Effect Of ADAM17-shRNA On MCF-7 Breast Cancer Xenografts In Nude Mouse

Objective To explore the inhibitory effect of ADAM17-sh RNA on MCF-7 breast cancer xenografts in nude mice and its mechanism.Methods ADAM17-sh RNA was transfected into MCF-7 breast cancer cells by recombinant lentiviral vector carrying red fluorescent protein(RFP)expression frame,and the expression of RFP was observed under fluorescence microscope to determine the transfection efficiency.Thirty nude mice were raised in a SPF environment,and injected intraperitoneally with estrogen everyday.MCF-7 breast cancer cells with transfection efficiency higher than 90% were selected to implant in nude mice subcutaneously: the control group received untreated MCF-7 cells,transfection control group received MCF-7 cells transfected with nonsense-sh NC,and transfection group received MCF-7 cells transfected with ADAM17-sh RN A.The tumor size was measured every four days when a hard tumor nodule was found;the average tumor volume of each group and the inhibition rate of transfection group were calculated.All nude mice were sacrificed on the 28 th days after implantation,and tumor samples were reserved.Morphological characteristics of the implanted tumor tissues from three groups were observed under a microscope after HE staining;the expressions of ADAM17,EGFR,p-EGFR,AK T,p-AKT,ERK and p-ERK in tumor tissues were detected by Western blot.Results Seventy-two hours after transfection(MOI:100),the transfection efficiency was close to 100% under fluorescence microscope.Obvious tumor nodules were found in all nude mice on the 12 th day after implantation.The implanted tumor showed a trend of sustained and rapid growth in the control group and transfection control group,and there was no statistical difference between the two groups(P>0.05);but in the transfection group,the tumor growth was slower and at each measured node,the tumor volume was significantly smaller than that in the other two groups(P<0.01).After nude mice were sacrificed,the average tumor volume of the control group,transfection control group and transfection group were 644.93±16.39mm3,649.30±16.57mm3 and 243.04±11.62mm3,respectively;compared with the control group and transfection control group,the maximum inhibition rate of transfection group was 62.31% and 62.56%,respectively.HE staining showed that the implanted tumors were characterized by breast infiltrating ductal carcinoma,and there was no obvious difference between the control group and transfection control group,but the tumor tissues in the transfection group developed larger areas of necrosis compared with the other two groups.Western blot results showed that ROD of the proteins were ADAM17(0.59±0.02,0.63±0.07,0.13±0.01),EGFR(0.98±0.11,0.96±0.13,0.33±0.03),p-EGFR(0.49±0.09,0.49±0.03,0.30±0.05),AKT(0.61±0.06,0.62±0.05,0.21±0.03),p-AKT(0.65±0.04,0.67±0.07,0.26±0.03),ERK(1.18±0.06,1.25±0.21,0.35±0.10),p-ERK(0.83±0.38,082±0.89,0.39±0.69)in the implanted tumors of control group,transfection control group and transfection group,respectively;the difference was not significant between the control group and transfection control group(P>0.05),but the expression of all these proteins in transfection group were lower than those in the other two groups,and the difference was statistically significant(P≤0.01).Conclusion The growth of MCF-7 breast cancer xenografts can be effectively inhibited by ADAM17-sh RNA in nude mice,and EGFR-PI3K-AKT and EGFR-MEK-ERK signaling pathway are involved in the process.