[Signaling pathways that control the growth and survival of prostate tumor cells in the absence of androgens]. / Signal'nye puti, kontroliruiushchie rost i vyzhivaemost' kletok raka predstatel'noi zhelezy v otsutstvie androgenov.

Androgen-dependent human prostate adenocarcinoma cell line LNCaP was used to study the effect of androgen deprivation on the cell response to TNF-related cytokines. Several signaling pathways were implicated in cell survival in the absence of androgens. In androgen-deprived LNCaP cells, TNF-alpha and TRAIL stimulated the cell growth and activated the mitogenic and antiapoptotic signaling pathways involving NF-kappa B, STAT3, PI3K, and beta-catenin. The results suggested a role of cytokines in the survival of prostate adenocarcinoma cells deprived of androgens in vitro.

[Differences in expression and functional organization of the rat tyrosine aminotransferase gene in two lines of Morris hepatoma, 8994 and 7777]. / Razlichiia v ékspressii, funktsional'no'i organizatsii gena tirozinaminotransferazy krys v dvukh liniiakh gepatom Morrisa 8994 i 7777.

Expression and structural organization of tyrosine aminotransferase (TAT) gene in Morris hepatoma cell line 7777 with active and glucocorticoid-inducible TAT gene and in hepatoma 8994, where TAT gene does not function were analysed. No differences in the number of receptor macromolecules, translocation and nuclear binding of hormone-receptor complexes in hormone sensitive (7777) and resistant (8994) cell lines were demonstrated. Dexamethasone increases TAT gene transcription in 7777 cell line but not 8994. Restriction analysis of TAT gene does not reveal any differences either in structural or in regulatory regions. Gel retardation assay with cloned TAT fragment (-400 b.p.) from normal hepatocytes showed identical shift of mobility in 7777 and 8994 cell lines. Moreover, 5'-flanking sequence (-890 b.p.) of TAT gene linked to the bacterial CAT gene is transiently expressed in both cell lines. We have shown that HpaII site (-105 b.p.) of TAT gene is methylated in those cells where TAT gene does not function (thymus, spleen, Zajdela ascites hepatoma) and is demethylated in TAT gene expressing hepatoma 7777 and normal rat hepatocytes. In hepatoma 8994 there are no DNAse I hypersensitive regions, typical to functioning TAT gene from hepatoma 7777 and normal hepatocytes.

[Activation of transcription of the tyrosine aminotransferase gene in the rat McA-RN 7777 hepatoma cell line by cycloheximide]. / Aktvatsiia transkriptsii gena tirozinaminotransferazy v kletochnoi linii gepatomy krysy McA-RN 7777 tsiklogeksimidom.

The expression of the tyrosine aminotransferase (TAT) mRNA after cycloheximide treatment was analysed by Northern blotting method in Morris rat hepatoma cell lines. The level of TAT mRNA increased after 6-8 h of cycloheximide treatment only in the McA-RH 7777 cell line. McA-RH 7777 nuclear run-off assay showed that TAT transcription was induced by cycloheximide treatment. Both glucocorticoid and cycloheximide modulated TAT gene transcription in a synergistic way. There was no induction of TAT expression following cycloheximide or cycloheximide glucocorticoid simultaneous treatment in another cell line (McA-RH 8994), while c-myc and c-fos expression was superinduced by cycloheximide treatment. The possible mechanism of transcription regulation and its damage in hepatoma cells is discussed.

[Regulation of proliferative and protein-synthesizing reactions in human peripheral blood lymphocytes by glucocorticoids]. / Reguliatsiia proliferativnykh i beloksinteziruiushchikh reaktsii v limfotsitakh perifericheskoi krovi cheloveka gliukokortikoidami.

Glucocorticoids control protein synthesis and [3H]thymidine incorporation into DNA in resting and mitogen-stimulated in vitro human peripheral blood lymphocytes. This effect depends on the dose and time of hormone addition to the culture medium. Using two-dimensional electrophoresis, it was demonstrated that the steroids can regulate the expression of various proteins in intact and mitogen-stimulated human peripheral blood lymphocytes. This is suggestive of a dynamic control by glucocorticoids of the synthesized protein transcription during the cell cycle of a given population. These results also indicate that such a dynamic control is not due to the fluctuations in the number of receptor macromolecules, the presence or absence of the acceptor site on the DNA but, rather, to the modulation of the biological activity of specific nuclear factors capable of regulating the transcription of definite genes.

[Nuclear factor A5 from the rat liver that requires a metal for specific interaction in vitro with distal element of the tyrosine aminotransferase gene promoter]. / Iadernyi belkovyi faktor A5 iz pecheni krysy, kotoromu neobkhodim metall dlia spetsificheskogo vzaimodeistviia in vitro s distal'nym élementom promotora gena tirozinaminotransferazy.

To detect nuclear protein factors which might account for a tissue-specific and inducible expression of the rat tyrosine aminotransferase (TAT) gene promoter, extracts from rat liver and spleen nuclei have been fractionated by heparin-sepharose chromatography and the fractions assayed for sequence-specific binding to the distal TAT gene promoter element (sequence between -313 and -210). Gel retardation experiments carried out in the presence or absence of Mg2+, Ca2+, or Zn2+ ions showed that there are at least two nuclear factors (A3 and A4) binding to the distal promoter element only in the presence of the chelator (20 mM EDTA). Incubation of the protein fractions with Zn2+ or Ca2+ instead of commonly used Mg2+allowed: (i) to avoid 3 2P-DNA-probe degradation by "contaminating" endogenous nucleases; and (ii) to detect another sequence-specific nuclear factor, A5. No other specific binding activities were found in the rat-liver nuclear fractions tested under these conditions. As the metal ions became inaccessible to chelation in excess of EDTA and EGTA when protein factor A5 was complexed to DNA we assumed that factor A5 is metalloprotein which requires Zn or Ca to maintain a structure of its DNA-binding domain. To identify the polypeptide possessing this domain, a protein gel blotting procedure was employed. By incubating gel blots with the 3 2P-DNA-probe in the buffer containing Zn2+, specific binding to the only polypeptide with approximate Mr 30 kDa was clearly revealed. Both gel retardation and gel blotting assays consistently showed that nuclear factor A5 is present in the liver, but not in the spleen extracts.

[Regulation of the transcription of the tyrosine aminotransferase gene by glucocorticoids in Morris hepatoma 7777 and 8994 cells]. / Reguliatsiia transkriptsii gena tirozinaminotransferazy gliukokortikoidami v kletkakh gepatomy Morrisa 7777 i 8994.

Kinetics of tyrosine aminotransferase (TAT) mRNA synthesis in Morris rat hepatoma cell lines 7777 and 8994 after dexamethasone treatment (10(-7) M) was studied by molecular hybridization of the RNA with cloned fragments of TAT gene from rat liver cells. It was demonstrated that initiation of TAT gene transcription increased 20 minutes after glucocorticoid treatment. The level of TAT mRNA was not induced by dexamethasone in rat hepatoma cell line 8994. Actinomycin D prevented the deinduction of TAT by stabilization of TAT mRNA.

[Criteria of the sensitivity of Zajdela and Morris hepatoma cells to glucocorticoids]. / Kriterii chuvstvitel'nosti kletok gepatom Zaidela i Morrisa k gliukokortikoidam.

Glucocorticoids induce tyrosine aminotransferase synthesis in 7777 Morris hepatoma but fail to do so in Zajdela hepatoma. This internal property indicates the resistance to the hormone. However, both hepatoma cell lines do respond to the triamcinolone acetonide in a similar way, as judged by some other criteria, e. g. interaction with the immobilized hormone on the inert carrier, adhesion to glass and kinetic parameters of alkaline phosphodiesterase I activity. Moreover, both cell types respond to glucocorticoids by modification of synthesis of some proteins, as revealed previously by two-dimensional electrophoresis. The results show that in case of tumour cells which retain their specific receptor apparatus but do not respond to glucocorticoids by usual criteria, the conclusion whether tumour cells are hormone-sensitive or not has to be drawn from the analysis of their multiple response judging by several assays.

[Autogenic regulation of the sensitivity of liver cells to glucocorticoids during prolonged hormonal stimulation]. / Autogennaia reguliatsiia chuvstvitel'nosti kletok pecheni k gliukokortikoidam v usloviiakh dlitel'noi gormonal'noi stimuliatsii.

The mechanisms of reversible decrease of hormone-dependent induction of tyrosine aminotransferase (TAT) by rat liver cells after prolonged administration of the glucocorticoid was studied. It was shown that the main links of the glucocorticoid action mechanism (i.e., the formation of a cytoplasmic hormone-receptor complex and the hormone accumulation in the nuclei) do not change under these conditions. It was found also that one of the necessary prerequisites for the decrease of the hormone-dependent induction of TAT is the constant production by liver cells of large amounts of TAT irrespective of whether this process is induced by the glucocorticoid or by a non-hormonal inducer, e.g., tryptophan. Using the dot-hybridization technique, it was demonstrated that the inhibition of hormone-dependent induction of TAT is correlated with the reduction of mRNA TAT. It was supposed that the main links in the mechanism of inhibition of the hormone-dependent induction are the formation of a large excess of the inducible protein--TAT--in the cells as well as the accumulation of end products of the TAT-catalyzed transamination reaction which cause a feed-back repression of the de novo synthesis of TAT. Studies with cell cultures of Morris hepatoma which is known to be sensitive to glucocorticoids revealed the ability of glucose, the end product of gluconeogenesis reactions, to provide for selective inhibition of the hormone-induced accumulation of mRNA TAT in hepatoma cells.

[Hormonal induction of tyrosine aminotransferase and RNA synthesis in the cells of Morris hepatoma strain 7777]. / Gormonal'naia induktsiia tirozinaminotransferazy i sintez RNK v kletkakh gepatomy Morrisa linii 7777.

The transfer of Morris hepatoma cells induced by the hormone within 10-60 min in to a hormone-free medium is associated with the augmentation of tyrosine aminotransferase synthesis. The kinetics of this process does not differ from that of the hormone-induced enzyme. The return of tyrosine aminotransferase synthesis to the basal level occurs 15-20 hours after the hormone withdrawal from the medium, although the concentration of the intranuclear hormone sharply decreases already after 3 hours. It was demonstrated that the presence in the hepatoma cell nuclei of 20-25% of the initially bound hormone for at least 20 hours after the cell transfer to the hormone-free medium is not sufficient for maintaining a high level of tyrosine aminotransferase gene expression. Using two-dimensional electrophoresis of 3H-labeled hepatoma cell proteins, it was demonstrated that the observed high activity of tyrosine aminotransferase is due to the de novo synthesis of enzyme molecules rather than to the existence of preformed long-living tyrosine aminotransferase molecules inside the cell. Study of [14C]uridine incorporation into non-ribosomal nuclear RNA of hepatoma cells showed a long-term presence of the label in the RNA throughout the chase experiment. It was assumed that the high activity of the enzyme for 10-15 hours after the hormone release from the hepatoma cell nuclei is due to the accumulation in the nuclei of long-living pre-mRNA molecules synthesized after the hormone addition to the cells and during the first hours after the cell transfer to the hormone-free medium.(ABSTRACT TRUNCATED AT 250 WORDS)

[Interaction of triamcinolone acetonide with Morris hepatoma cells in the presence antibiotics--inhibitors of RNA synthesis]. / Vzaimodeistvie triamsinolon atsetonida s kletkami gepatomy Morrisa v prisutstvii antibiotikov--ingibitorov sinteza RNK.

Some regularities of [3H]triamcinolone acetonide (TA)binding to glucocorticoid-sensitive Morris hepatoma cell nuclei were studied. It was shown that part of the hormone incorporated into the nuclei form highly stable complexes with nuclear structures that are not destroyed during nuclei lysis with 0.25% SDS. Such complex formation is not practically suppressed by a 500-fold excess of non-labeled TA. As the time of incubation of Morris hepatoma cells with the hormone rises from 10 min to 24 hours, the specific binding of TA to the nuclei decreases, while the specific radioactivity of the [3H]TA-nuclei complexes resistant to 0.25% SDS increases. The stable complexes are eluted from Sepharose 6B together with the bulk of the nuclear proteins and do not contain DNA. Actinomycin D extrudes, to some extent, the [3H]TA from the complexes having specific binding sites that are localized in the nuclei and induces the accumulation of the steroid in the firmly bound nuclear complexes resistant to 0.25% SDS. The ability to suppress hormonal induction of tyrosine aminotransferase was detected only in the antibiotics with a high affinity for the GC-pairs of DNA. i.e., actinomycin D and mitramycin. It was assumed that high concentrations of TA specifically bound to the nuclei are necessary only at initial steps of hormonal induction. At later stages, gradual dissociation of the complexes takes place and the hormone is accumulation within the composition of the SDS-resistant firmly bound complexes.