13-hydroxy-9-11-octadecadienoic-acid and Breast-Neoplasms

15-Lipoxygenase-1 (15-Lox-1) is a key enzyme mediating oxidative metabolism of polyunsaturated fatty acids and has attracted considerable interest as a potential target for the induction of apoptosis in cancer cells. Knowledge of relationship between 15-Lox-1 and histone deacetylase inhibitors is lacking in the breast cancer. This study is aimed to investigate the role of Trichostatin A (TSA) and 13(S)-HODE, as a metabolite of 15-Lox-1, in the regulation of breast cancer cell growth. The cytotoxic effect of TSA, as a potent HDAC inhibitor, was measured using MTT assay. Annexin V-FITC and PI staining were performed to detect apoptosis and cell cycle distribution using Flow cytometry. The role of 15-Lox-1 in the regulation of cell growth was assessed by 15-Lox-1 inhibitor and the level of 15-Lox-1 metabolite was measured to determine 15-Lox activity after treatment by TSA. The results demonstrated that TSA induced cell growth inhibition via 15-Lox-1, in a dose- and time-dependent manner, and subsequently accompanied by the cell cycle arrest and induction of apoptosis. Moreover, growth inhibitory effect of TSA was associated with the elevation of 15-Lox-1 metabolite (13(S)-HODE). This study provided evidences that the inhibitory effect of TSA on the breast cancer cell growth occurs via the induction of 15-Lox-1 activity and 13(S)-HODE production. Our findings underline the possible role of 15-Lox-1/13(S)-HODE pathway as a promising molecular approach for the induction of apoptosis in breast cancer cells.

Topics: Apoptosis; Arachidonate 15-Lipoxygenase; Breast Neoplasms; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Female; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Linoleic Acids; Lipoxygenase Inhibitors

The circadian production of melatonin by the pineal gland during the night provides an inhibitory signal to tissue-isolated steroid receptor SR+ and - MCF-7 human breast cancer xenografts in female nude rats. A pivotal mechanism for melatonin's anticancer effects in vivo involves a melatonin receptor-mediated inhibition of linoleic acid (LA) uptake and its metabolism to mitogenically active 13-hydroxyoctadecadienoic acid (13-HODE). Exposure of (SR-) xenograft-bearing rats to increasing intensities of polychromatic white light at night suppresses melatonin while increasing tumor growth rates, DNA content, [3H]thymidine incorporation into DNA, LA uptake, 13-HODE formation, cAMP levels and ERK1/2 activation a dose-dependent manner. Similar effects occur in SR- human breast cancer xenografts perfused in situ with melatonin-depleted blood from healthy female subjects after their exposure to a single bright intensity (2800 lux) of polychromatic light at night. Additionally, SR- human breast cancer xenografts exhibit robust circadian rhythms of LA uptake, 13-HODE formation and proliferative activity. Exposure of xenograft-bearing rats to dim light at night results in the complete elimination of these rhythms which culminates in unfettered, high rates of tumor metabolism and growth. The organization of tumor metabolism and growth within circadian time structure by the oncostatic melatonin signal helps create a balance between the cancer and its host that is disrupted by host exposure to light at night. This biological mechanism may partially explain the higher risk of breast and other cancers in women working rotating night shifts and possibly others who also experience prolonged exposure to light at night.

Topics: Animals; Anticarcinogenic Agents; Breast Neoplasms; Cell Growth Processes; Cell Proliferation; Circadian Rhythm; Female; Humans; Light; Linoleic Acid; Linoleic Acids; Melatonin; Neoplasm Transplantation; Photoperiod; Rats; Rats, Nude; Receptors, Melatonin; Signal Transduction; Transplantation, Heterologous

The type and content of dietary PUFAs have profound influences on the growth rate of transplantable human breast cancers in immunodeficient rodents. Diets enriched in linoleic acid (LA), an (n-6) fatty acid, stimulate tumor growth, whereas dietary fats containing (n-3) fatty acids slow such growth. Interactions between LA and (n-3) fatty acids capable of regulating cell proliferation in solid tumors in vivo are not yet well defined. Here we tested the hypothesis that plasma eicosapentaenoic acid (EPA), an (n-3) fatty acid, suppresses cell proliferation in MCF-7 human breast cancer xenografts via a pertussis toxin-sensitive reduction of intratumor cAMP, LA uptake, and formation of the mitogen 13-hydroxyoctadecadienoic acid (13-HODE) from LA. Plasma fatty acid uptake and 13-HODE release were determined in control and EPA-treated xenografts from arteriovenous differences measured during perfusion in situ. Intratumor cAMP, extracellular signal-regulated kinase p44/p42 (ERK1/2) phosphorylation, and [3H]thymidine incorporation (TTI) were measured in tumors freeze-clamped at the end of the perfusions. Arterial blood containing EPA caused significant decreases (P < 0.05) in cAMP, uptake of SFA, monounsaturated fatty acids, and (n-6) PUFA, 13-HODE formation, ERK1/2 phosphorylation, and TTI in MCF-7 xenografts. These effects of EPA were reversed by the addition of either pertussis toxin or 8-bromoadenosine-cAMP to the EPA-containing arterial blood. Addition of 13-HODE to the EPA-containing arterial blood restored phosphorylated ERK1/2 and TTI but not FA uptake. The results suggest that EPA regulates cell proliferation in MCF-7 xenografts via a novel inhibitory G protein-coupled, (n-3) FFA receptor-mediated signal transduction pathway.

Topics: 8-Bromo Cyclic Adenosine Monophosphate; Animals; Breast Neoplasms; Cell Line, Tumor; Cell Proliferation; Eicosapentaenoic Acid; Female; Humans; Linoleic Acids; Lipid Metabolism; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Neoplasm Transplantation; Pertussis Toxin; Phosphorylation; Rats; Signal Transduction; Transplantation, Heterologous

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

In established rodent tumors and human cancer cell lines, conjugated dienoic isomers of linoleic acid (CLA) suppress the growth-stimulating effects of linoleic acid (LA) and its metabolism to the mitogenic agent, 13-hydroxyoctadecadienoic acid (13-HODE). Here, we compared the effects of three CLA isomers on LA uptake and metabolism, and growth in human breast xenografts perfused in situ in female nude rats. The results demonstrated that two CLA isomers [10t, 12c-CLA>9t, 11t-CLA] caused a dose-dependent inhibition of LA uptake, cAMP content, 13-HODE formation, Erk 1/2 activity, and [(3)H]thymidine incorporation into tumor DNA; 9c, 11t-CLA showed no effect. The inhibitory effect is reversible with either pertussis toxin (PTX) or 8-Br-cAMP suggesting that CLA isomers differentially inhibit LA uptake and metabolism and cell proliferation in human breast cancer in vivo via a receptor-mediated, PTX-sensitive pathway.

Topics: 8-Bromo Cyclic Adenosine Monophosphate; Animals; Antithrombins; Biological Transport; Blotting, Western; Breast Neoplasms; Cell Line, Tumor; Cyclic AMP; Dose-Response Relationship, Drug; Fatty Acids; Female; Humans; Kinetics; Linoleic Acid; Linoleic Acids; Linoleic Acids, Conjugated; Male; Neoplasm Transplantation; Pertussis Toxin; Protein Isoforms; Rats; Rats, Nude; Rats, Sprague-Dawley

The relationship between 15(S)-HETE and 13(S)-HODE from different human tumor cells exposed to n-6 and n-3 essential fatty acids (EFAs) and E-cadherin expression was studied. Colon cancer cells (HRT-18) exposed to gamma linoleic acid (18:3n-6, GLA) and eicosapentaenoic (20:5n-3, EPA) (50microM) showed an increased expression of E-cadherin. Breast cancer (MCF-7) exposed to EPA showed an increment whereas GLA had no effect on E-cadherin expression. No expression of E-cadherin was observed for urothelial cancer (T-24) after GLA or EPA treatment. Significant levels of 15(S)-HETE and 13(S)-HODE were detected after GLA or EPA treatment for all tumor lines. E-cadherin expression was inversely proportional to the 13(S)-HODE:15(S)-HETE ratio when cells were pretreated with GLA or EPA. Nevertheless, the liberation of these metabolites seems to be independent of the E-cadherin expression. The increase in the13(S)-HODE:15(S)-HETE correlates to a decrease in the expression of E-cadherin. Both factors may play a role in metastasis development.

Topics: Arachidonic Acid; Breast Neoplasms; Cadherins; Cell Differentiation; Colonic Neoplasms; Female; Humans; Hydroxyeicosatetraenoic Acids; Immunohistochemistry; Linoleic Acid; Linoleic Acids; Neoplasm Metastasis; Tumor Cells, Cultured; Urinary Bladder Neoplasms; Urothelium

The nocturnal melatonin (MLT) surge is a relevant oncostatic signal for a variety of experimental malignancies. Population studies support the hypothesis that exposure to light at night may represent a new risk factor for breast cancer possibly through the suppression of pineal MLT production and/or circadian disruption. We tested the ability of constant light exposure to suppress MLT production in female nude rats and stimulate the growth of tissue-isolated MCF-7 human breast cancer xenografts via increased tumor linoleic acid (LA) metabolism. Rats maintained on an alternating light/dark cycle (L:D group) exhibited a robust circadian MLT rhythm that was abolished following constant light exposure. During the exposure of animals bearing tissue-isolated human MCF-7 breast cancer xenografts to constant light, the rate of tumor growth markedly increased relative to the L:D group. Tumor LA uptake and its metabolism to the mitogen 13-hydroxyoctadecadienoic acid (13-HODE) were also substantially higher under constant light conditions. This is the first biological evidence for a potential link between constant light exposure and increased human breast oncogenesis involving MLT suppression and stimulation of tumor LA metabolism.

Topics: Animals; Antioxidants; Antithrombins; Breast Neoplasms; Cell Transformation, Neoplastic; Circadian Rhythm; Female; Humans; Light; Linoleic Acid; Linoleic Acids; Melatonin; Mice; Mice, Nude; Pineal Gland; Transplantation, Heterologous

Epidemiological and experimental data suggest a role for polyunsaturated fatty acids in the etiology of breast cancer. In this report we have studied arachidonic acid and linoleic acid metabolism in the human breast carcinoma cell line BT-20 which overexpresses both EGF receptor and the homologous erbB-2 oncogene product. EGF and TGF alpha stimulated DNA synthesis in these cells which was attenuated by the addition of a lipoxygenase inhibitor, NDGA. The addition of a prostaglandin H synthase inhibitor did not alter DNA synthesis. Analytical studies reveal little arachidonic acid metabolism while linoleic acid was metabolized to 13-hydroxyoctadecadienoic acid (13-HODE). The formation of 13-HODE was inhibited by the addition of NDGA and was dependent on EGF or TGF alpha. These results suggest the metabolism of linoleic acid by a n-6 or 15-lipoxygenase regulated by EGF/TGF alpha, RT-PCR was used to isolate a clone, and sequenced the cDNA for this enzyme and it was found to be identical to the human 15-lipoxygenase previously characterized from human pulmonary tissue. EGF/TGF alpha did not alter the expression of this enzyme suggesting a potential post-translational regulation of activity. This study provides a link between metabolism of linoleic acid and growth factor regulation of cell proliferation in a human breast carcinoma cell line.

Topics: Arachidonate 15-Lipoxygenase; Arachidonic Acid; Breast Neoplasms; Cyclooxygenase Inhibitors; DNA; Epidermal Growth Factor; Female; Humans; Indomethacin; Linoleic Acid; Linoleic Acids; Lipoxygenase Inhibitors; Masoprocol; Polymerase Chain Reaction; Prostaglandin-Endoperoxide Synthases; RNA, Messenger; Transforming Growth Factor alpha; Tumor Cells, Cultured