S. E. Severin

Antitumor activity of conjugates of the oncofetal protein alpha-fetoprotein and phthalocyanines in vitro.

The several conjugates of aluminium and cobalt complexes of phthalocyanines with human alpha‐fetoprotein have been synthesized. Their cytotoxic activity against tumor cells and human peripheral blood lymphocytes was studied. The experimental data demonstrate that the cytotoxic activity of alpha‐fetoprotein‐phthalocyanine conjugates against three types of tumor cells of various origin is much higher (for aluminium and cobalt complexes more than 1000 and 50 times, respectively) in comparison with phthalocyanines themselves. The application of phthalocyanines as conjugates with alpha‐fetoprotein makes it possible to markedly enhance the selective toxicity of phthalocyanines against human tumor cells.

Localization of Mullerian inhibiting substance receptors in various human cancer cell lines.

Recombinant human MIS (rhMIS) produced in transfected Chinese hamster ovary cells has been purified by immunoaffinity chromatography. In the absence of reducing agents, 140 kD homodimer and several oligomers with molecular masses from 280 to 1000 kD are present. Homodimer, tetramer, and higher-molecular-weight rhMIS fractions reduced survival of tumor cells. For these experiments, FITC-labeled rhMIS was used for binding and endocytosis studies by flow cytometry. Flow cytometry performed on MIS-sensitive cancer cell lines demonstrated specific binding of rhMIS. The majority of rhMIS receptors have cytosolic localization. Thus, the level of MIS receptors on the cell membrane was pro-portional to the content of MIS-binding proteins in the whole cell and defines a level of receptor-mediated endocytosis. The immunopurified rhMIS caused significant growth inhibition of ovarian and prostate adenocarcinoma and melanoma human cell lines in inhibition assays.

Proliferative and Differentiation Potential of Multipotent Mesenchymal Stem Cells Cultured on Biocompatible Polymer Scaffolds with Various Physicochemical Characteristics

Biocompatibility of film and fibrous scaffolds from polylactide-based polymers and the relationship between their architecture and the functional characteristics of mesenchymal stem cells were studied. Cell culturing on polylactide-based film and fibrous matrixes did not deteriorate cell morphology and their proliferation and differentiation capacities. The rate of cell proliferation and penetration in microporous 3D matrices with the same porosity parameters and pore size depended on their spatial organization. The above materials can be used as scaffolds for mesenchymal stem cells for creation of tissue engineering implants. The scaffold size and structure should be determined by the defects in the organs in which the regeneration processes have to be stimulated.

Design of etoposide polymeric forms

The present work relates to the field of pharmacology and medicine, in particular, to a new generation of anticancer drugs based on biocompatible polymers containing etoposide as the drug substance. A polymeric composition containing a surfactant and cryoprotective agent in addition to polymer and drug substance was designed. The optimum formulation of the polymeric composition and process conditions for its preparation were selected. The samples of etoposide polymeric forms were found to exhibit in vitro cytotoxic activity against two human tumor cell lines, viz., MCF-7 breast adenocarcinoma and K562 myeloleukemia cell lines, which was either identical or higher than the activity of free etoposide. The samples of the PLGA-based polymeric form of etoposide exhibited the highest activity.

Molecular mechanisms of antitumor activity of niclosamide

The review summarizes literature data on the antitumor activity of niclosamide and its molecular mechanisms. Earlier niclosamide was used for treatment of intestinal parasitic infections. Recent screening of various drugs and chemical compounds, aimed at identifying putative agents with high antitumor activity, revealed that it possesses such activity. Niclosamide not only inhibits such signaling pathways as Wnt/β-cate-nin, mTORC1, Stat3, NF-κB and Notch, but also damages tumor cell mitochondria, inhibits proliferation and induces apoptosis. The effectiveness of niclosamide has been demonstrated in vitro experiments as well as in vivo models using xenotransplantation of human tumors to immunodeficient mice. Niclosamide was active not only against tumor cells but also cancer stem cells. Normal cells are resistant to niclosamide. The accumulated experimental data suggest that niclosamide is a promising pharmacological agent for the treatment of various types of cancer.

Antiproliferative Activity of Niclosamide Against Melanoma and Colorectal Cancer Cells

Studies of the actions of niclosamide against tumor cells and normal human cells (human embryo kidney cells and pulmonary embryo fibroblast cells) showed higher levels of cytotoxic activity against tumor cells, including melanoma (the Mel-8, Mel-10, MS lines) and colorectal cancer (the Caco-2, COLO 320 HSR, and SW827 cells). Niclosamide was shown to have a high level of cytotoxic activity against cells with the multidrug resistance phenotype due to high levels of expression of MDR1 protein on the plasma membrane (the Mel-8 and MCF-7Adr lines). The proportion of tumor stem cells (TSC) was measured by flow cytometry as the proportion of cells forming side populations (SP). Niclosamide was found to act on TSC cells either more effectively (colorectal cancer line SW 837, (decreases in SP fraction size) or with the same effectiveness as the main population of tumor cells (SP fraction size unaltered).

Antitumor Activity of a Polymer Composite of Etoposide and Biodegradable Poly(Lactide-Co-Glycolide)

A method for preparing an antitumor polymer form of etoposide (PFE) as submicron particles based on poly(lactide-co-glycolide) with a 50:50 ratio of monomers (PLGA 50/50) was described. It was shown that the PFE possessed high cytotoxicity against various types of human tumor cells. The activity of the PFE against multiple drug resistant K562ADR cell line was greater than that of free etoposide. A grafted solid P388 murine lymphatic leukemia model showed that the PFE exhibited high in vivo antitumor activity that was prolonged compared with that of free etoposide.

Preparation of polymeric composition of linezolid and study of its antimicrobial activity in vitro

This study focuses on the development of the polymeric composition of linezolid based on biodegradable polymeric carriers. Polymeric compositions within linezolid were prepared by the simple emulsification method using a series of polymers such as PLGA 50/50, PLGA 75/25, PLGA-COOH 50/50, Eudragit RL, and Eudragit RS. The best characteristics were achieved by a composition obtained by using the polymer PLGA 50/50. The content of linezolid in the composition was 9.4 ± 0.47%, the inclusion efficiency was 50 ± 2.50%, and the particle size was 275 ± 13 nm. A study of antimicrobial activity of the polymer composition was performed by standard methods using cambric tests on Myulton-Hiller medium at a concentration of active ingredient 500 μg/mL. Experimental results demonstrated that the polymeric composition exhibited higher specific activity against Staphylococcus aureus than the substance.

Regulation of the Physiological Functions of Human Dendritic Cells by Recombinant Heat Shock Protein Hsp70

Dendritic cells (DC) are the most important antigen-presenting cells in the body. They are the target of action of various vaccines and dendritic cells have been used as the basis for developing cellular antitumor and antiviral vaccines, i.e., DC vaccines. At the same time, dendritic cells may provide a suitable model for studies of the activity and mechanisms of action of different immunotherapeutic formulations. One aspect of the optimization of the use of dendritic cells for inducing antigen-specific immune responses relates to the use of heat shock proteins (Hsp), particularly Hsp70. This protein can be used to introduce protein antigens into dendritic cells and to control the activity of dendritic cells. Important aspects of achieving these aims include knowledge of dendritic cell physiology and the characteristics of the interaction of Hsp70 and its complexes with antigens with dendritic cells of different levels of differentiation. Human recombinant Hsp70 was found not only to deliver antigens to dendritic cells, but also to regulate the activity of mature dendritic cells and to optimize the induction of antigen-specific cellular immune responses.

Inactivation and sensitization of tumor cells after transfection with gene Bax

Experiments on the transfection of cultured SKOV3 tumor cells of human ovarian adenocarcinoma and HeLa cells of human cervical carcinoma with gene Bax have demonstrated that SKOV3 cells are highly sensitive to the protein product of this gene, whereas the sensitivity of HeLa cells is substantially lower. HeLa cells obtained as a result of Bax transfection and subsequent selection are characterized by an extremely high Bax protein content and a hypersensitivity to doxorubicin. All Bax-transfected SKOV3 cells with an increased Bax content have died. In the SKOV3 cell line, a Bax exon 3 mutation has been found that corresponds to genotype G7/G9, whereas the native type of the Bax gene corresponds to genotype G8/G8. The results suggest that the G7/G9 mutation in Bax exon 3 deprives the Bax protein of proapoptotic activity.