The Effect Of MiRNA-7 To Cisplatin Drug-resistance In Esophageal Cancer Cell TE-1

Background Esophageal cancer is a kind of common malignant tumor in our country.Currently the main treatment is surgery combined with radiation and chemotherapy [1].Cisplatin(DDP)is the first-line treatment of advanced esophageal cancer,but acquired drug-resistance easily[2].Cisplatin mainly affected the cell DNA and can cause DNA damage and induce cell apoptosis[3].The epidermal growth factor receptor(EGFR)is a kind of glycoprotein that has tyrosine kinase activity,mainly distribute-d in the membrane surface,and plays its biological effect by binding with the ligand.Studies showed that EGFR in the nucleus can influence the treatment response of tumor cells to cisplatin and radiotherapy by adjusting DNA repair.This may be one of the reasons of cisplatin drug-resistance[4].Therefore theoretically,inhibition of EGFR can restore the sensitivity of esophageal to DDP.Micro RNA-7(miRNA-7)is one of the members of the mic-ro RNAs family that can act directly on the EGFR 3 `-UTR section,inhibiting EGFR m RNA and its protein expression[5].Few reports can be found about whether miRNA-7 can enhance the sensitivity of esophageal cancer cell to DDP.This study to observe the influence of DDP sensitivity,in esophageal cancer cells TE-1 of miRNA-7 overexpression by transfection aims,and explore its possible mechanism,so as to provide reference for solving esophageal DDP resistance.Objective Explore the over-expression of microRNA-7(miRNA-7)how to impacts the EGFR(The epidermal growth factor receptor)in esophageal carcinoma cell lines TE-1 and relationship with cisplatin drug resistance.Methods 1.Transient transfected with miRNA-7 mimic into esophageal cancer cell lines TE-1 were taken as transfection group,mimic Negative Control were taken as transfection conrtol group with lipofectmin 2000.2.Detect the expression of miRNA-7 and EGFR m RNA in the above two groups and normal control group with RT-PCR.3.Detect total EGFR and EGFR in cytoplasmic,nucleus both in transfection group and transfection control group with Western blot.4.Detect cisplatin IC50 with CCK-8 in transfection group and transfection control group.5.Observe the expression of EGFR with immunofluorescence confocal microscope in two group.Results 1.RT-PCR results show that the miRNA-7 expression in transfection group obviously increased,EGFR m RNA has reduced(P<0.001).2.Western blot results shows transfection group within the total EGFR decreased,nuclear EGFR increased(P<0.01),and cytoplasm EGFR expression decreased than transfection control group(P<0.05).3.CCK-8 results show after miRNA-7 over expression in TE-1 with cisplatin(48h)IC50 increased than the control group(P<0.01).4.Immunofluorescence results show EGFG in the transfection group is higher than transfection control group in nuclear but in cell membrane and cytoplasm reduced.Conclusions MiRNA-7 overexpressed in esophageal cancer cells TE-1 can reduce cisplatin sen-sitivity by EGFR increased in nuclear translocation.