Antitumor effects of polynucleotides and theophylline. (1972)

[CANCERRESEARCH32,1814â€”1819,September1972]formation,anditwasshownthatstabilizersofcAMPlevels,namelytheophyllineorcaffeine,canmagnifytheeffectsofpoly(A,U)onantibodyformation(5).Sinceimmuneresponsesareimportantinthecontroloftumorgrowth(30)wehavenowexploredtheabilityofimmunoenhancingpoly(A,U),poly(I,C),and/ortheophyllinetoaffecttheintradermalgrowthofRLVcellsinsyngeneichosts.Thisreportwillsummarizedatathatindicateadegreeofantitumoractivityofpoly(A,U),poly(I,C),andtheophylline,anditwillprovideevidencethatsucheffectsarenotnecessarilytheresultofmodifiedhostresponsesbutinsteadcanbeattributedtoalargeextenttoadirectsuppressiveeffectontheneoplasticcells.MATERIALSANDMETHODSTumorCellLine.TheRLVtumorcellline(MCDV-l2),inducedbyRauscherleukemiavirus,wasmaintainedbyseriali.p.passagethroughBALB/cmice,transfersbeingmadeevery7days.Forexperimental use,tumorcellswereremovedfromtheperitoneal cavityofmicethathadreceivedthepassagetumor5to7dayspreviously.Thecellswereharvestedbyi.p.injectionof2mlofMEMandsubsequentaspirationof2mlfromtheperitonealcavity.Thecellswerecentrifuged,washedtwiceincoldMEM,counted,andthenresuspendedinanappropriatevolumeofcoldMEM.Somechangesinthepropertiesofthisline(rateofgrowth,responsestotreatment)werenotedtowardtheendoftheexperimentalperiod.Animals.BALB/cfemalemice,6to10weeksold,obtainedfromCumberlandViewFarms(Clinton,Tenn.),wereusedintestswiththeRLVtumorcells.TumorImplantation.Tumorcells(0.02ml)wereinjectedintradermally,witha1-mituberculinsyringeand27-gaugeneedle,intotheshavedflankofBALB/crecipients.Doselevelsofl0@,l0@,or106cells/animalwereused.Inlargeexperiments,wherethetimeintervalsbetweenthecollectionoftumorcellsandtheirimplantationdiffered,particularlyamongthegroupsgiveninjectionsfirstandlast,standingofthecellsinsuspensionsometimesresultedinclumpingandanoccasionalreductionofthesubsequentrateoftumorgrowthinvivo.Foravoidanceofsuchartifacts,arandomizationprocedurewasadoptedinallofthemorerecenttests.Allanimalsofagivenexperimentwerefirstimplantedwithtumorcellsandthenseparatedatrandomintotreatmentgroups.Suchrandomization, whileovercomingtheeffectsofdifferentialtimeofimplantationaftertumorcellcollection,confirmedthebasicvalidityofthedatatobereported.MeasurementofTumorDevelopment.Tumorgrowth,intermsoftheaveragearea(sqmm)ofpalpabletumors,wasSUMMARYPolyadenylic-polyuridylic acid and polyinosinic-polycytidylicacid,aswellastheophylline,retardtherateofintradermalgrowthofRauscherleukemiavirus-inducedascitestumorcellsinsyngeneicBALB/cmice.Thecombinationofpolyadenylic-polyuridylic acidandtheophylline tendstoaffectthegrowthmorethaneitheragentalone,theresultsbeingdependentondosages,timing,andthetumorcelllineused.Asubstantialpartoftheantitumoractivityoftheseagents,whicharealsoknowntomodifyimmuneresponses,appearstobeduetoadirecteffectonthetumorcells,sincetheeffectsofpolyadenylic-polyuridylicacidandtheophyllinewerealsoobservedinirradiatedmiceandusuallyalsoafterdirecttreatment ofthetumorcellsinvitropriortoimplantation. Inviewofdatafromothercellsystems,whichshowthatsyntheticpolynucleotidesstimulatetheenzymeresponsiblefortheformationofcyclicadenosine3',5'-monophosphateandalsoinviewofthefactthattheophyllineinhibitstheenzymesthatdegradecyclicadenosine3',5'-monophosphate,theinhibitoryeffectsnotedherearebelievedtoinvolvealterationsinthecyclicadenosine3',5'-monophosphatesystemofthetumorcells.INTRODUCIIONDouble-stranded syntheticpolynucleotides, particularlypoly(I,C),3showantitumoreffectsinanumberoftumorsystems(1,I2,14,17,23â€”25,29,33).Wehavepreviouslyreported(3,6,7)thatpoly(A,U)hassimilareffects,atleastagainstMCmurinetumorcelllines,andwehaveemphasizedthatpoly(A,U),incontrasttopoly(I,C),hasnoknownpyrogenicortoxiceffectsevenathighdosages(6).Bothpoly(I,C)andpoly(A,U)alsostimulateimmuneresponsesandinrecentstudies,principallywithpoly(A,U),weprovidedevidenceindicatingthatsucheffectsareduetochangesincAMP-mediatedeventsinimmunocompetent cells(4,5,19,20).Poly(A,U)wasrecognizedasanenhancerofadenylcyclaseactivity(32),i.e.,oftheenzymeresponsibleforcAMP