| Resistanc to chemotherapy is a major obstacle encountered in the treatment of human ovarian cancer and has been closely associated with treatment failure.This phenomenon is termed drug-multiresistance(MDR).Cisplatin are important drug in the treatment of ovarian cancer,but acquisition of MDR limits their effectiveness.In this study ,we have used human ovarian cancer cell lines as a model in vivo/vitro and nude mice of some multiresistant genes to invesgate mechanism of MDR and reversal MDR.The resistant cell line SKOV-3/DDP was established by stepwise exposure of ovarian cancer line SKOV-3 to cisplatin(DDP). The expressions of several genes related drug resistance and P-glycoprotein were measured by RT-PCR and Immunohistochemistry. The resistance index (RI) of SKOV-3/DDP cell to DDP, fluorouracil , doxorubicin was 13.94,10.83,4.52;G0/G1 of SKOV-3/DDP cell line was more than that of SKOV-3 cell line(P<0.01),while S,G2/M of SKOV-3/DDP cell line were less than that of SKOV-3 cell line(P<0.01). P-glycoprotein positive ratio of SKOV-3/DDP cell line was 65±5%,while that of SKOV-3 cell line was 6±2%(P <0.01).MDR1 gene was 1.91±0.25 in SKOV-3/DDP cell line and was 0.23±0.04 in SKOV-3 cell line,Survivin gene was 1.60±0.37 in SKOV-3/DDP cell line and was 0.35±0.05 in SKOV-3 cell line,the difference was obvious (P<0.05).Induction of cisplatin resistance in ovarian cancer may lead cross resistance of other drugs which are in different mechanism working on cancer cells,multiple drug-resistance involve not only one gene, suggesting more than one pathway leading to resistance transformation.The effects of different concentrations of MPA ,RU486 , MPA +RU486 on the DDP-resistance of drug-resistant human epithelial ovarian cancer cell line SKOV-3/DDP were examined with methyl thiazolyl tetrazolium (MTT) assay. Results SKOV-3/DDP cell growth was inhibited by MPA(32-256 ug/ml) or RU486 at different concentrations , which delyied on concentrations (r=0.983, r=0.925)。SKOV-3/DDP cell growth was inhibited by MPA〉32.00 ug/ml or by RU486〉20.00 ug/ml, which could reverse the DDP resistance of SKOV-3/DDP cell line . IC50 was negative correlation to the concentration of RU486 or MPA﹙r=-0.712,﹙r =-0.860) While lower concentrations of MPA (4-16 ug/ml) or RU486(5-10 ug/ml) had no effect on SKOV-3/DDP cell growth. The effect of RU486 combined with MPA was best when the concentrations of DDP was 1.25, 2.5,5.0ug/ml.The inhibit rate dely on the concentration of MPA ,which was linear correlative (r=0.921;r=0.866;r=0.899)。r=0.526;r= 0.227;r=0.336). When the concentrations of DDP was 10.0,20.0ug/ml,the inhibit rate was not dely on the concentration of MPA (r=-0.140;r=-0.168).On the same concentrations of MPA,the inhibit rate dely on the concentration of DDP, which was linear correlative concentration of MPA ( r=0.687;r=0.879;r=0.853;r=0.843;r=0.893).The h igher concentration of RU486 /MPA /RU486 and MPA could reverse the DDP resistance of SKOV-3/DDP cell line.The animal models was established by the transplantation of human ovarian epithelial cancer SKOV-3 and SKOV-3/DDP cells on 35 nude mice(xenograft of SKOV-3/DDP cells 30,xenograft of SKOV-3 cells 5,). 7 days after transplantation, 26 female nude mice with xenograft of SKOV-3/DDP cells were randomly divided into 5 groups and the treatment was started, which were treated with DDP, RU486+DDP,MPA+ DDP , RU486 +MPA+DDP. 4 female nude mice with xenograft of SKOV-3 cells were control. Result: The xenograft inhibited rate of RU486+DDP,MPA+DDP,RU486+MPA+DDP groups were risen slowly after treatment. 27 days after treatment, The sizes of nude mice transplanted tumor of RU486 + DDP , MPA + DDP , RU486 + MPA + DDP groups were not different(P>0.05),but they were different to DDP group obviously(P<0.01); The xenograft inhibited rate of these three groups were was different to DDP group obviously(P<0.01); the three groups were not different obviously(P>0.05).The amount of MDR1 and Survivin of xenograft in drug resistant model group and no- drug resistant model group were different(P<0.01), and that of MDR1 of RU486+DDP,MPA+DDP,RU486+MPA+DDP groups was similar to DDP group(P>0.05), Survivin of RU486+DDPand RU486+MPA +DDP groups was lower than that of DDP group and drug resistant model group(P<0.01),which indicated the RU486 and MPA could not reduce MDR1 expression , RU486 could reduce Survivin expression.The rate of P-gp positive cells of drug resistant model group ,no-drug resistant model group, DDP group,RU486+DDP group,MPA +DDP group,RU486+ MPA +DDP group were 62.30±11.20%,13.64±5.11%,70.15±10.44%,48.24±9.31%,31.47±6.22%,20.28±7.5%. The difference of drug resistant model group and no- drug resistant model group was obvious(P<0.01),that of DDP group and drug resistant model group was not obvious(P>0.05), that of DDP group and no-drug resistant model group was obvious(P<0.01),(P<0.01),The difference of RU486+DDP group,MPA +DDP group,RU486+ MPA +DDP group and DDP group was obvious(P<0.01)。The xenograft of every groups were different under microscope and telescope which indicated RU486, MPA, RU486+ MPA could reverse DDP induced drug resistance of nude mice xenograft ,and the effect of RU486 associated MPA was the best. The progestogen receptor of xenograft were negative, which indicted that RU486,MPA were effective to drug-resistant ovarian cancers were not dely on progestogen receptor.The shape, size and coefficient of the hearts, livers, spleens, renals of every treated groups were not different to that of drug-resistant tumor model .Above all, Mifepristone, medroxyprogesterone, Mifepristone associated medroxyprogesterone may inhance the effect of cisplatin to SKOV-3/DDP xenograft in nude mice.The side effect was less , so RU486 and MPA can be used clinically for adjuvant chemotherapy. The alive time may be prolonged for the drug-resistant patients suffered ovarian cancer by taking RU486 and MPA. |
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