methylnitronitrosoguanidine and Leukemia--Myeloid--Acute

FK866 is a novel anticancer agent that was previously shown to interfere with NAD superset+ biosynthesis by inhibition of nicotinamide phosphoribosyltransferase and to initiate apoptosis in cancer cells. As NAD superset+ is involved in cellular DNA repair processes, the present in vitro study on THP-1 and K562 leukemia cells was conducted to investigate the cytotoxicity of FK866 combination treatment with various cytotoxic agents: the antimetabolite Ara-C, the DNA-intercalating agent daunorubicin and the alkylating compounds 1-methyl-3-nitro-1-nitrosoguanidinium (MNNG) and melphalan. Cell viability after drug exposure was assessed by propidium iodide (PI) staining. Non-cytotoxic concentrations of FK866 (10 superset-9 M or less), applied simultaneously or 24 hours before adding cytotoxic agents, caused a depletion in the intracellular NAD superset+ and--to a lesser extent-- NADH levels in THP-1 cells. After 48 and 72 hours treatment with daunorubicin and Ara-C, respectively, increased cell death was observed in THP-1 cells that were pretreated with FK866, as compared to cells exposed to antineoplastic drugs alone. However, this effect was transient, and there was no difference in cell survival after 72 hours incubation with daunorubicin or 96 hours with Ara-C. - Non-toxic concentrations of FK866 added 8, 16, or 24 hours before starting treatment with the PARP-activating agent MNNG synergistically decreased intracellular NAD superset+ contents, and increased MNNG-induced cytotoxicity both in THP-1 and K562 cells for at least 72 hours. This effect was less pronounced when FK866 was used in combination with another alkylating agent, melphalan. The PARP inhibitor 3-aminobenzamide delayed MNNG-induced cytotoxicity by 24 hours both in cells that were pretreated with FK866 and in non-pretreated cells. 48 hours later, the protective effect of 3-aminobenzamide could no longer be observed, but FK866-pretreated cells retained increased sensitivity to MNNG. - In conclusion, the chemosensitizing effect of FK866 on cell death induced by antineoplastic drugs was particularly obvious in combination with substances like MNNG that cause NAD superset+ depletion per se. It was less pronounced and only transiently measurable in combination with daunorubicin, Ara-C, and melphalan, respectively. These results may indicate different levels of DNA damage implicated in the action of the cytotoxic agents used.

Topics: Acrylamides; Antibiotics, Antineoplastic; Antimetabolites, Antineoplastic; Antineoplastic Agents; Antineoplastic Agents, Alkylating; Cell Death; Cell Line, Tumor; Cell Survival; Cytarabine; Daunorubicin; Dose-Response Relationship, Drug; Drug Combinations; Humans; K562 Cells; Leukemia, Myeloid, Acute; Melphalan; Methylnitronitrosoguanidine; Monocytes; NAD; Piperidines

A small fraction of those individuals exposed to cytotoxic chemotherapy or radiation for the treatment of a primary malignant disease will develop a second malignancy some time later. Although exposure to the cytotoxic agents is believed to be the causative factor, the reason only certain individuals develop the second malignancy is unknown. Some studies have suggested that these individuals might be predisposed to cancer because of an inherent sensitivity to the alkylating agents used in cancer therapy. We have reported that these individuals with therapy-related acute nonlymphocytic leukemia (t-ANLL) have reduced endogenous levels of the repair protein O6-alkylguanine alkyltransferase (AGT). To further investigate the etiology of this disease, alkylation-induced sister-chromatid exchange (SCE) formation in individuals who developed second malignancies, was compared to other patient groups and normal controls. Peripheral blood lymphocytes from patients with (1) t-ANLL, (2) primary forms of acute nonlymphocytic leukemia (ANLL de novo), (3) patients with primary malignancies at risk of developing secondary disease, and (4) unexposed, healthy controls were treated in vitro with N-methyl-N'-nitro-nitrosoguanidine or mitomycin C. Baseline and mutagen-induced frequencies of SCEs were determined. These studies failed to detect any increased sensitivity in those patients who developed second malignancies as compared to controls or patients with de novo forms of the same disease. Also, no correlation between sensitivity to the alkylating agent N-methyl-N'-nitro-nitrosoguanidine and endogenous levels of the AGT repair protein was found. These results suggest that t-ANLL patients are not sensitive to SCE induction by either MNNG or MMC.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Antineoplastic Agents; DNA Replication; Hodgkin Disease; Humans; Leukemia, Myeloid, Acute; Lymphocytes; Lymphoma, Non-Hodgkin; Male; Methylnitronitrosoguanidine; Methyltransferases; Mitomycin; Mitomycins; O(6)-Methylguanine-DNA Methyltransferase; Sister Chromatid Exchange

Adriamycin caused significant interphase death in HL-60 cells during six hours of incubation, which was abolished by the poly(ADP-ribose) polymerase inhibitors, 3-aminobenzamide or nicotinamide. Neither agent changed adriamycin uptake by HL-60 cells. Although 3-aminobenzamide did not alter the number of DNA strand breaks caused by adriamycin, it prevented adriamycin-induced depletion of intracellular NAD+ and ATP, and maintained energy charge. These findings suggest that the activation of poly(ADP-ribose) synthesis plays an important role in the adriamycin-induced interphase death of proliferating HL-60 cells.

Topics: Benzamides; Cell Line; Cell Survival; DNA Damage; Doxorubicin; Humans; Interphase; Kinetics; Leukemia, Myeloid, Acute; Methylnitronitrosoguanidine; Niacinamide

The ribonucleotide reductase inhibitors deferoxamine and hydroxyurea induce monocyte-macrophage cell differentiation in the leukemic cell line HL-60 as judged by the expression of cell surface antigens, nonspecific esterase activity, and morphological changes. Treatment of HL-60 cells with deferoxamine results in inhibition of DNA synthesis and irreversible loss of colony-forming ability. In addition, both deferoxamine and hydroxyurea caused an increase in the number of DNA strand breaks in HL-60 cells. A DNA methylating agent, N-methyl-N'-nitro-N-nitrosoguanidine, also caused cellular differentiation in HL-60 cells associated with DNA strand breaks. These observations are consistent with a role for DNA damage or for inhibition of DNA synthesis and repair in the differentiation process of HL-60 cells.

Topics: Antigens, Surface; Benzamides; Cell Cycle; Cell Differentiation; Deferoxamine; DNA Repair; DNA, Neoplasm; Humans; Hydroxyurea; Leukemia, Myeloid, Acute; Methylnitronitrosoguanidine; Neoplasm Proteins; Ribonucleotide Reductases; RNA, Neoplasm; Tumor Cells, Cultured

Topics: Azaguanine; Cell Line; Drug Resistance; Genetic Markers; Humans; Hypoxanthine Phosphoribosyltransferase; Leukemia, Myeloid, Acute; Methylnitronitrosoguanidine; Mutation

Studies were made on whether differentiation and proliferation of antitumor drug-resistant leukemia cells could be controlled by specific inducers of terminal differentiation. Leukemia subclones resistant to daunomycin and/or cytosine arabinoside were isolated from differentiation-inducible mouse myeloid leukemia M1-B24 cells by selection with these antitumor drugs. The drug-resistant cells were found to retain their potential for terminal differentiation induced by various inducers, such as a protein inducer in the conditioned medium of mouse L929 cells, dexamethasone, 1 alpha,25-dihydroxyvitamin D3, 2-[2-(dodecyloxy)ethoxy]ethyl 2-pyridinioethyl phosphate, and poly I. Differentiated cells showed morphological changes to mature macrophage-like cells, increase in phagocytic activity, and decrease in proliferative activity. Clonal analysis of M1-B24 cells showed that the cellular responses to the protein inducer of differentiation were not significantly different between drug-resistant clones selected with anti-tumor drugs and control (drug-sensitive) clones randomly isolated without selection. These results suggest that induction of differentiation of leukemic cells with the specific inducers is another approach to control the drug-resistant leukemia.

Topics: Animals; Calcitriol; Cell Differentiation; Cell Division; Cell Line; Cytarabine; Daunorubicin; Dexamethasone; Drug Resistance; Leukemia, Myeloid, Acute; Methylnitronitrosoguanidine; Mice; Organophosphorus Compounds; Poly I; Pyridinium Compounds