Effects of Some Growth Factors and Cytokines on the Expression of the Repair Enzyme MGMT and Protein MARP in Human Cells In Vitro : Effect of Some Growth Factors and Cytokines.

The inducible repair enzyme O6-methylguanine-DNA methyltransferase (MGMT) eliminates O6-methylguanine adducts in DNA and protects the cells from damaging effects of alkylating agents. We have found that anti-MGMT antibodies recognize both the MGMT protein with a mol. weight ~ 24 kDa and a protein with a mol. weight ~ 48 kDa, which was named MARP (anti-methyltransferase antibody recognizable protein). A number of growth factors and cytokines were shown to regulate the expression of MGMT and MARP proteins. The ranges of concentrations of several growth factors and cytokines that caused increasing or decreasing protein amounts in human cell cultures were determined. The results of special biological experiments have allowed us to assume a possible role of MARP in the repair of alkyl adducts in human cells.

DNA loop domain organization in nucleoids from cells of different types.

The loop domain organization of chromatin plays an important role in transcription regulation and thus may be assumed to vary in cells of different types. We investigated the kinetics of DNA loop migration during single cell gel electrophoresis (the comet assay) for nucleoids obtained from human lymphocytes, lymphoblasts and glioblastoma T98G cells. The results confirm our previous observation that there are three parts of DNA in nucleoids: DNA on the nucleoid surface, loops up to ∼150 kb inside the nucleoid, and larger loops that cannot migrate. However, the relative amounts of the three parts were found to be very different for different cell types. The distributions of the loop length up to 150 kb were shown to be exponential, with the distribution parameter, the loop density, to be dependent on the cell type.

Possible mechanisms of Leukoagglutinin induced apoptosis in human cells in vitro.

Leukoagglutinin is one of the phytohemagglutinin isolectins isolated from Phaseolus vulgaris. In our recent study, we showed that this lectin is able to influence the growth of human cancer cells in vitro. In addition, using the acridine orange and ethidium bromide staining, we found that leukoagglutinin can induce apoptosis. In order to understand the molecular mechanisms of induction of apoptosis, we performed computational modeling with subsequent experimental verification of theoretical data in vitro. We developed computational models of leukoagglutinin interaction with pro- (FasR and TNFR) and anti-apoptotic (IGF-1 and EGFR) receptors, and confirmed that leukoagglutinin may specifically interact with these receptors. Furthermore, we proved that leukoagglutinin can induce apoptosis in cancer (HEp-2) and non-cancer (4BL) cells, and observed that PHA-L is able to induce apoptosis through the up-regulation of Bax protein and activation of the effector caspase-3 and initiator caspase-8. However, these proteins have no effect on the Bcl-2 expression level.

Design, synthesis and biological evaluation of naphthostyril derivatives as novel protein kinase FGFR1 inhibitors.

New class of FGFR1 kinase inhibitors with naphthostyril heterocycle has been identified. A series of N-phenylnaphthostyril-1-sulfonamides has been synthesized and tested in vitro. It was revealed that the most active compound N-(4-hydroxyphenyl)naphthostyril-1-sulfonamide inhibited FGFR1 with IC50 of 2 µM. In our preliminary studies, N-phenylnaphthostyril-1-sulfonamides demonstrated selectivity of FGFR1 inhibition and antiproliferative activity on cancer cell line. N-phenylnaphthostyril-1-sulfonamides have a good potential for further development as anticancer agents.

Influence of surface-modified maghemite nanoparticles on in vitro survival of human stem cells.

Surface-modified maghemite (γ-Fe2O3) nanoparticles were obtained by using a conventional precipitation method and coated with D-mannose and poly(N,N-dimethylacrylamide). Both the initial and the modified particles were characterized by transmission electron microscopy and dynamic light scattering with regard to morphology, particle size and polydispersity. In vitro survival of human stem cells was then investigated by using the methyl thiazolyl tetrazolium (MTT) assay, which showed that D-mannose- and poly(N,N-dimethylacrylamide)-coated γ-Fe2O3 particles exhibit much lower level of cytotoxicity than the non-coated γ-Fe2O3.

Influence of Sambucus nigra bark lectin on cell DNA under different in vitro conditions.

The biological activity of Sambucus nigra bark lectin on Chinese hamster cells in vitro was investigated by comet-assay and cytotoxicity testing. Mitogenic properties at the concentrations 0.063-0.25 microg/ml (but not higher) were found, and the induction of DNA breaks at concentrations 0.5 microg/ml and higher is demonstrated. S. nigra bark lectin at mitogenic concentrations decreased the level of nickel-induced DNA damage. The character and mechanism of this lectin protective activity was probably related to the induction of DNA reparation in the cells, decreasing nickel uptake in cells, and non-specific binding of nickel ions by protein molecules.