15-hydroxy-5-8-11-13-eicosatetraenoic-acid and Adenocarcinoma

15-Lipoxygenase-2 (15-LOX-2) and 15(S)-hydroxyeicosatetraenoic acid (15(S)-HETE) have been considered as latent mediators of diverse biological processes including cancer. However, their functions in lung adenocarcinoma (LAC) are unclear. In this study, we aimed to determine whether 15-LOX-2/15(S)-HETE is involved in the proliferation and migration of A549 cells and to identify the signaling pathways that participate in this process. We used immunohistochemistry to identify the expression levels of 15-LOX-2 in lung cancer tissue samples. The effects of 15(S)-HETE on the proliferation and migration of A549 cells under hypoxic conditions were assessed by cell viability assays, immunofluorescence, western blotting, scratch wound assays and transwell assays. We found that the expression of 15-LOX-2 was significantly up-regulated in LAC tissue samples compared with adjacent normal tissue samples. The content of 15(S)-HETE in A549 cells was increased under hypoxic conditions. Moreover, 15(S)-HETE could stimulate the expression of PCNA, cyclin A and cyclin D. In addition, siRNA of 15-LOX-2 inhibited the proliferation and migration of A549 cells in vitro. Our data also provide novel evidence demonstrating that the STAT3 pathway participates in the 15(S)-HETE-induced proliferation and migration of A549 cells. This study may provide a greater understanding of LAC metastasis and shed new light on the mechanisms by which the 15(S)-HETE/STAT3 pathway is related to this disease.

Topics: A549 Cells; Adenocarcinoma; Arachidonate 15-Lipoxygenase; Cell Hypoxia; Cell Movement; Cell Proliferation; Cell Survival; Humans; Hydroxyeicosatetraenoic Acids; Lung Neoplasms; Neoplasm Metastasis; RNA Interference; Signal Transduction; STAT3 Transcription Factor

Chronic inflammation and dietary fat consumption correlates with an increase in prostate cancer. Our previous studies in the colon have demonstrated that gamma-tocopherol treatment could upregulate the expression of peroxisome proliferator-activated preceptors (PPAR) gamma, a nuclear receptor involved in fatty acid metabolism as well modulation of cell proliferation and differentiation. In this study, we explored the possibility that gamma-tocopherol could induce growth arrest in PC-3 prostate cancer cells through the regulation of fatty acid metabolism. Growth arrest (40%) and PPAR gamma mRNA and protein upregulation was achieved with gamma-tocopherol within 6 h. gamma-Tocopherol-mediated growth arrest was demonstrated to be PPAR gamma dependent using the agonist GW9662 and a PPAR gamma dominant negative vector. gamma-tocopherol was shown not to be a direct PPAR gamma ligand, but rather 15-S-HETE (an endogenous PPAR gamma ligand) was upregulated by gamma-tocopherol treatment. 15-Lipoxygenase-2, a tumor suppressor and the enzyme that converts arachidonic acid to 15-S-HETE, was upregulated at 3 h following gamma-tocopherol treatment. Expression of proteins downstream of the PPAR gamma pathway were examined. Cyclin D1, cyclin D3, bcl-2, and NFkappa B proteins were found to be downregulated following gamma-tocopherol treatment. These data demonstrate that the growth arrest mediated by gamma-tocopherol follows a PPAR-gamma-dependent mechanism.

Topics: Adenocarcinoma; Arachidonate 15-Lipoxygenase; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cells, Cultured; Epithelial Cells; gamma-Tocopherol; Gene Expression; Gene Knockout Techniques; Humans; Hydroxyeicosatetraenoic Acids; Ligands; Male; PPAR gamma; Prostate; Prostatic Neoplasms; Protein Binding; RNA, Messenger; Signal Transduction

The influence of inhibitors of different lipoxygenases (LOX) on the growth of human tumor cells with different profiles of synthesized eicosanoids was studied. The studied LOX inhibitors had virtually no influence on the growth of A549 cells actively synthesizing cyclooxygenase and lipoxygenase metabolites of arachidonic acid (AA). The inhibitor of 12-LOX, baicalein, significantly inhibited proliferation in cultures of A431 epidermoid carcinoma cells with a characteristic domination of the major lipoxygenase metabolite of AA, 12-hydroxyeicosatetraenoic acid (12-HETE), in the profile of synthesized eicosanoids and reduced to 70% the incorporation of [3H]thymidine into DNA. Treatment of these cultures with 12-HETE virtually restored the growth potential of the tumor cells. The findings suggest that the lipoxygenase metabolite of AA, 12-HETE, is a growth-limiting factor for tumor cells of definite type.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adenocarcinoma; Arachidonate Lipoxygenases; Arachidonic Acid; Carcinoma, Squamous Cell; Cell Proliferation; Flavanones; Humans; Hydroxyeicosatetraenoic Acids; Lung Neoplasms; Nitrobenzenes; Salicylamides; Sulfonamides; Tumor Cells, Cultured; Umbelliferones

The proinflammatory cytokine IL-4 is secreted in large amounts during allergic inflammatory response in asthma and plays a pivotal role in the airway inflammation. IL-4 has been shown to up-regulate 15-lipoxygenase and produce 15(S)-hydroxyeicosatetraenoic acid (15(S)-HETE) in A549 cells via the Janus kinase/STAT6 pathway under coactivation of CREB binding protein/p300. IL-4 has also been shown to up-regulate peroxisome proliferator-activated receptor gamma (PPARgamma) nuclear receptors in macrophages and A549 cells. In this study we demonstrate that 15(S)-HETE binds to PPARgamma nuclear receptors and induces apoptosis in A549 cells. Moreover, pretreatment of cells with nordihydroguaiaretic acid, a 15-lipoxygenase inhibitor, prevented PPARgamma activation and apoptosis. The latter was accomplished by the interaction of the 15(S)-HETE/PPARgamma complex with the adapter protein Fas-associating protein with death domain and caspase-8, as shown by transfection of Fas-associating protein with death domain dominant negative vector and cleavage of caspase 8 to active subunits p41/42 and p18. Whereas IL-4 and PPARgamma ligands failed to induce cleavage of Bid and release of cytochrome c from mitochondria, they caused translocation of the proapoptotic protein Bax from cytoplasm to mitochondria with a concomitant decrease in the Bcl-x(L) level. We therefore believe that in unstimulated cells Bcl-x(L) and Bax form a heterodimer, in which Bcl-x(L) dominates and prevents the induction of apoptosis, whereas in IL-4-stimulated cells the 15(S)-HETE/PPARgamma complex down-regulates Bcl-x(L), and the resulting overweight of Bax commits the cell to apoptosis via caspase-3. However, this pathway does not rule out the direct caspase-8-mediated activation of caspase-3. In conclusion, IL-4-induced apoptosis may contribute to severe loss of alveolar structures and infiltration of eosinophils, mononuclear phagocytes, etc., into the lung tissue of chronic asthma patients.

Topics: Adaptor Proteins, Signal Transducing; Adenocarcinoma; Apoptosis; bcl-2-Associated X Protein; bcl-X Protein; BH3 Interacting Domain Death Agonist Protein; Binding Sites; Carrier Proteins; Caspase 8; Caspase 9; Caspases; DNA-Binding Proteins; Down-Regulation; Fas-Associated Death Domain Protein; Humans; Hydrolysis; Hydroxyeicosatetraenoic Acids; Interleukin-4; Ligands; Lung Neoplasms; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Receptors, Cytoplasmic and Nuclear; Signal Transduction; Transcription Factors; Tumor Cells, Cultured; Up-Regulation

Human 15S-lipoxygenase-2 (15-LOX-2) is a recently identified lipoxygenase that has approximately 40% sequence identity to the known human 5S-, 12S-, and 15S-lipoxygenases. 15-LOX-2 has a limited tissue distribution, with mRNA detected in prostate, lung, skin, and cornea, but not in numerous other tissues, including peripheral blood leukocytes. In the current study, we have characterized the distribution of 15-LOX-2 in the human prostate by immunohistochemistry, demonstrated the ability of benign prostate tissue to form 15S-hydroxyeicosatetraenoic acid (15S-HETE) from exogenous arachidonic acid (AA), and begun characterizing possible alterations in 15-LOX-2 in prostate adenocarcinoma. Incubation of benign prostate tissue with [14C]AA resulted in formation of [14C]15-HETE, as determined by reverse- and straight-phase high-performance liquid chromatography. 15-HETE was the major AA metabolite formed. By immunohistochemistry, 15-LOX-2 is located in secretory cells of peripheral zone glands and large prostatic ducts and somewhat less uniformly in apical cells of transition and central zone glands. 15-LOX-2 was not detected in the basal cell layer, stroma, ejaculatory ducts, seminal vesicles, or transitional epithelium. Immunostaining of 18 radical prostatectomy specimens showed a loss of 15-LOX-2 in the majority of prostate adenocarcinomas; 14 of 18 cases showed loss of 15-LOX-2 in >25% of the tumor (mean, 74.9% negative for 15-LOX-2; range, 38.9% to 100%). Incubation of paired pure benign and pure malignant prostate tissue from the same radical prostatectomies showed that 15-HETE formation was markedly reduced (>90%) or undetectable in incubations of prostate adenocarcinoma. 15-LOX-2 is a novel human lipoxygenase with a limited tissue distribution that is strongly expressed in benign prostate glandular epithelium and lost to a variable degree in the majority of prostate adenocarcinomas.

Topics: Adenocarcinoma; Animals; Arachidonate 15-Lipoxygenase; Epithelium; Humans; Hydroxyeicosatetraenoic Acids; Immunohistochemistry; Isoenzymes; Male; Prostate; Prostatic Neoplasms; Rabbits

The investigation was undertaken to characterize the profile of arachidonic acid metabolites in different spontaneous and transplantable tumors in mice. The five metabolites via the cyclooxygenase pathway (PGE2, PGF2 alpha, PGD2, TxB2, 6-keto-PGF1 alpha), as well as the three lipoxygenase products (5-HETE, 12-HETE, and 15-HETE) were monitored by thin layer chromatography and high performance liquid chromatography after "ex vivo" metabolism of exogenous [1-C14]-arachidonic acid by homogenates of tumor tissues. It was shown that all tumors had a unique profile of eicosanoids. The most cyclooxygenase activity along with the significant synthesis of PGE2, PGF2 alpha, and 6-keto-PGF1 alpha was noted in lung tumors. The antitumor effect of indomethacin was directly related to the ability of tumors to produce PGE2. On the other hand, there were varying lipoxygenase activities in tumors. In some cases, the extremely high levels of 15- and 12-HETE synthesis in neoplastic tissue could indicate that there was a basic possibility of using lipoxygenase inhibitors for suppressing malignant tumors.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adenocarcinoma; Animals; Arachidonic Acid; Carcinoma, Lewis Lung; Carcinoma, Squamous Cell; Chromatography, High Pressure Liquid; Chromatography, Thin Layer; Dinoprostone; Eicosanoids; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; Indomethacin; Leukemia L1210; Lipoxygenase Inhibitors; Mammary Neoplasms, Experimental; Melanoma, Experimental; Mice; Mice, Inbred C3H; Mice, Inbred C57BL; Mice, Inbred CBA; Mice, Inbred DBA; Neoplasm Transplantation; Neoplasms, Experimental; Skin Neoplasms