thischange in calcium concentration might be a critical regulatorof apoptosis Another plasma membrane effect of H

2O2is

on adhesion molecules that are important for permeabilityand signaling transduction in lung epithelium [20] WhenA549 cells were stimulated byH

2O2the levels of the adhesion

molecules CD49f CD49b CD29 and CD44 were increasedThe expression of these molecules is closely associated withthe stress response [21] The effect of H

2O2on the plasma

membrane and intracellular calcium concentration may bealready involved in triggering cell death (Figure 1)

4 H2O2 Induces Nuclear andMitochondrial DNA Damage

Cells are constantly exposed to reactive oxygen speciesincluding those metabolically generated as products of aer-obic respiration [32 33] and those originated from environ-mental pollutants [34] It has been observed that hydrogenperoxide concentrations above 100120583M are cytotoxic andgenotoxic in A549 cells [35] causing DNA damage [36]and inducing the catalytic activities of DNA topoisomerasecomplexes [37ndash39] Furthermore the H

2O2-induced damage

could be also revealed by the oxidation of DNA bases forinstance guanine adducts like 8-oxo-78-dihydro-21015840-deoxy-guanosine (8-oxo-dG) [40] H

2O2DNA damage triggers a

complex network of DNA damage response (DDR) pathwaysthatmay initiateDNArepair arrest cell cycle progression andtrigger apoptosis In A549 cells H

2O2activates DDR through

the Mre11 (MRN) complex of proteins (Mre11 Rad50 andNbs1) which are essential for activation of telangiectasiamutated protein kinase (ATM) checkpoint kinase 2 (Chk2)and H2AX (120574H2AX) After Chk2 activation the cells becomearrested at either the G2-M or G1-S transition [41] Moreovertotal p53 and p21Cip1Waf1 levels were increased after exposureof A549 cells to H

2O2[42] These DNA damage response

events induce the formation of DNA damage foci thatprobably will be activated by stalled replication forks as wellas by the induction of DNA double-strand breaks (DSBs)at the primary DNA lesion sites [43] It has been described


H2O2

H2O2

H 2O2

H2 O

2

H2 O

2H2O2

H2 O

2

Calciumrelease

adhesionmolecules

PARP-1

PARG

Strandbreaks

8-oxo-dG

[Ca2+]

TRPcalciumchannels

Nbs1 Mre11

Rad50

ATM

P

P

P

Chk2

H2AX

p53 p21

caspases 37

Cyt C

BAX

Bcl-2

Bcl-2

ΔΨm

aco-2 hOgg1

mtAPE1

Protectsagainst

mtDNAmutations




2O2[22] Chk2


2O2also







2O2










2O2on

DNA damage



2O2on cancer cell







2O2 the superoxide




2O2may be used






2O2



2O2may be









2O2




2O2








2O2-






2O2inducedMMP-2




2O2with









2O2has been used


















2O2






9 Conclusions








Abbreviations





H2O2

H2O2

H+

2 O2

H2O2

H2O2 ROS

Proliferation

Cancer cells

uarr apoptosis

darr proliferation


Normal tissue



Cell death


Anticancerdrugs

Anticancerdrugs

Anticancerdrugs

Anticancer


Repositioned drugs

Cell death



Resistant

Sensitive+




2O2










Disclosure


Competing Interests




References






















2O2induced
























2O2rdquo Chinese









































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















H2O2

H2O2

H 2O2

H2 O

2

H2 O

2H2O2

H2 O

2

Calciumrelease

adhesionmolecules

PARP-1

PARG

Strandbreaks

8-oxo-dG

[Ca2+]

TRPcalciumchannels

Nbs1 Mre11

Rad50

ATM

P

P

P

Chk2

H2AX

p53 p21

caspases 37

Cyt C

BAX

Bcl-2

Bcl-2

ΔΨm

aco-2 hOgg1

mtAPE1

Protectsagainst

mtDNAmutations




2O2[22] Chk2


2O2also







2O2










2O2on

DNA damage



2O2on cancer cell







2O2 the superoxide




2O2may be used






2O2



2O2may be









2O2




2O2








2O2-






2O2inducedMMP-2




2O2with









2O2has been used


















2O2






9 Conclusions








Abbreviations





H2O2

H2O2

H+

2 O2

H2O2

H2O2 ROS

Proliferation

Cancer cells

uarr apoptosis

darr proliferation


Normal tissue



Cell death


Anticancerdrugs

Anticancerdrugs

Anticancerdrugs

Anticancer


Repositioned drugs

Cell death



Resistant

Sensitive+




2O2










Disclosure


Competing Interests




References






















2O2induced
























2O2rdquo Chinese









































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of























2O2on

DNA damage



2O2on cancer cell







2O2 the superoxide




2O2may be used






2O2



2O2may be









2O2




2O2








2O2-






2O2inducedMMP-2




2O2with









2O2has been used


















2O2






9 Conclusions








Abbreviations





H2O2

H2O2

H+

2 O2

H2O2

H2O2 ROS

Proliferation

Cancer cells

uarr apoptosis

darr proliferation


Normal tissue



Cell death


Anticancerdrugs

Anticancerdrugs

Anticancerdrugs

Anticancer


Repositioned drugs

Cell death



Resistant

Sensitive+




2O2










Disclosure


Competing Interests




References






















2O2induced
























2O2rdquo Chinese









































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of


















2O2




2O2








2O2-






2O2inducedMMP-2




2O2with









2O2has been used


















2O2






9 Conclusions








Abbreviations





H2O2

H2O2

H+

2 O2

H2O2

H2O2 ROS

Proliferation

Cancer cells

uarr apoptosis

darr proliferation


Normal tissue



Cell death


Anticancerdrugs

Anticancerdrugs

Anticancerdrugs

Anticancer


Repositioned drugs

Cell death



Resistant

Sensitive+




2O2










Disclosure


Competing Interests




References






















2O2induced
























2O2rdquo Chinese









































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of


















2O2with









2O2has been used


















2O2






9 Conclusions








Abbreviations





H2O2

H2O2

H+

2 O2

H2O2

H2O2 ROS

Proliferation

Cancer cells

uarr apoptosis

darr proliferation


Normal tissue



Cell death


Anticancerdrugs

Anticancerdrugs

Anticancerdrugs

Anticancer


Repositioned drugs

Cell death



Resistant

Sensitive+




2O2










Disclosure


Competing Interests




References






















2O2induced
























2O2rdquo Chinese









































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















H2O2

H2O2

H+

2 O2

H2O2

H2O2 ROS

Proliferation

Cancer cells

uarr apoptosis

darr proliferation


Normal tissue



Cell death


Anticancerdrugs

Anticancerdrugs

Anticancerdrugs

Anticancer


Repositioned drugs

Cell death



Resistant

Sensitive+




2O2










Disclosure


Competing Interests




References






















2O2induced
























2O2rdquo Chinese









































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of



















Disclosure


Competing Interests




References






















2O2induced
























2O2rdquo Chinese









































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of






























2O2rdquo Chinese









































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of






































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of



























of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of





















of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of
















Documents

Review Article Molecular and Cellular Effects of …downloads.hindawi.com/journals/omcl/2016/1908164.pdfReview Article Molecular and Cellular Effects of Hydrogen Peroxide on Human