Development of target delivery system based on actinomycin class drugs and recombinant alpha-fetoprotein.

A recombinant alpha-fetoprotein (rAFP) was obtained in the yeast P. pastoris system, and its functional activity was confirmed. A method for producing polymer particles loaded with dactinomycin was developed, and a conjugate of these nanoparticles with rAFP was synthesized. The efficiency of the obtained conjugate on the HeLa, SKOV3, and MG-63 tumor cells and the absence of toxicity on the normal cells was shown. Experiments in vivo demonstrated a significant increase in the antitumor efficacy of the conjugate at a lower general toxicity as compared to the commercially available dactinomycin.

[Accumulation of doxorubicin conjugates with dendritic polymer and vector protein in normal and tumor cells in vitro].

Accumulation of doxorubicin (Dox), its conjugates with the second generation dendritic polymer (G2-Dox) and vector pro- tein (recombinant third domain of alpha-fetoprotein - 3D-G2- Dox) in normal and tumor cells was studied in vitro within the framework of the development of selective transport system of anticancer drugs to the target cells. The objects of the study were cells of peripheral blood mononuclear fraction of healthy donors and cells of breast adenocarcinoma lines MCF-7 and MCF-7/MDR1, differing in chemosensitivity. G2-Dox and 3D-G2-Dox accumulated in tumor cells of the both lines better than free Dox (p<0,05). However removal of these drugs out of cells MCF-7 and MCF-7/MDR1 was significantly different: in the latter case all free Dox was excluded from the cells for 24 hours while Dox, accumulated in composition with dendrimers, still remained in the cells. It was important that 3D-G2-Dox (unlike the G2-Dox) accumulated in normal cells worse than free Dox (p<0.01). Thus, the results indicate that the use of 3D-G2-Dox is the most promising because it accumulates in tumor cells better and in normal cells worse than free Dox. Furthermore it can be assumed that the use of 3D-G2-Dox would be especially useful in cases of multi-drug resistance associated with the high expression of P-glycoprotein.

[The Combined Effects of Ionizing Radiation and Dendritic Polymers Loaded with Doxorubicin on the MCF-7 Breast Cancer Cell Line].

The dendritic polymers (dendrimers) are perspective nanocontainers for transportation of anticancer drugs into cells and a controlled release of the delivered substances. However, the combined effect of ionizing radiation and dendrimers loaded with anticancer drugs has been poorly studied and is the aim of this research. We used poliamidoamin (PAMAM) dendrimers of the second generation (G2) covalently conjugated with doxorubicin (Dox) via an acid labile linker, cis-aconitic anhydride. We compared the intracellular accumulation of Dox and growth rate of the MCF-7 cell culture under the single and combined action of ionizing radiation at a dose of 4 Gy, free Dox and G2-Dox. It was found that within 2 hours free Dox accumulated in cancer cells better than Dox connected with G2 dendrimers (p < 0.05 in the concentration range of 1-5 µmol/l). The intracellular accumulation of Dox was higher by 1.7 times for the free Dox than that connected with dendrimers (for concentration 0.5 µmol/l p = 0.02) after 26 hours of incubation. Like the intracellular accumulation of Dox, inhibition of the cell culture growth was more pronounced when using free Dox than G2-Dox in the case of both a single and combined action of these drugs. Subadditivity effects of the combined action of both drugs and ionizing radiation are shown in terms of reducing the number of tumor cells 24 hours after irradiation. The results indicate the need for further development of selective delivery systems for Doxin tumor cells, providing a more intense accumulation of anticancer drug in target cells.