MicroRNA-21 Involves In Drug Resistance Of Epithelial Ovarian Cancer And The Mechanisms

Part ⅠExpression of Micro RNA-21 in Serum of Patients withEpithelial Ovarian Carcinoma and Its Clinical SignificancesObjective: To investigate the expression of micro RNA-21( mi R-21) in recurrence epithelial ovarian cancer drug-resistant and drug-sensitive serum samples and to investigate the possibility of serum mi R-21 used as drug-resistant biomarker for epithelial ovarian cancer.Methods: The expressions of micro RNA-21 in serum from 20 cases of epithelial ovarian cancer and 10 cases of normal population were detected and compared by Taqman real-time RT-PCR. The correlations of serum levels of micro RNA-21 and drug-resistace and clinicopathological characteristics of epithelial ovarian cancer were analyzed.Results: The serum levels of micro RNA-21 in normal population,drug-sensitive and drug-resistant epithelial ovarian cancer were respectively 0.573±0.318, 2.606±1.057, 26.766±26.710. The serum levels of micro RNA-21 in drug-sensitive and drug-resistant EOC were both higher than that of normal population(P<0.05). While the serum levels of micro RNA-21 in drug-resistant EOC was also higher than that of drug-sensitive epithelial ovarian cancer(P<0.05). The expression of mi R-21 had not correlation with surgical-pathological stages(P>0.05), and also not correlation with whether lymph nodes metastasis or not(P>0.05).Conclusion: The expression of mi R-21 in drug-resistant serum samples significantly higher than those in drug-sensitive serum samples,and it is expected to become a new tumor biomarker of epithelial ovarian cancer drug-resistant.Part ⅡMicro RNA-21 regulates cisplatin resistance by negative targetingPTEN in epithelial ovarian cancerObjective:To detect the expression of micro RNA-21 in SKOV3 and SKOV3 /DDP cells and explore the association between micro RNA-21 and cisplatin resistanc in epithelial ovarian cancer.Furthermore, to detect the expression of PTEN m RNA and protein and investigate the mechanism that micro RNA-21 contributes to the cisplatin resistance in epithelial ovarian cancer.Method:(1)The drug resistance of SKOV3/DDP cells was evaluated using MTT assay.(2)Real-time PCR was used to detect the expression of mi R-21 and PTEN m RNA in SKOV3 and SKOV3/DDP cells.(3)The expression of PTEN protein in SKOV3 and SKOV3/DDP cells were detected by western blot.(4)The SKOV3 and SKOV3/DDP cells were respectively transfected with the mimcs or inhibitors of mi R-21 and negative control(NC) by lipofectamine 2000.After transfection,MTT assay was used to analyze drug sensitivity again.The expressions of mi R-21,PTEN m RNA in SKOV3 and SKOV3/DDP cells were detected by real-time PCR. The expressions of PTEN protein in SKOV3 and SKOV3/DDP cells were measured by western blot.Result:(1) IC50 of cisplatin to SKOV3 and SKOV3/DDP cells were respectively 5.351μmol /L and 22.488 μmol /L(P<0.05). The drug resistance index of SKOV3/DDP cells relative to SKOV3 cells was 4.2.(2)The total RNA of the two cell lines was isolated.The expression level of mi R-21 in SKOV3/DDP cells was significantly higher than that of SKOV3 cells by real-time PCR(P<0.05).While the expression level of PTEN m RNA in SKOV3 and SKOV3/DDP cells were not significant differences(P>0.05).(3) The expression level of PTEN protien in SKOV3/DDP cells is higher than that in SKOV3 cells by western blot.(4) After transfection,real time PCR detected that mi R-21 inhibitors significantly reduced mi R-21 level in SKOV3/DDP cells and mi R-21 mimics significantly increased mi R-21 level in SKOV3 cells.(5) After transfection, the expression level of PTEN m RNA in SKOV3+mimics cells was significantly lower than that of negative control(P<0.05),while the expression level of PTEN m RNA in SKOV3/DDP+inhibitor cells and SKOV3/DDP+nc were not differences(P>0.05). The expression level of PTEN m RNA in SKOV3+nc cell and SKOV3/DDP+nc cell were also not significant differences( P>0.05).(6) After transfection, IC50 of cisplatin to SKOV3+nc and SKOV3++mimics cells were respectively5.205μmol /L and 25.763 μmol /L(P<0.05). IC50 of cisplatin to SKOV3/DDP+nc and SKOV3/DDP++inhibitors cells were respectively 21.914μmol /L and 15.524μmol /L.(7) After transfection, the upregulation of mi R-21 in SKOV3 cells was concurrent with the downregulation of PTEN protein.While the down regulation of mi R-21 in SKOV3/DDP cells was concurrent with the upregulation of PTEN protein.Conclusion:(1)The expressions of mi RNA-21 in SKOV3/DDP and SKOV3 cells are significantly different,which suggests that mi RNA-21 maybe participates in epithelial ovarian cancer’s cisplatin resistance.(2) mi RNA-21 maybe regulates cisplatin resistance by negative targeting PTEN in epithelial ovarian cancer.