Study Of The Reversal Effect Of Lobelin On Multidrug-resistance Of Colon Cancer Cell Lines HCT-8/VCR

Background and Objective: Chemotherapy is a main treatment of malignant tumor, The multiple drug resistance (MDR) of tumor cells towards chemotherapy drugs is the main cause for the failure of chemotherapy, which composes ninety percent. Therefore the reverse of MDR is of great meaning and value of clinical application. Natural effective components of alkaloid have been proven to reverse the MDR. Lobeline is a kind of piperidine alkaloid which can selectively active carotid chemoreceptor, reflectively actives respiratory center, and directly actives respiratory center with large dose. Some foreign scholars has found that lobeline can inhibite the activity of P-gp, the possibility of MDR reverse of lobeline can be proven in the cells under adriamycin chemotherapy and lobeline can sensitize the tumor cells to chemotherapy. The aim of this experiment is to study the mechanism of lobeline reverse of MDR and evaluate the validity of it comparing with verapamil, which is known to be of the reversion of P-gp mediated MDR.Methods: Hct-8/VCR, a cell line of human colon cancer, is taken as the object of study. MTT assay is used to determine the cell inhibiting ratio of vincristine and fluorouracil in different concentration and when they are intervened by lobeline, and therefore the multiple of drug resistance can be got. Microplate fluorescence spectrophotometer determines fluorescence intensity of Rhodamine 123 in Hct-8/VCR cells without any intervent, intervened with different concentration of lobeline. Flow cytometry is introduced to determine accumulation concentration of Rhodamine 123 in Hct-8/VCR cells without any intervent and intervened with lobeline 20μM and verapamil 20μM. Statistic analysis is done in SPSS13.0.Results: Cell growth inhabiting ratio which is got by MTT assay under the conditions mentioned above, shows the vincristine and fluorouracil of various concentration can inhibite the cell line of Hct-8/VCR and the inhibiting effect has a direct correlation with concentration. After being intervened with lobeline, the sensitivity of the cell line of Hct-8/VCR towards vincristine and fluorouracil increases. Rhodamine 123 efflux assay shows that fluorescence intensity of Rhodamine 123 in Hct-8/VCR cells processed with lobeline is higher than that not processed, and it has direct correlation with the concentration of lobeline. Flow cytometry shows that the effective rate of lobeline 20μM MDR reverse is 68 percent of that of verapamil 20μM.Conclusion: Lobeline can reverse VCR and 5-FU drug resistance of the cell line of Hct-8/VCR. Lobeline can increase the fluorescence intensity of rhodamine 123 in the cell line of Hct-8/VCR and inhibit P-gp efflux.