Development and characterization of PLGA microparticles containing polyamine/wild-typep53 complexes for the treatment of breast cancer

Breast cancer is the most commonly diagnosed cancer in American women and tumor suppressor gene p53 is found to be mutant in about 40% breast carcinomas. The reintroduction of wild-type p53 gene into breast cancer cells potentially inhibited tumor proliferation. However, the toxicity, immunogenicity, and possible insertional mutagenesis of currently available vectors impeded their clinical applications.; Therefore, the purpose of this research was to develop well-defined systemic non-viral p53 delivery systems to fulfill ideal vector requirements for the treatment of breast cancer. To achieve this goal, DNA was pre-condensed with polyamines to protect it from nuclease degradation and form a core of virus like particles to gain access to the target cells. The physicochemical and biological properties of p53-polyamine complexes were investigated. The main obstacle with this approach is that the use of whole proteins can be limiting for the scale-up of large gene therapy programs and the risk of inducing an immune response either by protein itself or by the transfection complexes. Therefore these complexes were then encapsulated in biodegradable polymeric materials. Biocompatible and biodegradable polymer, Poly (lactic-co-glycolic acid) (PLGA), was chosen to develop microparticles containing DNA-polyamine complexes and deliver p53 in a continuous and reproducible manner. PLGA microspheres containing p53-polyamine complexes were prepared by the solvent evaporation method and formulation parameters were optimized. The physicochemical properties were investigated in selected breast cancer cell lines and in animals.; The results reviewed an original and promising investigation in the aspect of encapsulating polyamine complexed-p53 into PLGA by taking the advantages of the DNA condensation abilities of selected polyamines. Strong DNA compaction with polyamines particularly with histone-H1 dramatically enhanced gene expression in selected human breast cancer cells and conferred the capacity to transfection in the presence of serum. Furthermore, encapsulation of the complexes into PLGA microparticles resulted in the improved cytotoxicity, increased p53 stability and sustained release effect. Findings of present research provide implications for advancing empirical research of human cancer treatment, specifically, the development of non-viral gene delivery systems in the gene therapy for human breast cancer.