5-hydroxy-6-8-11-14-eicosatetraenoic-acid and Breast-Neoplasms

The 5-lipoxygenase (5-LO) product 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE), which is a potent chemoattractant for myeloid cells, is known to promote the survival of prostate cancer cells. In the present study, we found that PC3 prostate cancer cells and cell lines derived from breast (MCF7) and lung (A-427) cancers contain 5-hydroxyeicosanoid dehydrogenase (5-HEDH) activity and have the ability to synthesize 5-oxo-ETE from its precursor 5S-hydroxy-6,8,11,14-eicosatetraenoic acid (5-HETE) when added as an exogenous substrate. H(2)O(2) strongly stimulated the synthesis of 5-oxo-ETE and induced dramatic increases in the levels of both glutathione disulfide and NADP(+). The effects of H(2)O(2) on 5-oxo-ETE and NADP(+) were blocked by N-ethylmaleimide (NEM), indicating that this effect was mediated by the glutathione reductase-dependent generation of NADP(+), the cofactor required by 5-HEDH. 5-Oxo-ETE synthesis was also stimulated by agents that have cytotoxic effects on tumor cells, including 4,7,10,13,16,19-docosahexaenoic acid, tamoxifen and MK-886. Because PC3 cells have only modest 5-LO activity compared with inflammatory cells, we investigated their ability to contribute to the transcellular biosynthesis of 5-oxo-ETE from neutrophil-derived 5-HETE. Stimulation of neutrophils with arachidonic acid and calcium ionophore in the presence of PC3 cells led to a large and selective increase in 5-oxo-ETE synthesis compared with controls in which PC3 cell 5-oxo-ETE synthesis was selectively blocked by pretreatment with NEM. The ability of prostate tumor cells to synthesize 5-oxo-ETE may contribute to tumor cell proliferation as well as the influx of inflammatory cells, which may further induce cell proliferation through the release of cytokines. 5-Oxo-ETE may be an attractive target in cancer therapy.

Topics: Alcohol Oxidoreductases; Arachidonate 5-Lipoxygenase; Arachidonic Acids; Breast Neoplasms; Chromatography, High Pressure Liquid; Docosahexaenoic Acids; Humans; Hydroxyeicosatetraenoic Acids; Lung Neoplasms; Male; Neutrophils; Oxidative Stress; Prostatic Neoplasms; Tumor Cells, Cultured

Pomegranate fruit extracts (PFEs) possess polyphenolic and other compounds with antiproliferative, pro-apoptotic and anti-inflammatory effects in prostate, lung, and other cancers. Because nuclear transcription factor-kB (NF-kB) is known to regulate cell survival, proliferation, tumorigenesis, and inflammation, it was postulated that PFEs may exert anticancer effects at least in part by modulating NF-kB activity.. The authors investigated the effect of a novel, defined PFE consisting of both fermented juice and seed oil on the NF-kB pathway, which is constitutively active in aggressive breast cancer cell lines. The effects of the PFE on NF-kB-regulated cellular processes such as cell survival, proliferation, and invasion were also examined.. Analytical characterization of the bioactive components of the PFE revealed active constituents, mainly ellagitannins and phenolic acids in the aqueous PFE and conjugated octadecatrienoic acids in the lipid PFE derived from seeds.The aqueous PFE dose-dependently inhibited NF-kB-dependent reporter gene expression associated with proliferation, invasion, and motility in aggressive breast cancer phenotypes while decreasing RhoC and RhoA protein expression.. Inhibition of motility and invasion by PFEs, coincident with suppressed RhoC and RhoA protein expression, suggests a role for these defined extracts in lowering the metastatic potential of aggressive breast cancer species.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Apoptosis; Breast Neoplasms; Cell Line, Tumor; Cell Movement; Cell Proliferation; Dinoprostone; Female; Fruit; Gene Expression; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Lythraceae; Neoplasm Invasiveness; NF-kappa B; NF-kappa B p50 Subunit; Phytotherapy; Plant Extracts; rho GTP-Binding Proteins; rhoA GTP-Binding Protein; rhoC GTP-Binding Protein; Transcription Factor RelA

Conjugated linoleic acid (CLA) consists of a group of linoleic acid geometric isomers that have been shown to reduce tumor growth and metastasis in animal models of breast, prostate and colon cancer. To delineate a possible mechanism of action for CLA, we have recently shown that the 5-lipoxygenase product, 5-hydroxyeicosatetraenoic acid (5-HETE), could play a role in CLA alteration of mammary tumorigenesis. In this study, we determined how CLA could modulate 5-lipoxygenase activity. The t10, c12-CLA isomer reduced production of 5-HETE but not 12- and 15-HETE in MDA-MB-231 human breast tumor cells. That isomer and the c9, t11-CLA isomer decreased 5-HETE production by competition with the lipoxygenase substrate, arachidonic acid (AA). Interestingly, t10, c12-CLA reduced the expression of five-lipoxygenase activating protein (FLAP) but not the 5-lipoxygenase enzyme. Over-expression of FLAP abrogated t10, c12-CLA-reduced viability of MDA-MB-231 cells. These data suggest that the reduction of 5-HETE by t10, c12-CLA was due to competition with AA and the reduction of FLAP expression.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; 5-Lipoxygenase-Activating Proteins; Arachidonate 5-Lipoxygenase; Arachidonic Acid; Breast Neoplasms; Carrier Proteins; Cell Line, Tumor; Cell Proliferation; Cell Survival; Female; Gene Expression; Humans; Hydroxyeicosatetraenoic Acids; Isomerism; Linoleic Acids; Linoleic Acids, Conjugated; Membrane Proteins; Transfection

Previous experimental studies have shown that high dietary fat intake is associated with mammary carcinogenesis. In the current study, the effect of 5-LOX or 12-LOX inhibitors on human breast cancer cell proliferation and apoptosis, as well as the possible mechanisms were investigated. The LOX inhibitors, NDGA, Rev-5901, and baicalein all inhibited proliferation and induced apoptosis in MCF-7 (ER+) and MDA-MB-231 (ER-) breast cancer cell in vitro. In contrast, the LOX products, 5-HETE and 12-HETE had mitogenic effects, stimulating the proliferation of both cell lines. These inhibitors also induced cytochrome c release, caspase-9 activation, as well as downstream caspase-3, caspase-7 activation, and PARP cleavage. LOX inhibitor treatment also reduced the levels of anti-apoptotic proteins Bcl-2 and Mcl-1 and increased the levels of the pro-apoptotic protein bax. In conclusion, blockade of both 5-LOX and 12-LOX pathways induces apoptosis in breast cancer cells through the cytochrome c release and caspase-9 activation, with changes in the levels of Bcl-2 family proteins.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Apoptosis; Blotting, Western; Breast Neoplasms; Caspase 3; Caspase 7; Caspase 9; Caspases; Cell Division; Chemotactic Factors; Cytochrome c Group; Cytosol; DNA; Dose-Response Relationship, Drug; Enzyme Activation; Enzyme Inhibitors; Flow Cytometry; Humans; Hydroxyeicosatetraenoic Acids; Lipoxygenase Inhibitors; Mitogens; Myeloid Cell Leukemia Sequence 1 Protein; Neoplasm Proteins; Poly(ADP-ribose) Polymerases; Proto-Oncogene Proteins c-bcl-2; Tumor Cells, Cultured

Many arachidonic acid metabolites function in growth signaling for epithelial cells, and we previously reported the expression of the major arachidonic acid enzymes in human breast cancer cell lines. To evaluate the role of the 5-lipoxygenase (5-LO) pathway on breast cancer growth regulation, we exposed cells to insulinlike growth factor-1 or transferrin, which increased the levels of the 5-LO metabolite, 5(S)-hydrooxyeicosa-6E,8C,11Z,14Z-tetraenoic acid (5-HETE), by radioimmunoassay and high-performance liquid chromatography. Addition of 5-HETE to breast cancer cells resulted in growth stimulation, whereas selective biochemical inhibitors of 5-LO reduced the levels of 5-HETE and related metabolites. Application of 5-LO or 5-LO activating protein-directed inhibitors, but not a cyclooxygenase inhibitor, reduced growth, increased apoptosis, down-regulated bcl-2, up-regulated bax, and increased G1 arrest. Exposure of breast cancer cells to a 5-LO inhibitor up-regulated peroxisome proliferator-activated receptor (PPAR)a and PPARg expression, and these same cells were growth inhibited when exposed to relevant PPAR agonists. These results suggest that disruption of the 5-LO signaling pathway mediates growth arrest and apoptosis in breast cancer cells. Additional experiments suggest that this involves the interplay of several factors, including the loss of growth stimulation by 5-LO products, the induction of PPARg, and the potential activation of PPARg by interactions with shunted endoperoxides.

Topics: Apoptosis; Arachidonic Acid; bcl-2-Associated X Protein; Breast Neoplasms; Cell Division; Eicosanoids; Humans; Hydroxyeicosatetraenoic Acids; Indoles; Insulin-Like Growth Factor I; Ligands; Lipoxygenase Inhibitors; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Receptors, Cytoplasmic and Nuclear; Signal Transduction; Transcription Factors; Tumor Cells, Cultured