Reverse Effect And Mechanism Of Effective Component Of Verbena Officinalis L. On Multidrug Resistant Human Choriocarcinoma JAR/VP16 Cell Line

accompanied by more and more multidrug resistant cases. The generationof tumorous resistance is a complex process which involves multiplefactors and mechanisms. It has been discovered that varieties ofcompounds can reverse tumorous multidrug resistance in vitro but usuallylead to severe toxic and side effects in clinical trials.4'-Methylether-scutellarein (4'-M-S), flavonoids chemical, is an effectivecomponent extracted from Verbena Officinalis L.. Studies in vitro hasconfirmed that it possesses specific inhibitory effect on cell proliferationof human choriocarcinoma JAR cells. Our aim is to explore the reverseeffect on drug resistance of 4'-M-S and related mechanisms using themodel of drug resistant human choriocarcinoma JAR/VP16 cell line andto establish the experimental foundation of the treatment on drug resistantchoriocarinoma.1,Reverse Effect of 4'-Methylether-scutellarein on MultidrugResistant Human Choriocarcinoma JAR/VP16 Cell LineMTT assay demonstrated that 4'-M-S had a significant inhibitoryeffect on cell proliferation in a dose dependent manner, and it couldremarkably reverse the resistance of JAR/VP16 to VP16 at theconcentration of 20μg/ml. Its reverse multiple and efficiency were 5.02and 81.19% respectively. Monoclonal antibody enzyme-linkedimmunoquantitation showed that the secretion of hCG in JAR/VP 16 cellswas obviously repressed when treated with the combination of 4'-M-Sand VP16. The results of flow cytometry(FCM) analysis showed that thecell cycle was blocked at the G₂/M phase and the ratio of cell apoptosisincreased. The earlier apoptotic alterations were observed by light andtransmission electron microscope, including irregularly shaped cells andhigher electron density condensed chromatin that accumulated at theintro-surface of the nuclear membrane, In conclusion, 4'-M-S could efficiently reverse the resistance of JAR/VP16 to VP16, which could bean synergistic action of 4'-M-S and VP16 by inhibiting the growth ofdrug-resistant cells and inducing cell apoptosis.2,Mechanism of 4'-Methylether-seutellarein on Multidrug ResistantHuman Choriocarcinoma JAR/VP16 Cell LineThe results of FCM analysis determined that the intracellularaccumulation of RH123 in JAR/VP16 cells obviously increased aftertreated with 4'-M-S. The expression of mdr1 mRNA in JAR/VP16 cellswas down-regulated detected by RT-PCR. Meanwhile, western blot andimmunohistochemistry indicated that the expression of P-gp, a product ofmdrl was down-regulated as well. Thus, the reverse effect of 4'-M-S onJAR/VP16 cells may be due to the increase of intracellular accumulationof chemotherapeutic drugs and the decrease of expression of mdr1 mRNAand P-glycoprotein.In summary, based on the model of drug resistant humanchoriocarcinoma JAR/VP16 cell line, we demonstrated that 4'-M-S couldefficiently reverse the resistance of JAR/VP16 cells to chemotherapeutics,down-regulate the expressions of mdr1 mRNA and P-gp and induce cellapoptosis.