Binding of adriamycin to sulphated mucopolysaccharides

A Differential Interaction of Doxorubicin and Daunorubicin with Human Serum Proteins

The results of a comparative investigation on the interaction of doxorubicin (adriamycin) and daunorubicin with serum proteins are reported. Whereas a strong interaction occurs in vitro between doxorubicin and human serum proteins, no appreciable binding to proteins could be detected for daunorubicin under similar experimental conditions. Since the protein-bound drug is only partially dissociated by physical procedures including gel-electrophoresis, column-chromatography and solvent extraction, the formation of a covalent bond is suggested. The doxorubicin binding to serum proteins is apparently nonselective for a class of proteins; it is strongly reduced in acid conditions and slightly dependent on the ionic strenght. Two tentative reaction mechanisms have been considered.

Tumor pH controls the in vivo efficacy of weak acid and base chemotherapeutics

The extracellular pH of tumor tissue is significantly lower than the extracellular pH of normal tissue, whereas the intracellular pH of both tissues is similar. In principle, extracellular acidity may be expected to enhance the intracellular uptake and cytotoxicity of weak acid chemotherapeutics that are membrane permeable in their uncharged state and inhibit the efficacy of weak bases. However, procedures for assessing the role of the gradient as a determinant of drug efficacy in vivo by altering the pH gradient may also alter drug availability and thus mask or exaggerate the effect of the gradient change. In the present study, we have altered the extracellular pH of tumors and compared the effect of the resultant pH gradient change on the efficacy of a weak acid versus a weak base. This experimental design gives rise to a change in the ratio of chlorambucil- to doxorubicin-induced tumor growth delay, independent of possible changes in drug availability. The extracellular pH of the 54A human tumor in NCr/Sed/nu/nu mice was altered by administration of 5 mg/g i.v. glucose. The resultant 0.2 pH unit increase in the tumor cell pH gradient gives rise to a predicted 2.3-fold increase in the ratio of chlorambucil to doxorubicin growth delay. The experimentally measured change in the growth delay ratio was 2.1. The results provide compelling evidence that the pH gradient in a determinant of the efficacy of weak electrolytes in the complex in vivo environment and may be exploited for the treatment of cancer.

Doxorubicin-heparin complex: reduction of cardiotoxicity of doxorubicin

We have compared the antitumor activity and cardiotoxicity of free doxorubicin (Dox) and doxorubicin-heparin complex in vivo and in vitro. Dox and Dox-heparin complex equally inhibited the DNA synthesis of leukemic cells and showed a similar anticancer activity against tumor-bearing mice. Acute toxicity of Dox at the dose of 20 mg/kg or 30 mg/kg was significantly more profound than that of the Dox-heparin complex, which was demonstrated by survival rate (P < 0.01). Chronic toxicities of Dox and the Dox-heparin complex were compared by giving the respective reagent (2 mg/kg) weekly for 20 weeks. The weight gains of the mice given Dox-heparin complex were greater than those of the mice given Dox alone (P < 0.01). The pathological damage to the cardiac tissue in mice treated with Dox-heparin complex was significantly less severe than that of mice treated with Dox. Thus, the present study indicates that complexing with heparin diminished the acute and chronic toxicity of Dox without reducing its antitumor activity in mice, and suggests a possible clinical application of Dox-heparin complex in humans.

Interaction of mitoxantrone with heparin and its application to the quantitation of heparin

The interaction of heparin of high molecular weight with mitoxantrone, an anthraquinone derivative, had been studied by spectrophotometry. Heparin links the mitoxantrone and the binding sites are probably the anionic groups of the mucopolysaccharide since the linking is displaced by Na+. This interaction of mitoxantrone with heparin could provides a sensitive and simple method for quantitation of heparin in non proteic medium and could appear of clinical relevance in some circumstances.

Doxorubicin is a potent inhibitor of interleukin 1 induced cartilage proteoglycan resorption in-vitro

Since interleukin 1 (IL-1) induces the transcriptional synthesis of enzymes responsible for cartilage resorption it was decided to examine the effects of the antitumour drug, doxorubicin, a DNA transcriptional inhibitor, on alpha IL-1-induced cartilage--resorption in-vitro. Doxorubicin inhibited the resorption in a concentration-dependent fashion, an effect which was shown to be reversible. Fine structure of the chondrocytes was preserved by the doxorubicin treatment with IL-1 in contrast to the extensive cellular destruction evident in cartilage treated with IL-1 alone. [14C]doxorubicin was bound to cartilage proteoglycans, and this effect was promoted by treatment of the cartilage with IL-1. This binding of the drug may prevent access of the proteoglycans to destructive enzymes during the resorptive process induced by IL-1.

Interaction of adriamycin with human erythrocyte membranes. Role of the negatively charged phospholipids

The interaction of the antitumor compound adriamycin with human erythrocyte membranes, used as models of target cell membranes, has been studied using circular dichroism measurements. In order to elucidate the nature of the sites involved in the electrostatic interaction between adriamycin and erythrocyte membranes, its interaction with the following macromolecular systems was studied: phosphatidylserine-containing small unilamellar vesicles (SUV), prepared from total lipid extracts of erythrocytes, sialic acid-depleted erythrocyte ghosts and mucopolysaccharides. We have shown that the interaction between adriamycin and carboxylate groups is very weak and that negatively charged phosphate groups, in the case of membranes, or sulfate groups, in the case of mucopolysaccharides, are responsible for the prime interaction of adriamycin with these macromolecular systems.

Morphometric studies on wound healing after systemic administration of adriamycin and local application of fibrin sealant. Application of a new wound healing model using spongiosa implants

For investigations on the development of regenerative granulation tissue in wound healing a new model using bone spongiosa ("Kieler Spongiosa") implants is presented. Particular attention was devoted to developing a model which permits studies on wound healing without disturbance by foreign body reaction and infections. Two test groups of rats received four blocks of "Kieler Spongiosa" each in a symmetrical fashion in a paramedian region underneath the dorsal skin. The spongiosa blocks had previously been treated with glutaraldehyde to achieve cross-linkage of the collagenous structures of the surfaces of the spongiosa trabeculae. After one week (group 1) and two weeks (group 2) the animals were sacrificed. The spongiosa blocks were removed, fixed and evaluated in layered serial sections after decalcification. Two blocks which had been removed randomly from the back and front served for morphometric determination of the total volume of bony substance and the developed granulation tissue. Moreover, the cellular composition of the granulation tissue was morphometrically examined with regard to its content of capillaries, granulation tissue cells and inflammatory cells. The two other blocks were examined for DNA and hydroxyproline content of granulation tissue. Comparison of the two experimental groups yielded marked differences in spongiosa space infiltrated by granulation tissue and its composition. Our model was used to assess the influence of systemic administration of adriamycin and/or local application of a fibrin sealant system on granulation tissue formation and its morphologic structure.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of the C14-OH group of adriamycin with DNA phosphate as spectroscopically evidenced

Monitoring the band of the antisymmetric stretching vibration of the backbone PO-2 group in DNA-anthracycline complexes demonstrates an extraordinary wavenumber shift for the adriamycin complex compared to that of daunomycin. The structures of both anthracyclines, however, are very closely related and differ only by a surplus hydroxyl group of adriamycin in the C14 position. The wavenumber shift observed for the DNA-adriamycin complex is unequivocally attributed to an additional linkage of the C14-OH of adriamycin to the phosphate group of DNA. Thus, several of the hypothetical structural models for the DNA-adriamycin complex for which a hydrogen bond between the C14 hydroxyl of the drug and DNA phosphate was postulated (S. Neidle, Cancer Treatment Rep. 61, 928 (1977); G. J. Quigley et. al., Proc. Natl. Acad. Sci. USA 77, 7204 (1980)) get the first clear-cut experimental evidence.

Doxorubicin binds in a cooperative manner to myocardial cells. Two binding sites

Experimental evidence indicates that the anthracycline antibiotic doxorubicin (adriamycin) localizes mainly in cell nuclei of cardiac cells and has a high affinity to several cellular constituents in addition to DNA. In the present study the cellular kinetics of doxorubicin in cultured rat myocardial cells were determined by measuring its uptake, its binding pattern over a concentration range of 0.1 mM to 80 microM, and the cellular release by means of [14-14C]doxorubicin. The binding kinetics of doxorubicin were compared with the doxorubicin-induced inhibition of [methyl-3H]thymidine incorporation into DNA. It is demonstrated that at micromolar concentrations doxorubicin is readily taken up by myocardial cells and that myocardial cells have the ability to bind doxorubicin at two specific binding sites and that a noncooperative high-affinity/low-capacity type and a positive cooperative type of binding are involved, as indicated by the positive slope in the initial region of the binding isotherm (Scatchard plot). A dose-dependent inhibition of [methyl-3H]thymidine incorporation into DNA is demonstrated. It is suggested that this is associated with the positive cooperative binding of doxorubicin. The cellular release of doxorubicin appeared to be biphasic, with estimated half-lives of about 5-6 h for the initial phase and 50-60 h for the terminal phase. The results of this study indicate that doxorubicin preferably binds to sites within myocardial cells and that the positive cooperative binding pattern is due to DNA as one of the binding sites. A relationship between the noncooperative high-affinity/low capacity binding and the pharmacological activity has yet to be determined.

The mechanisms of target cell injury by nephrotoxins

Hexachlorobutadiene-N-acetylcysteine (HCBD-NAC), adriamycin and 2-bromoethanamine hydrobromide are three renal toxins that have shown in vivo a highly selective target cell toxicity--to the proximal tubules, the glomerular epithelial cells and the medullary interstitial cells, respectively. To study some aspects of the mechanisms of this selective toxicity, the three types of target cell were isolated from the kidneys of Wistar rats, and cultures of the cells or tissue fragments were exposed to various concentrations of the three toxins. Using fluorescence microscopy combined with enzyme and histochemical probes, the selective target-cell toxicity of the three compounds already established in vivo was demonstrated also in vitro. Moreover, the in vitro toxic effect of HCBD-NAC was ameliorated by probenecid, as is the case in vivo. Several functional characteristics specific to each of the target cells, such as the selective uptake of a toxin, the presence of lipid droplets and the level of peroxidative enzyme activity, have been identified as probable factors in the occurrence of the target cell necrosis.

Impaired PWM-induced polyclonal B-cell activation in patients with malignancies treated with various intermittent combination chemotherapies including doxorubicin

The effect of various intermittent combination chemotherapies on the immune status of 30 patients with malignancies was examined 1-3 weeks after they received their last injection. PWM-induced polyclonal B-cell activation of lymphocytes from patients treated with combination chemotherapies that included doxorubicin was impaired despite a normal 3H-thymidine uptake by lymphocytes stimulated with PHA, PWM, and insoluble SPA. This suppressive effect was always found in patients with ALL. However, in patients with solid tumors, PWM-induced immunoglobulin production returned to normal 7-8 weeks after the last doxorubicin injection. Serum immunoglobulin levels in patients treated with doxorubicin were slightly lower than in those treated without doxorubicin. It is hypothesized that doxorubicin may change the lymphocyte surface membrane and interrupt the T- and B-cell interaction that is needed for immunoglobulin production.

Adriamycin-induced changes in the surface membrane of sarcoma 180 ascites cells

Adriamycin increases (a) the rate of agglutination of Sarcoma 180 cells by concanavalin A after brief exposure of 2-3 h and (b) membrane fluidity as measured by ESR within 30 min of exposure at concentrations of the anthracycline of 10(-7)-10(-5) M. The effect of adriamycin on agglutination is not due to an increase in the number of surface receptors for concanavalin A, since the extent of binding of the lectin is not altered by adriamycin and no change occurs in the rate of occupancy of the concanavalin A binding sites by the lectin in cells treated with the antibiotic. The order parameter, a measurement of membrane fluidity, decreases in cells exposed to adriamycin and is dose-related. The results indicate that adriamycin can induce changes in the surface membrane of Sarcoma 180 cells within a brief period of exposure to a low but cytotoxic level of this agent.

Comparative nuclear and cellular incorporation of daunorubicin, doxorubicin, carminomycin, marcellomycin, aclacinomycin A and AD 32 in daunorubicin-sensitive and -resistant Ehrlich ascites in vitro

The kinetics of cellular and nuclear incorporation of a number of new anthracyclines into daunorubicin-sensitive and -resistant Ehrlich ascites cells were determined in vitro. For comparative quantitative analyses the substances were extracted with a 0.3 N HCl/50% ethanol (v/v) solution from either whole cells or purified citric acid nuclei after various intervals of in vitro incubation. At steady state the intracellular and intranuclear concentrations of daunorubicin and doxorubicin were reduced by about 50% in the resistant cell line. Marcellomycin and carminomycin concentrations were only reduced by 9% and 11%, respectively, and no differences between sensitive and resistant cells were seen in the case of aclacinomycin A and AD 32. When the ratios of nuclear to cellular drug were determined at steady state lowest value was found for AD 32 (0.26). In contrast, aclacinomycin A and carminomycin were mainly (78% and 74%) and marcellomycin almost exclusively (95%) concentrated in the nucleus. When the total amounts of drug incorporated per cell were compared, the highest values were measured for aclacinomycin A and the lowest for AD 32 both in the sensitive and the resistant tumor. Additional determinations of the 50% inhibitory concentrations for thymidine uptake showed similar differences between these anthracyclines which were not related to the potency of the drugs in vivo. It is concluded that apart from nuclear incorporation and inhibition of DNA synthesis other factors may be decisive for anthracycline-induced cytotoxicity.

Characteristics and effect of antiinflammatory drugs on adriamycin-induced inflammation in the mouse paw

A subplantar injection of 5--100 micrograms adriamycin in the mouse hind paw produced a biphasic inflammatory response. The first phase peaked at 2 h while the second, more severe phase peaked at four to five days. The magnitude of inflammation was dose related. Administration of [EH]adriamycin revealed that 78% of the drug was lost from the paw within one day. The loss of the remaining drug followed a biphasic decay curve. The first-phase half-life was 1.2 days, and the second-phase half-life was 16.0 days. Vascular permeability, as measured by the leakage of intravenously administered [125I]albumin, was increased between day 4 and day 8. Pathologically, the paw had mild edema and hemorrhage by 4 h after adriamycin injection. The most severe pathological response was seen at 5 days with diffuse inflammation characterized by edema of the dermis, cellular debris, and mononuclear inflammatory cells. By 10 days the inflammatory response was still present but the edema was milder. The antihistamine diphenhydramine, an H1-blocker, inhibited the first phase of inflammation at the highest dose tested but had no effect on the second phase of inflammation. The antihistamine metiamide, an H2-blocker; the antiserotonin drug, p-chlorophenylalanine; and the antiinflammatory drugs, aspirin, hydrocortisone, and ibuprofen failed to antagonize adriamycin-induced inflammation at 2 h or 5 days after adriamycin injection. Indomethacin reduced the inflammation after 5 days but only at toxic dose levels.

Evidence of a specific complex between adriamycin and negatively-charged phospholipids

Membrane-model systems (monolayers, small unilamellar vesicles) were used to study the interaction between adriamycin (ADM) and phospholipids. Adsorption of 3H-labeled adriamycin on different phospholipid monolayers demonstrated the specificity of adriamycin for negatively-charged phospholipids (cardiolipin, phosphatidylserine, phosphatidic acid). The stoichiometry has been found to be approx. 2 mol (1.8) adriamycin per mol cardiolipin and approx. 1 mol (0.75) adriamycin per mol phosphatidylserine and phosphatidic acid. No adsorption was detected with neutral lipids. Surface-potential measurements confirm the formation of a complex stabilized by electrostatic interactions without penetration of the drug into the lipid lipophilic phase. Some adriamycin derivatives were used to discriminate between the ionized hydrophilic and hydrophobic contributions in the complex formation. The absorption spectrum of adriamycin in the presence of cardiolipin resembles the behavior of the ADM-DNA complex. Moreover, the association constants of the two complexes are very similar (cardiolipin-ADM, 1.6 . 10(6) . M-1; ADM-DNA, 2.4 . 10(6) . M-1). To explain the high affinity of cardiolipin for adriamycin, we proposed that two essential interactions are responsible for the complex stabilization: an electrostatic interaction between the protonated amino groups of the sugar residues and the ionized phosphate residues, and an interaction between adjacent anthraquinone chromophores. These data strongly suggest competitive behavior between a membrane site and the target. Consequently, it must be assumed that the lipidic components of the cell membrane structure may be an important determinant in the behavior of adriamycin. This observation should be kept in mind in the building of new derivatives.

The interaction of adriamycin with small unilamellar vesicle liposomes. A fluorescence study

The interaction of the antineoplastic agent adriamycin with sonicated liposomes composed of phosphatidylcholine alone and with small amounts (1-6%) of cardiolipin has been studied by fluorescence techniques. Equilibrium binding data show that the presence of cardiolipin increases the amount of drug bound to liposomes when the bilayer is below its phase transition temperature and when the ionic strength is relatively low (0.01 M). At higher ionic strength (0.15 M) and above the Tm (i.e. conditions which are closer to the physiological state) the binding of the drug to the two liposome types is nearly the same. Thus the differences in the interactions of adriamycin with cardiolipin-containing membranes, as opposed to those composed of phosphatidylcholine alone, are not due simply to increased binding but rather to an altered membrane structure when this lipid is present. Quenching of adriamycin fluorescence by iodide shows that bound drug is partially, but not completely, buried in the liposomal membrane. Both in the presence and absence of cardiolipin the bulk of the adriamycin is more accessible to the quencher below the Tm than above it; that is, a solid membrane tends to exclude the drug from deep penetration. Above the Tm, the presence of cardiolipin alters the nature of liposome-adriamycin interaction. Here the fluorescence quenching data suggest that the presence of small amounts of cardiolipin (3%) in a phosphatidylcholine matrix creates two types of binding environments for drug, one relatively exposed and the other more deeply buried in the membrane. The temperature dependence of the adriamycin fluorescence and the liposome light scattering reveal that cardiolipin alters the thermal properties of the bilayer as well as its interaction with adriamycin. At low ionic strength lateral phase separations may occur with both pure phosphatidylcholine and when 3% cardiolipin is present; under these conditions the bound adriamycin exists in two kinds of environment. It is notable that only adriamycin fluorescence reveals this phenomenon; thebulk property of liposome light scattering reports only on the overall membrane phase change. These data suggest that under certain conditions the drug binding sites in the membranes are decoupled from the bulk of the lipid bilayer.

Electrostatic complexes of mitomycin C with nucleic acids and polyanions

Reductively activated mitomycin C exhibits strong, non-covalent electrostatic binding to polyanions such as polyvinylsulfate and polyphosphate. The protonated C-2 amino group generated by the reduction is most likely responsible for this type of interaction. At moderate drug and salt concentrations only covalent binding to nucleic acids is observable. This is shown to be guanine-specific in DNA for the first time, as well as in synthetic polyribo- and polydeoxyribonucleotides at 10--20 times higher binding levels than previously tested. At higher mitomycin C concentration, however, strong non-covalent electrostatic binding to nucleic acids also occurs, resulting in a binding ratio up to 1 mol drug bound per mol mononucleotide, although this non-specific binding is relatively inhibited compared to polyvinylsulfate. Salts also have an inhibitory effect on the non-specific binding to nucleic acids. A series of mitomycin derivatives were compared for their binding and cross-linking abilities using DNA as substrate, with the following results: (a) the presence of a basic nitrogen . funtion at C-2 promotes binding, both covalent and electrostatic, presumably by kinetically facilitating the approach between positively charged nitrogen and DNA. (b) The aziridine ring is the major covalent binding site, indispensable for crosslinking and determines the guanine-specificity of the binding.

Adriamycin stimulates canine kidney (MDCK) cells to deacylate cellular lipids and to produce prostaglandins

Dog kidney (MDCK) cells treated with adriamycin (0.5 micrograms/ml) for 1 hr, produced from 2 to 7 times more prostaglandins E2 and F2alpha when measured in culture media 24, 48 and 72 hrs after the treatment. Indomethacin (ID50 less than 2 x 10(-8) M) and cycloheximide (0.5 micrograms/ml) inhibited this adriamycin-stimulated prostaglandin production. The aglycone of adriamycin (0.5 to 5.0 micrograms/ml) had little stimulating effect. Treatment of [3H]arachidonic acid-labeled MDCK cells with adriamycin (0.5 micrograms/ml) for 1 hr also stimulated deacylation of cellular lipids during subsequent incubation. Altered morphology of MDCK cells resulted from such treatment with adriamycin; indomethacin did not inhibit this change, but cycloheximide did.