The Inhibitory Effect Of MTDH Gene Silence In Breast Cancer MDA-MB-231Cell On Nude Mouse Transplanted Tumor

Objective:The inhibitory effect and its mechanism of MTDH gene silence in MDA-MB-231breast cancer cell on nude mouse transplanted tumor.Methods:15female SPF nude mice were randomly allocated into three groups:the tumor group (MDA-MB-231cell strain), the experimental group (MDA-MB-231/P cell strain) and the control group (MDA-MB-231/PO cell strain). We injected the cells above to mouse’s right breast of each group respectively to construct nude mouse tumor model. We measured the diameter of the tumor from the third week to observe the change of tumor volume. Mice were sacrificed in the eighth week, and tumor tissues were collected and weighted. Tumor tissues, axillary nodes and lung tissues were used for pathological examination. MTDH mRNA expression was analyzed by PT-PCR, MTDH protein expression were detected by Weston-blot and Immunohistochemistry.Results:1. The tumor volume of the experimental group was smaller than that of the other2groups (P<0.01), and the tumor volume of the tumor group and the control group have no significant difference (P>0.05). The tumor of the experimental group grew slower than the other2groups, and the tumor grew at almost the same speed on both the tumor group and control group.2. The tumor weight of the experimental group was lighter than that of the control group at the8th week (P<0.01). The tumor weight of the tumor group and the control group have no significant difference (P>0.05).3. According to the HE stain, the tumor cell arrangement, tumor cell growth and tumor vessel growth were the same. 4. Number of positive axillary nodes in the tumor group, control group and experimental group were10/18,8/16and2/18respectively after HE stain. The positive rates were56%,50%and11%, respectively. The metastasis rate of the experimental group was lower than that of the control group (P<0.01), however, the metastasis rate of the tumor group and the control group have no significant difference (P>0.05).5. Number of positive lung tissues in the tumor group, control group and experimental group were1/5,2/5and0/5respectively after HE stain.6. When analyzed by RT-PCR, the MTDH mRNA expression of the tumor group was lower than that of the control group (P<0.01), the MTDH mRNA expression of the tumor group and control group have no significant difference (P>0.05).7. The MTDH protein expression in the experimental group was lower than that of the other2groups in Western blot (P<0.01). The MTDH protein expression in the tumor group and control group have no significant difference (P>0.05).8. The positive visual fields of the tumor tissues in the tumor group, control group and experimental group were18/25,17/25and4/25respectively in Immunohistochemistry. The positive rates were72%,68%and16%, respectively. The MTDH protein expression of the experimental group was lower than that of the tumor group (P<0.01). The MTDH protein expression of the control group and tumor group have no significant difference (P>0.05).Conclusions:1. miRNA-MTDH can inhibit breast cancer cell proliferation and the metastasis in nude mice;2. miRNA-MTDH can inhibit the expression of MTDH mRNA and MTDH protein in nude mice.