[The effect of monovalent cations on the structure of chromatin from Ehrlich ascites carcinoma cells]. / Vliiznie monovalentnykh kationov na strukturu khromatina kletok astsitnoi kartsinomy Erlikha.

Changes in the intracellular ratio of monovalent cations resulting in the alteration of transcriptional activity in some cell-specific genes have been investigated. It was found that at varying intracellular Na+/K+ concentration ratios the accessibility of the beta-actin gene to the effect of exogenous DNAaseI changes drastically. The use of hybridization of restricted DNA of the nuclear matrix with appropriate probes revealed that the number of copies for oncogenes c-fos and c-myc within this DNA changes with alteration of the intracellular ratio of monovalent cation concentrations.

Intracellular ratio between monovalent cations (Na+/K+), and transcriptional activity of genes in tumour cells.

The effects of the intracellular Na+/K+ ratio on transcriptional activity of ribosomal, c-fos, beta-actin and histone genes of Ehrlich ascites tumour cells and P-388 leukaemia cells have been investigated. Optimum values of the Na+/K+ ratio for selective transcription of genes are shown, they are in accordance with the Na+/K+ ratio and mRNA content of respective genes during the cell cycle. Differential activation and repression of these genes do not correlate with the total synthesis rate of RNA during the cell cycle. The data indicate a selective nature of the action of monovalent cations on gene expression during the cell growth.

[Effects of intracellular Na+/K+ ratio on expression of c-fos oncogene and beta-actin gene in ascitic cells of leukemia P-388 and Ehrlich tumor]. / Vliianie vnutrikletochnogo sootnosheniia Na+/K+ na ékspressiiu onkogena c-fos i gena beta-aktina v astsitnykh kletkakh leikoza P-388 i raka Erlikha.

The intracellular Na+/K+ ratio was studied for its effect on expression gene beta-actin and oncogene c-fos and activity of these genes during the mitotic cycle in ascites cells of leukemia P-388 and Ehrlich tumour. It was established that gene beta-actin was activated at high and low ratios of Na+/K+, while c-fos only at high ones. The expression of these genes during the mitotic cell cycle was due to changes in the intracellular Na+/K+ ratio. The obtained data showed an important role of intracellular homeostasis of monovalent cations in regulation of gene expression during the mitotic cell cycle.

[Effects of intracellular Na+/K+ ratio on histone gene expression in ascitic cells of leukemia P-388 and Ehrlich cancer]. / Vliianie vnutrikletochnogo sootnosheniia Na+/K+ na ékspressiiu gistonovykh genov v astsitnykh kletkakh leikoza P-388 i raka Erlikha.

The intracellular Na+/K+ ratio was studied for its effect on histone genes expression in Ehrlich carcinoma and leukemia P-388 ascites cells. After equilibration with certain Na+/K+ ratio buffers at 0-4 degrees C the cells were treated during 1 h at 37 degrees C with ouabain added to the corresponding medium. Then total RNAs were extracted and analyzed by the reaction of blot-hybridization with histone genes cluster in plasmid p604. The maximal level of histone genes expression in leukemia P-388 cells was observed under conditions when intracellular Na+/K+ ratio corresponded to those at S-phase of the mitotic cycle. In Ehrlich carcinoma ascites cells the expression of histone genes was not dependent on the Na+/K+ ratio. A conclusion is drawn that the intracellular ratio of monovalent cations is one of the possible mechanisms which regulates the gene expression during the mitotic cycle.

[The effect of inhibitors of ionic passive transport on the structure of a cell population of Ehrlich's ascites carcinoma]. / Vliianie ingibitorov passivnogo transporta ionov na strukturu kletochnoi populiatsii astsitnoi kartsinomy Erlikha.

Triampur is a drug, containing triamterene and dichlotiazide, which inhibits passive influx of Na+ through cell membrane. Triampur was injected intraperitoneally to mice with the Ehrlich ascite carcinoma. The drug was injected in the exponential phase of tumor growth with 2 hour intervals within 24 hours. A subsequent sedimentation and fractionation of cells according to the cell cycle position displayed an additional peak in sedimentogram, that was absent in the control sedimentogram. This peak is due to cell blocking in G1-period; the pool of blocked cells contains 20-25% of the total cell population. If the drug was injected during 3 days and nights with 8-hour intervals, the pool of blocked cells amounted up to 40%. This effect is reversible: when the drug is cancelled, the peak of G1-blocked cells is reduced. Estimation of intracellular Na(+) and K(+) concentration and Na+, K(+) pump indicates a significant decrease in Na+ permeability in the blocked cells due to Triampur effect. The obtained data well compare with an idea of the importance of increasing a passive influx of Na+ for G1-S transition, and indicate a possibility to affect the structure of tumor cell population via the system of intracellular ionic homeostasis.

[Interaction of the ligand molecules with the membrane receptors of tumor cells]. / Vzaimodeistvie molekul liganda s retseptorami membran opukholevykh kletok.

The mechanism of the ligand molecule interaction with cell membrane receptors is considered. The equation is obtained which describes dynamics of change in the number of ligand-receptor complexes on membranes with their constant internalization. It is shown that the in vivo internalization leads to saturation of the cell surface with the ligand-receptor complexes, the ligand concentrations being less than Kd. Theoretical conclusions are compared with the experimental data.

Cationic control of gene transcription in tumour cells.

Using ascites tumour cells (Ehrlich carcinoma, plasmacytoma MOPS-21, leukaemia P-388, lympholeukaemia NK/Ly) and bone marrow cells from normal rats, we have demonstrated that transcription of a gene coding for the 35S RNA can be regulated via alteration of the Na+/K+ ratio in the cells. The 35S RNA was transcriptionally active within the range 1 less than or equal to Na+/K+ less than 3 but was switched off at Na+/K+ less than 1. In synchronized Ehrlich carcinoma cells this gene was activated in the early phases of the cell cycle, when the Na+/K+ ratio in the cells exceeded 1. It was concluded that so-called cationic mechanism of regulation of transcription determines the time and sequence of stimulation of certain genes during the course of the cell cycle and that it accounts for transcription of normally repressed genes as a result of malignant transformation.

[Characteristics of the regulation of the process of protein phosphorylation on tumor cell membranes]. / Osobennosti reguliatsii protsessov fosforilirovaniia belkov na membranakh opukholevykh kletok.

The regulation mechanism of intracellular protein concentrations which are phosphorylated by membrane-bound protein kinases is considered. It is shown that cells depending on intracellular parameters may be in two alternative states which are characterized either by the absence (or very low concentration) or the presence of phosphorylated proteins, that provides their different sensitivity to the growth factors. A conclusion is drawn on the possibility of existence of transformed cells which sensitivity to growth factors is inhibited.

[Morphometric characteristics and functional activity of the cells of Ehrlich ascites cancer found in different phases of the cell cycle]. / Morfometricheskaia kharakteristika i funktsional'naia aktivnost' kletok astsitnogo raka Erlikha, nakhodiashchikhsia v razlichnykh fazakh kletochnogo tsikla.

The Ehrlich ascites carcinoma cells at different interphase periods have been studied for dynamics of ultrastructural and morphometric characteristics and biochemical analysis of metabolism of the given cells has been made. A distinctive structure-function correlation detectable by stage coincidence in the re-structure with the cell metabolism alterations is shown.

[Cationic control of the transcription of various genes in tumor cells]. / Kationnyi kontrol' transkriptsii nekotorykh genov v opukholevykh kletkakh.

Using ascite tumour cells (Ehrlich carcinoma, plasmacytoma MOPC-21, leukemia P-388, lympholeucosis NK/Ly) and bone marrow cells of intact rats, the possibility of regulation of transcription of a gene encoding 35S RNA via the alteration of the univalent cations Na+/K+ intracellular ratio was demonstrated. Gene 35S RNA was transcriptionally active within the range of 1 less than or equal to Na+/K+ less than 3 but was switched off at Na+/K+ less than 1. In synchronized Ehrlich carcinoma cells this gene was activated at the early steps of the mitotic cycle, when the cationic ratio was above 1. It was assumed that the so-called cationic mechanism of regulation of transcription predetermined the time and other of stimulation of certain genes in the course of the mitotic cycle and provided for the transcription of normally repressed genes as a result of malignant transformation.

[Effect of monovalent cations on the ratio of RNA transcripts from DNA with different repetitive sequences in leukemia P-388 cells]. / Vliianie monovalentnykh kationov na sootnoshenie RNK-transkriptov s raznykh po povtorennosti posledovatel'nostei DNK v kletkakh leikemii P-388.

Using leukemic P-388 cells, it was demonstrated that alterations of the intracellular Na+/K+ ratio results in qualitative changes of newly synthesized mRNA, which manifests itself as changes in the kinetics of hybridization of heterogeneous nuclear RNA (hnRNA) with DNA. The decrease of the Na+/K+ value from 3.8:1 to 1:1 leads to inhibition of mRNA synthesis in mRNA cells hybridized at 10(3) greater than Dot greater than 10(4), but weakly affects the transcription of mRNA sequences hybridized with DNA within the Dot interval of 10(3.4)-10(3.8). A similar phenomenon is observed during hybridization of hnRNA with homogeneous fractions of unique and averagely repeating sequences of DNA. The hybridization rate constants of hnRNA synthesized by cells at different values of Na+/K+ and the limit values of hybridization (H infinity) were calculated. It was shown that the rate constants for RNA hybridization with DNA decrease by more than two orders of magnitude during the transition of the averagely repeating DNA fraction to the unique one; however, in both cases these constants give equal values for the RNA synthesized by cells at different cationic balance. The H infinity values for the RNA synthesized by cells at higher Na+ ratio appeared to be 1.5-2.0 times as high as compared with those for the RNA in the cells, in which the Na+/K+ ratio was 1:1. Thus, the monovalent cation ratio seems to exert a strong influence on the expression of sequences of different repeatedness in the genome and to play a role in the regulation of proliferative activity of the cell.

[Energy characteristics of the transport of monovalent cations in ascites tumor cells]. / Energeticheskie osobennosti transporta odnovalentnykh kationov v kletkakh astsitnykh opukholei.

The intensity of O2 adsorption by ascite tumour cells does not practically depend on the monovalent cation concentration gradient between the cells and the incubation medium, whereas the rate of glycolysis decreases simultaneously with the diminution of the concentration gradient. In synchronized cultures at the beginning of the mitotic cycle, the bulk of ATP resynthesized via glycolysis is utilized for the synthesis of biopolymers, whereas that at the end of the S-phase and in the G2-phase--for cation transport across plasma membranes. From 35 to 100% of the whole amount of ATP resynthesized via glycolysis is utilized for transport purposes. The experimental results and theoretical calculations suggest that in glucose-containing media Na+ transport increases from 0.75 to 1.78 pmol/hour on a per cell basis. The activation of Na+ transport is due to the exchange of protons formed via glucose conversion into lactate for Na+, i.e., to the stimulation of Na+/H+ antiport. The permeability of plasma membranes for K+ increases 2.75-fold, while the passive flux of Na+ diminishes. It is concluded that the observed increase in the Na+/K+ ratio in ascite tumour cells is connected with their enhanced ability to synthesize lactic acid. Presumably, glycolysis is one of regulatory mechanisms of intracellular ratios of monovalent cations.

[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.

[Biosynthesis of protein and RNA during changes in the Na and K ratios in Ehrlich carcinoma cells]. / Biosintez belka i RNK pri izmenenii sootnosheniia Na+ i K+ v kletakh raka Erlikha.

The changes in the intracellular ratios of Na+ and K+ by equilibration of Ehrlich carcinoma cells in salt media at 0-4 degrees C leads to the changes in the rate of rRNA and protein synthesis. Using competitive hydridization, it was shown that with a decrease of the Na+/K+ ratio from 1:1 to 1:2, the rate of pre-rRNA synthesis is markedly diminished. The incorporation of labelled amino acids into histones, nonhistone proteins, and cytoplasmic proteins also depends on the ratio of monovalent cations in cancer cells. At the translation level, Na+ and K+ are responsible for the selectivity of protein synthesis, whereas upon transcription these cations determine the rate of synthesis of corresponding mRNAs. It is concluded that the intracellular ratio of monovalent cations is one of the mechanisms, by means of which the cells operate their genetic control.

[Analysis of the statistical characteristsics of the distribution of NK/Ly lymphoma cells obtained by laser flow cytometry]. / Analiz statisticheskikh kharakteristik raspredelenii kletok limfomy NK/Ly, poluchennykh metodom lazernoi protochnoi tsitometrii.

Distributions in volumes of NK/Ly ascite lymphoma cells in different periods after inoculation were studied by laser cytometry. With the age of tumour the primary peak of distribution shifts to an area corresponding to large cells, but from the sixth day there appears an additional peak of distribution due to an accumulation of a pool of nonproliferating quiscent G0(R1) cells. The obtained data are in good agreement with results of sedimentation fractionation of NK/Ly lymphoma cells. Discrepancies in statistical characteristics of distributions, found by the both methods, are not more than 20%.

[Effects of monovalent cations on synthesis and degradation kinetics of RNA in cells of Ehrlich carcinoma]. / Vliianie monovalentnykh kationov na sintez i kinetiku raspada RNK v kletkakh raka Erlikha.

The changes in intracellular ratio of Na+/K+ by equilibrating the cells in saline media at 0-4 degrees C cause changes in the rate of RNA synthesis in the cells. The optimum of [3H]uridine incorporation lies within the range of the Na+/K+-ratio of 7 : 1 to 3 : 1. Within the Na+/K+ ratio of 3 : 1 to 1 : 1 the rate of RNA synthesis is decreased about 2.5-fold, showing a further fall at the Na+/K+ ratio of about 1 : 3. Using competitive hybridization of labelled and non-labelled heterogenous nuclear RNA with DNA, it was shown that the total rate of synthesis and the nature of newly formed transcripts are changed. When the cells equilibrated with a certain saline medium were labelled with [3H]uridine for 15 min and their cationic equilibrium was changed by another equilibration in a medium having a different Na+/K+ ratio, the processing of labelled heterogenous nuclear RNA was drastically changed, i.e. part of the labelled RNA was rapidly depolymerized, while the other part was deposited in the nuclei or cell cytoplasm. Hence the intracellular cationic homeostasis can control the transcription and its changes cause recoding of gene expression. Besides, the cells contain an active system which controls the transcription program and depends on intracellular ionic homeostasis. This system prevents the release of non-essential mRNAs into the cytoplasm by depolymerizing or depositing them in the nuclei.