Mechanism of introduction of exogenous genes into cultured cells using DEAE-dextran-MMA graft copolymer as non-viral gene carrier.

Comparative investigations were carried out regarding the efficiency of introduction of exogenous genes into cultured cells using a cationic polysaccharide DEAE-dextran-MMA (methyl methacrylate ester) graft copolymer (2-diethylaminoethyl-dextran-methyl methacrylate graft copolymer; DDMC) as a nonviral carrier for gene introduction. The results confirmed that the gene introduction efficiency was improved with DDMC relative to DEAE-dextran. Comparative investigations were carried out using various concentrations of DDMC and DNA in the introduction of DNA encoding luciferase (pGL3 control vector; Promega) into COS-7 cells derived from African green monkey kidney cells. The complex formation reaction is thought to be directly proportional to the transformation rate, but the complex formation reaction between DDMC and DNA is significantly influenced by hydrophobic bonding strength along with hydrogen bonding strength and Coulomb forces due to the hydrophobicity of the grafted MMA sections. It is thought that the reaction is a Michaelis-Menten type complex formation reaction described by the following equation: Complex amount = K1 (DNA concentration)(DDMC concentration). In support of this equation, it was confirmed that the amount of formed complex was proportional to the RLU value.

Supermolecular drug challenge to overcome drug resistance in cancer cells.

Overcoming multidrug resistance (MDR) of cancer cells can be accomplished using drug delivery systems in large-molecular-weight ATP-binding cassette transporters before entry into phagolysosomes and by particle-cell-surface interactions. However, these hypotheses do not address the intratumoral heterogeneity in cancer. Anti-MDR must be related to alterations of drug targets, expression of detoxification, as well as altered proliferation. In this study, it is shown that the excellent efficacy and sustainability of anti-MDR is due to a stable ES complex because of the allosteric facilities of artificial enzymes when they are used as supermolecular complexes. The allosteric effect of supermolecular drugs can be explained by the induced-fit model and can provide stable feedback control systems through the loop transfer function of the Hill equation.

Characteristics of DEAE-dextran-MMA graft copolymer as a nonviral gene carrier.

A stable and soapless latex of diethylaminoethyl-dextran-methyl methacrylate (DEAE-dextran-MMA) graft copolymer (DDMC) has been developed for nonviral gene delivery vectors that are possible to autoclave. DDMC relatively easily formed a polyion complex between DNA and DDMC by the hydrophobic force of graft poly(MMA) depending on its large positive entropy change (DeltaS). DDMC has been confirmed as having a high protection facility for DNase by DNase degradation test.Transfection activity was determined using the beta-galactosidase assay, and a higher value of 16 times or more was confirmed for the DDMC samples in comparison with one of the starting DEAE-dextran hydrochloride samples. The resulting DDMC, having an amphiphilic domain so as to form a polymer micelle, should become a stable latex with a hydrophilic-hydrophobic microseparated domain. The complex of DDMC and plasmid DNA may be formed on the spherical structure of the amphiphilic microseparated domain of DDMC and have a good affinity to the cell membrane. The infrared absorption spectrum shift to a high-energy direction at around 3450 cm(-1), because of the complexes between DNA and DDMC, may cause the formation of more compact structures, not only by a coulomb force between the phosphoric acid of DNA and the DEAE group of DEAE-dextran copolymer but also by a force from the multi-intermolecule hydrogen bond in the backbone polymer DEAE-dextran and a hydrophobic force from the graft poly(MMA) in DDMC. It is thus concluded that DNA condensation may possibly have a high transfection efficiency via DDMC. The high efficiency of this graft copolymer, which is sterilized by an autoclave, may thus make it a valuable tool for safe gene delivery.

Medicinal facilities to B16F10 melanoma cells for distant metastasis control with a supramolecular complex by DEAE-dextran-MMA copolymer/paclitaxel.

The resistance of cancer cells to chemotherapeutic drugs (MDR) is a major problem to be solved. A supramolecular DEAE-dextran-MMA copolymer (DDMC)/paclitaxel (PTX) complex was obtained by using PTX as the guest and DDMC as the host having 50-300 nm in diameter. The drug resistance of B16F10 melanoma cells to paclitaxel was observed, but there is no drug resistance of melanoma cells to the DDMC/PTX complex in vitro. The cell death rate was determined using Michaelis-Menten kinetics, as the DDMC/PTX complex promoted allosteric supramolecular reaction to tubulin. The DDMC/PTX complex showed a very superior anti-cancer activity to paclitaxel alone in vivo. The median survival time (MST) of the saline, PTX, DDMC/PTX4 (particle size, 50 nm), and DDMC/PTX5 (particle size, 290 nm) groups were 120 h (T/C, 1.0), 176 h (T/C, 1.46), 328 h (T/C, 2.73), and 280 h (T/C, 2.33), respectively. The supramolecular DDMC/PTX complex showed the twofold effectiveness of PTX alone (p < 0.036). Histochemical analysis indicated that the administration of DDMC/PTX complex decreased distant metastasis and increased the survival of mice. A mouse of DDMC/PTX4 group in vivo was almost curing after small dermatorrhagia owing to its anti-angiogenesis, and it will be the hemorrhagic necrotic symptom of tumor by the release of "tumor necrosis factor alpha (TNF-α)" cytokine. As the result, the medicinal action of the DDMC/PTX complex will suppress the tumor-associated action of M2 macrophages and will control the metastasis of cancer cells.