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M M Wick

Publications and source records attributed to M M Wick.

At least 37 records · Page 2Linked to original sources
PubMed1989

A comparison of dihydrofolate reductase activity in intact leukemia cells and squamous cell carcinoma.

This report examines the intracellular activity of dihydrofolate reductase using an in situ assay designed to measure enzymatic activity in intact cells. The rate of uptake of folic acid exceeded the rate of in situ dihydrofolate reductase activity suggesting that the reduction of folate to dihydrofolate, rather than transport, was the rate limiting step. In situ dihydrofolate reductase activity varied linearly with cell number. A comparison of the in situ activity revealed that a squamous cell carcinoma selected for methotrexate (MTX) resistant (SCC-15R) had 100 times greater dihydrofolate reductase (DHFR) activity than L1210 leukemia. In agreement with this finding, the in situ DHFR activity in SCC-15R cells was 50-fold less sensitive to the inhibitory effects of MTX than the L1210 in situ DHFR activity (IC50 = 1.1 x 10(-5) M and 2.4 x 10.7(-7) M respectively). The inhibition of in situ dihydrofolate reductase activity by MTX was found to correlate with the inhibition of growth, DNA synthesis (CdR incorporation) and in situ thymidylate synthase activity.

Animals↗
PubMed1987

Antitumor effects of biologic reducing agents related to 3,4-dihydroxybenzylamine: dihydroxybenzaldehyde, dihydroxybenzaldoxime, and dihydroxybenzonitrile.

This report describes a structure-activity analysis of isomers of three classes of dihydroxybenzene derivatives, including dihydroxybenzaldoxime, dihydroxybenzaldehyde, and dihydroxybenzonitrile. These derivatives were examined for their effect on ribonucleotide reductase activity, macromolecular synthesis, cell growth, and in vivo antitumor activity against the L1210 murine leukemia. One of the compounds studied exhibited significant antitumor activity against the growth of L1210 leukemia cells. A comparison of the various analogues revealed a possible correlation for 3,4-dihydroxybenzaldoxime between its potent inhibitory effect toward ribonucleotide reductase activity (IC50 = 38 microM) and its superior L1210 antitumor activity [percent increased life span (% ILS) = 100].

Animals↗
PubMed1987

Comparison of the inhibitory effects of hydroxyurea, 5-fluorodeoxyuridine, 3,4-dihydroxybenzylamine, and methotrexate on human squamous cell carcinoma.

A cell line (SCC-25) derived from a human squamous cell carcinoma was found to have a higher level of in situ thymidylate synthase activity when compared to a faster-growing cell line, L1210 leukemia, and approximately 5 times the level of activity of a cell line with the same growth rate, S91-A melanoma. These results led to an examination of the effects of both direct and indirect inhibitors of this enzyme using intact SCC-25 cells. It was found that drugs that have an indirect effect on this enzyme--methotrexate (MTX), hydroxyurea (HU), and 3,4-dihydroxybenzylamine (3,4-DHBA)--acted as noncompetitive inhibitors and the inhibition of thymidylate synthase by these drugs did not result in the accumulation of its substrate, dUMP. This suggested that these drugs are also inhibiting steps leading to the formation of dUMP by a mechanism that is coordinated with the inhibition of thymidylate synthase. 5-Fluorodeoxyuridine (FUDR), a competitive inhibitor of thymidylate synthase, did cause an increase in the dUMP pool size indicating that this drug did not affect the synthesis of this substrate. There was a good correlation for the inhibition of growth, DNA synthesis, and thymidylate synthase with HU, 3,4-DHBA, and FUDR. However, the results suggested fundamentally different mechanistic reasons for the close relationship among these three inhibitory effects. Finally the inhibition of growth by MTX did not appear to correlate with the inhibition of DNA synthesis. The implication of these results for the therapy of epidermally derived proliferative disorders, especially with combinations such as MTX and 5-FU, is discussed.

Animals↗
PubMed1987

Inhibition of transformation by levodopa-carbidopa in lymphocytes derived from patients with melanoma.

Levodopa-carbidopa has been widely used in the treatment of Parkinson's disease. We are currently investigating the effectiveness of this combination for the treatment of patients with advanced malignant melanoma. As part of this study, we have examined the effects of this combination on the phytohemagglutinin-induced transformation of human lymphocytes, isolated from patients with malignant melanoma prior to undergoing treatment. Levodopa, as well as carbidopa and 3 additional levodopa synthetic analogs, inhibited the transformation of phytohemagglutinin-stimulated DNA synthesis at pharmacologically attainable levels. These results confirm our earlier preclinical observations suggesting that catechols have profound intracellular metabolic effects in a variety of cells other than melanoma cells. It is possible that some of the effects of catechols in other diseases might also be mediated by similar intracellular metabolic effects, and effects on human melanoma might be mediated in part through effects on the immune system. We are currently awaiting introduction of synthetic catechols, including 3,4-dihydroxybenzylamine (NSC 263475), to extend these observations to our clinical studies in patients with advanced metastatic disease.

Carbidopa↗
PubMed1987

Inhibition of thymidylate synthase in intact L1210 cells by ara-C, daunomycin, hydroxyurea and 3,4-dihydroxybenzylamine.

The use of an in situ assay for thymidylate synthase has shown that a variety of clinically important drugs, including arabinofuranosylcytosine, hydroxyurea, and daunomycin, inhibit thymidylate synthase in intact cells. In contrast to the inhibition observed with 5-fluorodeoxyuridine, inhibition occurs by an indirect mechanism, is delayed in onset, and is incomplete. Inhibition occurred at concentrations that corresponded to those that inhibit DNA synthesis, suggesting that this phenomenon might contribute to the biological action of these agents. Since the inhibition of thymidylate synthase by this indirect mechanism appears to be a general property of drugs that inhibit DNA synthesis, our findings may have important implications for the mechanism of killing of tumor cells, as well as the rationale for combination regimens.

Animals↗
PubMed1986

Methotrexate analogues-27. Dual inhibition of dihydrofolate reductase and folylpolyglutamate synthetase by methotrexate and aminopterin analogues with a gamma-phosphonate group in the side chain.

gamma-Phosphonate analogues of methotrexate (MTX) and aminopterin (AMT) were synthesized from 4-amino-4-deoxy-N10-methylpteroic acid and 4-amino-4-deoxy-N10-formylpteroic acid, respectively, by reaction with methyl D,L-2-amino-4-phosphonobutyrate followed by gentle alkaline hydrolysis. The products were compared with the corresponding D,L-homocysteic acid derivatives as inhibitors of dihydrofolate reductase and folylpolyglutamate synthetase, and as inhibitors of cell growth in culture. The gamma-phosphonates were somewhat less active than either the gamma-sulfonates or the parent drugs as inhibitors of murine dihydrofolate reductase. The MTX gamma-sulfonate and gamma-phosphonate analogues were equally inhibitory toward mouse liver folylpolyglutamate synthetase (Ki = 190 microM), but in the AMT series the gamma-phosphonate (Ki = 8.4 microM) was more potent than the gamma-sulfonate (Ki = 45 microM). The AMT analogues were consistently more inhibitory than the MTX analogues against cultured L1210 murine leukemia cells, but neither the gamma-phosphonates nor the gamma-sulfonates were as potent as their respective parent drugs. The gamma-phosphonate analogue of MTX was three times more potent than MTX against the MTX-resistant mutant line L1210/R81, but the AMT gamma-phosphonate was less potent than AMT; however, these differences were small in comparison with the level of resistance to all these compounds in the L1210/R81 line. The results suggest that N10-methyl and N10-unsubstituted compounds altered at the gamma-position do not necessarily follow identical structure-activity patterns in every test system.

Aminopterin↗
PubMed1986

Sequential inhibitory effects of antitumor agents related to levodopa and dopamine upon DNA synthetic enzymes.

Novel antitumor agents related to levodopa and dopamine exhibit a selective and rapid inhibition of DNA synthesis as measured by thymidine incorporation. Our investigations have attempted to determine the biochemical basis of the selective inhibition of tumor cells and in this present study we examined the effects of these agents on thymidylate synthase. The dihydroxybenzene derivatives were found to inhibit thymidylate synthase in situ at concentrations ranging between 100 and 800 microM. The quinols did not inhibit partially purified thymidylate synthase, although the oxidized quinones did cause inhibition at concentrations between 10 and 100 microM. Time course experiments suggested that the inhibition of thymidylate synthase in situ by the dihydroxybenzene derivatives occurs after the inhibition of thymidine incorporation, indicating that an earlier event was critical to the inhibition of DNA synthesis. With the use of a novel in situ assay which measured the release of [3H]water from [5-3H] uridine in intact cells, we were able to show that one of the earliest biochemical events is the inhibition of ribonucleotide reductase and that the inhibition of thymidylate synthase, which is delayed by approximately 30 min, was indirectly mediated possibly through effects on ribonucleotide reductase.

Animals↗
PubMed1986

Methotrexate analogues. 28. Synthesis and biological evaluation of new gamma-monoamides of aminopterin and methotrexate.

Lipophilic gamma-monoamide derivatives of aminopterin (AMT) were synthesized in high overall yield from 4-amino-4-deoxy-N10-formylpteroic acid and gamma-N-tert-alkyl-, gamma-N-aralkyl-, or gamma-N-arylamides of alpha-benzyl L-glutamate via a modification of the mixed carboxylic-carbonic anhydride coupling method. Coupling was also accomplished with p-nitrophenyl 4-amino-4-deoxy-N10-formylpteroate. Compounds obtained in this manner included the gamma-tert-butylamide, gamma-(1-adamantylamide), gamma-benzylamide, gamma-(3,4-dichlorobenzylamide), gamma-(2,6-dichlorobenzylamide), gamma-anilide, gamma-(3,4-methylenedioxyanilide), and gamma-(3,4-dihydroxanilide) derivatives of AMT. Also prepared, from 4-amino-4-deoxy-N10-methylpteroic acid via diethyl phosphorocyanidate coupling, was the gamma-(3,4-methylenedioxyanilide) of MTX. The methylenedioxyanilides were cleaved smoothly to dihydroxyanilides with boron tris(trifluoroacetate) in trifluoroacetic acid. All the gamma-monoamides were tested as inhibitors of purified dihydrofolate reductase (DHFR) from murine L1210 leukemia cells and as inhibitors of the growth of wild-type L1210 cells and a subline (L1210/R81) with high-level resistance to MTX and AMT based mainly on a defect in drug uptake via active transport. Several compounds were also tested against human leukemic lymphoblasts (CEM cells) and a resistant subline (CEM/MTX) whose resistance is likewise based on uptake. The IC50 of the gamma-monoamides against DHFR was 1.5- to 5-fold higher than that of the parent acids, but the IC50 against cultured cells varied over a much broader range, suggesting that uptake and/or metabolism rather than DHFR binding are principal determinants of in vitro growth inhibitory activity for these compounds. gamma-N-Aryl and gamma-N-aralkyl derivatives appeared to be more potent than gamma-N-tert-alkyl derivatives. Where comparison could be made, AMT gamma-monoamides were more potent than MTX gamma-monoamides. Several of the gamma-monoamides showed potency comparable to that of the parent acid against wild-type L1210 and CEM cells; all of them were more potent than MTX against the L1210/R81 subline; and some of the AMT gamma-monoamides were also more potent than the parent acid against resistant CEM/MTX cells. As a group, however, the gamma-monoamides were considerably more active against the murine cells than against the human cells, suggesting that the former may take up the amides better or may be able to metabolize them more efficiently than the parent acids. All the gamma-monoamides were tested in vivo against L1210 leukemia in mice.(ABSTRACT TRUNCATED AT 400 WORDS)

Amides↗
PubMed1986

Methotrexate analogues. 29. Effect of gamma-aminobutyric acid spacers between the pteroyl and glutamate moieties on enzyme binding and cell growth inhibition.

A series of "stretched" methotrexate (MTX) analogues containing up to five 4-aminobutyryl (Gab) spacers between the 4-amino-4-deoxy-N10-methylpteroyl (MeAPA) moiety and the glutamate (Glu) side chain was prepared. Interest in these compounds stemmed from their relationship to MTX gamma-polyglutamates, from which they differ only in lacking "internal" alpha-carboxyl groups. The ability of the MeAPA-Gabn-Glu derivatives to inhibit dihydrofolate reductase (DHFR) and thymidylate synthase (TS) in vitro and to inhibit the growth of tumor cells in culture was evaluated. The IC50 for DHFR inhibition increased progressively from 0.082 to 0.84 microM as the number of Gab spacers was varied from one to five. At the same time the introduction of Gab spacers was found to produce substantial TS inhibition (Ki 0.1-0.4 microM) similar to that reported for MTX polyglutamates. Despite the activity of the MeAPA-Gabn-Glu derivatives as combined inhibitors of TS and DHFR, there was a steep loss of cell growth inhibitory potency as the number of Gab spacers was increased. This most likely reflects low cell uptake and the fact that when n greater than 1 there is almost total abolition of substrate activity for folylpolyglutamate synthetase, which had previously been observed with n = 1.

Animals↗
PubMed1985

Inhibition of ribonucleotide reductase by antitumor agents related to levodopa and dopamine.

Using partially purified enzyme from L1210 cells, dihydroxybenzene derivatives related structurally to dopamine were shown to reversibly inactivate ribonucleotide reductase. A structure-activity analysis revealed that derivatives with side-chains, which contain a negatively-charged group, had significantly reduced inhibitory activity. The ability of these compounds to inhibit ribonucleotide reductase was dependent on the hydroxyl groups being in the ortho position and did not correlate with free radical inhibitory activity. A kinetic analysis by the method of Lineweaver-Burk indicated that the inhibition of ribonucleotide reductase by the derivative 3,4-dihydroxybenzylamine was competitive with the reducing substrate dithioerythritol. This analog, in combination with hydroxyurea, gave synergistic inhibition or ribonucleotide reductase, suggesting different sites of action. Using Tween 80-treated L1210 cells, it was found that these drugs had an immediate inhibitory effect on ribonucleotide reductase activity in intact, reversibly permeabilized cells. Furthermore, although these drugs had no immediate effect on DNA polymerase, in permeabilized L1210 cells (when the cells were preincubated with the dihydroxybenzene derivatives for 1 hr prior to permeabilization), there was significant inhibition of DNA polymerase activity. The two key enzymes for DNA synthesis appear to be sequentially inhibited by these analogs, with the reduced form (quinol) inhibiting ribonucleotide reductase and the oxidized form (quinone) inhibiting DNA polymerase.

Animals↗
PubMed1984

Inhibition of ribonucleotide reductase by naturally occurring quinols from spores of Agaricus bisporus.

gamma-L-glutaminyl-4-hydroxybenzene, a stable phenol found in high concentrations in the gill tissue of the common mushroom, Agaricus bisporus, was shown to be capable of selectively inhibiting DNA synthesis in L1210 leukemia cells. Studies with isolated enzymes and permeabilized L1210 cells revealed that this compound inhibits ribonucleotide reductase ( RNR ) but has no effect on DNA polymerase. The results indicated a good correlation between the inhibition of DNA synthesis and the ability of this compound to inhibit RNR . The concentration of glutaminyl-4-hydroxybenzene required to elicit these inhibitory effects has physiological relevance to the gill tissue during the prodromal period of sporulation.

Agaricales↗
PubMed1984

The relationship of the eye uptake of N-isopropyl-p-[123I]iodoamphetamine to melanin production.

Eye uptake has been a potential concern with N-isopropyl-p-[123I]iodoamphetamine (I-123 IMP) because it has been observed in certain animal species. We have investigated the cause of the eye uptake and its relationship to melanin synthesis. In a 1-yr-old cynomolgus monkey, high concentration of the tracer was seen in the eyes regardless of the type of anesthesia (pentobarbital or ketamine) or the oral administration of Lugol's solution. The eye uptake at 24 hr after injection of I-123 IMP was equally high in an 8-yr-old rhesus monkey. The ratio of radioactivity in the eye of black compared with white albino mice was 10:1 at 30 min, 18:1 at 2 hr and 36:1 at 24 hr after injection of I- 123 IMP. No eye uptake above soft-tissue background was seen in five patients at 2, 24, and 48 hr after injection. I-123 IMP is avidly incorporated into melanocytes actively producing melanin, but substantially less in melanocytes where production of melanin has ceased as in the human eye.

Amphetamines↗
PubMed1983

3,4-Dihydroxybenzylamine: an improved dopamine analog cytotoxic for melanoma cells in part through oxidation products inhibitory to dna polymerase.

The dopamine analog 3,4-dihydroxybenzylamine (3,4-DHBA), a novel antitumor agent, was shown to inhibit directly DNA polymerase in cells of the deeply pigmented murine melanoma, S-91A, permeabilized to nucleotides by lysolecithin. In contrast, levodopa and dopamine did not inhibit DNA polymerase in permeabilized cells in the absence of exogenous tyrosinase. Analysis using isolated DNA polymerase showed that the inhibitory activity of the ortho dihydroxy compounds was totally dependent upon enzymatic activation. The enzymatic activation of the ortho derivative 3,4-DHBA by tyrosinase results in two reactive species: a semiquinone intermediate and a less reactive quinone. Inhibition of DNA polymerase by activated 3,4-DHBA was shown by dialysis and kinetic studies to involve an irreversible reaction which occurs at two inhibitor interaction sites as determined by a Hill plot analysis. Double-stranded DNA protected the enzyme from inhibition by 3,4-DHBA, suggesting that the inhibitory sites are at or near the template-initiator binding site.

Animals↗
PubMed1983

The chemotherapy of malignant melanoma.

Advanced human malignant melanoma continues to be an intractable tumor unresponsive to most forms of therapy. We have been engaged in the design of selective agents for the chemotherapy of malignant melanoma based on the unique biochemical features within this tumor. Several analogues have been prepared with significant antitumor activity against experimental melanoma models, and these include levodopa, dopamine, and the nonneurotoxic analogue 3,4-dihydroxybenzylamine. Pending the clinical availability of the improved analogues, we have investigated the effects of levodopa and dopamine on advanced human malignant melanoma. Dopamine has been shown to cause a significant biochemical inhibition of tumor in 4 patients treated, but cardiovascular effects have precluded its repetitive use. The combination of levodopa/carbidopa has been used in an attempt to circumvent these toxicities as well as deliver drug to the central nervous system (CNS). Of 12 patients treated to date, 8 are evaluable, and there have been 4 significant clinical responses. Importantly, the plasma levels achievable with levodopa are in tumoricidal range as predicted by in vivo assays (10(-5) M). One patient had a complete resolution of a CNS lesion as measured by CAT scan and a corresponding improvement in symptoms. Pending the availability of improved analogues, further study of the use of levodopa/carbidopa as therapy for malignant melanoma in humans appears warranted, and different methods of delivery, either alone or in combination with conventional agents, will be explored.

Carbidopa↗
PubMed1982

Lipophilic 5'-(alkyl phosphate) esters of 1-beta-D-arabinofuranosylcytosine and its N4-acyl and 2,2'-anhydro-3'-O-acyl derivatives as potential prodrugs.

Lipophilic 5'-(alkyl phosphate) esters of 1-beta-D-arabinofuranosylcytosine (ara-C) and several N4-acyl and 3'-O-acyl-2,2'-anhydro derivatives of ara-C were synthesized as potential prodrugs of ara-C 5'-monophosphate (ara-CMP). Alkylphosphorylation of ara-C, N4-palmitoyl-ara-C, and N4-stearoyl-ara-C was achieved in a single continuous operation by allowing the nucleoside to react with POCl3 in trimethyl or triethyl phosphate and adding the appropriate anhydrous alcohol directly to the intermediate phosphorodichloridate without isolation. Similar reaction of cytidine yielded cytidine 5'-(alkyl phosphate) esters, which on treatment with myristoyl or palmitoyl chloride in the presence of boron trifluoride gave 3'-O-acyl-2,2'-anhydro-ara-C 5'-(alkyl phosphate) esters. Ara-C 5'-(n-butyl phosphate) (1b), N4-palmitoyl-ara-C 5'-(n-butyl phosphate) (1h), and 2,2'-anhydro-3'-O-palmitoyl-ara-C 5'-(n-butyl phosphate) (2h) were tested against L1210/ara-C leukemia in mice in the hope that this kinase-deficient tumor would respond to treatment with these "prephosphorylated" derivatives, but no activity was observed. Of the simple 5'-(alkyl phosphate) esters tested in culture against l1210 leukemic cells, only ara-C 5'-(glyceryl phosphate) (1g) showed toxicity comparable to ara-CMP (ID50 = 0.35 and 0.65 microM, respectively), suggesting that beta-hydroxyalkyl phosphate esters may be worthwhile to examine further as prodrugs of ara-CMP.

Animals↗
PubMed1982

Therapeutic effect of dopamine infusion on human malignant melanoma.

Dopamine is a novel antitumor agent that has shown activity against B16 melanoma. Four patients with advanced malignant melanoma were infused with dopamine at 20 micrograms/kg/min for 48--120 hours. Tumor and bone marrow samples were obtained before and after treatment for comparison. Each of the patients tested showed significant reduction in the labeling index of tumor cells following treatment. These results suggest that dopamine is capable of attaining cytotoxic levels necessary to induce a biochemical inhibition of human malignant melanoma.

Antineoplastic Agents↗
PubMed1981

Effect of high-dose thymidine infusions in patients with mycosis fungoides.

The antitumor effect of thymidine has been demonstrated in patients with leukemia and lymphoma. This report summarizes the treatment of three patients with mycosis fungoides, a chronic T-cell lymphoma. Four courses of thymidine (75 g/m2/day) were administered by continuous infusion for 4-7 days. Steady-state serum thymidine levels were in the range of 1-3 mM. Associated toxicities were minimal and consisted of milk headache and anorexia. Myelosuppression was manifested by transient declines in the peripheral leukocyte count. One patient had extensive clearing of diffuse erythematous plaques on the trunk and extremities that persisted for over one month. A second patient had partial clearing of plaques that persisted for two weeks following therapy and a third patient had a minimal response with 25% reduction in lymphadenopathy and noduloulcerative lesions. These responses indicate the effectiveness of thymidine as a single agent in the treatment of mycosis fungoides.

Aged↗