Effect Of Anti-HER-2 Ribozyme On Breast Cancer Cells

Objective: To construct two anti-HER-2 ribozyme plasmids Rz1 and Rz2; observe their effects on HER-2 expression and the growth of MCF-7, a kind of human breast cancer cells; and discuss the mechanisms as well; as to construct the platform of caner gene therapy with small RNA technique in our institute.Methods: The DNA sequences of Rz1 and Rz2 were synthesized and directly cloned into pcDNA3.1-, a eukaryotic expression plasmid. The constructed plasmids, Rz-pcDNA3.1-, were then transfected into MCF-7 cells. The consequent tests were semi-quantitative RT-PCR, reflecting mRNA quantity of HER-2 and other cancer-related important genes; fluorescence activated cell sorting (FACS), detecting HER-2 protein expression; and the tumor implantation into nude mice. The stable Rz transfected cell clones were injected subcutaneously into nude mice, with the control group injected with untreated MCF-7 cells. The growth rate and the volume of tumor were measured from one week later on.Results: No distinct effect was observed on Rz2. 48 hours after the transient transfection of Rz1, decrease in mRNA and protein of HER-2 appeared, which was further confirmed in the stable transfected cell clones, accompanied by the decrease of expression of some genes, k-ras for example, and the increase of expression of others, p53 for instance. In the tumor implantation, the growth rate of Rz1 transfected cells was found to be much lower than that of the control group and the tumorigenicity was also decreased.Conclusions: Anti-HER-2 ribozyme Rz1 was able to inhibit HER-2 expression in MCF-7 cells. The decrease of k-ras expression and increase of p53 expression was observed when HER-2 expression inhibited. Rz1 also reduced the tumorigenicity of MCF-7 in nude mice.