Effects Of Lycium Barbarum Polysaccharide On P-glycoprotein

OBJECTIVETo study the mechanism of interaction between Lycium barbarum polysaccharide and P-glycoprotein by assessing the effects of Lycium barbarum polysaccharide on the function and expression of P-glycoprotein, and investigating the effect of these componets on the Rhodamine-123bidirectional transport though Caco-2cells monolayer.METHODS1Cell culture and Cytotoxicity assay The expression of P-glycoprotein in the cells was identified by immunofluorescence assy.MTT (diphenyltetrazolium bromide) assay was used to find the non-cytotoxicity dosage of Lycium barbarum polysaccharide-. cyclosporine and verapamile in Caco-2and ECV304cells. The dosage at which the survival rate of cells is above90%was considered as the highest non-cytotoxic dosage.2Effect of Lycium barbarum polysaccharide on P-glycoprotein functionThe effect of Lycium barbarum polysaccharide on P-glycoprotein function was analyzed using Rhodamine-123assay.3Effect of Lycium barbarum polysaccharide on P-glycoprotein expression Flowcytometry was used to measure the expression of P-glycoprotein in Caco-2cell.4Effect of Lycium barbarum polysaccharide on Rhodamine-123bidirectional transport through Caco-2cells monolayerWe investigated the effects of Lycium barbarum polysaccharide on Rhodamine-123bidirectional transport though Caco-2cells monolayer. RESULTS1Cell culture and Cytotoxicity assayBoth Caco-2cells and ECV304cells grew well in the experimental conditions.The expression of P-glycoprotein is plentiful in Caco-2cell but sparse in ECV304cell. Caco-2cells is suitable for studying Lycium barbarum polysaccharide on the function and expression of P-glycoprotein,and ECV304cells is fit to be the negative control.Lycium barbarum polysaccharide at concentrations of10-150μg/mL and verapamile at concentration of0.01-100umol/L and Cyclosporine at concentration of0.01-10μmol/L were found to be non-cytotoxic towards the Caco-2cells, these compounds were non-toxic to ECV304at the experimental concentrations.2Effect of Lycium barbarum polysaccharide on P-glycoprotein functionCompared with the negative group,after incubated with cells for60min, Lycium barbarum polysaccharide showed the inhibited effect on P-glycoprotein functiom, the maximal inhibition of P-glycoprotein function appeared to occur at20μg/mL of Lycium barbarum polysaccharide, which produced a150%decrease in the cellular Rhodamine-123.3Effect of Lycium barbarum polysaccharide on P-glycoprotein expressionAt the protein level, long term (72h) co-incubation of the Caco-2cells with100μg/mL of Lycium barbarum polysaccharide, the fluorescent intensity of Lycium barbarum polysaccharide group was produced a47.9%increase in the negative group. The result of P-glycoprotein expression and function is opposite.4Effect of Lycium barbarum polysaccharide on Rhodamine-123bidirectional transport through Caco-2cells monolayer100μg/mL of Lycium barbarum polysaccharide produced a25.6%decrease in the negative group. The result of Rhodamine-123bidirectional transport accorded with the result of P-glycoprotein function. CONCLUSION1. Lycium barbarum polysaccharide can inhibit the function of P-gp, but Lycium barbarum polysaccharide can induce the expression of P-gp. Since Lycium barbarum polysaccharide has been used as Biological immunomodulating agents for the treatment of cancer, the patient always needs a long-term medication.2. The highest concentration of Lycium barbarum polysaccharide can decreace the value of ER of Rhodamine-123and the absorbtion of oral drugs may be under the influence of this effect.