VEGF-R1 as a Potential Molecular Target for Anticancer Therapy.

The possibility of using VEGF-R1 receptor for targeted therapy in oncology was investigated. Using the approach to measuring the protein content in intact nuclei of cells, which was developed by us, we showed the presence of this receptor in the nuclei of tumor, but not normal cells. A direct correlation between the level of VEGF-R1 expression in the nucleus and the degree of malignancy of tumor cells, indicating the prognostic value of this parameter, was found. The mechanisms of the functioning of this receptor and the pathways of inhibiting its activity are discussed, and the validity of the selection of VEGF-R1 as a molecular target for anticancer therapy is conformed.

[Structural rearrangements of the chromatin during the adaptive response in two genetically close djungarian hamster fibroblast cell lines with different radiosensitivity].

The capacity of cell for the adaptive response (AR) induction after gamma-irradiation using micronuclear test was investigated. Our model consists of the parental djungarian hamster embryonic fibroblast cell line DH-TK- and its radioresistant progeny (PIC-20). We demonstrated that AR for the more radiosensitive parental cell line was shifted to the lower adaptive and to the challenge doses. The maximal AR for DH-TK- cells was induced at 0.3 Gy adaptive dose and 1.5 Gy challenge dose (adaptive response coefficient (ARC) was 0.4+/- 0.1), whereas for PIC-20 cells these means were 0.5 Gy and 3.0 Gy correspondingly (ARC = 0.45+/-0.1). Using the method of anomalous viscosity time dependence (AVTD) we demonstrated the chromatin rearrangements in both cell lines during 3-5 h after adaptive dose application. The rearrangement degree evaluated by the relative maximal reduced viscosity was considerably higher in PIC-20 cell line than that in DH-TK cells (2.4+/-0.3 vs 1.4+/-0. 1). Interestingly, the time of chromatin rearrangement did not depend neither on the dose nor on the cell type and was similar in both cell lines after 5 h of adaptive dose application. It was also shown that during the AR chromatin relaxation was lower after exposure to both the adaptive and challenge doses than after challenge dose only. In contrast, in the degree of AR chromatin relaxation was higher for both cell lines.

[Acquired radioresistance of progeny of irradiated cells is accompanied by rearrangements in chromatin organization]. / Priobretennaia radiorezistentnost' potomkov obluchennykh kletok soprovozhdaetsia perestroikami v organizatsii khromatina.

gamma-Irradiation action within a dose range of 0-20 Gy on parental djungarian hamster fiborblasts, DH-TK- cell line, and the progenies of these irradiated cells, surviving acute exposure to 20 Gy irradiation, PIC-20 cell line, was examined. The PICs were 3 times more radioresistant than the parental cells as calculated from D0. Using a method of anomalous viscosity time dependence (AVTD) it was revealed that starting (initial) level (in untreated cells) of chromatin compactness in radioresistant progenies was more than 1.4 times as high as for parental cells. The analysis of dose dependence has shown that irradiation with a dose of 5 Gy resulted in complete chromatin loop relaxation in radiosensitive DH-TK- cells and partial one in radioresistant PIC-20 cells. Besides, the beginning of DNA-membrane complexes degradation following the irradiation with doses over 15 Gy in DH-TK- cells was observed. It was shown that the increased state of relative chromatin relaxation in PIC-20 cells determines an increasing in reparation effectiveness that resulted in lower percent of residual damages in these cells. Using the Nosern hybridization method the expression level of mts 1, tag 7 and vseap 1 genes was studied. It is revealed that tag 7 and vseap 1 gene expression in radioresistant cells were correspondingly 6 and 10 times higher than in radiosensitive parental cells and the level of mts 1 gene expression was not changed. So, based on the results obtained we suggest that acquired radioresistance in progenies of irradiated cells is determined by rearrangements in chromatin structure and accompanied constitutive changes of gene expression.

[Retention of tumorigenicity in radioresistant progeny of cells surviving exposure to high doses of gamma irradiation]. / Sokhranenie tumorogennosti u radiorezistentnykh potomkov kletok, vyzhivshikh posle vozdeistviia gamma-izlucheniia v bol'shikh dozakh.

The cell tumorigenic ability and the cell clonogenicity in semi-solid medium of highly radioresistant variant cell line, PIC-20 (the progeny of djungarian hamster fibroblast cell line DX-TK- surviving acute exposure to 20 Gy of gamma-irradiation), were examined. In the absence of additional radiation, no differences between tested features of non-irradiated PIC-20 cells and parental DX-TK- cells were observed. On the contrary, after gamma-irradiation with high doses the essential differences in the properties of the examined cell lines were revealed. After exposure to 10 Gy the surviving fraction of PIC-20 cells was 20 times higher than that of the parental cells. Both irradiated and non-irradiated PIC-20 cells produced colonies of similar size. It is revealed that even after irradiation with doses of 5, 10 or 15 Gy, the PIC-20 cells kept their tumorigenicity as high as non-irradiated ones. In all these cases the 90-100% of animals had the tumour, with the average latent period of tumour appearance after inoculation being the same both for irradiated and non-irradiated PIC-20 cells. After irradiation of parental DX-TK- cells with the highest dose of 15 Gy, the amount animals with tumour decreased by 70% and the average latent period of tumour appearance increased fivefold as compared with that for non-irradiated DX-TK- cells. The data obtained indicate that PIC-20 is highly radioresistant cells, which are able to proliferate both in semi-solid medium and in an animal organism even after radiation exposure to high doses.

[Small doses of ionizing radiation as radiation modifying factor]. / Malye dozy ioniziruiushchego izlucheniia kak radiomodifitsiruiushchii faktor.

To investigate the biological effects of small dose ionizing radiation has been acquiring greater importance. The awareness of how and in what direction it show its modifying effects in small doses is an essential scientific basis for developing standards, living conditions under specific environmental conditions. Cultured Hela cells and DEF 4/21 fibroblasts were used to evaluate the biological effects of small-dose ionizing radiation, by examining the conditions under which it showed its modifying effect in small doses (0.1 Gy) in particular. Preexposure to small-dose radiation was shown to alter cell responses to subsequent radiation in large doses. The modifying effects of small-dose radiation turned out to depend on the interval of exposure to small and large doses. Sensitization was recorded at an interval of 2-3 min; an adaptive response was achieved when the interval increased up to 3-5 hours. Upon exposure, intercellular contacts contribute to the modifying effects of small-dose radiation. There was neither effect of sensitization nor adaptive response if single cells were exposed to radiation.

[The appearance of a fracture of radioresistant cells in a fibroblast population irradiated at high doses]. / Vozniknovenie fraktsii radiorezistentnykh kletok v obluchennoi bol'shimi dozami populiatsii fibroblastov.

Two sublines of Djungarian DEF 4/21 hamster cells survived after gamma irradiation with the doses of 10 and 20 Gy were obtained. The survived cell posterity (SCP) of both cell lines are considerably more clonogenic. They show a higher proliferative activity and a shorter period of generation than the control cells. The sublines are several times more radioresistant as compared to the original cells. After exposure to high doses of radiation, the cell culture of the SCP exhibits a 17 to 20% high-resistant fraction. Supposedly, the cells of this fraction are responsible for repopulation after exposure to lethal doses of gamma irradiation.

Inhibition of the bacterial mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine by ascorbic acid and ascorbyl palmitate.

The mechanism of antimutagenic activity of ascorbic acid (AA) and its derivatives was studied using the Salmonella typhimurium TA100 bacterial test system. All substances studied inhibited N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced mutagenesis. Ascorbyl palmitate (AP) markedly decreased the numbers of his+ revertants, behaving as a membrane-active antimutagen. A comparative study of the antioxidative activity of the investigated substances in the methyl oleate (MO) system has demonstrated that AA and its derivatives have pro-oxidant properties within the limits of the concentrations studied. The results obtained do not agree with the common view of the mode of action of these antimutagens, including both inhibition of free radical processes and MNNG reductive inactivation.

[Homology of histones H2B from calf thymus and P4B from slime mold Physarum polycephalum]. / Gomologichnost' gisgonovykh fraktsii H2B timusa telenka i P4B miksomitseta Physarum polycephalum.

A comparative study of the amino acid composition of histone fractions P4b from slime mold Physarum polycephalum and H2B from calf thymus was carried out using peptide mapping. It was shown that 75% of peptides are common for both proteins. The slime mold histones contain two fractions (P4B and P3), which are homologous to the H2B histone fraction of calf thymus. The data of amino acid analysis, peptide mapping and some physico-chemical properties of the histones revealed the following correlation of the two types of histone fractions: P1--H1, P4a--H3, P4b and P3--H2B, P5-H2A, P6--H4.

[Comparative study of histones from slime mold Physarum polycephalum and calf thymus]. / Sravnitel'noe izuchenie gistonov miksomitseta Physarum polycephalum i timusa telenka.

The histones from slime mold Physarum polycephalum and calf thymus were characterized in terms of some physico-chemical properties. The molecular weights of six principal histone fractions of Ph. polycephalum were found to be the following: P1--22 700, P3--15 700, P4a--15 000, P4b--14 300, P5--12 800 and P6--10 500. Electrophoretically homogenous histone fractions H1, H2b and H4 of calf thymus and histones P1, P3, P4b and P6 of slime mold were obtained by gel-filtration on Acrylex P-60. These findings suggest that fractions P1, P4a, P4b, P5 and P6 of slime mold Ph. polycephalum are homologus with respect to the histone fractions H1, H3, H2b, H2a and H4 of calf thymus. Only fraction P3 has no corresponding fraction in the calf thymus histones; a fraction corresponding to histone P3 of slime mold was absent.