| Esophageal cancer is one of the most common malignant carcinoma in our country.The incidence and mortality of esophageal cancer is rather high in China,which is a great threaten to human health.Due to lack of early diagnosis,most patients are in the middle-late stage at their first visit to the hospital,so chemotherapy becomes their main treatment method.But multidrug resistance(MDR)is a major barrier to the success of chemotherapy.Numerous clinical studies indicate that the multidrug resistance in tumor is related to death of more than 90% of carcinoma patients.Therefore,investigate the drug resistance mechanism of esophageal cancer and seek efficient MDR reversal agent is one of the hot spot in the esophageal cancer research currently.Curcumin(Cur)is a kind of polyphenolic plant pigment which extracted from the rhizome of zingiberaceae plants,which have pharmacological effects such as inducing apoptosis of tumor cells and inhibiting their proliferation.In recent years,studies have shown that curcumin can reverse the multidrug resistance of tumor cells.However,its mechanism of MDR on cancer cells remains unclear.Notch1 signaling pathway plays a key role in carcinogenesis and progression of various human malignancies and is involved in contributing to chemo-resistance in multiple tumors.But it has not been reported that curcumin have the ability to reverse multidrug resistance of esophageal carcinoma through inhibition of the Notch1 signaling pathway.In this study,vincristine(VCR)resistance of human esophageal cancer Eca-109/VCR cells were used as the object and divided into four treatment groups: control group,curcumin group,VCR group and curcumin combined with VCR group,to investigate the reversal and apoptosis effect of curcumin on drug resistance of Eca-109/VCR cells,the regulation of the expression levels of Notch1,Jagged1,Hes1 and P-glycoprotein(P-gp),and to explore its possible mechanisms.The effects of different concentrations of Cur on the proliferation of Eca-109/VCR cells and the reversal effect of Cur(25 μmol/L)on drug resistance of Eca-109/VCR cells were measured by MTT method;The apoptosis was assayed by flow cytometry(FCM)and Hoechst33258 fluorescence staining;The expression levels of Notch1,Jagged1 and Hairy and enhancer of split 1(Hes1)m RNAs were detected by real-time fluorescent quantitative PCR.The expressions of Notch1,Jagged1,Hes1 and P-glycoprotein(P-gp)proteins were measured by Western blotting.MTT assay showed that the proliferation inhibitory rate was(8.82±0.80)% after Eca-109/VCR cells were treated by 25 μmol/L Cur for 24 h;when Cur(25 μmol/L)combined with various concentration of VCR for 24 h,the half inhibitory concentration(IC50)of VCR on Eca-109/VCR cells decreased from 7.70 μg/m L in VCR group to 2.55 μg/m L,the reversal fold of Cur was 3.02.After Eca-109/VCR cells were treated by Cur(25 μmol/L),VCR(2 μg/m L)alone or Cur(25 μmol/L)combined with VCR(2 μg/m L)for 24 h respectively,flow cytometry(FCM)analysis indicated that the apoptosis rate of Eca-109/VCR cells was(11.27±0.21)%,which was significantly higher than that in Cur group(5.48±0.84)% and VCR group(7.11±1.09)%(both P < 0.05);the changes of apoptotic morphology and apoptosis rates after Hoechst33258 fluorescence staining were consistent with the result of FCM.Real-time fluorescent quantitative PCR results showed that the expression levels of Notch1,Jagged1 and Hes1 m RNAs in combination treat group were lower than those in Cur and VCR group(P<0.01).Furthermore,the expressions of Notch1,Jagged1,Hes1 and P-gp proteins in the combined group were significantly decreased as compared with Cur and VCR group(P<0.05).These results showed that Cur can obviously enhance the sensitivity of Eca-109/VCR cells to VCR and reverse drug resistance of human esophageal cancer Eca-109/VCR cells.The mechanism may be related to the inhibition of Notch1 signaling pathway,down-regulation of P-gp expression and inducing apoptosis. |
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