The Preparation And Antitumor Mechanism Of EGFR-specific PEGylated Immunoliposomes Delivering SiRNA

Breast cancer is one of the most common malignant tumor in women, and has become the "the first killer" to women's health. At present, surgery treatment,endocrine treatment,radiotherapy and chemotherapy are the commonly traditional treatments. But the treatment effort is very limited, long-term alleviation or cure is hard to achieve and even have serious side effects. Nowadays, with the rapid development of molecular biology and biochemistry, how to really know and treat diseases from their molecular level has gradually become the focal point of human beings. Fortunately, gene therapy has gained great breakthrough progress, and already play an important role in treat carcinoma,cardiovascular diseases,auto-immune diseases and viral infection diseases that can not be cured effectively. However, the biggest hindrance of gene therapy is its delivery problems, only safe and effective drug delivery in cells can ideal therapy effect achieved.RNA interference (RNAi) is a specific gene silencing phenomenon that induced by a small interfering RNAs to isogeny mRNA. Because specificity,high performance and duration, its investigation and application has become a hot spot for molecular biology. At the same time, the technology also develop a new pathway for gene therapy of correlated clinic diseases.DC-chol liposomes were the first FDA-approved cationic liposomes (CLs) for clinical trials and their safety was also demonstrated in treating cystic fibrosis in vivo. At present, CLs composed of 3β-[N-(N',N'-dimethylaminoethane) carbamoyl] cholesterol (DC-chol) and dioleoylphosphatidyl ethanolamine (DOPE) (DC-chol/DOPE liposomes) have been classified as one of the most efficient gene delivery systems. DC-chol/DOPE liposomes were biocompatible and showed low cytotoxicity. However, the further development of DC-chol/DOPE liposomes was severely hampered by their low transfection efficiency, poor serum stability and short circulation lifetime. If these problems were overcome, a better clinical use would be achieved for DC-chol/DOPE liposomes.Our study is on the basis of early days, we use DC-chol/DOPE liposomes conjugated with anti-HER1-Fab' to prepara an immunoliposome that can targeted deliver drugs into HER1-overexpressing breast cancer and solve the problems of poorly specificity. The results demonstrated that the lyophilized PIL (LPIL) prepared by the lyophilization/rehydration method possessed a significantly enhanced GFP gene, a model target, silencing ability compared with PIL in HER1-overexpressing MDA-MB-231 cells. Among a series of LPIL with different PEGylation degree, LPIL containing 2.5%PEG (2.5%PEG LPIL) showed the best HER1 gene silencing activity. Confocal microscope studies demonstrated that 2.5%PEG LPIL could specifically bind to MDA-MB-231 cells and were sequentially internalized into them. Using RhoA as a cancer therapeutic target, 2.5%PEG LPIL entrapping anti-RhoA siRNA could specifically silence RhoA expression and inhibit cell invasion in MDA-MB-231 cells. In conclusion, these finding demonstrated the potential use of 2.5%PEG LPIL in specifically delivering siRNA to HER1-overexpressing cancers.