The Effect Of ADAM17-shRNA On MCF-7 Xenograft Tumor In The Nude Mouse

Objectives To explore ADAM17-sh RNA in vivo antitumor effect in nude mice implanted with MCF-7 breast cancer cells.Methods MCF-7 breast cancer cells were cultured, and then transfected with ADAM17-sh RNA. The expression of RFP in MCF-7 was detected by Confocal laser scanning microscope(CLSM), which mediated by Lentivirus ADAM17-sh RNA-RFP.Thirty nude mice were randomly divided in to transfected group(MCF-7-ADAM17-sh RNA), vector group(MCF-7-sh NC) and control group(MCF-7). Three groups of cell suspension were prepared and 0.2 ml/(5 × 107/ml) of cell suspension were implanted subcutaneously in the right side of the footpath of each nude mouse. The tumor nodule was found on the 10 thday after implanation, and the tumor size and the general condition of nude mice were observed every 4 days. All nude mice were sacrificed on the 26 th day after implanation by cervical dislocation. The morphological structure was obseved by HE staining and expression ADAM17 and Ki-67 was measured by IHC. The expression of ADAM17 protein in three groups were detected by Western blotting.Results Confocal laser scanning microscope results showed that Lentivirus ADAM17-sh RNA could be successfully transferred into MCF-7 cell and the transfection rate was80%. Ten days after planting,tumor with irregular shape, clear boundary and toughness was found in each nude mice, and the color of skin over tumor was pink. After sacrifice,the size of tumors in control group and vector group were significantly bigger than the transfected group, and the nude mice of the control and vector group were seriously poorer appetite and weight loss compared with the transfected group. The tumor size of transfected group, control group and vector group was 241.96±17.14 mm3、609.50±15.13 mm3 and 611.40±15.97 mm3, respectively. There was significant difference on tumor size in three groups(F=1765.96、P<0.001). Compared with control group and vector group, the tumor inhibition rate of transfected group was 63.11% and63.26%. HE staining results showed that three groups of transplanted tumor were characteristic of typical human breast infiltrating duct carcinoma(cords of breast cancer cells, infiltrating cancer cells, and interstitial hemorrhage). Compared with the transfected group, there were lager necrosis areas in the vector and control groups. The IHC results showed that the positive expression of ADAM-17 was in the cytoplasm. The tumor staining score of ADAM-17 in the transfected group was 2.65±0.49, which was significantly lower than the vector group(7.11±0.21) and control group(7.17±0.27)(F=174.12, P<0.001). The positive expression of Ki-67 protein was in the nuclei and the tumor staining scores score of the transfected group was 3.76±0.23, which was significantly lower than the vector group(8.94±0.42) and control group(9.05±0.34)(F=490.93, P < 0.001). Western blotting result showed that the ADAM17 protein of control group, vector group and transfected group was 0.611±0.037, 0.618±0.028 and0.367±0.034, respectively. Compared with the vector and control group, the expression of ADAM17 protein was significantly lower in the transfected group(F=56.23, P<0.001).Conclusions The growth of human breast cancer MCF-7 cells transfected with ADAM17-sh RNA was significantly inhibited in nude mice.