Research of Synergetic Reversal in Adriamycin - Resistance by the Application of Magnetic Nanoparticle of Fe₃O₄ and Tetrandrine in K562/A02 Leukemic Cells.

Objective: To prepare functionalized Fe₃O₄-magnetic nanoparticles(Fe₃O₄-MNPs) loaded with adriamycin(ADM) or Fe₃O₄-MNPs co-polymerized with ADM and tetrandrine(Tet) to investigate whether the temperature, time or ratio of drug to nanoparticles influences the polymerization. To study the reversal role that the drug-loaded nano-composites play in K562 and one of its resistant cell line K562/A02 and to learn the reversal mechanism of this kind of treatments so as to provide theoretic evidence for the clinical application of them as resistance modifying agents.

Method: The drug-loaded nanoparticles were prepared using mechanical absorption polymerization process in different condition of 4° or 37° for 24h or 48h. To investigate whether Fe₃O₄-MNPs loaded with ADM and Tet would play a synergetic reverse role in multidrug resistant cell, the drug-loaded nanoparticles by mechanical absorption polymerization were prepared to act with K562 and one of its resistant cell line K562/A02. The survival of cells which were cultured with drug-loaded nano-composites for 48h was observed through MTT assay, the growth inhibition efficacy of cells was calculated then. Using cells under the same condition described before, we took use of fluorescence microscope to measure fluorescence intensity of intracellular ADM at a wavelength of 488nm. P-glycoprotein (P-gp) was analyzed with flow cytometer. The expression of mdr1 mRNA was measured by RT-PCR.

Results: The results showed that the growth inhibition efficacy of both the two cells increased with augmenting concentration of Fe₃O₄-MNPs which were loaded with drugs. The condition of 4° and 48h was significantly better than that of 37° and 24h respectively. Both Fe₃O₄-MNPs loaded with ADM or Fe₃O₄-MNPs co-polymerized with ADM and Tet elevated the intracellular ADM accumulation in K562/A02. However, no linear correlation was found between fluorescence intensity of intracellular adriamycin and augmenting concentration of Fe₃O₄-MNPs in K562/A02. Tet could downregulate the level of mdr-1 gene and decrease the expression of P-gp. Furthermore, Tet polymerized with Fe₃O₄-MNPs reinforced this downregulation, causing a 100-fold more decrease in mdr1 mRNA level, but did not reduce total P-gp content.

Conclusions: Fe₃O₄-MNPs can load ADM or both ADM and Tet by mechanical absorption polymerization, which depends on proper temperature and time. Furthermore, the drug-loaded nano-composites have the ability in multidrug resistance reversal. Fe₃O₄-MNPs loaded with ADM or Tet can enhance the effective accumulation of the drugs in K562/A02 and Fe₃O₄-MNPs loaded with Tet obviously reverse multidrug resistance by reinforcing mdr1 gene downregulation. Functionalized Fe₃O₄-MNPs loaded with Tet probably have synergetic effect on reversal in multidrug resistance.