Common Cnidium Fruit, Reverse Human T24 Bladder Tumor/adm Cells Resistant Effect And Its Mechanism

【Objective】Chemotherapy is one of the most important modalities for treating malignanttumors．However，the problem of drug resistance is the most important cause for chemotherapyfailure，and it is also the key factor affecting the clinical efficacy．The reverse of MDR mayconduct more clinical medicine and practical value . Osthole , a natural coumarin derivative , isextracted from a Chinese herb Cnidium monnie.It was proved that Osthole can inhibitproliferation,induce tumor cell differentiation and promote apoptosis，Verapamil ,a calciumchannel blocker,can add the intracellular concentration of chemotherapy drug and reverse themultidrug resistance. But its neglect effect is severe.Osthole was found to have the function ofcell membrane calcium channel blocker.The purpose of this experiment is to analysize whetherOsthole could reverse MDR，and investigate its reversal mechanism.【Methods】1. The low or no cytotoxicity concentration of OST for T24/ADM cells by MTT, and takethese concentrations as the experimental concentrations.2. To confirm the Multidrug Resistance of T24/ADM cells, MTT experiment was used todetermine the median inhibitory concentration(IC50) value of ADM, CTX, DDP in T24 andT24/ADM cells.3. To analysize the reversal effete of osthole，MTT experiment was applied to determinethe median inhibitory concentration (IC50) value of ADM, CTX, DDP in T24 and T24/ADMcells after the addition of osthole.4.The concentrations of P-gp in T24/ADM cells with and without OST were measured byflow cytometey（FCM).【Results】1. Osthole at the concentration of 17 mol/L had no significant cytoxicity to T24/ADMcells.2.T24/ADM cells were resistant to ADM,CTX and DDP and the resistance index was5.06、1.84、6.04 respectively.3.The sensitivity of T24/ADM to ADM, CTX and DDP was significantly increased byOsthole in the concentration of 17 mol/l. The inhibitive concentration 50 ( IC50) of ADMdeclined from (10.590±0.615) g/ml to (3.810±0.663 ) g/ml with a reversion index of2.77.The IC50of CTX declined from (3.667±0.945) g/ml to (2.973±0.271) g/ml with areversion index of 1.23.The IC50of DDP declined from (12.567±0.142) g/ml to (3.753±0.585)g/ml with a reversion index of 3.35. 4.FCM results indicated that the positive expression rate of P-gP dropped（p<0.05）.【Conclusion】Osthole has the reversal effect on Multidrug Resistance of T24/ADM cell ,the mechanism of reversion is related with down regulation of expression of P-gp.