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Z Darzynkiewicz

Publications and source records attributed to Z Darzynkiewicz.

At least 217 records · Page 12Linked to original sources
PubMed1988

Interactions of antitumor drug ditercalinium with nucleic acids in solutions and in situ.

Ditercalinium (7-H-pyridocarbazole dimer), a prospective antitumor drug, is a bis-intercalator characterized by a very high affinity towards nucleic acids. Specificity of binding of this drug has been studied using spectroscopy and flow cytometry. The competition experiments between the drug and 4',6-diamidino-2-phenylindole.2HCl (DAPI) or acridine orange indicate that in solution the drug had higher affinity to DNA whereas in situ it binds preferentially to RNA. The results suggest that despite their high affinity towards DNA, the intracellular target of some intercalating drugs may be RNA.

Antineoplastic Agents↗
PubMed1988

Cytostatic and cytotoxic effects of Pannon (P-30 Protein), a novel anticancer agent.

P-30 Protein is a novel protein, of molecular weight approximately 15 KD, obtained from the extract of a vertebrate tissue showing in vivo antitumour activity. Cytostatic and cytotoxic effects of this product in its purified form (P-30 Protein) or in partially purified extracts (Pannon) were studied in vitro on human leukaemic HL-60, human submaxillary carcinoma A-253, human colon adenocarcinoma Colo 320 CM and murine erythroleukaemia (Friend leukaemia) cell lines. Of these cells, HL-60, A-253 and Colo 320 CM were sensitive and Friend leukaemia resistant to this agent. The effects were time- and concentration-dependent. During the initial 24-48 h of treatment, a slowdown in cell proliferation was apparent but cell death was not extensive. After 24-48 h, there was a reduction in the proportion of cells in S phase of the cell cycle and the cells became preferentially arrested in G1 phase. The G1 cells showed high heterogeneity with respect to RNA content and some cells were characterized by very low RNA content. Progressive cell death occurred in cultures maintained with Pannon for up to 7 d in proportion to its concentration. Reductions of 50 and 90% in clonogenicity of A-253 cells were observed during their growth in the presence of 0.13 and 1.5 micrograms/ml of this protein, respectively. Exponentially growing cells were more sensitive to Pannon compared with cells from confluent cultures. Colonies of A-253 cells growing in the presence of Pannon were much smaller in size compared with control colonies, indicating that the rate of proliferation of clonogens is reduced by this agent. It appears that P-30 Protein induces cytostatic effects via modulation of cell transition to quiescence or differentiation. The mechanism of its cytotoxic activity is unclear.

Animals↗
PubMed1988

Unstainable DNA in cell nuclei. Comparison of ten different fluorochromes.

Ten fluorochromes with specificity for DNA were used to compare the stainability of nuclei of exponentially growing, nondifferentiated Friend leukemia (FL) cells with that of dimethylsulfoxide-induced, fully differentiated FL cell nuclei. Decreased accessibility of DNA to several dyes, particularly pronounced in the case of some intercalators, was observed in differentiated cells. Dye binding was also compared for both sets of nuclei following extraction of nuclear proteins, mostly histones, with 0.1-N HCl. Acid extraction of nuclear proteins increased the accessibility of DNA to varying degrees, depending upon the fluorochrome. In most cases, the differences in fluorescence between differentiated and nondifferentiated nuclei stained with most intercalating dyes was abolished by acid treatment. The results are discussed in terms of the mode of interaction between DNA and the various fluorochromes and the factors associated with chromatin structure, which may affect or be associated with different degrees of proliferative activity.

Cell Nucleus↗
PubMed1988

Flow cytometry in cytopathology. Overview and perspectives.

The future applications of flow cytometry (FCM) are briefly discussed. Whereas the early goals of its clinical applications were cancer diagnosis and classification, it has now become apparent that FCM can more successfully provide information on a variety of cell constituents of crucial importance in the evaluation of tumor prognosis and treatment sensitivity. It is suggested that (1) the data being provided by FCM will probably lead to a more clinically relevant classification of tumors, based more on the biochemical/molecular markers of individual cells and an assessment of tumor heterogeneity and less on classical cell morphology and tumor progression, and (2) FCM seems likely to become established as a routine methodology in cytopathology.

Cytological Techniques↗
PubMed1987

DNA in situ sensitivity to denaturation: a new parameter for flow cytometry of normal human colonic epithelium and colon carcinoma.

Modal DNA (ploidy) and sensitivity of DNA in situ to denaturation by acid have been analyzed by flow cytometry of 10 colorectal adenomas and 35 adenocarcinomas; 39 normal mucosa samples served as controls. A new method was developed to denature DNA in chromatin of the freshly isolated, intact, and unfixed individual cell nuclei from surgically resected material. The sensitivity of DNA denaturation (T alpha) was assayed by metachromatic staining with acridine orange and calculated as a ratio of the alpha t index of the tumor sample to the alpha t index of normal mucosa; the alpha t index is that fraction of DNA, following treatment at pH 1.4, that stains metachromatically with acridine orange at pH 2.6. All adenomas were diploid and in nine of 10 the T alpha value was close to 1.00, indicating no difference from control specimens in DNA sensitivity to denaturation. Forty-nine% of adenocarcinomas were aneuploid. Forty-six% of adenocarcinomas differed from normal in sensitivity of DNA to denaturation; the T alpha value was lower than 0.90 indicating that chromatin of the tumor cells was more resistant to denaturation than control cells. There was no correlation between sensitivity to denaturation of DNA and incidence of aneuploidy. However, there was a correlation between T alpha and the pathologically determined stage of disease. There was increased resistance to denaturation in 58% of tumors classified as Dukes' C/D stage, in 36% of tumors classified as Dukes' B, and in 20% classified as Dukes' A stage of the disease. Statistical analysis of these results revealed significant differences between distributions of T alpha in noninvasive (Adenomas and Dukes' A) versus invasive (Dukes' B and C/D) tumors with level of significance at P = 0.02. The data suggest that acid denaturation of DNA in situ may be a valuable adjunct in assessing the biology of colon cancer. The molecular basis for this phenomenon is discussed.

Acridine Orange↗
PubMed1987

Effects of a new amsacrine derivative, N-5-dimethyl-9-(2-methoxy-4-methylsulfonylamino)phenylamino-4- acridinecarboxamide, on cultured mammalian cells.

The effects of N-5-dimethyl-9-(2-methoxy-4-methylsulfonylamino)-phenylamino-4- acridinecarboxamide (CI-921; NSC 343499), a lipophilic and water-soluble derivative of amsacrine (NSC 249992), on cell viability, growth, clonogenicity, and progression through the cell cycle were investigated in suspension cultures of Friend erythroleukemic cells and in in suspension cultures of Friend erythroleukemic cells and in adherent cultures of Chinese hamster ovary cells. CI-921 was less toxic toward stationary than toward exponentially growing Chinese hamster ovary cells; colony formation was inhibited by 50% following a 1-h pulse of 190 versus 80 nM CI-921, respectively. Cell viability was unaffected in Friend erythroleukemic cell cultures at concentrations up to 50 nM, although growth was inhibited by 50% following 24 h of continuous exposure to 9.5 nM or a 1 h pulse of 67.5 nM CI-921. Constant exposure of Friend erythroleukemic cells to 10 nM CI-921 slowed proliferation and resulted in prolongation of cell transit through late S and G2 phases. Higher drug concentrations (50 nM) caused a complete cessation of growth marked by greatly suppressed cell transit through S phase and an irreversible block in G2 phase, about 30 min prior to division. In such cases, unbalanced growth was observed with total RNA and protein content of drug-treated cells increasing by 74 and 34%, respectively. Pulse exposure of cells to CI-921 resulted in transient accumulations of cells in S and/or G2 phase depending upon dose. The cell cycle distribution of stationary cultures treated for 1 h with drug and replated at a low cell density were identical to that of controls. Binding of the drug affected the sensitivity of DNA in situ to acid denaturing conditions which provides additional evidence that CI-921 binds to DNA by intercalation.

Amsacrine↗
PubMed1987

Interactions of pyronin Y(G) with nucleic acids.

Spectral properties of pyronin Y(PY) alone or in complexes with natural and synthetic nucleic acids of various base compositions have been studied in aqueous solution containing 10 or 150 mM NaCl and 5 mM Hepes at pH 7.0. The dimerization constant (KD = 6.27 X 10(3), M-1) and the absorption spectra of the dye in monomeric and dimeric form were established. The complexes of PY with single-stranded (ss) nucleic acids show a hypsochromic shift in absorption, and their fluorescence is quenched by over 90% compared to free dye. In contrast, complexes with double-stranded (ds) RNA or DNA (binding by intercalation) exhibit a bathochromic shift in their absorption (excitation) spectrum, and their fluorescence is correlated with the base composition of the binding site. Namely, guanine quenches fluorescence of PY by up to 90%, whereas A, C, I, T, and U bases exert a rather minor effect on the fluorescence quantum yield of the dye. The intrinsic association constant of the dye to ds RNA (Ki = 6.96 X 10(4), M-1) and to ds DNA (Ki = 1.74 X 10(4), M-1) was measured in 150 mM NaCl; the binding site size was 2-3 base pair for both polymers. Implications of these findings for qualitative and quantitative cytochemistry of nucleic acids are discussed.

DNA↗
PubMed1987

Application of pyronin Y(G) in cytochemistry of nucleic acids.

Chinese hamster ovary (CHO) cells or isolated nuclei were stained with pyronin Y(PY) and analyzed by absorption or fluorescence microscopy, as well as by flow cytometry. Specificity of the staining reaction was assayed by testing sensitivity of the stainable material to RNase or DNase. The colored complexes detected by light absorption in fixed cells stained with PY are nonfluorescent and are most likely the products of condensation of single-stranded (ss) RNA by PY; the poly(rA) and poly(rA,rG) are the most sensitive to condensation. The products of PY interaction with double-stranded (ds) nucleic acids are fluorescent and can be detected in cells by cytofluorometry. PY used alone stains both DNA and RNA, and the staining capabilities of these nucleic acids vary depending upon the PY concentration at equilibrium; at a concentration above 330 microM, the RNA stainability decreases, perhaps due to its denaturation and condensation caused by the dye. In the presence of Hoechst 33342, PY can specifically stain RNA in fixed cells or isolated cell nuclei. Because only complexes of PY with ds RNA are fluorescent, this dye can be used as a probe of RNA conformation, e.g., to monitor denaturation of RNA in situ. The RNA stainability of mitotic cells is about 25% lower than that of cells in G2 phase, which indicates that during mitosis proportionately less cellular RNA is in the ds conformation. The advantages and limitations of the two cytochemical methods for DNA/RNA detection, one based on the use of Hoechst 33342 and PY, and another employing the metachromatic properties of acridine orange, are compared.

Animals↗
PubMed1987

Effect of recombinant tumor necrosis factor on HL-60 cells: cell-cycle specificity and synergism with actinomycin D.

The tumor necrosis factor (TNF) exhibits a multitude of activities depending on the type of target cells. We characterized the cytostatic and cytotoxic effects of recombinant TNF, alone and in combination with actinomycin D (AMD), on the human leukemic cell line HL-60. Because HL-60 cells, when triggered to monocytic differentiation by phorbol esters, are known to produce and secrete TNF, their sensitivity to the factor could indicate an autocrine function of TNF in this cell system. Indeed, HL-60 cells were affected by TNF; their doubling time was increased by about 50% and progression through the cell cycle was perturbed. Initially, (up to 8 h) TNF induced a temporary arrest in G2 while later (24-48 h) it delayed progression through the G1 phase. Also, a transient increase in RNA content peaking at 6-8 h was apparent. The cytotoxicity of TNF alone was low. Thus, TNF may be involved in the regulation of the cell cycle of HL-60 cells during early stages of their differentiation. The cytotoxicity of TNF was markedly potentiated in the presence of AMD; the effect was AMD but not TNF concentration-dependent. Whereas at 20 and 50 ng/ml of AMD alone nonviable cells did not exceed 20% during the first 24 h of treatment, their proportion increased to 80 and 90%, respectively, in the presence of TNF. The most sensitive were cells in the S phase of the cell cycle. The observed synergistic effect of TNF and AMD does not appear to be caused by the action of TNF increasing the permeability of the cell membrane to AMD. The results indicate that HL-60 cells, ordinarily resistant to the cytotoxic action of TNF, can be rendered sensitive by treatment with AMD. This implies that a combination of TNF and AMD may be considered in oncology for treatment of tumors otherwise nonresponding to TNF alone.

Cell Cycle↗
PubMed1987

Effects of inhibition of RNA or protein synthesis on CHO cell cycle progression.

Chinese hamster ovary (CHO) cells, synchronized by selective detachment at mitosis, were treated with various concentrations of actinomycin D (AMD) or cycloheximide (CHX) either immediately, or 1, 2, or 3 hr after mitosis. Since the minimum duration of G1 phase in these cultures was 3.4 hr, the addition of RNA or protein synthesis inhibitors took place at the beginning, first third, second third, or end (G1-S boundary) of G1 phase. The kinetics of exit from G1 phase, the rate and extent of traverse of S phase, and the reaccumulation of RNA were estimated under each set of growth conditions by flow cytometry of acridine orange-stained cells. A mathematical model was constructed to describe the trajectories of the cell populations with respect to their increase in RNA and DNA content in the absence or presence of the inhibitor. The chronologic synchrony imposed on the CHO cell population began to decay within 3 hr, resulting in stochastic entrance of cells into S phase in the absence of inhibitor. Addition of AMD or CHX at 0, 1, 2, or 3 hr after mitosis, regardless of the inhibitor concentration, did not provide evidence of a critical restriction point in G1 beyond which cells were committed to enter S phase and were no longer sensitive to moderate suppression of RNA or protein synthesis. The observed kinetics of cell entrance into an traverse of S phase were consistent with an inherently heterogeneous response to serum stimulation occurring at or just after cell division.

Animals↗
PubMed1987

In situ factors affecting stability of the DNA helix in interphase nuclei and metaphase chromosomes.

The data from earlier cytochemical studies, in which the metachromatic fluorochrome acridine orange (AO) was used to differentially stain single vs double-stranded DNA, suggested that DNA in situ in intact metaphase chromosomes or in condensed chromatin of G0 cells is more sensitive to denaturation, induced by heat or acid, than DNA in decondensed chromatin of interphase nuclei. Present studies show that, indeed, DNA in permeabilized metaphase cells, in contrast to cells in interphase, when exposed to buffers of low pH (1.5-2.8) becomes digestible with the single-strand-specific S1 or mung bean nucleases. A variety of extraction procedures and enzymatic treatments provided evidence that the presence of histones, HMG proteins, and S-S bonds in chromatin, as well as phosphorylation or poly(ADP)ribosylation of chromatin proteins, can be excluded as a factor responsible for the differential sensitivity of metaphase vs interphase DNA to denaturation. Cell treatment with NaCl at a concentration of 1.2 N and above abolished the difference between interphase and mitotic cells, rendering DNA in mitotic cells less sensitive to denaturation; such treatment also resulted in decondensation of chromatin visible by microscopy. The present data indicate that structural proteins extractable with greater than or equal to 1.2 N NaCl may be involved in anchoring DNA to the nuclear matrix or chromosome scaffold and may be responsible for maintaining a high degree of chromatin compaction in situ, such as that observed in metaphase chromosomes or in G0 cells. Following dissociation of histones, the high spatial density of the charged DNA polymer may induce topological strain on the double helix, thus decreasing its local stability; this can be detected by metachromatic staining of DNA with AO or digestion with single-strand-specific nucleases.

Acridine Orange↗
PubMed1987

Model for intermediate steps in monocytic differentiation: c-myc, c-fms, and ferritin as markers.

A mature hematopoietic cell represents the end product of a stepwise differentiation process. As a model system for studying differentiation, the human promyelocytic leukemia cell line HL-60 undergoes terminal monocytic/macrophagic differentiation following exposure to either phorbol 12-myristate 13-acetate or 1,25-dihydroxyvitamin D3. We have derived and analyzed a variant HL-60 cell line, 1F10, that permits the study of several intermediate steps in the myeloid differentiation process. These intermediate steps are documented by cell cycle data and phenotype analysis as well as markers such as c-myc, c-fms, and both subunits of ferritin.

Antibodies, Monoclonal↗
PubMed1987

Interactions of acridine orange with double stranded nucleic acids. Spectral and affinity studies.

Spectral properties of acridine orange (AO) alone or in complexes with natural and synthetic nucleic acids of various base composition have been studied in aqueous solutions by absorption and fluorescence spectroscopy. The dimerization constant and absorption spectra of the dye in monomeric and dimeric form were established; dimerization of AO resulted in quenching of its fluorescence. Complexes of the dye with synthetic nucleic acids differed in the degree of enhancement of fluorescence quantum yield, varying between 1.42 to 2.38 fold as compared to AO monomer; these differences, however, were not base-dependent. Affinity of the dye to natural and synthetic polymers was studied and analyzed using McGhee-von Hippel model of polymer-ligand interactions. Because the sterical requirement for intercalative binding assumes interaction of dye monomer, the correction for AO dimerization was made in all calculations. All studied DNAs (natural and synthetic ones, the latter being homopolymer pairs or alternating copolymers of A,T or G,C or I,C base composition) had similar intrinsic association constants (KI = 5 X 10(4) - 1 X 10(5), M-1) and binding site size (n = 2.0-2.4 b.p.). The exception was poly(dA).poly(dT), having KI = 1.2 X 10(4) and n = 19.3 b.p. The results of KI measurement for calf thymus DNA and AO in different sodium ion concentration were in good agreement with predictions of the counterion condensation theory. The intercalation of AO into DNA is discussed in view of recent theoretical models of DNA-ligand interactions.

Acridine Orange↗
PubMed1987

Sensitivity to X-irradiation in relation to cell size of CHO cells synchronized in early G1.

A population of line CHO Chinese hamster cells was synchronized by mitotic selection and allowed to enter early G1, after which the largest and smallest cells in the population were sorted, irradiated, and their viability determined. Despite sizeable differences in volume, metabolic capability and cell cycle progression rates, an equivalent level of survival was obtained for the two populations, indicating that the factors responsible for the volume, metabolic and progression heterogeneity do not contribute greatly to radiation sensitivity.

Animals↗
PubMed1987

Cytokinetic effects of bifunctional antitumor intercalator ditercalinium on Friend erythroleukemia cells.

Ditercalinium (NSC 335153) is a novel 7H-pyridocarbazole dimer in which the two monomers are joined by a rigid bis(ethylpiperidinyl)-linking chain producing a molecule capable of bisintercalation into DNA with extremely high affinity. The effect of ditercalinium on cell proliferation and its interaction with DNA in situ has been investigated in the Friend leukemia cell system. Ditercalinium caused an inhibition of cell growth at 0.5 microM and cell death at 2.5 microM. However, both the cytokinetic and cytotoxic effects became evident only after 1-2 days of continuous drug exposure. In contrast, monointercalators generally affect cell growth within several hours of administration. Furthermore, whereas most intercalators arrest cells in G2 phase, ditercalinium demonstrated no cell cycle phase specificity. In fact, a stathmokinetic experiment, in which vinblastine was used to prevent cell division in exponentially growing Friend leukemia cell cultures, demonstrated that ditercalinium effectively "froze" cells in position throughout the cell cycle, in a dose-dependent fashion. By determining the sensitivity of DNA in situ in fixed Friend leukemia cells to acid-induced denaturation, it was apparent that ditercalinium, rather than stabilizing DNA as do monointercalators, increased the sensitivity of DNA in situ to denaturation induced by acid. It appears, therefore, that the cytokinetic effects and interaction with chromatin of an agent that has the ability to bisintercalate into DNA are qualitatively different from those induced by classical monointercalating drugs.

Animals↗
PubMed1986

Changes in accessibility of DNA to various fluorochromes during spermatogenesis.

Accessibility of mouse testicular and vas deferens (vas) sperm cell DNA to acridine orange, propidium iodide, ellipticine, Hoechst 33342, mithramycin, chromomycin A3, 4'6-diamidino-2-phenylindole (DAPI), and 7-amino-actinomycin D (7-amino-AMD) was determined by flow cytometry. Permeabilized cells were either stained directly or after pretreatment with 0.06 N HCl. For histone-containing tetraploid, diploid, and round spermatid cells, HCl extraction of nuclear proteins caused an approximately sixfold increase of 7-amino-AMD stainability but had no significant effect on DAPI stainability. For these same cell types, the stainability with other intercalating (acridine orange, propidium iodide, ellipticine) and externally binding (Hoechst 33342, mithramycin, chromomycin A3) dyes was increased by 1.6- to 4.0-fold after HCl treatment. In sharp contrast, HCl treatment of vas sperm did not increase the staining level of 7-amino-AMD, DAPI, or propidium iodide but did increase the staining level for the other intercalating dyes (1.3- to 1.5-fold) and external dyes (1.3- to 1.9-fold). Elongated spermatids that contain a mixture of protein types including histones, transition proteins, and protamines demonstrated the greatest variability of staining with respect to type of stain and effect of acid extraction of proteins. In general, for nearly all dyes, the round spermatids had an increased level and tetraploid cells had a decreased level of stainability relative to the same unit DNA content of diploid cells. The observed differential staining is discussed in the context of chromatin alterations related to the unique events of meiosis and protein displacement and replacement during sperm differentiation.

Acridine Orange↗