15-hydroxy-5-8-11-13-eicosatetraenoic-acid and Precursor-Cell-Lymphoblastic-Leukemia-Lymphoma

Several reports have demonstrated an important role of leukotriene B(4) (LTB(4)) in the immune system. We investigated whether leukemic blasts from acute myeloid leukemic (AML) and acute lymphoid leukemic (ALL) patients produced LTB(4), 12- and 15-hydroxyeicosatetraenoic acids (12-HETE and 15-HETE) and whether these compounds affected blast proliferation and apoptosis. Leukemic blasts from AML M(0-2) and ALL patients expressed 5-LOX, 12-LOX and 15-LOX transcripts. Quantitative polymerase chain reaction indicated that 5-LOX transcripts were far more abundant than 12-LOX and 15-LOX ones. Leukemic blasts expressed 5-LOX activating protein (FLAP) transcripts and produced LTB(4) in response to calcium ionophore. In contrast no 15-HETE production was found. Calcium ionophore-stimulated leukemic blasts produced 12-HETE but also released thromboxane A(2) suggesting that contaminating platelets accounted for the release of these compounds. No significant effect of LTB(4), 12-HETE or 15-HETE could be documented on leukemic blast growth and on their apoptose rate. Results of the present study indicate that immature form of leukemic blasts produce LTB(4). However, the three major lipoxygenase metabolites of arachidonic acid; i.e., LTB(4), 12-HETE or 15-HETE, had no evident effect on their growth and apoptosis. We may speculate that LTB(4)-derived blast cells might initiate, augment or prolong tissue inflammation and damages by affecting the marrow and blood cytokine network.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Apoptosis; Arachidonate 12-Lipoxygenase; Arachidonate 15-Lipoxygenase; Arachidonate 5-Lipoxygenase; Arachidonic Acid; Blast Crisis; Calcium; Cell Proliferation; Humans; Hydroxyeicosatetraenoic Acids; Ionophores; Leukemia, Myeloid, Acute; Leukotriene B4; Polymerase Chain Reaction; Precursor Cell Lymphoblastic Leukemia-Lymphoma; RNA, Messenger; Thromboxane A2

This study examines the effects of oxidized low density lipoprotein (ox-LDL) on mononuclear cell arachidonic acid (AA) metabolism. U937 and HL60 cells, employed as models for mononuclear cells and promyelocytic cells, respectively, were exposed to ox-LDL (20 micrograms protein/ml) for 24 hours. HPLC analysis of 1-14C-AA metabolites indicates that ox-LDL increases U937 and HL60 cell production of 15-hydroxyeicosatetraenoic acid (15-HETE) and 5-hydroxyeicosatetraenoic acid (5-HETE). Northern analysis indicates that ox-LDL increases U937 cell FLAP transcript levels 10-times control levels but did not appear to alter 5-lipoxygenase (5-LO) mRNA levels. In contrast, ox-LDL increases HL60 cell transcript levels for FLAP and 5-LO 1.5 times and 10 times control levels, respectively. Thus, we propose that ox-LDL plays an important role in the up-regulation of the 5-LO pathway in mononuclear cells. Such activation may explain, in part, the mechanisms by which ox-LDL promotes atherogenesis.

Topics: 5-Lipoxygenase-Activating Proteins; Arachidonate 5-Lipoxygenase; Arachidonic Acid; Blotting, Northern; Carrier Proteins; Cell Line; Enzyme Activation; Gene Expression; Humans; Hydroxyeicosatetraenoic Acids; Kinetics; Leukemia; Lipoproteins, LDL; Lymphoma, Large B-Cell, Diffuse; Malondialdehyde; Membrane Proteins; Oxidation-Reduction; Precursor Cell Lymphoblastic Leukemia-Lymphoma; RNA, Neoplasm; Transcription, Genetic; Tumor Cells, Cultured

MOLT-4 lymphocytes metabolize 13-hydroxy-9,11-octadecadienoic acid, via the beta-oxidation pathway with retention of the omega 6 hydroxyl group and the conjugated diene system. The products which accumulate include 11-hydroxy-7,9-hexadecadienoic acid and 9-hydroxy-5,7-tetradecadienoic acid. In addition, it was possible to isolate two beta-hydroxy acids which were shown to be 3,13-dihydroxy-9,11-octadecadienoic acid and 3,11-dihydroxy-7,9-hexadecadienoic acid. The odd chain aldehyde, 12-hydroxy-8,10-heptadecadien-1-al, also was detected. However, neither the pathway nor the immediate precursor for the synthesis of this compound was established.

Topics: Adult; Chromatography, High Pressure Liquid; Humans; Hydroxyeicosatetraenoic Acids; Linoleic Acids; Male; Mass Spectrometry; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Tumor Cells, Cultured

MOLT-4 lymphocytes metabolize 15-hydroxy-5,8,11,13-eicosatetraenoic acid (15-HETE) via beta-oxidation with retention of the hydroxyl group at the omega 6-carbon atom. 15-HETE oxidation is accompanied by the time-dependent accumulation of both beta-hydroxy acids and metabolites produced by repetitive cycles of the beta-oxidation spiral. Detection of 7-hydroxy-5-dodecenoic acid shows that these cells continue to beta-oxidize the substrate when the conjugated diene is allylic to a hydroxyl group. When 15-HETE was the substrate, it was also possible to detect 12-hydroxy-5,8,10-heptadecatrien-1-al and 3,15-dihydroxy-8,11,13-eicosatrienoic acid. The former product may be produced by alpha-oxidation of 13-hydroxy-6,9,11-octadecatrienoic acid followed by its decarboxylation. Detection of a 20-carbon metabolite, lacking a double bond at position 5, suggests that an intermediate of beta-oxidation was used as a substrate for chain elongation. When 13-hydroxy-6,9,11-octadecatrienoic acid was used as a substrate, it was indeed possible to detect 3,15-dihydroxy-8,11,13-eicosatrienoic acid as well as 15-hydroxy-8,11,13-eicosatrienoic acid. In addition, 13-hydroxy-6,9,11-octadecatrienoic acid was a precursor for the biosynthesis of both 14-hydroxy-7,10,12-nonadecatrien-1-al and 1,14-dihydroxy-7,10,12-nonadecatriene. These studies with MOLT-4 cells as well as with T-lymphocytes isolated from blood show that products of the 15-lipoxygenase pathway are metabolized with the accumulation of a variety of compounds. Since 15-HETE has been implicated as a modulator of T-cell function, these findings raise the possibility that the newly described metabolites may be involved in regulating lymphocyte function.

Topics: Adult; Chromatography, High Pressure Liquid; Diazomethane; Fatty Acids, Unsaturated; Humans; Hydroxyeicosatetraenoic Acids; Kinetics; Male; Mass Spectrometry; Oxidation-Reduction; Precursor Cell Lymphoblastic Leukemia-Lymphoma; T-Lymphocytes; Tumor Cells, Cultured