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M R Mattern

Publications and source records attributed to M R Mattern.

At least 55 records · Page 3Linked to original sources
PubMed1987

Characterization of a subline of P388 leukemia resistant to amsacrine: evidence of altered topoisomerase II function.

Sensitive (P388/S) and amsacrine-resistant (P388/amsacrine) sublines of P388 leukemia were cloned in vitro and tested for differential chemosensitivity against a panel of drugs. P388/amsacrine, resistant both in vivo and in vitro to amsacrine, was cross-resistant to other putative topoisomerase II inhibitors including teniposide, etoposide, bisantrene, and doxorubicin. P388/amsacrine, was however, as sensitive as cloned P388/S to camptothecin, an inhibitor of topoisomerase I. The pattern of cross-resistance suggested that an alteration in topoisomerase II may be involved in the resistance of P388/amsacrine to these drugs. No differences in the uptake of amsacrine were detected between the two sublines. Cross-resistance to vinblastine was evident in P388/amsacrine; however resistance to vinblastine was associated with alterations in uptake or efflux of the drug. The number of protein-concealed single-strand breaks induced in whole cells by amsacrine, teniposide, bisantrene, and camptothecin was measured. Diminished numbers of strand breaks in the resistant subline were consistent with decreases in DNA-protein crosslinks. In the absence of drug treatment, resistant cells sustained approximately one-half as many single-strand breaks and DNA-protein crosslinks as the sensitive cells during preparation of nuclei. As measured by the P4 phage DNA unknotting assay, 0.35 M NaCl nuclear extracts from P388/S contained approximately 2.3-fold more topoisomerase II catalytic activity than did extracts from P388/amsacrine. The amount of protein that immunoreacted with a specific antibody to calf thymus topoisomerase II was also decreased in the resistant cells. These data suggest that alterations in topoisomerase II which lead to differential drug sensitivities are partially responsible for the resistance of P388/amsacrine to a specific group of drugs.

Amsacrine↗
PubMed1986

Reduced formation of protein-associated DNA strand breaks in Chinese hamster cells resistant to topoisomerase II inhibitors.

DNA intercalating drugs and the epipodophyllotoxins etoposide and teniposide interfere with the action of mammalian DNA topoisomerase II by trapping an intermediate complex of the enzyme covalently linked to the 5'-termini of DNA breaks. This effect can be observed in intact cells by alkaline elution measurement of protein-associated DNA strand breaks. To assess the cytotoxic role of this effect, we have studied a subline of DC3F Chinese hamster lung cells selected for resistance to the intercalating agent 9-hydroxyellipticine. This subline (DC3F/9-OHE) was cross-resistant to other intercalators as well as to etoposide. Resistance to Adriamycin was associated with reduced uptake. However, resistance to 4'-(9-acridinylamino)methanesulfon-m-aniside and 2-methyl-9-hydroxyellipticinium was observed in the absence of changes in drug uptake, suggesting a second mode of resistance. DC3F/9-OHE cells formed fewer protein-associated DNA strand breaks in response to 4'-(9-acridinylamino)methanesulfon-m-aniside, 2-methyl-9-hydroxyellipticinium, or etoposide than did the sensitive parental cells. The same was true for isolated nuclei from these cells, which is consistent with a mode of resistance unrelated to drug uptake through the plasma membrane. These data suggest that resistance to DNA topoisomerase II inhibitors exhibited by DC3F/9-OHE cells is due in part to a modification of topoisomerase II activity.

Alkaloids↗
PubMed1986

Effects of the bifunctional antitumor intercalator ditercalinium on DNA in mouse leukemia L1210 cells and DNA topoisomerase II.

Ditercalinium, a 7H-pyridocarbazole dimer (bisintercalator) belongs to a new class of antineoplastic intercalating agents. To investigate its mechanism of cytotoxicity, the effects of ditercalinium on DNA were assessed using normal (L1210) and drug-resistant (L1210/PyDi1) mouse leukemia cells. Alkaline elution assays demonstrated that ditercalinium produced no DNA strand breaks, DNA-protein cross-links, or DNA-DNA cross-links, eliminating these effects as cytotoxic lesions. This result sets ditercalinium apart from other intercalating agents with respect to its interaction with DNA. Nucleoids (histone-depleted chromatin) from ditercalinium-treated L1210 cells were considerably more compact than those from untreated cells, as determined by sedimentation in neutral sucrose gradients. In contrast, nucleoids from ditercalinium-treated L1210/PyDi1 (resistant) cells were similar in compactness to those from control cells. Thus, ditercalinium altered chromatin structure in vivo. The effect of the bisintercalator on purified DNA topoisomerase II, an intracellular target of monointercalators, was measured in vitro. Ditercalinium (5 X 10(-7) M) completely inhibited both the formation of covalent complexes between this enzyme and simian virus 40 DNA and the enzyme-induced DNA cleavage. In addition, ditercalinium induced DNA catenation in the presence of topoisomerase II and adenosine triphosphate. Thus, the cytotoxicity of ditercalinium may derive from a mechanism that, although involving topoisomerase II, is manifested by condensation of DNA rather than by the induction of protein-associated DNA strand breaks.

Amsacrine↗
PubMed1986

Cellular pharmacology of mu-[1,2-bis(diphenylphosphino)ethane]bis[(1-thio-beta-D-gluco pyranosato-S)gold(I)]: a novel antitumor agent.

SK&F 102912 (mu-[1,2-bis(diphenylphosphino)ethane]bis[(1-thio-beta-D- glucopyranosato-S)gold(I)], [(Autg)2(dppe)]) has shown reproducible and significant activity in transplantable murine tumor models and represents a structurally unique class of antineoplastic agents. A number of in vitro studies were performed to elucidate the cellular pharmacology of this gold-containing complex. [(Autg)2(dppe)] is a potent cytotoxic agent in vitro as demonstrated by its ability to inhibit the clonogenic capacity of a variety of tumor cell lines following a brief exposure to the drug. Cell-cycle analysis using HL-60 cells showed that low concentrations (2 microM) of [(Autg)2(dppe)] induced an S-phase block and higher concentrations induced a secondary block at the G1/S boundary. [(Autg)2(dppe)] had several effects on DNA metabolism and structure including preferential inhibition in cells of DNA synthesis (relative to RNA and protein synthesis) and the production of DNA single- and double-strand breaks as measured by alkaline elution. The cytoxic mechanism of this gold complex appears to be distinct from that of the monophosphine-gold complex auranofin.

Antineoplastic Agents↗
PubMed1986

In vivo antitumor activity and in vitro cytotoxic properties of bis[1,2-bis(diphenylphosphino)ethane]gold(I) chloride.

We have previously reported the cytotoxicity and antitumor activity of bis(diphenylphosphino)ethane (DPPE) and a variety of its transition metal complexes. During studies of the chemistry of a gold complex of this group [(AuCl)2(DPPE)], it was observed that this complex readily underwent ring closure on reaction with DPPE to form the tetrahedral complex [Au(DPPE)2]+. Various counterion forms (e.g., Cl-) of this cation were isolated and were found to exhibit a remarkably high stability in solution. Evaluation of [Au(DPPE)2]Cl in mice bearing i.p. P388 leukemia demonstrated that the compound produced an average of 87% increase in life span at its maximally tolerated dose (2-3 mumol/kg/day for 5 days). Activity was also seen in i.p. M5076 reticulum cell sarcoma (60% increase in life span) and s.c. mammary adenocarcinoma 16/c. Modest activity was evident in i.p. B16 melanoma and L1210 leukemia. A subline of P388 leukemia resistant to cisplatin was not cross-resistant to [Au(DPPE)2]Cl. In addition, combination therapy of [Au(DPPE)2]Cl and cisplatin against i.p. P388 demonstrated an advantage over single-agent therapy. In vitro studies of [Au(DPPE)2]Cl showed that the compound: is cytotoxic to tumor cell lines; is only minimally inhibited in its cytotoxic activity by the presence of serum; produces DNA protein cross-links and DNA strand breaks in cells; and inhibits macromolecular synthesis with a preferential inhibitory effect on protein synthesis relative to DNA and RNA synthesis. 31P nuclear magnetic resonance spectroscopy indicated that the compound is stable in the presence of serum proteins, thiols, or disulfides and that it reacts with Cu(II) resulting in the formation of a Cu(I)DPPE complex. The results of these in vivo and in vitro experiments suggest that the contrasting pharmacological profile of [Au(DPPE)2]Cl with respect to other gold(I) phosphine complexes may be related to both the kinetic stability of the complex and its stability in the presence of thiols.

Animals↗
PubMed1984

Absence of swiveling at sites of intercalator-induced protein-associated deoxyribonucleic acid strand breaks in mammalian cell nucleoids.

The sedimentation of DNA-nuclear protein complexes in 1.9 M salt-neutral sucrose gradients (nucleoid sedimentation) was used to examine the effects of the DNA intercalator 4'-(9-acridinylamino)methanesulfon-m-anisidide (m-AMSA) on mouse leukemia cell DNA. Mild detergent cell lysis and neutral pH make nucleoid sedimentation an extremely gentle, but sensitive, method to detect DNA scission. DNA breaks reduce the compaction of nucleoids and slow their sedimentation. Nucleoids from m-AMSA-treated cells sedimented as did those from untreated cells, indicating no detectable m-AMSA-dependent alterations in compaction despite an apparent underlying DNA break frequency of approximately 3 per 10(6) nucleotides, as measured by alkaline elution with proteinase. Mild proteinase digestion of cell lysates prior to nucleoid sedimentation unmasked some, but not all, of the underlying breaks. The frequency of DNA-protein cross-links in nucleoids from cells treated with m-AMSA was comparable to the single-strand break frequency produced by m-AMSA in whole cells. These results indicate that m-AMSA-induced DNA-protein cross-links conceal DNA breaks so as to prevent swiveling around the breaks within the nucleoids. This unique sort of DNA scission is consistent with the involvement of topoisomerases in the DNA breaks elicited by intercalators in mammalian cells.

Aminoacridines↗
PubMed1984

Changes in deoxyribonucleic acid linking number due to treatment of mammalian cells with the intercalating agent 4'-(9-acridinylamino)methanesulfon-m-anisidide.

Treatment of mammalian cells with DNA intercalating agents produces protein-associated DNA strand breaks. These breaks have been proposed to represent the action of a topoisomerase, which would alter the DNA linking number. Changes in DNA linking number in cells treated with the intercalating agent 4'-(9-acridinylamino)methanesulfon-m-anisidide (m-AMSA) were studied by ethidium titration of nucleoid sedimentation. m-AMSA treatment was found to produce an increase in DNA linking number. Previously, we had proposed that intercalator-induced protein-associated DNA breaks act to reduce DNA torsional strain that results from the intercalator-induced decrease in DNA twist. In such a model, linking number would be expected to decrease. The finding that the DNA linking number increased following m-AMSA treatment suggests that intercalators may block enzymes that normally decrease linking number. Such enzymes would have DNA gyrase like properties. Consistent with this possibility, a DNA gyrase inhibitor, novobiocin, inhibited the restoration of normal linking number and, to a lesser degree, the reversal of protein-associated strand breaks after removal of intercalator.

Aminoacridines↗
PubMed1984

Relationship of DNA repair phenotypes of human fibroblast and tumor strains to killing by N-methyl-N'-nitro-N-nitrosoguanidine.

Two DNA repair assays were used to group human cells. (a) The first assay, survival of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-treated adenovirus infecting cellular monolayers, was previously used to define the Mer phenotype of the strain. Strains that supported the growth of MNNG-treated viruses as well as did human fibroblasts were "Mer+"; those that gave rise to clearly less virus survival were "Mer-." (b) The second assay, data from which are presented in this paper, was that of post-MNNG colony-forming ability, and defined the Rem phenotype of the strain. Strains having post-MNNG colony-forming ability like that of human fibroblasts were "Rem+"; more sensitive strains were "Rem-". In all, 22 human cell strains were analyzed for their post-MNNG colony-forming ability. The most resistant strains (eight Mer+ Rem+ strains) had an average inactivation slope of 0.32 "lethal hit"/microM and were those fully able to repair O6-methylguanine (O6mGua) produced in their DNA by a 5 microM dose of MNNG. The most sensitive strains (9 Mer- Rem- strains) had an average inactivation slope of 7.0 "lethal hits"/microM, and were strains that failed to repair O6mGua. Five strains of intermediate sensitivity (Mer+ Rem-) had an average inactivation slope of 0.93 "lethal hit"/microM and were able to repair some labeled O6mGua produced by a 5 microM dose of labeled MNNG, but they repaired significantly less labeled O6mGua if pretreated with unlabeled MNNG. Representative strains from each group were treated with MNNG and assayed for ability: (a) to perform DNA repair synthesis (and DNA repair replication); (b) to support the growth of MNNG-treated adenoviruses; and (c) to restore control levels of tertiary structure to their DNA as assayed by nucleoid sedimentation. The results support the hypothesis that a lesion (both produced by agents that produce O6mGua and repaired by cell strains that repair O6mGua, but not by those that do not) is a lesion lethal to Mer- Rem- strains. This lesion may also initiate induction of excess DNA repair synthesis, the relaxed conformation of nucleoids, the reduced ability to repair MNNG-treated adenovirus, and sister chromatid exchanges as well.

Adenoviridae↗
PubMed1984

Sensitivity of human cell strains having different abilities to repair O6-methylguanine in DNA to inactivation by alkylating agents including chloroethylnitrosoureas.

In order to investigate the mechanisms of cellular damage by alkylating agents, human fibroblasts and tumor cell strains having different sensitivities to killing by N-methyl-N'-nitro-N-nitrosoguanidine [and different abilities to repair O6-methylguanine ( O6mGua ) in their DNA] were treated with other alkylating agents. Methyl methanesulfonate, 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), 1-(2-hydroxyethyl)-3-(2-chloroethyl)-3-nitrosourea, and N-ethyl-N'-nitro-N-nitrosoguanidine gave rise to sensitivity differences, but the differences were less than those observed with N-methyl-N'-nitro-N-nitrosoguanidine. After treatment with UV light, the strains showed similar survival. The data show that the DNA repair mechanism(s) responsible for the differential survival of the strains after N-methyl-N'-nitro-N-nitrosoguanidine treatment probably play(s) a role in repairing DNA damage produced by methyl methanesulfonate, N-ethyl-N'-nitro-N-nitrosoguanidine, BCNU, and 1-(2-hydroxyethyl)-3-(2-chloroethyl)-3-nitrosourea but not that produced by UV. Furthermore, the results support the idea that a breakdown product of BCNU, that does not cause damage repairable by O6mGua repair mechanisms, contributes to the lethal effects due to BCNU-produced DNA-damage that is repairable by O6mGua repair mechanisms. The survival data, along with nucleoid sedimentation and adenovirus host-cell reactivation data, are consistent with the hypothesis that the lesion(s) lethal to tumor cells defective in O6mGua DNA repair are lesions in which DNA oxygen atoms are alkylated.

Alkylating Agents↗
PubMed1983

The reconstitution of higher-order DNA structure after X-irradiation of mammalian cells.

X-ray-induced DNA repair in mouse leukemia (L1210) cells was studied by alkaline elution, which measures the amount of DNA strand breakage, coupled with nucleoid sedimentation, which measures DNA compactness. Two phases of X-ray repair were detected. An initial phase was rapid (t1/2 less than 10 min). During this phase most strand breaks were rejoined and some compaction occurred. After a lag of 1-2 hours, a second phase occurred which exhibited very little or no additional ligation but further compaction of the nucleoid DNA. Both the DNA strand rejoining and initial nucleoid compaction of the first phase were inhibited by 3-ABA2 but not by novobiocin, and the second phase was inhibited by novobiocin but not by 3-ABA. The two phases of reconstitution of nucleoid compactness following X-irradiation are thus distinguishable by their time of occurrence and by their sensitivity to inhibitors of DNA-related enzymes. A coordinated process of ligation followed by compaction may be intrinsic to DNA repair following X-irradiation.

Animals↗
PubMed1983

Ataxia-telangiectasia cells are not uniformly deficient in poly(ADP-ribose) synthesis following X-irradiation.

The synthesis of poly(adenosine diphosphoribose) [poly(ADR-R)] follows the DNA strand breakage produced by a number of physical and chemical agents, including X-radiation, and may be important for repair of several types of DNA damage. The reduction or abolition of its synthesis following X-irradiation might explain the enhanced sensitivity of ataxia-telangiectasia (A-T) cells to X-ray. We have examined 8 lines of human fibroblasts (including 4 A-T lines) for stimulation of the synthesis of poly(ADP-R) by X-irradiation. Similar amounts of X-ray-stimulated synthesis of poly(ADP-R) were detected in 4 lines of A-T fibroblasts, and in fibroblasts from a xeroderma pigmentosum (XP) patient, a Fanconi's anemia (FA) patient and 2 normal patients. 6 lines of human lymphoblastoid lines were also examined for X-ray-stimulated poly(ADP-R) synthesis. 4 A-T lines displayed an unusually high synthesis of poly(ADP-R) in unirradiated cells compared with 2 normal lines. Despite this complication, some but not all, of the A-T lymphoblastoid lines did synthesize poly(ADP-R) following X-irradiation similarly to the normal lines. Thus, deficient poly(ADP-R) synthesis following X-irradiation is not likely to explain the enhanced sensitivity of all A-T cells to this DNA-breaking agent.

Ataxia Telangiectasia↗
PubMed1983

Effects of dimethyl sulfoxide and thiourea upon intercalator-induced DNA single-strand breaks in mouse leukemia (L1210) cells.

The free radical scavengers, dimethyl sulfoxide (Me2SO) and thiourea, were used to assess the role of free radicals in the production of intercalator-induced DNA breaks and cytotoxicity in mouse leukemia L1210 cells. Both agents decreased X-ray break production, and this decrease was comparable in magnitude to the degree of inhibition of X-ray-induced cell killing. By contrast, Me2SO increased the DNA breaks produced by the intercalators, Adriamycin, 5-iminodaunorubicin, and 4'-(9-acridinylamino)methanesulfon-m-anisidide. This was not due to an enhancement of Adriamycin or 4'-(9-acridinylamino)methanesulfon-m-anisidide uptake by Me2SO. Strand break production by intercalators was decreased by thiourea. This was not due to an inactivation of the intercalators or to a decrease of Adriamycin or 4'-(9-acridinylamino)methanesulfon-m-anisidide uptake by thiourea. Experiments using nucleoid sedimentation to assess the DNA linking number and domain size from cells treated with Me2SO and thiourea indicated that these chemicals alter chromatin structure in a fashion which may account for effects on intercalator-induced DNA scission. The alterations in intercalator-induced DNA scission were not accompanied by corresponding alterations in cytotoxicity, thus dissociating intercalator-induced strand break production from lethality and the mechanism of X-ray break production.

Animals↗
PubMed1981

Dependence of mammalian DNA synthesis on DNA supercoiling. III. Characterization of the inhibition of replicative and repair-type DNA synthesis by novobiocin and nalidixic acid.

Novobiocin and nalidixic acid, inhibitors of the bacterial enzyme DNA gyrase, inhibit DNA, RNA and protein synthesis in several human and rodent cell lines. The sensitivity of DNA synthesis (both replicative and repair) to inhibition by novobiocin and nalidixic acid is greater than that of protein synthesis. Novobiocin inhibits RNA synthesis about half as effectively as it does DNA synthesis, whereas nalidixic acid inhibits both equally well. Replicative DNA synthesis, as measured by incorporation of [3H]thymidine, is blocked by novobiocin in a number of cell strains; the inhibition is reversible with respect to both DNA synthesis and cell killing, and continues for as long as 20--30 h if the cells are kept in novobiocin-containing growth medium. Both novobiocin and nalidixic acid inhibit repair DNA synthesis (measured by BND-cellulose chromatography) induced by ultraviolet light or N-methyl-N'-nitro-N-nitrosoguanidine (but not that induced by methyl methanesulfonate) at lower concentration (as low as 5 micrograms/ml) than those required to inhibit replicative DNA synthesis (50 micrograms/ml or greater). Neither novobiocin nor nalidixic acid alone induces DNA repair synthesis. Incubation of ultraviolet-irradiated cells with 10--100 micrograms/ml novobiocin results in little, if any, further reduction of colony-forming ability (beyond that caused by the ultraviolet irradiation). Novobiocin at sufficiently low concentrations (200 micrograms/ml) apparently generates a quiescent state (in terms of cellular DNA metabolism) from which recovery is possible. Under more drastic conditions of time in contact with cells and concentration, however, novobiocin itself induces mammalian cell killing.

Cell Line↗
PubMed1981

Human tumor strains defective in the repair of alkylated DNA fail to regenerate rapidly-sedimenting nucleoids after N-methyl-N'-nitro-N-nitrosoguanidine treatment.

Upon treatment with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), human cell strains characterized as either proficient or defective both in repair of alkylation-damaged DNA and in supporting the growth of MNNG-treated adenovirus (Mer+ and Mer- phenotypes (1,2)), all underwent a rapid relaxation of nucleoid DNA, as judged by sedimentation in 15--30% neutral sucrose gradients. DNA in the repair-proficient Mer+ strains (normal fibroblast and tumor) was restored to the rapidly-sedimenting (control) form within 2--4 h after the removal of MNNG. In contrast, nucleoid DNA of the repair-deficient Mer- tumor strains remained slowly-sedimenting even after 48 h of incubation. The delayed recovery of Mer- nucleoid DNA was specific for MNNG damage, since after u.v. irradiation, to which Mer+ and Mer- strains are equally resistant (2), all cell lines tested underwent DNA relaxation within the first hour after irradiation (3 J/m2) and regenerated rapidly-sedimenting nucleoids within 4--6 h of repair incubation.

Cell Line↗