| Objective To investigate the reversal effects of tannic acid(TA) on the multidrug resistance of LLC/cMOAT cells and the possible mechanism.Methods①MTT assay was used to determine the sensitivity of LLC/CMV and LLC/cMOAT cells to the various kinds of chemotherapeutics ,and the activity of LLC/CMV and LLC/cMOAT cells treated with different concentrations of TA;②The non-cytotoxic concentrations of TA were determined for the cells and the reversal effects of the chemotherapeutics were observed. The intracellular concentration of DNR, the cell cycle distribution and the apoptosis rate of the cells treated with different concentrations of TA were determined by flow cytometry(FCM).Results①The IC50 of LLC/CMV cells to VP-16,TAX,CPT-11,ADM,DDP and VCR were 6.364±0.759,4.025±0.372,23.026±4.512,1.142±0.215,2.203±0.412 and 0.035±0.004 respectivly, and the IC50 of LLC/cMOAT cells to chemotherapeutics above were 7.243±0.758,4.473±0.385,47.968±5.326,3.446±0.273,8.841±0.867 and 0.326±0.021, the results show that LLC/cMOAT cells were resistant to CPT-11,ADM,DDP,VCR to a certain extent, and the RF were 2.08,3.02,4.01,9.31 respectivly ( p < 0.05),but not resistant to VP-16,TAX, and the RF were 1.14 and 1.11( p > 0.05 );②The inhibition ratio (%)of LLC/CMV cells treated with TA at the concentration of 2.5μmol. L-1,5.0μmol. L-1 and 10.0μmol. L-1 were 2.06±0.36,4.87±0.58 and 9.21±0.67, and the IR of LLC/cMOAT cells were 1.87±0.35,4.32±0.50 and 8.79±0.68 respectivily, the results tell that TA was not significantly cytotoxic to LLC/CMV and LLC/cMOAT cells at 10.0μmol.L-1 and below; ③The IC50 value of LLC/CMV cells treated with TA at 2.5,5.0,10.0(μmol. L-1)and VCR were 0.031±0.006,0.029±0.005,0.028±0.007.There is no significant reverse effect to LLC/CMV cells and the RI were 1.13,1.21,1.25(p>0.05);TA at the concentr- ation of 2.5,5.0,10.0μmol.L-1may remarkably decrease the IC50 of LLC/cMOAT cells, and the IC50 were 0.064±0.007,0.051±0.005 and 0.042±0.004,and the RI were 5.09,6.33 and 7.76(P<0.05);④The intracellular DNR fluorescence intensity in LLC/cMOAT cells was significan- tly enhanced with the increase of TA concentration in a concentration-depend manner, when the LLC/cMOAT cells were pretreated with TA at the concentration of 2.5,5.0,10.0μmol.L-1 for 24 hours;⑤Treatment with TA at 5.0μmol. L-1 increased G1 population from 46.35±3.74% at 0h to 66.43±5.87% at 12 hours(p<0.05);⑥The cell apoptosis rate were 1.65%,12.1% and 19.0% at 0h,24h,48h when treated with TA at 5.0μmol. L-1 and VCR,and the apoptosis rate were 4.96%,11.2%,17.9% and 25.1% when treated with TA at 0,2.5μmol. L-1,5.0μmol. L-1,10.0μmol. L-1 and VCR fou 24h.The results show that cell apoptosis was enhanced in a time-and concentration-dependent manner by treating with TA.Conclusions TA is able to reverse the multidrug resistance of LLC/cMOAT cells an- d may remarkably raise drug concentrations in a concentration-dependent manner, TA is able to block cell cycle at G1 stage,and its function of inducing apoptosis acts in a time-and dose-depended manner.The mechanism may involve the decrease of chemot- herapeutics excretion and the increase of intracellular drug concentration, growth arr- est at G1 and apoptosis. |
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