inosinic-acid and Leukemia--Myeloid--Acute

Topics: Adenine Nucleotides; Aged; Aged, 80 and over; Cell Survival; Chromatography, High Pressure Liquid; Female; Guanine Nucleotides; Humans; Inosine Monophosphate; Leukemia, Lymphocytic, Chronic, B-Cell; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Leukemia, Myeloid, Acute; Leukocytes; Male; Middle Aged; NAD; Neutrophils; Purine Nucleotides; Reference Values

A sensitive and rapid assay for the quantitation of thioinosine monophosphate and thioguanosine monophosphate, the major intracellular active metabolites of mercaptopurine and thioguanine, respectively, has been developed. Neoplastic cells are extracted with trichloracetic acid, and the neutralized acid extracts are analyzed by ion-pairing high-performance liquid chromatography with dual-channel uv-wavelength detection. This technique provides a lower limit of sensitivity of 30 pmol of thioinosine monophosphate and 10 pmol of thioguanosine monophosphate. The number of cells assayed per sample was 2 X 10(7). This assay makes it possible to detect and quantitate low levels of thioinosine monophosphate and thioguanosine monophosphate present in neoplastic cells obtained directly from patients receiving mercaptopurine or thioguanine chemotherapy.

Topics: Bone Marrow; Cell Line; Chromatography, High Pressure Liquid; Guanine Nucleotides; Humans; Inosine Monophosphate; Inosine Nucleotides; Leukemia, Myeloid, Acute; Lymphoma; Mercaptopurine; Thioguanine; Thionucleotides

In studies with the human promyelocytic leukemia cell line HL-60, we defined changes in intermediary purine metabolism that appear to contribute to the regulation of terminal maturation in myeloid cells. When HL-60 cells were exposed to compounds that induce maturation, consistent alterations in purine metabolism were found to occur within 24 h of culture. Perturbation of guanosine nucleotide synthesis and decreases of up to 50% in intracellular guanylate pool sizes were associated with the induced maturation of these cells in response to diverse inducing agents. While immature HL-60 cells were observed to synthesize purine nucleotides by both de novo and salvage pathways, the activity of both pathways decreased in cells induced to mature, although the relative contribution of purine salvage increased. Moreover, incorporation of the salvage pathway precursor, [14C]hypoxanthine from the intermediate, inosine monophosphate (IMP), into guanylates was reduced by approximately 65% in induced HL-60 cells, reflecting decreased activity of both hypoxanthine phosphoribosyltransferase and IMP dehydrogenase. When various inhibitors of IMP dehydrogenase (mycophenolic acid, 3-deazaguanosine, and 2-beta-D-ribofuranosylthiazole-4-carboxamide) were evaluated for their effects upon HL-60 cells, each agent was found to induce the cells to mature morphologically and functionally. Like other inducers, these agents decreased HL-60 cell proliferation and caused the cells to acquire an ability to phagocytose opsonized yeast and reduce nitroblue tetrazolium. Each agent reduced intracellular guanosine nucleotide pool sizes and induced HL-60 cell maturation at micromolar concentrations. These observations suggest that the size of intracellular guanosine nucleotide pools, the biosynthesis of guanosine nucleotides, and the activity of IMP dehydrogenase may be central to the regulation of terminal maturation in myeloid cells.

Topics: Adenine Nucleotides; Cell Differentiation; Granulocytes; Guanine Nucleotides; Humans; Hypoxanthine Phosphoribosyltransferase; IMP Dehydrogenase; Inosine Monophosphate; Leukemia, Myeloid, Acute; Purine Nucleotides; Stem Cells

The PRPP concentrations, PRPP formation, and phosphorylation of 6-mercaptopurine in leukocyte suspensions and homogenates prepared from leukemic patients were studied...

Topics: Amidophosphoribosyltransferase; Animals; Humans; Hypoxanthine Phosphoribosyltransferase; Hypoxanthines; In Vitro Techniques; Inosine; Inosine Monophosphate; Leukemia; Leukemia L1210; Leukemia, Myeloid, Acute; Leukocytes; Mercaptopurine; Phosphoribosyl Pyrophosphate; Purine-Nucleoside Phosphorylase