Role Of Inhibition Of Wnt/JNK Signaling Pathway In Reverse P-glycoprotein-mediated Colon Cancer Multidrug Resistance

Background and objectives：Colorectal cancer is the most common malignant tumor of digestive system,accounting for about40%of new cancers in the digestive tract, the incidence isincreasing year by year.Chemotherapy is one of the major treatment modalities forpatients who suffer from colorectal cancer.A significant challenge to the triumph ofchemotherapy is drug resistance, by which cells resist to a number of structurally andfunctionally diverse therapeutic drugs including anticancer and antivirus agents,leading to poor prognosis. Although there have been many studies showed that JNKsignaling pathway can regulate the multidrug resistance mediated by P-gp; Wnt/JNKsignal pathway and tumor development, invasion and metastasis and angiogenesis areclosely related, but the relationship between multidrug resistance of colon carcinomamediated by P-gp and Wnt/JNK signal transduction pathway is still not clear.To investigate the expression of Wnt/JNK signaling pathway and the relationshipbetween the pathway and p-gp-mediated multidrug resistance of human coloncarcinoma HCT8/VCR cells. Methods：1．Human colon cancer drug sensitive cell line HCT-8and human colon cancerdrug-resistant cell line HCT-8/VCR were cultured in RPMI-1640complete culturemedium containing10%fetal bovine serum at37℃in a5%CO2, saturatedhumidity.HCT8/V cells were routinely incubated in a medium containing2mg/L VCRto maintain drug resistance and cultured in a drug-free medium for2weeks beforeexperiment.2．To detect the expressions of protein Wnt11,c-Jun,p-c-Jun and P-gp inHCT-8/VCR cells and HCT-8cells and analyze the changes of the expression level.3．To detect the expressions of protein Wnt11,c-Jun,p-c-Jun and P-gp in HCT-8WIF-1cells and HCT-8/VCRWIF-1,which were intervened by Wnt/JNK signalingpathway inhibitor (WIF-1) and analyze the changes of the expression level.4．Statistical analyses were conducted using the SPSS15.0software.Statisticalsignificance was determined with t test. All results are reported as the mean±standarddeviation（x±s）.A P value of<0.05was considered to be a statistically significantdifference.Results：1．The expressions of protein Wnt11,c-Jun and p-c-Jun were detected inHCT-8/VCR cells and HCT-8cells and both cell lines contained Wnt/JNK signalingpathway.2．The expression levels of Wnt11, c-Jun and p-c-Jun in HCT-8/VCR cells werehigher than in HCT-8cells and the changes of the trend of the three proteins isconsistent in the two cell lines. The expression level of P-gp in HCT-8/VCR cells washigher than in HCT-8cells and with changes of the expression levels of Wnt11, c-Junand p-c-Jun, P-gp varied.The activation degree of Wnt/JNK signaling pathway wasenhanced in HCT-8/VCR cells than HCT-8cells and positively correlated with theexpression level of P-gp.(P<0.05)3．The expressions of protein Wnt11,c-Jun,p-c-Jun and P-gp had no obviousdifference in HCT-8WIF-1cells and HCT-8/VCRWIF-1after addition of WIF-1.The resistance and activation degree of Wnt/JNK signaling pathway were quite in thetwo cell lines.(P>0.05)4． The expression level of protein Wnt11,c-Jun,p-c-Jun and P-gp weresignificantly decreased.The resistance of HCT-8/VCR cells was significantlyinhibited and reversed.(P<0.01)5．The expression level of protein Wnt11,c-Jun,p-c-Jun and P-gp changed littlein HCT-8cells after addition of WIF-1. With the results of3and4comparisonshowed that Wnt/JNK signaling pathway was inhibited significantly after addition ofWIF-1in HCT8/VCR cells,but not in HCT8cells.The expression level of proteinWnt11,c-Jun,p-c-Jun and P-gp were quite in HCT-8/VCRWIF-1cells, HCT-8cells andin HCT-8WIF-1cells.Conclusions：1．Inhibition of Wnt/JNK signaling pathway can reverse P-gp-mediated coloncancer multidrug resistance.2．Wnt/JNK signaling pathway can provide new therapeutic targets for reversalof multidrug resistance in colorectal cancer.