The anticancer efficacy of a supramolecular complex that was used as an artificial enzyme against multi-drug-resistant cancer cells was confirmed. A complex of diethylaminoethyl-dextran-methacrylic acid methylester copolymer (DDMC)/paclitaxel (PTX), obtained with PTX as the guest and DDMC as the host, formed a nanoparticle 50-300 nm in size. This complex is considered to be useful as a drug delivery system (DDS) for anticancer compounds since it formed a stable polymeric micelle in water. The resistance of B16F10 melanoma cells to PTX was shown clearly through a maximum survival curve. Conversely, the DDMC/PTX complex showed a superior anticancer efficacy and cell killing rate, as determined through a Michaelis-Menten-type equation, which may promote an allosteric supramolecular reaction to tubulin, in the same manner as an enzymatic reaction. The DDMC/PTX complex showed significantly higher anticancer activity compared to PTX alone in mouse skin in vivo. The median survival times of the saline, PTX, DDMC/PTX4 (particle size 50 nm), and DDMC/PTX5 (particle size 290 nm) groups were 120 h (treatment (T)/control (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 twice the effectiveness of PTX alone (p < 0.036). Above all, the DDMC/PTX complex is not degraded in cells and acts as an intact supramolecular assembly, which adds a new species to the range of DDS.
Keywords: artificial enzyme; diethylaminoethyl–dextran–MMA; graft copolymer; multi-drug resistance of cancer cells; paclitaxel; supramolecular complex.