[Protein kinase C and its role in normal and transformed cells]. / Proteinkinaza C i ee rol' v normal'nykh i transformirovannykh kletkakh.

Data are reviewed on protein kinase C (PK-C) and its function in phosphorylation and regulation of different cellular proteins--enzymes, receptors, contractile and cytoskeletal proteins, as well as expression of cellular oncogenes. Besides, interactions between PK-C and cAMP-dependent PK are discussed. The evidence provided suggests that PK-C-phosphorylation may be one of the mechanisms of transformation of extracellular transmembrane signals (hormones, neuromediators, growth factors) into responsive biochemical cell reactions.

[Correlation between the proliferative activity and protein kinase C activities in ethidium bromide-sensitive and -resistant cells]. / Korreliatsiia mezhdu proliferativnoi aktivnost'iu i aktivnost'iu proteinkinazy C v kletkakh, chuvstvitel'nykh i ustoichivykh k bromistomu étidiiu.

The protein kinase C (PK C) activity was determined in the cytosolic and membrane fractions of L- and CHO-K1-cells, both sensitive and resistant to ethidium bromide (EB). In the resistant cells (Lebr-25 and Cebr) a decreased enzyme activity was found in addition to alteration of the enzyme elution profile in the membrane preparations purified by DE-52 cellulose column chromatography. Methyltestosterone treated cells had a decreased enzyme activity in nonpurified membrane preparations in Lebr-25 cells, whereas the enzyme quantity in purified preparations remained the same. The decreased PK C activity on membranes correlates with the rapid proliferation of the resistant cells. The differences found between Lebr-25 and Cebr-cell lines in proliferation response to methyltestosterone correspond to the change of PK C developed due to hormone treatment.

[Cholesterol and phospholipid content of cells sensitive and resistant to ethidium bromide and its alteration in resistant cells as affected by methyltestosterone]. / Soderzhanie kholesterina i fosfolipidov v kletkakh, chuvstvitel'nykh i ustoichivykh k bromistomu étidiiu, i ego izmenenie v ustoichivykh kletkakh pri deistvii metiltestosterona.

The content of cholesterol (Chl) and phospholipids (Phl) in cell lines L and CHO-K1, sensitive and resistant to the toxic action of ethidium bromide, has been studied. EB-resistant cells were shown to have lower amounts of Chl and Phl, and the ratio Chl/Phl in these cells was decreased too. EB-resistant cells, grown in serum-free medium, have dramatically decreased contents of Chl, while compared with the cells growing with serum. Treatment of EB-resistant cells with methyltestosterone in concentration of 3 X 10(-7) M caused the increase in Chl and Phl contents, thus approximating these indices to those of EB-sensitive ones.

[cAMP-dependent protein phosphorylation and its regulatory role in the cell]. / tsAMF-zavisimoe fosforilirovanie belkov i ego reguliatornaia rol' v kletke.

Literary data are reviewed on the role of the cAMP-dependent phosphorylation of proteins in the regulation of cell metabolism, membrane permeability, and muscle contraction. It is suggested that a low cAMP level in the tumor and other actively proliferating cells may be associated with a raised exit of cAMP from cells into the surrounding medium because of the increased phosphorylation of the membrane proteins of these cells.

[Cyclic adenosine monophosphate content and its regulatory characteristics in Chinese hamster cells with genetically determined changes in the cell surface]. / Soderzhanie tsiklicheskogo adenozinmonofosfata i nekotorye osobenmosti ego reguliatsii v kletkakh kitaiskogo khomiachka s geneticheski obuslovlennymi izmeneniiami kletochnoi poverkhnosti.

The intra- and extracellular concentrations of cyclic adenosine monophosphate (cAMP) in cell line CHO-K1, sensitive (clone 773) and resistant to cytotoxic action of ethidium bromide (EBr), colchicine (Cr) and actinomycin D (ADr), as well as the amount of cAMP in response to isoproterenol, 10% serum and ethidium bromide (EB) in these cells were studied. The increased level of cAMP in EBr- and, Cr-cells, and the decreased one--in ADr cells was found as compared with sensitive cells. The amount of cAMP extruded in the surrounding medium was lower for EBr- and Cr-cells and higher for ADr-cells, in comparison with sensitive cells. All the variants of resistant cells were characterized by a less intensive but a longer reaction for isoproterenol, as compared with sensitive cells. In all the investigated variants 10% serum induced a remarkable increase in the intracellular cAMP by the 2nd hour after their insignificant decrease. 1 mcg/ml concentration of EBr increased intracellular cAMP only in 773-cells. The rules changing the cAMP level to isoproterenol and EB2; are determined by differences in reaction of adenylate cyclase, as it has been demonstrated for the 773- and EBr-cells.

[Effect of the tumor promotor 12-o-tetradecanoyl phorbol-13--acetate on cyclic adenosine monophosphate levels in cell cultures. Relation to cell proliferation]. / Vliianie opukholevogo promotora 12-o-tertadekanoil-fornbol-13-atsetata na uroven' tsiklicheskogo adenozinmonofosfata v kletochnykh kul'turakh. Sviaz' s proliferatsiei kletok.

A considerable increase in the level of cyclic adenosine monophosphate (cAMP) was found in hepatoma cultures (clones G-10, G-1c) and L-cells (clones Lebr 625, Lebr f. s.) in 30, 60 and 120 minutes after their treatment with the tumor promoter 12-o-tetradecanoyl-phorbol-13-acetate (TPA). In the mutant cells with changed membranes (clones G-1c, Lebr 625, Lebr 625 f. s.) the rising of cAMP was less expressed under the influence of TPA. The contents of cAMP decreases to the control level by 22 hours after their TPA treatment. A consequence of biochemical changes, leading to the tumor growth after TPA treatment of the cells, has been proposed. A considerable increment in cAMP amount is supposed to be a trigger in this chain.

[Cyclic adenosine monophosphate and the enzyme activity of its metabolism in L cells sensitive and resistant to the cytotoxic action of ethidium bromide]. / Tsiklicheskii adenozinmonofosfat i aktivnost' fermentov ego metabolizma v kletkakh linii L, chuvstvitel'nykh i ustoichivykh k tsitotoksicheskomu deistviiu bromistogo étidiia.

Using L-cells both sensitive and resistant to cytotoxic action of ethidium bromide (EB), a study was made of the intracellular level of cAMP, activities of adenylcyclase, phosphodiesterase and cAMP, liberated from cells into the surrounding medium. In EB resistant L-cells compared to EB sensitive ones, the higher level of cAMP with a decreased activity of adenylcyclase and an increased activity of the phosphodiesterase was shown to be associated with an impeded exit of cAMP from cells. It is suggested that the differences in cAMP levels in the EB sensitive and resistant cells are associated with the properties of cAMP-dependent protein kinases of these cells.

[Control of cell multiplication in vitro. II. Relationship between cell multiplication and cyclic AMP concentration]. / Kontrol' razmnozheniia kletok in vitro. II. Zavisimost' razmnozheniia kletok ot soderzhaniia v nikh tsiklicheskogo AMF.

Compairing non-transformed mouse fibroblasts and some L-cell variants, it was shown that the decrease of dependence on serum mitogenic factors, and the decease of sensitivity to the contact inhibition of growth do not always correlate with the decrease of intracellular cAMP content. The decrease of sensitivity of transformed cells to the factors limiting non-transformed cell growth in vivo might be also connected with a relative independence of the cell growth on the intracellular level of a cAMP.

[Effect of 0.005M CaCl-2 and 0.14M NaCl on the yield and extractibility of histones from rat liver nuclei]. / Vliianie 0.005M CaCl-2 i 0.14M NaCl na vykhod i ékstragiruemost' gistonov iz iader pecheni krys

The release and extraction of histones from the nuclei of rat liver under the influence of 0.005 M CaCl2 and 0.14 M NaCl was investigated. A considerable loss of nuclear histones, especially lysine-rich ones, was shown biochemically and cytophotometrically. The preliminary incubation of the nuclei in the respective salt solutions resulted in a more complete extraction of histones. This may be explained by a weaker binding capacity of histones to DNA under the latter conditions. Electrophoresis in polyacrylamid gel showed an increased mobility of histone fractions removed from the nuclei by incubation in the salt solutions.

[Corticosteroid hormones and histones (on the mechanism of action of hormones)]. / Kortikosteroidnye gormony i gistony (k mekhanizmu deistviia gormonov)

The role of interaction between corticosteroid hormones and histones is considered with regard to hormonal activation of genes and some secondary changes of cells functional condition due to the presence of the hormones.