[Expression of the gene for transforming growth factor type alpha, transferred into A431 cells by a recombinant retroviral vector]. / Ekspressiia gena transformiruiushchego faktora rosta tipa alpha, perenesennogo rekombinantnym retrovirusnym vektorom v kletki A431.

Cells of human epidermoid carcinoma A431 were used for obtaining of the cell line constantly expressing TGF-alpha. Recombinant virions were obtained by introducing the proviral DNA into PA317 cells by means of electrotransfection. A protein with the EGF-competing activity was found in a conditioned media of the chosen clone A431/1522-4. The concentration of this protein was several times higher than in a conditioned media of wild type A431 cells. By means of electrophoresis, isoelectric focusing, and immunochemical analysis it was shown that the protein is TGF-alpha. Similarly to EGF, the extracted TGF-alpha entirely displaced 125I-EGF specifically bound to receptor. TGF-alpha produced by the A431/1522 cells also stimulated autophosphorylation of the EGF receptor.

[The effect of epidermal growth factor on protein phosphorylation in normal and transformed hepatocytes]. / Vliianie épidermal'nogo faktora rosta na fosforilirovanie belkov v normal'nykh i transformirovannykh gepatotsitakh.

Qualitative differences in the content of tyrosine-phosphorylated proteins in normal and transformed hepatocytes have been found using the method of two-dimensional electrophoresis. Epidermal growth factor (EGF) has induced quantitative changes in the spectra of phosphotyrosine-containing proteins in normal cells and qualitative changes in the transformed ones. Results of immunoprecipitation with antibodies against phosphotyrosine permit revealing a protein with Mm 50 kDa which is subjected to EGF-dependent tyrosine-phosphorylation in normal hepatocytes. The intensity of protein phosphorylation is 10 times higher in the transformed cells but the dependence of this process on the EGF is not exhibited. The role of protein-tyrosine-kinases in the transmission of a mitogenic signal and in liver carcinogenesis is discussed.

[Changes in the epidermal growth factor receptors in the liver cells of rats in N-nitrosodiethylamine-induced hepatic carcinogenesis]. / Izmenenie retseptorov épidermal'nogo faktora rosta v kletkakh pecheni krys pri gepatokantserogeneze, indutsirovannom N-nitrozodiétilaminom.

A sharp decrease in the number of epidermal growth factor receptors (EGF-R) in the rat liver plasma membranes had been found at different stages of diethylnitrosamine-induced carcinogenesis. The complete loss of high-affinity binding sites for EGF did not prevent EGF-dependent autophosphorylation of EGF-R. Hepatocytes from the rat liver tumors in the primary culture had two classes of EGF-R: high and low affinity ones, though their number had been twice less than in the normal hepatocytes. The dynamics of internalization and down-regulation of EGF-R was very similar in the primary culture of transformed and normal hepatocytes. It testifies that there are some factors of microenvironment in the liver during carcinogenesis which cause the loss of EGF-R (down-regulation) and a decrease of their affinity (activation of protein kinase C). A possible autocrine or paracrine nature of these factors is discussed.

[Increase in the level of polypeptide growth factors and their receptors in induced carcinogenesis and regeneration of the intestinal mucosa in rats]. / Povyshenie urovnia nekotorykh polipeptidnyk faktorov rosta i ikh retseptorov pri indutsirovannom kantserogeneze i regeneratsii slizistoi obolochki kishechnika krys.

It has been established for the first time that in extracts of the regenerating and preneoplastic (4 months after the beginning of carcinogen introduction) intestine as well as in the peritumor tissue the content of EPR-similar polypeptides and insulin raises, whereas in tumours it remains not high. Proteins with molecular weight greater than 120 kD able to compete with 125I-EPR for the binding with the receptors of EPR and being, evidently, the precursors of EPP are found in case of carcinogenesis. Besides, the content of insulin receptors rises, this process being most typical of the large intestine.

[Changes in the contents of epidermal growth factor and EGF-like polypeptides in the liver tissue of rats in N-nitrosodiethylamine-induced hepatocarcinogenesis]. / Izmenenie soderzhaniia épidermal'nogo faktora rosta i podobnykh emu polipeptidov v tkani pecheni krys pri gepatokantserogeneze, indutsirovannom N-nitrozodiétilaminom.

It has been determined that concentration of EGF-like substances in the liver of rats with N-diethylnitrosamine-induced hepatocarcinogenesis increases and reaches its maximum in tumours (50-150 ng/mg protein). In the regenerating liver the amount of these peptides does not exceed 10 ng/mg protein. High pressure gel-filtration of appropriate extracts has revealed EGF-competing substances with m. w. about 20-30 kD in the liver carcinomas. The presented data confirm that registered EGF-like substances belong to TGF-alpha peptides.

[The production of epidermal growth factor and polypeptides similar to it in the intestinal mucosa of rats in 1,2-dimethylhydrazine-induced carcinogenesis and compensatory regeneration]. / Produktsiia épidermal'nogo faktora rosta i podobnykh emu polipeptidov slizistoi obolochke kishechnika krys pri indutsirovannom 1,2-dimetilgidrazinom kantserogeneze i kompensatornoi regeneratsii.

The production of EGF and EGF-like polypeptides in the normal intestinal mucosa and during 1,2-dimethylhydrazine (DMH)-induced carcinogenesis and postresection regeneration was studied in albino rats using chromatographic separation of acid-ethanol extracts. Fractions after gel filtration on Biogel P-60 with subsequent reverse-phase high performance liquid chromatography in acetonitrile gradient were tested in radioreceptor assay for competition with EGF. It has been established that intestinal tumours induced by DMH and regenerating intestinal mucosa have amplified production of EGF--alpha-TGF and related proteins of high molecular weight (approx. 30; 45-55; 120 kD) with the EGF-competitive activity. It is supposed that the high molecular weight EGF-competitive material represents nonprocessed forms of EGF and/or alpha-TGF which are accumulated in rapidly proliferating low-differentiated cells due to the intensified expression of their genes.

[Effect of sialadenectomy on hepatic carcinogenesis in rats induced by N-nitrosodiethylamine]. / Vliianie sialadenéktomii na gepatokantserogenez, indutsirovannyi u krys N-nitrozodiétilaminom.

It is established that sialadenectomy leads to inhibition of hepatocarcinogenesis induced in adult rats by diethylnitrosamine, which is confirmed by a decrease in the incidence of tumours, their delayed growth and an increase of longevity. But sialadenectomy 2 weeks after the beginning of carcinogen treatment has no effect on the hepatocarcinogenesis. A significant molecular heterogeneity of the epidermal growth factor-competing activity is observed in acid-ethanol extracts of the liver tumour of the sialadenectomized rats.

[Characteristics of hepatocarcinogenesis after single exposure of synchronized cells of the regenerating liver to N-nitrosodiethylamine and subsequent administration of phenobarbital]. / Osobennosti gepatokantserogeneza pri odnokratnom vozdeistvii N-nitrozodiétilaminom na sinkhronizirovannye kletki regeneriruiushchei pecheni krys i posleduiushchem vvedenii fenobarbitala.

The frequency of tumour incidence in rats subjected to the single action of diethylnitrosamine to regenerating liver cells synchronized in different phases of the mitotic cycle was maximal in rats exposed to carcinogen when 62.5% of regenerating liver hepatocytes were in the S-phase. Dietary added phenobarbital increased the number and size of hepatocarcinomas especially in rats which received DENA in the G2-M phase of hepatocytes or during maximal proliferation of nonparenchymal cells. The role of proliferation of different cell populations in initiation and promotion of carcinogenesis is discussed.

[Effect of the epidermal growth factor on 1,2-dimethylhydrazine-induced carcinogenesis in the rat intestinal mucosa]. / Vliianie épidermal'nogo faktora rosta na kantserogenez, indutsirovannyi 1,2-dimetilgidrazinom v slizistoi obolochke kishechnika krys.

The radioimmunological and radioreceptor methods have been used to show that sialadenectomy leads to the stable decrease of the epidermal growth factor (EGF) concentration in saliva and blood serum. The mean number of colon tumours per rat was significantly lower among the rats which had been sialadenectomized before injections of the carcinogen, than in the control. But a sharp stimulation of carcinogenesis in the duodenal mucosa was observed after sialadenectomy. The production of the alpha-transforming growth factor with the EGF-competing activity for the EGF-receptors was found in the chemically-induced rat colon tumours.

[The use of a primary culture of liver cells from rat embryos subjected to transplacental exposure to N-nitrosodiethylamine for the study of hepatocarcinogenesis promoters]. / Ispol'zovanie pervichnoi kul'tury kletok pecheni émbrionov krys, podvergnutykh transplatsentarnomu vozdeistviiu N-nitrozodiétilamina, dlia izucheniia promotorov gepatokantserogeneza.

Primary culture of rat embryonic liver cells subjected to transplacental effect of N-nitrosodiethylamine can be used for studying the influence of hepatocarcinogenesis promoters on different types of mixed culture cells.

[Sensitivity of rat hepatocytes to phenobarbital after a single dose of N-nitrosodiethylamine in the embryonal and postnatal period or after partial hepatectomy]. / Chuvstvitel'nost' k deistviiu fenobarbitala gepatotsitov krys posle odnokratnogo vvedeniia N-nitrozodiétilamina v émbrional'nom, postnatal'nom periode ili posle chastichnoi gepatéktomii.

For the hepatocarcinogenesis initiation one-fold N-nitrosodiethylamine (NDENA) action upon the livers of embryos and of the 4-weeks rats, before or after partial hepatectomy was used. Phenobarbital and repeated partial hepatectomies were used as the promotive factors. The promotion effect was evaluated by the quantity and size of hyperplastic liver nodules, where gamma-glutamyltranspeptidase activity was revealed. It was determined, that NDENA-affected rat liver cells in the embryonic period or at the age of 4 weeks after single partial hepatectomy proved to be more sensitive to the action of promoters.

[Approaches to ecological monitoring of chemical carcinogens]. / Podkhody k ékologicheskomu monitoringu khimicheskikh kantserogenov.

The approaches to ecological monitoring of carcinogens including the principles of its organization as well as the choice of the animals and plants as nature monitors are discussed. The classification of integral monitoring of carcinogens including bioecological (natural), sanitary-hygienic and medicobiological monitoring is proposed.

[Characteristics of the epidermal growth factor receptors in the epithelium of the gastrointestinal tract of rats and in intestinal tumors induced by 1,2-dimethylhydrazine]. / Kharakteristika retseptorov épidermal'nogo faktora rosta v épitelii zheludochno-kishechnogo trakta krys i v opukholiakh kishechnika, indutsirovannykh 1,2-dimetilgidrazinom.

Using the Scatchard analysis of 125J-EGF binding it was shown that plasma membranes of gastric and small intestinal epithelial cells contain approximately 20 times less EGF-receptors (EGF-R) than liver cells. Investigation of the phosphorylation activity of EGF-R-kinase was performed in vitro on plasma membranes from intestine, intestinal tumours and liver cells. The main protein phosphorylated at tyrosine in the tumours was p34 but the intensity of EGF-R autophosphorylation and its total protein-tyrosine kinase activity were reduced (as compared with small-intestinal and liver cell membranes). In the tumours of the colon induced by DMH an increased binding of 125J-EGF has been observed as compared with normal colonic enterocytes and increased number of EGF-R was clearly demonstrated. Phosphorylation of p34 in the intestinal membranes proceeds much more intensively than that of EGF-R.

[Cellular proliferation of the regenerating liver in rats after a single administration of N-nitrosodiethylamine]. / Proliferatsiia kletok regeneriruiushchei pecheni krys posle odnokratnogo vvedeniia N-nitrozodiétilamina.

Proliferative kinetics of hepatocytes and nonparenchymal cells of the regenerating rat liver has been studied after a single injection of the carcinogen in S- or G2-M-phase cell cycle of hepatocytes. Disturbances of proliferation in the mentioned cell populations and resistance of normal proliferating hepatocytes during the S-phase of the mitotic cycle to the cytotoxic effect of the carcinogen are established. Possible mechanisms of the resistance of the proliferating cells to the toxic action of the carcinogen are discussed.

[TPA enhancement of the mutagenic and transforming action of bovine adenovirus type 3 on cultured mouse cells]. / Usilenie s pomoshch'iu TFA mutagennogo i transformiruiushchego deistviia bych'ego adenovirusa tipa 3 na kul'tiviruemye kletki myshi.

The cultured 10TI/2C3H mouse cells were infected with bovine adenovirus 3(BAV-3) and treated by TPA. This combined treatment induced ouabain-resistant mutants 19 to 26 times more often than action of only BAV-3. BAV-3- and TPA-treated cells were implanted to syngenic mice. The tumours appeared 10 times more often than in the mice after implantation of only adenovirus treated cells.

[Characteristics of hepatocyte proliferation in the regenerating rat liver with hydroxyurea synchronization of the proliferative processes]. / Osobennosti proliferatsii gepatotsitov regeneriruiushchei pecheni krys pri sinkhronizatsii proliferativnykh protsessov oksimochevinoi.

5-week old rats underwent a partial hepatectomy (2/3 of the liver was removed). The operated rats were repeatedly injected hydroxyurea, within 9-24 or 12-24 hours following operation. Proliferation of hepatocytes and non-parenchymal cells in the regenerating liver was studied. Five or six injections of hydroxyurea increased the labelling index of hepatocytes up to 62.5% and induced proliferation of bile duct cells significantly.

[Use of the method of nucleus sedimentation fractionation for studying the dynamics of cell populations in the regenerating liver]. / Ispol'zovanie metoda sedimentatsionnogo fraktsionirovaniia iader dlia issledovaniia dinamiki kletochnykh populiatsii regeneriruiushchei pecheni.

In different periods after partial hepatectomy (0, 11, 18, 24, 48 and 72 hours) isolated liver cell nuclei were separated according to their sizes using free sedimentation at 1 g in the exponential 0.1-1.0 M concentration gradient of sucrose at 4 degrees C. A sedimentogram of the intact liver cell nuclei displays three peaks corresponding to the nuclei of stromal cells, and diploid and tetraploid nuclei of hepatocytes. At 18 and 24 hours after the operation, but not at 0 or 11 hours, a curve of 3H-thymidine incorporation is represented by three maxima suggesting the influx of hepatocytes of different ploidy in the S-period. Then, 48 and 72 hours after the partial hepatectomy two additional peaks appear corresponding to 8- and 16-ploid nuclei, and a decrease in the portion of diploid nuclei is seen up to the full absence of the corresponding peak. Thus, the method of sedimentation at unit gravity of isolated nuclei using radioisotope labeling allows to obtain the information on the structure of the heterogeneous proliferating cell population.