LPSreceptorsubunitshaveantagonisticrolesinepithelialapoptosisandcoloniccarcinogenesisW-TKuo1,T-CLee1,2,H-YYang1,C-YChen1,Y-CAu1,Y-ZLu1,L-LWu1,S-CWei2,Y-HNi3,B-RLin4,YChen5,6,Y-HTsai5,6,JTKung7,FSheu8,L-WLin9andLC-HYu*,1Colorectalcarcinoma(CRC)ischaracterizedbyunlimitedproliferationandsuppressionofapoptosis,selectiveadvantagesfortumorsurvival,andchemoresistance.Lipopolysaccharide(LPS)signalingisinvolvedinbothepithelialhomeostasisandtumorigenesis,buttherelativeroleshadbyLPSreceptorsubunitsCD14andToll-likereceptor4(TLR4)arepoorlyunderstood.OurstudyshowedthatnormalhumancolonocyteswereCD14+TLR4−,whereascanceroustissueswereCD14+TLR4+,byimmunofluorescentstaining.Usingachemical-inducedCRCmodel,increasedepithelialapoptosisanddecreasedtumormultiplicityandsizeswereobservedinTLR4-mutantmicecomparedwithwild-type(WT)micewithCD14+TLR4+colonocytes.WTmiceintracolonicallyadministeredaTLR4antagonistdisplayedtumorreductionassociatedwithenhancedapoptosisincanceroustissues.Mucosa-associatedLPScontentwaselevatedinresponsetoCRCinduction.EpithelialapoptosisinducedbyLPShypersensitivityinTLR4-mutantmicewaspreventedbyintracolonicadministrationofneutralizinganti-CD14.Moreover,LPS-inducedapoptosiswasobservedinprimarycolonicorganoidculturesderivedfromTLR4mutantbutnotWTmurinecrypts.GenesilencingofTLR4increasedcellapoptosisinWTorganoids,whereasknockdownofCD14ablatedcelldeathinTLR4-mutantorganoids.InvitrostudiesshowedthatLPSchallengecausedapoptosisinCaco-2cells(CD14+TLR4−)inaCD14-,phosphatidylcholine-specificphospholipaseC-,sphingomyelinase-,andproteinkinaseC-ζ-dependentmanner.Conversely,expressionoffunctionalbutnotmutantTLR4(Asp299Gly,Thr399Ile,andPro714His)rescuedcellsfromLPS/CD14-inducedapoptosis.Insummary,CD14-mediatedlipidsignalinginducedepithelialapoptosis,whereasTLR4antagonisticallypromotedcellsurvivalandcancerdevelopment.OurfindingsindicatethatdysfunctionintheCD14/TLR4antagonismmaycontributetonormalepithelialtransitiontocarcinogenesis,andprovidenovelstrategiesforinterventionagainstcolo...
