The analysis of the order of chromosome involving to interchromosome associations by the type of Robertsonian translocation (RB) in 28 cell populations in relation with three factors: their origin from different mouse lines (CBA/Ca, C3H/He, C57BL/6, BALB/c), direction of cytodifferentiation (fibroblasts and leucocytes) and the stage of its disruption (minimal, maximal and medial tumorigenicity) was carried out. The influence of all three factors on the frequencies of individual chromosome involving in RB was revealed.

Phenotypic characteristics of cells and extracellular matrix (ECM) of 14 salivary gland pleomorphic adenomas were studied by indirect immunofluorescence. All cells in the epithelial structures expressed cytokeratin 8, the majority of cells produced vimentin, laminin and IV type collagen. Cells of myxoid areas expressed vimentin: type IV collagen was observed in the form of fibrillar structures. Fibrous areas were characterized by vimentin and cytokeratin 8 expression; types I, III, IV collagens and fibronectin with ED-A sequence were present in ECM. Terms "epithelial structures", "epithelial" and "myoepithelial" cells in relation to pleomorphic adenoma may be used only relatively as it is mainly represented by cells with features of both epithelial and mesenchymal phenotype. Characteristics of ECM synthesized in various structures of pleomorphic adenoma may serve an additional criterion of cell transformation.

55 breast carcinomas and 9 its benign conditions were studied immunohistochemically. Oncoprotein c-erbB-2 was found in 22% carcinomas and in 33-37% comedo-carcinomas. Coincidence of predominant expression of oncoprotein c-erbB-2 and tenascin was observed. Maximal damage of the basal membrane in the intraductal carcinoma detected by the disturbance of type IV collagen staining was observed in cases of the highest expression of oncoprotein c-erbB-2 and tenascin.

DNA-binding activity of small nuclear alpha-RNP identified in acid-soluble fraction of chromatin of human proerythroleukemic cell line K-562 was studied using the technique of gel retardation. We found that nuclear alpha-RNP isolated from K-562 cells through treatment with dimethylsulfoxide, an agent inducing differentiation, acquire a capacity to specific interaction with Alu repeats of DNA leading to the formation of alpha-RNP-Alu-DNA complexes; nuclear alpha-RNP from cells that were not treated with dimethylsulfoxide do not show such capacity, although they are tightly bound with chromatin in the cell. Thus, the capacity of nuclear alpha-RNP to direct interaction with DNA Alu repeats appearing after the induction of K-562 cells to differentiation along erythroid pathway is an inducible property. We discuss hypothesis about the involvement of nuclear alpha-RNP in the control of expression of inducible genes at the level of chromatin and interaction with DNA.

The influence of three alkylating anticancer preparations phosphamide, sarcolysine, cyclophosphane on content of the 5-methylcytosine and parameters of the melting DNA of the liver healthy animals and tumor sarcoma 45 was investigated. It was shown, that among the investigated preparations cyclophosphane has stronger anticancer influence and comparatively weaker side effect on DNA liver. We came to the conclusion that it is preferable to use this preparation.

Using trypan blue exclusion test it has been shown that a 18 hour incubation of human erythromyeloleukosis cell line K562 together with AlF(-4) (10 mM NaF + 20 mkM AlCl3) reduced cell proliferation and survival. However, the latter parameter did not change during 4 hours of incubation. Nevertheless, AlF(-4) increased fragmentation of 3H-thymidine-labelled DNA by 2-4 times. This effect may be suppressed by cultivation of cells with 20 mkM nicotinamide (inhibitor of poly(ADP-ribose)polymerase enzyme). We found that incubation of K562 and YAC-1 cells with 10 mM nicotinamide for 24 hours much reduced their susceptibility to non-MHC-restricted lysis by rat spleen cells. This effect may be induced by a share of intracellular NAD+ and NADH from destroyed K562 cells; their concentration in cells increased under the influence of nicotinamide by 3 times, but this effect should be the least because in these conditions nicotinamide does not influence the survival of K562 cells. The effect of nicotinamide in both cases may be explained by suppression of poly(ADP-ribose)polymerase activity and, thus, the rate of DNA reparation. Analysis of AlF(-4) and nicotinamide effects on the K562 cells enables us to suppose that suppression of the K562 proliferation by tetrafluoroaluminate results in accumulation of reversed damages of DNA.

Lymphoblastoid cell lines from patients with xeroderma pigmentosum (2 forms) and progeria (unusual form) were established using transformation of peripheral blood lymphocytes by Epstein--Barr virus. The influence of different UV doses on cell vitality, proliferation and cell cycle progression was studied by means of flow cytometry. The cell vitality was determined after incubation of cells with etidium bromide and FDA. We used cytograms with two logarithmic signals (log green/log red) to discriminate the cell cycle status. Cell cultures were used with density of 500,000 cells per 1 ml, previously synchronized at G-phase by the incubation in a medium with low serum content. The effect of UV irradiation was followed during 72 h. Among four analysed cell lines only line XP2SP demonstrated enhanced UV sensitivity, expressed by decreasing of the amount of living cells after the UV dose of 2.5 J/m2 and higher. The cell cycle studies showed that cells were blocked in S-phase and simultaneously the amount of apoptotic cells with both reduced DNA content and ability to bind FDA was seen increased. Similar events were observed in the control line only after the dose of 20 J/m2 and higher.

Using a radioresistant subline of murine lymphoma cells L5178(R) DNA damages, their repair and the process of second DNA degradation in dynamics following X-radiation (5 Gy), and in the distant cell progeny have been studied by the method of DNA-comet assay (the alcaline conditions). The repair of DNA damages was found to be finished by 6 h, and by 18 h the second DNA-degradation was observed. The cell progeny was followed throughout 30 generations, with the enhancement of sensitivity to repeat irradiation, and the decrease in repair rate and degree of the second DNA degradation being registered. In the population of the 30th generation, the lack of the second DNA degradation was observed. If the second DNA degradation is indicative of apoptosis, as it is generally considered in literature, it can be supposed that in the distant progeny of irradiated L5178Y(R) cells radiation induces no programmed cell death and is not a trigger of apoptosis.

SHR mice received single injections of N-nitrosomethylurea (NMU, 50 mg/kg, i.p.), cyclophosphamide (CP, 200 mg/kg, i.p.) or 1,2-dimethylhydrazine (DMH, 15 mg/kg, s.c.) alone or in combination with melatonin (5 mg/kg, s.c.). For mutagenic study chromosome aberrations tests (ChA) in bone marrow cells and sperm head anomaly test (SHA) were used. Melatonin did not appear mutagenic in either of the tests and significantly reduced the level of ChA (%) from 16.9 +/- 1.6 (NMU), 13.7 +/- 3.5 (CP) and 8.7 +/- 0.3 (DMH) to 4.5 +/- 0.6, 4.3 +/- 0.9 and 5.6 +/- 0.2, respectively, (p < 0.05). Similarly, SHA frequency (%) under the melatonin influence was reduced from 18.6 +/- 0.4 (NMU), 17.7 +/- 0.4 (CP) and 10.0 +/- 0.5 (DVH) to 9.9 +/- 0.5, 6.1 +/- 0.3 and 7.5 +/- 0.2, respectively, (p < 0.05). Unlike in controls, exposure to melatonin in drinking water (20 mg/l, at night) or in injections (5 mg/kg, s.c.) alone or in combination with NMU or CP failed to influence subcutaneously-transplanted Ehrlich carcinoma growth. These findings suggest that melatonin reduced the mutagenicity of the cytostatic drugs without affecting their anti-tumor action.