Daunomycin inhibition of DNA and RNA synthesis

Proteasome is a carrier to translocate doxorubicin from cytoplasm into nucleus

When an effective concentration of doxorubicin (DXR) was added into L1210 of a mouse leukemia cell line, DXR was rapidly distributed much more in the nuclei than in the other organelle within a few minutes. A [14C]DXR-binding fraction was obtained from the cytosol prepared from L1210 cells. The fraction was adsorbed to hydroxylapatite matrix and eluted from the matrix by 50-150 mM potassium phosphate buffer. The fraction showed high DXR-binding and Suc-Leu-Leu-Val-Tyr-MCA-degrading activity. The binding of [14C]DXR was inhibited by unlabeled DXR. Gel chromatography of the fraction with Sephacryl S-300 separated two fractions of high molecular weight (Peak I, approx. 750 kDa) and low molecular weight (Peak II). Peak I showed proteolytic activity. [14C]DXR-binding Peak I had much higher affinity to DNA-cellulose than [14C]DXR-binding Peak II. [14C]DXR-Peak I complex also was retained into the nuclei isolated from L1210 cells, temperature-dependently. These results suggest that a specific carrier to translocate DXR from cytoplasm into nucleus exists in L1210 cell and the carrier is proteasome.

One-electron reduction of daunorubicin intercalated in DNA or in a protein: a gamma radiolysis study

The one-electron reduction of daunorubicin, an anthracycline antibiotic, intercalated in DNA or in the apoprotein of the riboflavin binding protein, was studied by gamma radiolysis. The two reduction mechanisms appear very similar to the one found for the non-intercalated drug. Hydrogen peroxide, which oxidizes non-intercalated hydroquinone daunorubicin with two electrons in one step (C. Houée-Levin, M. Gardès-Albert and C. Ferradin, FEBS lett., 173, 27-30, (1984)), reacts with daunorubicin hydroquinone in DNA but not in the protein. It appears thus that the site accessibility to hydrogen peroxide in DNA is better than in the protein. Biological consequences are discussed.

One-electron reduction of daunorubicin intercalated in DNA or in a protein: a gamma radiolysis study

The one-electron reduction of daunorubicin, an anthracycline antibiotic, intercalated in DNA or in the apoprotein of the riboflavin binding protein, was studied by gamma radiolysis. The two reduction mechanisms appear very similar to the one found for the non-intercalated drug. Hydrogen peroxide, which oxidizes non-intercalated hydroquinone daunorubicin with two electrons in one step (C. Houée-Levin, M. Gardès-Albert and C. Ferradin, FEBS lett., 173, 27-30, (1984], reacts with daunorubicin hydroquinone in DNA but not in the protein. It appears thus that the site accessibility to hydrogen peroxide in DNA is better than in the protein. Biological consequences are discussed.

gamma-radiolysis study of the reduction by COO- free radicals of daunorubicin intercalated in DNA

The reduction of daunorubicin intercalated in DNA was studied using COO- free radicals produced by gamma-radiolysis as reductants. The reduction process of the drug intercalated in DNA was found to be very similar to the one of daunorubicin in aqueous solution without DNA. (a) the final product is the same (7-deoxy daunomycinone); (b) the reduction yield is the same [2.6 +/- 0.2) x 10(-7) mol.J-1); (c) H2O2 reacts with hydroquinone daunorubicin giving back the drug in a one-step reaction. However 7-deoxy daunomycinone precipitation was so slow that this aglycone could be reduced by COO- free radicals giving its hydroquinone form, which cannot be observed without DNA. This shows that the whole 4-electron reduction process takes place in DNA. The implications of these findings are discussed.

Anthracycline induced myocardial damage. An analysis of 16 autopsy cases

The hearts of 16 autopsy cases with a past history of administration of anthracycline antitumor drugs (DNR, ADR and ACM) and a sign of cardiac failure were investigated morphologically. In macroscopic observation, both ventricles were more or less dilated with thinning of the ventricular wall. Mural thrombi were recognized in the left ventricle of 2 cases. Histologically, the myocardial lesions could be roughly classified into two groups, a) myocardial changes in cases with rapidly developed cardiac failure (acute form), and b) myocardial changes in cases with relatively slowly developed cardiac failure. In acute form, myocardial cells showed marked swelling with dilatation of central sarcoplasmic core, marked reduction of myofibrils, vacuolization of cytoplasm and enlargement of nucleus accompanied by distinct large nucleolus. Necrotic myocardial cells were scattered among these degenerative cells. These degenerative and necrotic cells were distributed diffusely in both ventricular walls, but were more frequent in the left ventricular wall than in the right one. Inflammatory cell infiltration was also recognized not only in the myocardium, but also in the endocardium and epicardium. In chronic form, on the other hand, atrophy and attenuation of myocardial cells with a hypereosinophilic change of the cytoplasm and an increase in number of brown pigments, and marked reduction of myocardial cells were most common findings. These changes of chronic form, however, could not be identified as the specific changes of anthracycline cardiotoxicity. Fibrosis was hardly seen in the myocardium of both acute and chronic forms.

Mutagenic and cytotoxic activity of doxorubicin and daunorubicin derivatives on prokaryotic and eukaryotic cells

The mutagenic and cytotoxic activity of two newly synthesized doxorubicin derivatives and of one daunorubicin derivative were studied in V79 Chinese hamster cells and bacteria (Salmonella typhimurium and Escherichia coli). The results showed that all the compounds tested were cytotoxic and mutagenic for both prokaryotic and eukaryotic cells. However, in both systems, the two 4-desmethoxy- and the 4'-desoxy-derivatives were more active than the parent compounds, indicating that modifications in the aglycone or in the sugar moiety can produce appreciable changes in the biological properties of the anthracycline antibiotics. The in vitro activities observed in this study correlated with the in vivo antitumour potency.

On the interaction of adriamycin with DNA: investigation of spectral changes

The aerobic reduction of adriamycin by NADPH-cytochrome c-(ferredoxin)oxidoreductase was determined spectrophotometrically and found to consist of an initial slow phase, followed by a rapid stage. Superoxide was found to play a role in the reduction of the quinone drug only during the first phase. The second, faster stage of the reaction was not inhibited by superoxide dismutase, apparently due to the decreased oxygen tension in the reaction cuvette. When adriamycin was fully bound to DNA, no direct reduction by the enzymatic system was observed. However, in the presence of a superoxide-generating system, reduction of the adriamycin-DNA complex did occur.

Cytofluorescence localization of adriamycin in resistant colon cancer cells

A simple fluorescent microscopic method demonstrated that adriamycin was distributed in two cellular compartments of living rat colon cancer cells. Adriamycin accumulated slowly in cytoplasmic granules, probably lysosomes, where it persisted long after the drug was removed from the medium. On the other hand, adriamycin accumulated rapidly in the nucleus, but was rapidly cleared in adriamycin-free medium. Drug efflux from the nucleus was blocked by sodium azide in glucose-free medium or by verapamil, a calcium-blocking agent. When colon cancer cells were cultivated for 1 day or longer in adriamycin-containing medium no nuclear fluorescence was observed. However, the addition of sodium azide to glucose-free medium or verapamil restores the nuclear fluorescence. The colon cancer cells had low sensitivity to adriamycin, but the addition of verapamil strongly enhanced adriamycin toxicity. Thus adriamycin is permanently cleared from the nucleus of rat colon cancer cells through an energy-dependent efflux mechanism, which is blocked by verapamil. The efficiency of this efflux mechanism is enhanced by exposure of the cell to adriamycin. This mechanism could be involved in the resistance of colon cancer to adriamycin.

Daunorubicin and doxorubicin, anthracycline antibiotics, a physicochemical and biological review

Daunorubicin and doxorubicin, two antibiotics belonging to the anthracycline group, are widely used in human cancer chemotherapy. Their activity has been attributed mainly to their intercalation between the base pairs of native DNA. Complex formation between daunorubicin or doxorubicin with polydeoxyribonucleotides and DNAs of various base composition or chromatins has been investigated by numerous techniques. Many authors have tried to correlate biological and therapeutic activities with the affinity of the drugs for DNA or some specific sequences of DNA. In vivo these anthracycline drugs cause DNA damage such as fragmentation and single-strand breaks. The mechanism of action of anthracyclines involves the inhibition of RNA and DNA syntheses. There exists two limiting factors in the use of anthracyclines as antitumoral agents: a chronic or acute cardiotoxicity and a spontaneous or acquired resistance. In both cases, there is probably an action at the membrane level. It has to be noted that daunorubicin and doxorubicin have a particular affinity for phospholipids and that the development of resistance is linked to some membrane alterations.

Metabolism of daunorubicin in sensitive and resistant Ehrlich ascites tumor cells. Determination by high pressure liquid chromatography

The intracellular metabolism of daunorubicin (DNR) has been studied in sensitive and resistant Ehrlich ascites tumor (EAT) cells. The subcellular localization of metabolites has been followed by normal-phase and reverse-phase high-pressure liquid chromatography (HPLC). The metabolism of DNR by either sensitive or resistant EAT cells is not significant; unmetabolized DNR is always the main intracellular compound. Daunorubicinol (DOL) accounts for less than 5% after 24 h and an unidentified product is also observed. This highly apolar compound, having an intrinsic fluorescence one order of magnitude greater than that of DNR is formed in acellular conditions and could be a chemical artifact. DNR and DOL are mainly associated with DNA-containing fractions. No significant differences can be observed in the metabolism of DNR in sensitive and resistant EAT cells.

Binding specificity of chemically and enzymatically activated anthracycline anticancer agents to nucleic acids

Partial reduction of the quinone containing anticancer drugs, adriamycin and daunorubicin, generated semiquinone intermediates. Incubation of these intermediates with DNA in vitro resulted in covalent binding. The activated adriamycin has a greater binding affinity for nucleic acids, than the daunorubicin intermediate. This covalent binding reaction is essentially complete in 0.5 h. Studies with synthetic polynucleotides have shown a very high preference for poly(dG); however, poly(dC) is also an excellent substrate. Polymers containing either poly(dA) or poly(dT) showed lesser binding. Activation of adriamycin and daunorubicin by microsomes and NADPH also resulted in covalent binding to DNA with identical binding affinities. Longer incubation of these drugs with microsomes decreased binding. This binding is also decreased by Mg2+.

Inhibition of DNA synthesis in mammalian cells by daunomycin. Preferential inhibition of replicon initiation at low concentrations

The effect of the intercalating agent daunomycin on DNA synthesis was studied in cultured bovine liver cells. At low daunomycin concentrations (1 and 2 muM) the rate of [3H]thymidine incorporation decreased progressively with the duration of exposure to the inhibitor. This was accompanied by a shift of nascent DNA intermediates of replicon size to higher sedimentation values on sucrose gradients, indicating that daunomycin preferentially affects the initiation of replicating units, both in asynchronous and synchronized cells. At high daunomycin concentrations (12 muM) the rate of chain growth was also markedly reduced. This was indicated by a rapid and nearly complete cessation of the [3H]thymidine incorporation and an accumulation of nascent DNA intermediates of low molecular weight. These observations are discussed in relation to a pre-fork mode of DNA synthesis.

Binding mode of chemically activated semiquinone free radicals from quinone anticancer agents to DNA

Chemical reduction of the highly active quinone-containing antitumor drugs, adriamycin and daunorubicin formed the same partially reduced free radical previously reported [9] by microsomal activation. In vitro incubation of the chemically activated free radical intermediates with DNA resulted in covalent binding of these drugs to DNA. The adriamycin semiquinone radical has a greater affinity for DNA and covalent complexes up to one adriamycin per 12 nucleotides were obtained. The daunorubicin semiquinone radical, on the other hand, showed a lesser binding affinity and gave rise to complexes in which one drug molecule was covalently bound per 135 nucleotides. The stronger covalent binding of adriamycin to DNA may account for more severe DNA damage induced by this drug.

Methylcholanthrene induced murine primitive neuroectodermal tumor: ultrastructure and nuclear RNA polymerase activity

The histology, ultrastructure, and nuclear RNA polymerase activity are described in a murine primitive neuroectodermal tumor derived by serial transplantation from a tumor originally induced with methylcholanthrene and classified as an ependymoblastoma. The light microscope and ultrastructural studies show that this tumor does not contain the distinguishing morphological features of differentiated ependymal cells which are also commonly seen in human ependymomas. One outstanding feature is the size and number of the nucleoli. The mean number of nucleoli/nucleus is 4 which is two to four times that of the normal neuroglial cell. The nucleolar diameter is about twice that found in normal neuroglial cells. The nucleolar diameter is about twice that found in normal neuroglial cells. The nuclear RNA synthesizing activity is the highest of the chemically induced animal tumors we have studied. The alpha amanitin inhibition is the lowest seen in any of these tumors which suggests that RNA polymerases inhibited by alpha amanitin contribute less to the total nuclear RNA synthesis. Adriamycin significantly inhibits the nuclear RNA polymerase activity of this tumor.

Thermodynamics of the interaction of daunomycin with DNA

The association constant for the interaction of daunomycin with DNA was determined as a function of temperature (using [3H] daunomycin in conventional equilibrium dialysis cells) and ionic strength (using a spectrophotometric titration method). The association constant varied between 3.1 X 10(-6) M(-1) (4 degrees C) and 3.9 X 10(5) M(-1) (65 degrees C). The free energy change was -8.2 to -8.8 kcal/mol, the enthalpy change -5.3 kcal/mol and the entropy change +10 to +11 eu, all values being consistent with that expected of an intercalation process. The apparent number of intercalation sites detected (0.15 to 0.16 per nucleotide) was independent of temperature. The large positive entropy change accompanying the interaction appears to be due to extensive release of water from the DNA and daunomycin. The apparent number of binding sites increased dramatically with decrease of ionic strength, although the apparent association constant remained largely unaffected by ionic strength.

Metabolism of daunorubicin by a barbiturate-sensitive aldehyde reductase from rat liver

A barbiturate-sensitive aldehyde reductase was purified to homogeneity from rat liver and shown to metabolize the cancer-chemotherapeutic antibiotic daunorubicin. The aldehyde reductase may have important roles in the metabolism of exogeneous drugs as well as the aldehyde derivatives of the biogenic amines.

Daunorubicin inhibition of DNA-dependent RNA polymerases from Ehrlich ascites tumor cells

Two different forms of DNA-dependent RNA polymerase have been solubilized and purified from nuclei of Ehrlich ascites tumor cells. The purification procedure involves ammonium sulfate precipitation and gel filtration on Sephadex G-25. The separation of A and B activities is achieved by chromatography on DEAE-cellulose. Nuclei are prepared from cells, sensitive or resistant to daunorubicin. RNA polymerases A and B have an absolute requirement of divalent cations for activity. Native DNAs are better templates than heat-denatured DNAs for RNA polymerase A. On the contrary heat-denatured DNA is more transcribed than the native one by RNA polymerase B. The low level of transcription of total and nucleolar ascites DNAs is due to the DNA, the same results being obtained with ascites and calf thymus RNA polymerases A and B. The inhibitory action of daunorubicin on RNA polymerases A and B from Ehrlich ascites tumor cells has been studied in vitro. The same results are obtained with enzymes extracted from sensitive or resistant cells. Daunorubicin does not inhibit the binding of RNA polymerases to the DNA template, but prevents the transformation of the DNA-daunorubicin-RNA-polymerase unstable complex into the highly stable one. This inactive ternary complex has a dissociation rate faster than the stable complex formed without daunorubicin. The size of the RNA synthesized in the presence or absence of daunorubicin is the same.

Interaction specificity of the anthracyclines with deoxyribonucleic acid

The interaction specificity of salmon sperm DNA with various derivatives of daunorubicin has been studied. The results of binding, viscometric, 1H nuclear magnetic resonance (NMR), flow dichroism, DNA template inhibition, rates of dissociation, and circular dichroism studies are found to be consistent with an intercalation mode of binding of the anthracycline ring as has been shown by other investigators. Moreover, it is observed that (i) strength of binding, (ii) the ease of dissociation of DNA-anthracycline complexes, and (iii) the degree of inhibition of the DNA-dependent RNA polymerase are dependent on the presence of the amino sugar moiety of daunoseamine. The results are consistent with specific H bonding of the amino group of the sugar moiety with DNA as has been suggested earlier by Pigram et al. (Pigram, W.J., Fuller, W., and Hamilton, L.D. (1972), Nature (London), New Biol. 235, 17). Peptide derivatives substituted at the amino sugar function of daunorubicin lower the affinity of the drug to DNA and presumably interfere with the "full insertion" of the anthracycline drugs between base pairs of DNA. The significance of these findings in relation to the biological efficacy of daunorubicin and related derivatives as antileukemic agents is discussed.

Interaction of daunomycin with meiotic chromosomes in Vicia faba

Daunomycin interferes with the meiotic cycle and structural integrity of chromosmes if administered to microsporocytes of Vicia faba during the meiotic prophase substages prior to diplotene. The principal cytological consequences of daunomycin treatment are as follows: induced achromatic lesions, chromosome fragmentation, terminal and interstitial deletions, loose or non-pairing regions, multivalent associations, reduced chromosome condensation, chromosome stickiness, dicentric and side-arm bridges and chromatid loops. A correlation between inhibition of DNA or RNA and the cytological manifestation of structural anomalies or unfolding of meiotic events is discussed.

Mode of action of chemotherapy in vivo on human acute leukemia. I. Daunomycin

The leukocytes of 16 adult patients with acute myeloblastic leukemia were studied by autoradiographic methods to elucidate the mode of action of daunomycin. It was shown that daunomycin, at clinically useful doses, exhibits a cytolytic effect on all leukemic blasts whatever their cell-cycle phase. This cytolytic action affects, however, preferentially S-phase cells. It was shown also that blasts of patients less sensitive to daunomycin or receiving a lesser dose of the drug are temporarily blocked in G(2) phase (delayed mitosis) or in G(2) phase (prolonged generation time). Finally daunomycin appeared to hamper the passage of G(2)-blocked blasts from the bone marrow to the blood, while G(2)-phase cells crossed freely.

Comparison between3H-Daunomycin and its Antimitotic and Antimetabolic Activities in Ascites Sarcoma 180

Daunomycin uptake and its antimitotic and antimetabolic activities have been studied in S 180 ascites cells in vivo. The uptake of the tritiated antibiotic was determined by radiochemical methods 15 min and 2 h after the i. p. administration of scalar doses. The inhibiting effects on nucleic acids biosynthesis was evaluated by determining with autoradiographic and radiochemical methods, the incorporation of3H-thymidine and3H-uridine 2 h after daunomycin administration. Parallel studies were carried out on the antimitotic activity. The results obtained indicate that daunomycin is already present in the cells 15 min after injection and in proportion to the dose given. Two hours after the injection the level of incorporated radioactivity is lower. Mitotic activity, measured two h after the treatment, is reduced dose proportionally and is completely absent at doses of 2 mg/kg. The incorporation of3H-thymidine and3H-uridine is increased in the cells treated with low doses and is reduced only at doses of 2 mg/kg or higher. In these experimental conditions DNA synthesis is reduced to greater extent than RNA synthesis. A comparison of daunomycin uptake and of nucleic acid synthesis inhibition showed a direct proportionality whereas the effect of daunomycin on mitotic activity and on nucleic acids metabolism appear to be dissociated.