Polycations For Tumor Gene Therapy And Reversing Multi-Drug Resistence With Anti-Cancer Drug

We mainly studied the polycation vector used to solve gene delivery and multi-drug resistence problems. The main content and conclusion of this dissertation are summarized below:1) A PEI-mimic PSI derivative named PEE was successfully synthesized.1H-NMR confirmed the structure of PEE. Morphology characterization confirmed that PEE could form spherical complexes with plasmid. In vitro study on the cellular uptake, cell toxicity and transfection demomstrated the transfection effiency of PEE was the same as PEI 25 kD. To study the in vivo toxicity, the hemogram was tested and the immunohistochemistry of heart, liver, kidney was carried out using mice. To study the in vivo transfection effiency, EGFP transfection was carried out using nude mice bearing B16BL6 tumor. The results showed that in vivo transfection efficiency of PEE was similar to PEI 25kD. Thus, PEE had a low in vivo toxicity and was a PEI-mimic gene vector.2) A type of micelles called PCC comprising a polycationic shell to condense the siRNA and hydrophobic core to package doxorubicin was synthesized.The structure of the polymer was determined by 1H NMR, FT-IR, DSC, and XRD and the micelles were characterized by DLS,2D-NOESY NMR, and TEM to study the self-assembly of the micelles with siRNA and drugs. In vitro studies demonstrated controlled release and temporal enhancement of the therapeutic efficacy of P-gp siRNA and doxorubicin. Release of siRNA down-regulated the mRNA and protein levels of P-gp in the MCF-7/ADR cell lines effectively and the accumulated doxorubicin facilitated apoptosis of the cells to reverse MDR. Moreover, in vivo research revealed that the siRNA and doxorubicin loaded micelles induced tumor cell apoptosis and inhibited the growth of MDR tumor. The western blotting and RT-PCR results illustrated that the synergistic treatment of siRNA and doxorubicin led to efficient reduction of the P-gp expression as well as cell apoptotic induction in MDR tumors. The micelles have large clinical potential in drug/RNAi synergistic treatment via restoration of the chemosensitivity in MDR cancer therapy.3) An initial research on A2780/T cells exposed to PTX, PCC/PTX, PCC/PTX/siMDRl system was carried out.The gene differences of each group was found. Through the analysis of the GeneMANIA database and STRING database, we found that low doses of PTX had an impact on cell cycle, apoptosis, DNA damage, and amino acid metabolism of A2780/T cells. The gene differences analysized by GeneMANIA in A2780/T cells treated by PCC/PTX and PCC/PTX/siMDR1 showed interaction type were co-localization or gene interaction. Bioinformatics methods were introduced into the research of material mediated multi-drug resistance.