the key roles of cationic antitumor and antiviral peptides

23 Pages·2013·1.01 MB·English

by  Octávio L. Franco

REVIEWARTICLE
published:31October2013
doi:10.3389/fmicb.2013.00321
Current scenario of peptide-based drugs: the key roles of
cationic antitumor and antiviral peptides
KellyC.L.Mulder,LoianeA.Lima,VivianJ.Miranda,SimoniC.Dias andOctávioL.Franco*
ProgramadePós-GraduaçãoemCiênciasGenômicaseBiotecnologia,CentrodeAnálisesProteômicaseBioquímicas,UniversidadeCatólicadeBrasília,
Brasília,Brazil
Editedby: Cationic antimicrobial peptides (AMPs) and host defense peptides (HDPs) show vast
NádiaS.Parachin,Universidadede potential as peptide-based drugs. Great effort has been made in order to exploit their
Brasília-UnB,Brazil mechanismsofaction,aimingtoidentifytheirtargetsaswellastoenhancetheiractivity
Reviewedby: and bioavailability. In this review, we will focus on both naturally occurring and designed
PaulA.Hoskisson,Universityof
antiviralandantitumorcationicpeptides,includingthoseherecalledpromiscuous,inwhich
Strathclyde,UK
LiliaMacovei,TheForsythInstitute, multipletargetsareassociatedwithasinglepeptidestructure.Emphasiswillbegivento
USA their biochemical features, selectivity against extra targets, and molecular mechanisms.
*Correspondence: Peptides which possess antitumor activity against different cancer cell lines will be
OctávioL.Franco,Programade discussed,aswellaspeptideswhichinhibitvirusreplication,focusingontheirapplications
Pós-GraduaçãoemCiências
for human health, animal health and agriculture, and their potential as new therapeutic
GenômicaseBiotecnologia,Centro
deAnálisesProteômicase drugs. Moreover, the current scenario for production and the use of nanotechnology as
Bioquímicas,UniversidadeCatólica deliverytoolforbothclassesofcationicpeptides,aswellastheperspectivesonimproving
deBrasília,SGAN916N,ModuloC, themisconsidered.
AvenueW5,DistritoFederal,Brasilia
71837-360,Brazil
Keywords:cationicpeptides,antiviral,antitumor,targetselectivity,therapeuticdrugs
e-mail:[email protected]
INTRODUCTION mechanisms of action and targets, as well as their potential as
Antimicrobial peptides (AMPs) are natural peptides found in newtherapeuticstrategiestocombatbothvirusesandmalignant
microorganisms,plants,andanimals,andareconsideredtheevo- cells.
lutionarilyconservedeffectorsininnateimmunity(Hancockand
Chapple, 1999; Hancock and Sahl, 2006). These peptides can CATIONICANTITUMORPEPTIDES
be classified by physical–chemical properties such as cationic, Cancerhasbecomeamajorconcerninrelationtohumanmor-
anionic, hydrophilic, and amphipathic (Peter et al., 2010). bidity and mortality. All types of cancer are characterized by
Althoughtheyarediverseinlengthandsequence,twophysical- irregularcellgrowthoriginatingfromasmallnumberofinherited
chemical features are often the hallmarks of these molecules: orenvironmentally-stimulatedgeneticmutations(Renan,1993).
they are cationic, often ranging from +2 to +7 at pH 7, and Many strategies have been adopted to combat the propagation
amphipathic, therefore their stereogeometry confers relatively ofcancercellsandtheirelevatedgrowthsuchaschemotherapy,
polarized hydrophilic and hydrophobic facets (Nguyen et al., surgery, and radiation (Wang and Zhang, 2013). These typical
2011). Despite their structural conservation, they have a broad procedures have often been revealed to be non-specific forcan-
spectrum of activity such as antibacterial (Okubo et al., 2012; cercells(Yangetal.,2013),additionallyactingonthecelldivision
Tavaresetal.,2012),antioxidative(Poweretal.,2013),antihyper- ofhealthycells,consequentlyimpairingtherestorationofnormal
tensive(Escuderoetal.,2012),antifungal(Mandaletal.,2013), tissues(Smithetal.,2000).Antitumordrugsaresubjecttodiffer-
antiviral(Findlayetal.,2013),antitumoraswellasmodulationof encesinabsorption,metabolism,andtargettissue,whichcanbe
theimmuneresponse(Silvaetal.,2012).Themodulationofthe particular to each patient; moreover, tumors can be positioned
immune response role is specific to a group of peptides named in places into which drug penetration is impaired or possibly
hostdefensepeptides(HDPs).Moreover,multiplefunctionsmay shelteredbyrestrictedenvironmentsduetoamplifiedhydrostatic
be associated with a single peptide according to the concept of pressure in the tissue or modified tumor vasculatures (Szakacs
promiscuity. They may act over different targets, therefore pre- et al., 2006). Furthermore, the intrinsic or acquired drug resis-
sentingdifferentfunctionsdependingontheirphysical-chemical tance is considered the widespread cause for tumor recurrence
(namely pure promiscuity) or on their amino acid modifica- (Szakacsetal.,2006).
tion(namelyfamilypromiscuity)(Franco,2011).Thesefeatures Acknowledging the limitations of these currently available
confer to AMPs and HDPs many physiological advantages over therapies, researchers have been encouraged to seek novel anti-
other molecules for application in the field of drug develop- cancer agents with only one exclusive mechanism of action
ment. As is summarized here, many AMPs and HDPs isolated (Szakacs et al., 2006; Hoskin and Ramamoorthy, 2008). In this
fromawidevarietyoforganismsincludingmammals,amphib- context,naturalAMPsfromdifferentsourcesandtheirsynthetic
ians, insects, plants, and bacteria have been reported to have analogshavebeenthebasisforanumberofstudiesperformedto
antiviraland/orantitumoractivities.Thisreviewcomprisestheir discovernewtherapiesfortreatingmalignantcells(Table1).
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Mulderetal. Antitumorandantiviralcationicpeptides
Table1|Cationicantitumorpeptidesfromdifferentsources,theirapplication,andtheirmechanismsofaction.
Peptides Source Group Application Mechanismofaction References
AGAP Buthusmartensii Insect Lymphoma,leukemia,human Cellcyclearrest Caoetal.,2010;Zhao
malignantglioma,humancolon etal.,2011;Guetal.,
cancer 2013
Alloferon Calliphoravicina Insect Leukemia InducesNKand Chernyshetal.,2002
IFN—Immune-modulatory
Aplidine Aplidiumalbicans Tunicate Melanoma,non-smallcelllung, Multifactorialapoptosis Faivreetal.,2005
prostate,ovarian,colorectal inducer/cellcycle
arrest/inhibitionofprotein
synthesis
ApratoxinA Lyngbya Cyanobacteria HeLa(humancervicalcancer) Cellcyclearrest Maetal.,2006
majuscula
ArenastatinA Dysidiaarenaria Sponge HumanKBcarcinoma NR Kobayashietal.,1994
Aurein1.2 Litoriaraniformis Frog Leukaemia,lung,colon,CNS, Barrelstavemechanism Rozeketal.,2000
melanoma,ovarian,renal
prostate,breast
BMAP-27 Bostaurus Mammal Leukemia,human InfluxofCa2+ Rissoetal.,1998,2002
BMAP-28 erythromyeloblastoidleukemia, DNAfragmentation
humanleukemicmonocyte Increasemembrane
lymphoma permeabilization
Brevinin-2R Ranaridibunda Frog Leukemia,lymphoma,colon Depolarizethe Ghavamietal.,2008
carcinomas,fibrosarcoma,breast transmembrane
adenocarcinoma,lungcarcinoma potential/lysossomalpathway
BuforinIIb Bufobufo Frog Leukemia,breastcancer, Apoptosisbya Leeetal.,2008
gargarizans non-smallcelllungcancer,CNS mitochondria-dependent
cancer,melanoma,renal,ovarian, pathway/caspase-9
prostateandcoloncancer activation/cytochromec
Cecropins Hyalophora Insectand Leukemia,bladder Carpet Steineretal.,1981;Chen
cecropia mammals mechanism/Membrane etal.,1997;Papoand
disruption Shai,2005;Lehmann
etal.,2006;Suttmann
etal.,2008;Xuetal.,
2008
Cherimolacyclo Annonacherimola Plant HumanKBcarcinoma NR Weleetal.,2004
peptideC
Citropin1.1 Litoriacitropa Frog Leukemia,lung,colon,CNS, Carpetmechanism Doyleetal.,2003
melanoma,ovarian,renal,
prostate,breast
Cn-AMP1 Cocosnucifera Plant Colorectaladenocarcinoma NR Silvaetal.,2012
CoibamideA Leptolyngbyasp. Cyanobacteria Breast,CNS,colon,melanoma, Cellcyclearrest Medinaetal.,2008
leukemia,ovarian
CPAP Chlorella Algae Humanlivercancer Condensation/fragmentation WangandZhang,2013
pyrenoidosa ofnuclearchromatin
Cr-ACP1and Cycasrevoluta Plant Humanepidermoidcancer,colon Cellcyclearrest Mandaletal.,2012
Cr-AcACP1 carcinoma
(Continued)
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Table1|Continued
Peptides Source Group Application Mechanismofaction References
CS5931 Cionasavignyi Tunicate Humancolorectalcarcinoma Mitochondrialpathwayof Chengetal.,2012
apoptosis
Cyclotide Clitoriaternatea Plant Lungcancer NR Senetal.,2013
Cycloxazoline Lissoclinum Ascidian MRC5CVlfibroblasts,T24 Cellcyclearrest/inhibitionof Hambleyetal.,1992;
bistratum bladdercarcinoma,leukemia cytokinesis Wattersetal.,1994
DianthinsE Dianthus Plant Liverhepatocellularcells NR Hsiehetal.,2004
superbus
Didemnin Trididemnun Ascidian Leukemia,melanoma Proteinsynthesis Rinehartetal.,1983
solidum inhibition/apoptosis
Dolastatin10 Symplocasp., Cyanobacteria, Murineleukemiacells,lung Bcl-2 Baietal.,1990;
Dolabella mollusk cancer phosphorylation/Caspase-3 Kalemkerianetal.,1999
auricularia proteinactivation
Gaegurins Ranarugosa Frog Kidney,lung,colon,breast, Poreformationby Wonetal.,2006
stomach,liver,prostate,skin, carpet-model
ovary
GeodiamolideH Geodia Sponge Breastcancer Alteringtheactin Freitasetal.,2008
corticostylifera cytoskeleton
GlidobactinsA, Polyangium Bacterium Melanoma,leukemia,colon NR Okaetal.,1988
BandC brachysporumsp. carcinoma
Homophymines Homophymiasp. Sponge Pancreaticcancer,human NR Zampellaetal.,2009
erythromyeloblastoidleukemia,
breast,liverhepatocellular,
humanKBcarcinoma,human
colonadenocarcinoma,human
ovarian,humanprostate,
glioblastoma,lungepithelialcells
Human Homosapiens Human Humanlungadenocarcinoma Apoptosisbycytochromec Xuetal.,2008
alpha-defensin-1 frommitochondria
(mitochondrialpathway)
Human Homosapiens Human Leukemiaandsolidtumor Inducemembraneproteolysis McKeownetal.,2006
neutrophil
Peptides(HNP-1:
β-defensin)
JamaicamideA Lyngbya Cyanobacterium Humanlung,neuroblastomacell NR Edwardsetal.,2004
majuscula
Jaspamides Jaspissplendens Sponge Lymphoma Caspase-3 Ebadaetal.,2009;
activation/decreasinginBcl-2 Ghoshetal.,2010
proteinexpression
KahalalideF(KF) Elysiarufescens Mollusk Colon,breast,non-smallcell Inhibitexpressionofgenes Hamannetal.,1996;
lung,prostatecarcinoma, involvedinDNA Graciaetal.,2006;Singh
melanoma,hepatocellular replication/modifieslysosome etal.,2008
carcinoma membrane/apoptosisinducer
KeenamideA Pleurobranchus Mollusk Leukemia,humanlung NR WessonandHamann,
forskalii adenocarcinoma,humancolon 1996
adenocarcinoma
(Continued)
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Mulderetal. Antitumorandantiviralcationicpeptides
Table1|Continued
Peptides Source Group Application Mechanismofaction References
LactoferricinB Bostaurus Mammal Humanleukemia,fibrosarcoma, Mitochondriapathwayof Maderetal.,2005;
carcinoma,neuroblastoma apoptosis/cytochromec Eliassenetal.,2006
release/activationofthe
caspasecascade
LL-37 Homosapiens Human Ovariancancer Poreformationby Chuangetal.,2009
carpet-model
LongicalycininA Dianthus Plant Humanlivercarcinoma NR Hsiehetal.,2005
superbus
Lunasin Soybeanand Plant Breastcancer NR Hsiehetal.,2010
otherseeds
Lyngbyabellins Lyngbya Cyanobacterium KBcarcinoma NR Williamsetal.,2003
majuscula
Magainins Xenopuslaevis Frog Hematopoietictumor, Mitochondriapathwayof Zasloff,1987;Cruciani
melanoma,ovariancancer, apoptosis/Poreformationby etal.,1991;Jacoband
bladdercancer,humancervical toroidalmodel/cytochromec Zasloff,1994;Takeshima
carcinoma release/activationofthe etal.,2003;Lehmann
caspasecascade/Carpet etal.,2006
mechanism
MalevamideD Symploca Cyanobacterium Leukemia,lungcancer,human NR Horgenetal.,2002
hydnoides coloncarcinoma
Melittin Apismellifera Insect Humanhepatocellularcarcinoma InfluxofCa2+/carpet Tostesonetal.,1985;
mechanism/toroidalpore Wangetal.,2009a
Mere15 Meretrixmeretrix Bivalve Humanlungadenocarcinoma Inducereleaseofcytochrome Wangetal.,2012
c/cleavageofcaspases/poly
ADP-ribosepolymerase
MicrocolinA Lyngbya Cyanobacterium Breastcarcinoma Inductionofapoptosis ZhangandLongley,1999
majuscule
Mollamide Didemnummolle Ascidian Leukemia,humanlung NR Carrolletal.,1994
carcinoma,humancolon
carcinoma
Pardaxinis Pardachirus Fish Humansarcoma Elevationofcaspase Huangetal.,2011
marmoratus activities,disruptionofthe
mitochondrialmembrane
Phakellistatin13 Phakelliafusca Sponge Humanhepatoma NR Lietal.,2003
RA-XVII Rubiaceous Plant Leukemia Activationofcaspaseactivity Hitotsuyanagietal.,2004
plantsandAster
tataricus
SansalvamideA Fusariumssp. Fungi Pancreatic,colon,breast,and Cellcyclearrest Vaskoetal.,2010
prostatesarcoma,melanoma
ScopularideA Scopulariopsis Marinefungi, Pancreatictumor,colontumor NR Yuetal.,2008
andB brevicaulisand sponge
TethyaAurantium
StAP1and Solanum Plant Leukemia Inducesapoptosis Mendietaetal.,2010
StAP3 tuberosum
(Continued)
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Table1|Continued
Peptides Source Group Application Mechanismofaction References
Symplostatin1 Symplocasp. Cyanobacterium Breast,colontumor Disruptsmicrotubules/mitotic Mooberryetal.,2003
arrest/inducesapoptosis
TachyplesinI Tachypleus Japanese Humanhepatocellular Non-cytolyticmechanism Chenetal.,2005
tridentatus horseshoecrab carcinoma,prostatecarcinoma
TamandarinsA Family Ascidian Pancreaticcarcinoma,prostatic Proteinsynthesisinhibition Vervoortetal.,2000
andB Didemnidae cancer,headandneckcarcinoma
TrapoxinsAand Helicoma Fungi Colorectalcancer NR Itazakietal.,1990
B Ambiens
Virenamides Diplosomavirens Ascidian Leukemia,humanlung Proteinsynthesisinhibition Carrolletal.,1996
A–C carcinoma,humancolon
carcinoma
Viscotoxins Viscum Plant Osteoblast-likeSarcoma,Yoshida NR XuandJin,1999
coloratum, sarcoma(rat)
Viscumálbum
Vitilevuamide Didemnum Ascidian Colontumor,lungcancer, Tubulinpolymerization/cell Edleretal.,2002
cuculiferum melanoma,kidneycancer cyclearrest
(Ascidians)
NR,Notreported.KB,nasophryngealcancer;CNS,centralnervoussystem.
Cationicantitumorpeptideshavebeensuggestedaspromising peptidesmightalsoinducedisruptionofintracellulartargetsby
agents for antitumor therapy due to their numerous advan- so-called non-membranolytic mechanisms. For instance, there
tages over other chemical agents such as their low molecular arereportsofantitumorpeptidesthatcausenecrosisbytriggering
masses, relatively simple structures, greater specific cytotoxicity intracellularapoptoticpathways(e.g.,byinactivatingmitochon-
totumorcellsoverhealthycells,feweradversereactions,easeof dria;activatingcaspasecascade)(Maderetal.,2005;Chenetal.,
absorption, a variety of routes of administration and low risk 2012;Paredes-Gameroetal.,2012).Cationicantitumorpeptides
for inducing multi-drug resistance (Alberts et al., 1980; Mader can also impair the activity of proteins of the signal transduc-
and Hoskin, 2006; Hoskin and Ramamoorthy, 2008; Schweizer, tion pathways involved in oncogene activities (Sharma, 1992).
2009;Riedletal.,2011;Liuetal.,2013).Theycanalsofunction Both membranolytic and non-membranolytic mechanisms are
incombinationwithconventionaltherapiesandotherpotential discussedinthisreviewandarerepresentedinFigure1.
anticancer molecules, usually improving the results of therapy Cationic peptides that kill cancer cells are arranged into two
(Chuang et al., 2009; Wang et al., 2009a). The intrinsic rela- groups:(1)AMPswhichareeffectiveagainstbacteriaandcancer
tionshipbetweentheirchemicalstructure,i.e.,theircationicand cellsbutnotagainstnormalmammaliancellssuchascecropins
hydrophobic features, and their high specificity to tumor cells from insects and magainins from amphibians and (2) AMPs
is likely to be the key role for their cytotoxicity. These charac- whicharecytotoxicforbacteria,cancercells,andnormalmam-
teristics allow the cationic AMPs to bind to and invade cancer malian cells such as melittin, tachyplesin II, human neutrophil
cells, quickly disrupting membranes and leading to the outflow defensins, and insect defensins (Papo and Shai, 2005; Hoskin
ofintracellularcontentsandconsequentcelldeath(Yeamanand and Ramamoorthy, 2008; Schweizer, 2009). It is believed that
Yount, 2003; Leuschner and Hansel, 2004; Jenssen et al., 2006). the difference between both groups relay mainly on the differ-
This happens due to the negatively-charged tumor cell mem- ence of the membrane of tumorous and normal cells (Hoskin
brane[derivedfromagreaterthannormalexpressionofanionic and Ramamoorthy, 2008), therefore it would be essential to
moleculessuchassialicacid-richglycoproteins,phosphatidylser- detailed understand these important changes at the molecular
ine (PS) or heparan sulfate], which present essential differences level. To date, it is here understood that besides the differ-
with the neutrally-charged healthy cell membranes. Therefore, ence on the electrostatic charge between tumorous and normal
thesechemicaldifferencesaidtheelectrostaticinteractionofthe cells cited above, the membrane fluidity may also interfere on
positively-chargedpeptideandthenegatively-chargedtumorcell the susceptibility of the peptide to disrupt the cells (Hoskin
membranes(Dobrzynskaetal.,2005;HoskinandRamamoorthy, and Ramamoorthy, 2008). The fluidity of cancer cells is greater
2008). The membranolytic mechanism was first discovered in a than that of mammalian normal cells (Sok et al., 1999) which
study of magainin and its synthetic analogs against hematopoi- may facilitate membrane destabilization favoring the binding
eticandsolidtumors(Crucianietal.,1991).Cationicantitumor of cationic antitumor peptides, and the amount of cholesterol,
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Mulderetal. Antitumorandantiviralcationicpeptides
FIGURE1|Mechanisms of action of cationic antitumor peptides. (1) Increase of the influx of Ca2+. (6) Formation of pore by either the
Modification of the lysosome membrane leading to an acidification of the toroidal or the barrel-stave models. (7) Activation of an immune
intracellular environment and cell death. (2) Amplification of the modulatory pathway by induction of NK and IFN. (8) Inhibition of genes
proteasome activity. (3) Induction of mitochondrial pathway of apoptosis involved in DNA replication. (9) Arrest of cell cycle G0, G1, or S phases.
by either the cytochrome c release into the cytoplasm or activation of Lfcin, lactoferrcin; BMAP, bovine myeloid antimicrobial peptide; Cr-AMP,
the caspase cascade. (4) Pore formation by the carpet model. (5) Chlorella pyrenoidosa antitumor polypeptide.
the major component of eukaryotic cell membranes (Simons removalofanetchargefrom−1to+2)fromthisplantspecies.
and Ikonen, 2000), alters the membrane fluidity, therefore pro- They showed significant cytotoxicity against human lung can-
tecting eukaryotic cells from cytolytic effects of antitumor pep- cer cells (A549) and demonstrated a reduction of 2- to 4-fold
tides.Forinstance,membrane-insertionoftheantitumorpeptide of the IC (half maximal inhibitory concentration) value of
50
cecropin is shown to reduced when synthetic lipid vesicles and cyclotides when compared to a mitotic inhibitor used in can-
Gram-negativebacteriahavetheircholesterolamountenhanced cer chemotherapy. Moreover, these peptides were less cytotoxic
(Silvestroetal.,1999).Furthermore,thesurfaceareaofthemem- against A549/paclitaxel (a sub-linage of A594) than only A549,
braneoftumorouscells,wherethenumberofmicrovilliishigher which demonstrates a possible use of chemo-sensitization for
than on non-tumorous cells (Chaudhary and Munshi, 1995), treatingcancer(Senetal.,2013).
may also allow an increased number of peptides to bind to the Along with cyclic peptides, many active non-cyclic antitu-
membrane(Chanetal.,1998a,b). mor peptides have also been isolated from different plants. For
In the following sections, cationic antitumor peptides from instance,thepromiscuouspeptideCn-AMP1,isolatedandpuri-
both groups which are derived from many sources includ- fied from coconut water (Cocos nucifera), was tested against
ing plants, vertebrates, and invertebrates will be presented (see CACO-2-humanepithelialcolorectaladenocarcinomacellsand
Table1). showed a 13% reduction of cell viability (Silva et al., 2012).
Additionally, the peptide lunasin, isolated from soybeans and
CATIONICANTITUMORPEPTIDESISOLATEDFROMPLANTS other seeds, was capable of suppressing in vitro and in vivo
Highquantitiesofnaturalcompoundsandmoleculesfromplants chemicalcarcinogen-inducedtumorigenesis(Hsiehetal.,2010).
havebeenintenselystudiedforthetreatmentofadiversenumber StAP1 and StAP3, isolated from the potato Solanum tubero-
of diseases including cancer. Reviewed here is a specific class of sum, were shown to induce apoptosis in Jurkat T leukemia
cyclicpeptidesoriginallyfoundonlyinplantsaswellasnon-cyclic cells (Mendieta et al., 2010; Guevara et al., 2011). Other
peptideswithantitumorproperties. examples are the peptides Cr-ACP, isolated from Cycas rev-
Clitoria ternatea is a rich source of a specific class of pep- oluta, and its acetylated-modified Cr-AcACP1, both repres-
tidesnamedcyclotides,composedofacyclicbackbonecombined sors of cell proliferation of human epidermoid cancer (Hep2),
with a conserved six cystine knot (Craik and Malik, 2013). A and colon carcinoma through the induction of cell cycle
studycarriedoutbySenetal.(2013)hasisolatedfivecyclotides arrest at the G0–G1 phase of Hep2 cells (Mandal et al.,
named CT2, CT4, CT7, CT10, and CT12 (with an addition or 2012).
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Mulderetal. Antitumorandantiviralcationicpeptides
Among chlorophyllous organisms, few studies have been its immunomodulatory properties. The interferonogenic activ-
developed. One example is the polypeptide Chlorella pyrenoi- ity was more evident in vitro using human cells than in vivo,
dosa antitumor polypeptide (CPAP) isolated from the unicellu- while in comparison to mouse cells the opposite result was
lar green algae Chlorella pyrenoidosa. It has shown the highest observed.TheNK-IFNnetworkiswell-documentedanddemon-
inhibitory activity on human liver HepG2 cancer cells (49%). stratesthepotentialimmunemodulatorypropertiesofthisAMP.
CPAP induces apoptosis and necrotic death of HepG2 cells via Furthermore, it has been recently shown that the combination
membraneshrinkage,condensationandfragmentationofnuclear of chemotherapy and alloferon I, referred to as pulse immune
chromatinaswellasformationofblackapoptoticbodies(Wang chemotherapy,demonstratedsignificantadvantagescomparedto
andZhang,2013). eachtreatmentappliedseparately(Chernyshetal.,2002,2012).
Alsofromthegroupofinsects,theAMPmelittin,isolatedfrom
CATIONICANTITUMORPEPTIDESISOLATEDFROMINVERTEBRATES Apismellifera,isalsoanactivemoleculeagainstantitumorcells.
Bioactive peptides isolated from insects present many different Itiscytotoxicagainsthumanhepatocellularcarcinoma(Tosteson
activitiesandhavestrongpotentialastherapeuticagents(Table1) et al., 1985; Wang et al., 2009a). Studies indicate that melittin
(Chernysh et al., 2002). Cecropins, alloferons, and melittins are damagescellmembraneseitherviathebarrel-stavemechanism,
examplesofAMPsisolatedfrominsectswhichfunctionasantitu- i.e.,itactsunderitsmembranolyticproperties(Suietal.,1994),
mormoleculeswithapplicationsforvariouskindsoftumorcells or via its non-membranolytic properties through a mechanism
(Figure1). The AMP cecropin was first isolated from the giant that engages the hyperactivation of phospholipase A2 and the
silk moth Hyalophora cecropia (Steiner et al., 1981). Cecropins influx of Ca2+, resulting in the destruction of the transformed
shares their potential antitumor activity with structural analogs cells(Figure1)(Sharma,1992,1993).
from other families of AMPs such as magainins and defensins AnotherantiviralAMPwithinthegroupofinvertebratesisthe
(PapoandShai,2005;Lehmannetal.,2006).Ithasbeenshown peptideAGAPisolatedfromthescorpionButhusmartensii.Ithas
thattwocecropinBanalogs,cecropinB1(CB1)whichpossesses beenreportedtopossessbothanalgesicandantitumoractivities.
twoamphipathichelices,andcecropinB3(CB3)whichhastwo Recently,aheterologousexpressionsystemhasbeenconstructed
hydrophobic helices, exhibit strong cytotoxic activity against a using small ubiquitin-related modifier-AGAP (SUMO-AGAP)
number of human leukemia cell lines and do not lyse normal whichisaproductofrecombinantAGAP(rAGAP)linkedwitha
fibroblasts or erythrocytes (Srisailam et al., 2001). Both analogs hexa-histidinetagfromEscherichiacoli.Thisrecombinantsystem
exhibit drastically different mechanisms of actions on anionic showedconsiderableinhibitionoflymphomaandgliomapropa-
lipid vesicles and show the importance of the structure and gation(Guetal.,2013).UsingSW480humancoloncancercells,
sequenceofacationicantitumorpeptideanditspotencytoward itwasproposedthatrAGAPinducescellcyclearrestintheG0/G1
differentcancercells(Srisailametal.,2001).Ithasbeenclaimed phase,attendedbythedecreaseintheSphasewithoutsignificant
that the discontinuous helical segments in the structure of CB3 changeintheG2/Mphase(Guetal.,2013).
donotfavorhelix—helixinteractionswhicharecrucialforpore Othersourcesofcationicpeptidesisolatedfrominvertebrates
formation; these mechanisms are likely to be adopted by CB1 arefoundinthemarineecosystem.Thebiodiversityofthisenvi-
where the continuous helical conformation interacts with cell- ronmenthasbeenshowntobearichsourceofbiologicallyactive
surfacestructuressuchasmicrovilliincancercells.Inadifferent molecules and has been considered an unlimited resource of
study,CB1wasamorepowerfulcytolyticagentthancecropinB newantitumoragents(Zhengetal.,2011;MalakerandAhmad,
againstHL-60humanpromyelocyticleukemiacells(Chanetal., 2013). Several AMPs with antitumor activity have been isolated
1998a,b).CecropinAandBhavebeenshowntoreducetheviabil- frommarineinvertebratessuchascyclicdepsipeptidedidemnins.
ityofbladdercancercells(Suttmannetal.,2008)andtodirectly IsolatedfromtheascidianofthegenusTrididemnum,ithasshown
inducetumorcelllysisviacellmembranedisruption,whichstim- antitumoractivityagainstL1210leukemiacellsinvitroandP388
ulates cytolysis/necrosis. Furthermore, it was shown that these leukemiaandB16invivo(Rinehartetal.,1983).Theantitumor
peptidesarecapableofimposingthedisruptionofmitochondrial role of the peptide kahalaide F from Elysia rufescens, a marine
membranes,consequentlyleadingtotheactivation ofapoptosis gastropod mollusk, has also been reported. It has shown sig-
pathways(Suttmannetal.,2008). nificant in vitro and in vivo activity against non-small cell lung
Another important AMP isolated from insects is alloferon: cancer, colon and human breast tumor cell lines, melanoma,
a tridecapeptide isolated from the bacteria-challenged larvae of androgen-independentprostatecancerandhepatocellularcarci-
the blow fly Calliphora vicina. Synthetic alloferon I has been noma (Martin-Algarra et al., 2009; Malaker and Ahmad, 2013).
showntoact ontumorgrowth control intwodifferent ways.It Thispeptideactsontheliposomemembraneoftumorcellsand
stimulatesnaturalkiller(NK)lymphocytesandinterferon(IFN) modifiesitsbasalfunction(Figure1)(Hamannetal.,1996;Singh
in vitro by using mouse spleen lymphocytes and human blood et al., 2008). Moreover, it modifies the role of the lysosomal
mononuclearcells.Thepeptidewasadministratedinpicomolar membrane, leading to intracellular acidification and cell death,
concentrations where its potential to stimulate natural cyto- a characteristic that discriminates it from all other known anti-
toxicity in these models was confirmed. Alloferon also induces tumor agents (Gracia et al., 2006). This peptide also appears to
IFN synthesis in vivo which was demonstrated using animal inhibittheexpressionofcertainspecificgenesthatareinvolvedin
and human models, and consequently enhancing its antitumor DNAreplicationandcellproliferation,therebyinhibitingtumor
activity (Figure1). Based on these results, the researchers have spreading and growth. Recently another marine AMP isolated
suggested an interaction of alloferon anticancer activity with fromthebivalveMeretrixmeretrix,namedmere15,hasshownto
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Mulderetal. Antitumorandantiviralcationicpeptides
significantlyinhibitthegrowthofhumanlungadenocarcinoma antibacterialpeptide.Besidesitsstrongactivityagainstbacteria,
A549xenograftinnudemice(Wangetal.,2012). ithasalsoshowntobecytotoxicagainstovariancancer(Chuang
et al., 2009) and is toxic to eukaryotic cells at a slightly higher
CATIONICANTITUMORPEPTIDESISOLATEDFROMVERTEBRATES concentration (25–30mM) (Hoskin and Ramamoorthy, 2008).
Many peptides have been discovered from a variety of verte- Regardingitsmechanismofaction,itisknownthatuponbinding
brates that are responsible for improving the innate immune tomembranesitchangestheheadgroupconformationofphos-
response (Table1) They have been found at relatively low con- pholipids,inducespositivecurvaturestrainonlipidbilayers,and
centrations in the normal tissues of mammals and are usually significantly disorders the hydrophobic core of the membranes,
present within the granules of neutrophils, in mucosal or skin exhibiting the carpet-like rather than the channel/pore-forming
secretionsfromepithelialcells,andasthedegradationproductsof mechanism of cytotoxicity (Figure1) (Henzler Wildman et al.,
proteins(Boman,1995;Hancock,2001).Amongthemammalian 2003;Henzler-Wildmanetal.,2004;HoskinandRamamoorthy,
organisms, bovines have been a promising source of molecules 2008).
which show a broad range of physiological activities, including Within the class of amphibians, the order Anura has been
immune function enhancement and defense against pathogenic showntobearichsourceofAMPs.Theirskinhasdiversephys-
bacteriaandviruses.Amongthesemolecules,threeAMPsnamed iological activities and forms an essential part of their defense
BMAP-27, BMAP-28 and lactoferricin have been reported as systems. In response to a multiplicity of stimuli, AMPs can be
activeantitumorpeptides.ThebovinemyeloidAMPsBMAP-27 secreted from specific glands onto the dorsal surface and into
andBMAP-28(27and28aminoacidresidues,respectively)have the gut of the amphibian (Bevins and Zasloff, 1990; Barra and
showncytotoxicactivityagainstneoplasticcells.Thesepeptides, Simmaco,1995;Doyleetal.,2003).
whentestedagainstfreshtumorleukocytesfrompatientsaffected In comparison to synthetic magainins A, B, and G, the nat-
bymyeloidorlymphoidleukemia,haveshowntoincreasemem- ural peptide magainin-2, isolated from the skin of the frog
branepermeabilizationandtheinfluxofCa2+,followedbyDNA Xenopuslaevis,isthemostefficientpeptideandcausesfastlysisof
fragmentation,whichischaracteristicofprogrammedcelldeath hematopoieticandsolidtumorcelllinesincludingmanyhuman
(Figure1)(Rissoetal.,1998). bladdercelllines(Crucianietal.,1991;JacobandZasloff,1994).
Thecytotoxicactivityofbovinelactoferricin(LfcinB)hasbeen Magainin-2hasbeenshowntoenterthecellmembraneofHeLa
demonstrated in vitro with different rat and human cancer cell humancervicalcarcinomacellsbybindingnumerousmagainin
lines including leukemia, fibrosarcoma, various carcinoma, and helicesformingatoroidalporeinthelipidmoleculesofartificial
neuroblastoma cells, and did not influence the viability of nor- membranes(Matsuzakietal.,1996).Ithasalsobeenreportedthat
malfibroblasts,lymphocytes,epithelialcells,endothelialcells,or pore formation is followed by a dispersing membrane potential
erythrocytes(Yooetal.,1997;Maderetal.,2005;Eliassenetal., and leakage of intracellular molecules, consequently leading to
2006).IthasbeenproposedthatLfcintargetstumorcellsbythe celldeath(Takeshimaetal.,2003).Magaininareshowntoaccess
changes that occur in their cell membranes, such as the expo- the cytosolic compartment of cancer cells and cause the mito-
sureofnegatively-chargedhead-groupsderivedfromthelossof chondrial pathway of apoptosis via a mechanism that involves
phospholipid asymmetry in diseased cells (Gifford et al., 2005; cytochromecreleaseintocytoplasmandanamplifiedproteasome
Pepe et al., 2013). The activities against fibrosarcoma and neu- activity, confirming its apoptotic effect (all these mechanisms
roblastomaratcellsandhumanT-leukemiacellscanbedescribed areshowninFigure1)(Westerhoffetal.,1989;Cruz-Chamorro
by a mechanism that induces the formation of transmembrane etal.,2006).
poresallowingthepeptidetoenterthecytoplasmiccompartment Another example of potential antitumor AMPs belonging to
ofthecancercell,co-localizewithnegatively-chargedmitochon- theorderAnuraaregaegurinandbuforin.Thepeptidegaegurin
driaandconsequentlydepolarizethem,resultingincytochrome waspurifiedfromtheskinoftheKoreanfrogRanarugosa.Itis
Creleaseoractivationofthecaspasecascade,therebyleadingto a potent mediator of cytolysis using either the carpet or barrel-
celldeathviaapoptosis(Figure1)(Maderetal.,2005;Pepeetal., stave mechanism (Park et al., 1994; Hoskin and Ramamoorthy,
2013). Moreover, it may interfere with the interaction between 2008) and is also reported to follow the mitochondria pathway
growth factors and their receptors on the surface of endothe- ofapoptosisasdescribedaboveforthemagaininmechanismof
lialcells,resultingindecreasedendothelialcellproliferationand action(Lietal.,2000;Maietal.,2001).
diminished angiogenesis (Mader et al., 2006). As reviewed by BuforinII,alinearα-helicalpeptidesimilartocecropinsand
Gifford and colleagues, other mechanisms have been proposed. magainins, was isolated from the stomach of the Bufo bufo gar-
Inbrief,uponbindingtothetumorcells,Lfcinisthoughttotrig- garizansandisknowntopenetratecellmembranesthroughnon-
geraCa2+/Mg2+endonucleaseandoxidant-dependentapoptotic permeabilizingpore-likestructureswhichallowitstranslocation
pathway. Although the structural parameters that describe the into the cytoplasm without cell lysis, and consequently inhibits
antitumoreffectsofLfcinareverysimilartothosethatdescribeits intracellularfunctions(Parketal.,1998).Ithasbeenshownthat
antibacterialactivity,ahighernetpositivecharge(+7whencom- thecytotoxicactivityofbuforinIIislowwhencomparedwithcit-
pared to +4 for antibacterial activity) isrequired for antitumor ropin1.1,pexigananMSI-78andprotegrin1,andthatitdoesnot
activitytopromoteastrongelectrostaticinteractionbetweenthe permanentlydisruptthecellmembranelikeothermolecules,i.e.,
peptideandthemembrane(Figure1)(Giffordetal.,2005). itsantitumoractivitycorroborateswiththemechanismdescribed
Among the human-derived mammalian AMPs, the amphi- above (Koszalka et al., 2011). A synthetic analog of buforin II
pathic α-helical LL-37 has been extensively studied as an named buforin IIb has shown greater cytolytic activity against
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Mulderetal. Antitumorandantiviralcationicpeptides
cancer cells (leukemia, breast cancer, non-small cell lung can- are well-represented by peptides such as melittin, cecropin, and
cer, CNS cancer, melanoma, renal, ovarian, prostate, and colon alloferon.Describedaboveasanantitumorpeptide,melittinhas
cancer)thanbuforinII(Leeetal.,2008). also been reported to have inhibitory activity against enveloped
From the group of marine vertebrates, the cationic peptide viruses such as HIV-1, HSV-2, and the Junin virus (JV), an
pardaxinisolatedfromthesmallfishPardachirusmarmoratushas arenavirus,includingthispeptideundertheconceptofpromis-
been shown to be a potential active antitumor peptide against cuity(Figure2).Aproposedmechanismofactionhassuggested
human sarcoma (Huang et al., 2011). It has been reported that thatmelittinsuppressescellfusionmediatedbyHSV-1syncytial
+ +
this peptide disrupts the membrane via the barrel-stave mech- mutantsprobablybyinterferingwiththeactivityoftheNa K
anism (Hallock et al., 2002), and changes its transmembrane ATPase,acellularenzymeinvolvedinthemembranefusionpro-
orientation depending on membrane composition (Hoskin and cess(AlbiolMatanicandCastilla,2004).Analysisoftheeffectof
Ramamoorthy,2008). melittin on the production of HIV-1 transcripts was assayed in
acutely infected T-cells cultured with various concentrations of
CATIONICANTIVIRUSPEPTIDES melittin. Levels of all HIV-1 transcript classes were suppressed
The success of viruses in evolution has been assured by four (reductionof∼30%whencomparedwithcellswithoutmelittin)
general attributes: genetic variation, variety in means of trans- in a dose-dependent manner (Wachinger et al., 1998). Another
mission, efficient replication within host cells, and the abil- mechanism whereby melittin interferes with viral gene expres-
ity to persist in the host (Wagner et al., 1999). Due to these sionhasbeenproposedandinvolvesintracellularimmunization
attributes, the control of viral diseases has not been an easy againstHIV(Figure3).Melittininterfereintheprocessofcellu-
task. Despite the existence of antiviral drugs, there is a need to lar signal transduction, such as the activation of phospholipase
explore novel antiviral compounds in order to control emerg- A2forinstance,andthedecreaseinactivitiesofcalmodulinand
ingviralpathogens.Inthisperspective,AMPsareanalternative proteinkinaseC(Sharma,1993;Fisheretal.,1994;Gravittetal.,
in drug design. Several cationic antiviral peptides from vari- 1994). These properties may therefore change the balance and
ous sources have been isolated since the 1980s (Table2) and activities of cellular stimulators of HIV transcription (as NFkB,
they have shown strong potential for novel therapeutic drugs AP-1andNFAT)orinduceinhibitoryfactors(interferon-induced
against many viral infections. Due to the promiscuity of these cellularinhibitor)(Wachingeretal.,1998).
peptides, it is possible to verify a broad spectrum of antiviral Thepeptidesalloferon1and2haveshownactivityagainstthe
activities within the same peptide. Moreover, this promiscuous influenzavirus,throughthesamemechanismdescribedabovefor
activitycanbeextendedtosimultaneouscytotoxicactivityagainst itsroleasanantitumorpeptide,byinductionofimmunemodu-
tumor cells (Figure2). The first study reporting an antiviral latoryactivities.Bothactivitiesagainsttumorandviralinfections
role of a cationic peptide was published in 1986, in which the emphasizethemechanismsofcell-mediatednaturalcytotoxicity
activity of α-defensin was described as inhibiting a number of andIFNsynthesis(Figure3).Therefore,thesepeptidesseemtobe
viruses including herpes simplex virus types 1 and 2 (HSV), potential candidates as biopharmaceutical compounds contain-
cytomegalovirus(CMV)aswellasinhibitingthevesicularstom- ing the capability of improving important effector mechanisms
atitis virus with human neutrophil peptide 1 (HNP1) in vitro oftheinnateimmuneresponse(Chernyshetal.,2002).
(Daheretal.,1986;Findlayetal.,2013).Sincethen,manyreports Anotherexampleofinvertebratepeptideswithantivirusactiv-
haveshowntheantiviralactivityofcationichost-defensepeptides ityagainst humanvirus-related diseasesisthesyntheticpeptide
such as α-, β-, and θ-defensins, and the use of effective antivi- T22([Tyr5,12,Lys7]-polyphemusinII),whichisassociatedwith
ral therapy with cathelicidins, as previously reviewed (Findlay the promiscuous peptide tachyplesin (Figure2) and the pep-
et al., 2013). It is very promising that in the last years many tidepolyphemusin,whichareabundantinthehemocytesofthe
newantiviralpeptideshavebeeneitheridentifiedorsynthesized horseshoe crab Tachypleus tridentatus and Limulus polyphemus,
in order to aid the development of new therapeutic antivirus respectively. It has shown potent antiviral activity against HIV-
therapies. 1 and HIV-2 in vitro. The inhibitory activity of this peptide is
related to its specific binding to a chemokine receptor CXCR4,
CATIONICANTIVIRALPEPTIDESDRUGSAPPLIEDTOHUMANHEALTH
whichservesasaco-receptorfortheentryofHIV-1intoTcells
Cationic antiviral peptides have been isolated from various
(Figure3)(Nakashimaetal.,1992;Tamamuraetal.,1998).
sources and present broad antiviral activities against several
viruses with different antiviral mechanisms of action (Table2).
Theycaneitherinhibitviralattachmentbybindingtoviraltargets CATIONICANTIVIRALPEPTIDESISOLATEDFROMVERTEBRATES
onthehostcellsurface,ortargetviralproteins,thereforeblock- ThereareseveralAMPsderivedfrommammaliansourceswhich
ingviralfusionandentryintothehostcell.Anothermechanism havedemonstratedstrongactivityagainstmanyvirusesthatcom-
of action is intracellularly driven where spreading of the virus promise human health (Table2). In this group are included
is inhibited through the suppression of viral gene expression, defensins,LfcinandLL-37(Figure2).Defensinsarepotentcan-
inhibition of translation or by immune modulatory activities didatesforthedevelopmentofantiviraldrugs.Theyarepeptides
(Figure3). with conserved structures, usually with α-helix and antiparallel
β-sheetsstabilizedbydisulfidebonds(Terrasetal.,1992;Bastian
CATIONICANTIVIRALPEPTIDESISOLATEDFROMINVERTEBRATES and Schafer, 2001; Franco et al., 2006), and belong to three
AMPs isolated from the group of invertebrates which present subfamilies,designatedα,β,andθdefensins.TheHNP-1isanα-
strongantiviralactivityagainstmaladiesthataffecthumanhealth defensinthathavebeenwidelytestedforitsantiviralactivity.This
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Mulderetal. Antitumorandantiviralcationicpeptides
Table2|Cationicantiviralpeptidesfromdifferentsources,theirapplication,andtheirmechanismsofaction.
Peptide Source(s) Group Application Mechanismofaction References
HUMANHEALTH
Alloferon1 Calliphoravicina Insect IAV Immunomodulatory Chernyshetal.,2002
Alloferon2 activity
Brevinin-1 Ranabrevipoda Frog HSV Viralinactivation Yasinetal.,2000
Caerin1.1 – AmphibianSkin HIV Disruptstheintegrityof Vancompernolleetal.,2005
Caerin1.9Maculatin thevirionmembrane
CAP37 Homosapiens Human HSV-1 Disruptstheenvelope Gordonetal.,2009
leococytes AdV and/orcapsid
Cecropin Hyalophoracecropia Insect JV Suppressesviralprotein Wachingeretal.,1998;Albiol
HSV synthesisCellulartarget MatanicandCastilla,2004
HIV Suppressesviralgene
expression
CirculinA Chassaliaparvifolia Plant HIV Dalyetal.,1999
Defensin Homosapiens Human HSV Interactswith Daheretal.,1986;Nakashima
IAV glycosaminoglycans etal.,1993;Groppetal.,1999;
HCMV Inactivatesviralparticle Yasinetal.,2000;Bastianand
VSV Cellulartarget Schafer,2001;Sinhaetal.,2003
HIV Unknown
AdV
Dermaseptin GenusPhyllomedusa Frog HIV Disruptisviralmembrane Belaidetal.,2002
HSV
DidemninsA GenusTrididemnum Tunicate HSV InhibitsRNAandDNAviral Rinehartetal.,1981;Aneirosand
DidemninsB Parainfluenza replication Garateix,2004
Dengue
virus
HNP-1 Homosapiens Human HSV Blocksearlystepsofviral Ganzetal.,1985;Bastianand
HNP-3 AdV replication Schafer,2001;Hooketal.,2006
Hp1090 Heterometruspetersii Scorpion HCV Disruptsviralmembrane Yanetal.,2011
integrity
Indolicidin Bostaurus Bovine HIV Inhibitsintegrase Robinsonetal.,1998
HSV Targetsviral
glycosaminoglycans
Lactoferricin Homo Human,Bovine HCMV Activityatvirus-cell Andersenetal.,2001;Jenssen
sapiens HIV interface etal.,2004;Mistryetal.,2007
Bostaurus HSV Blocksheparansulfate
Papilloma
LL-37 Homosapiens Human HSV Viralreceptor-based Yasinetal.,2000;Barlowetal.,
IAV mechanisms 2011
Magainin Xenopuslaevis Frog HSV Suppressesviralgene Aboudyetal.,1994;Albiol
HIV expression MatanicandCastilla,2004
Mellitin Apismellifera Insect HSV Cellulartarget Wachingeretal.,1998;Yasin
JV etal.,2000;AlbiolMatanicand
Castilla,2004
Microspinosamide Sidonops Marinesponge HIV Inhibitscytopathiceffectof Rashidetal.,2001
microspinosa HIV-1infection
(Continued)
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