15-hydroxy-5-8-11-13-eicosatetraenoic-acid and Cell-Transformation--Neoplastic

Pioglitazone (PGZ), a synthetic peroxisome proliferator-activated receptor gamma (PPARγ) ligand, is known to have anti-tumor activity by inducing tumor cell apoptosis. However, it is unknown whether it can be used to prevent smoking carcinogen-induced lung tumor development. We induced mouse lung tumors using smoking carcinogen 4- methylnitrosamino-l-3-pyridyl-butanone (NNK). PGZ was given at two early stages before the tumor formation. The role and the functional mechanism of PGZ were investigated in the development of mouse pulmonary tumors. The tumor development was monitored and PPARγ activity and endogenous PPARγ ligands 15(S)-HETE, 13(S)-HODE were determined. The application of PGZ before alveolar hyperplasia formation (Group NPa) and at the early phase of alveolar hyperplasia formation (Group NPb) significantly prevented the lung tumor development especially in Group NPb mice (all p < 0.05). PGZ not only prevented the NNK-mediated reduction of endogenous ligands 15(S)-HETE and 13(S)-HODE, but also increased 13(S)-HODE level in Group NPb mice. PPARγ transcriptional activity was increased in NNKstimulated lung tissues when PGZ was given. The in vivo results were confirmed in the human lung cancer cells, which showed that PGZ induced lung cancer cell apoptosis through up-regulating nuclear PPARγ expression, inducing PPARγ transcriptional activity and increasing the levels of PPARγ ligands in NNK-treated cells. The early application of PGZ is able to prevent NNK-induced lung tumor development through maintaining the level of endogenous PPARγ ligands 15(S)-HETE and 13(S)-HODE and activation of PPARγ.

Topics: Animals; Anticarcinogenic Agents; Apoptosis; Cell Line, Tumor; Cell Proliferation; Cell Transformation, Neoplastic; Gene Expression Regulation, Neoplastic; Humans; Hydroxyeicosatetraenoic Acids; Hyperplasia; Ligands; Linoleic Acids; Lung Neoplasms; Mice; Nitrosamines; Pioglitazone; PPAR gamma; Pulmonary Alveoli; Smoking; Thiazolidinediones; Time Factors; Transcription, Genetic

15-S-Hydroxyeicosatetraenoic acid (15(S)-HETE) and 13-S-hydroxyoctadecadienoic acid (13(S)-HODE), both of which are metabolites of 15-lipoxygenases (15-LOXs), are endogenous ligands for peroxisome proliferator-activated receptor gamma (PPARgamma). The activation of PPARgamma inhibits cell growth and induces apoptosis in some cancers. The role of 15(S)-HETE) and 13(S)-HODE in the development of lung cancer is not clear.. 15-LOXs, 15(S)-HETE and 13(S)-HODE were monitored during the development of mouse lung tumours induced by the tobacco smoke carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and the levels of these markers were determined in 54 human non-small cell lung cancers.. 15-LOXs, 15(S)-HETE and 13(S)-HODE levels were significantly reduced in human lung cancer tissue compared with non-tumour lung tissue (p=0.011 and p=0.022, respectively). In mouse experiments, 15(S)-HETE and 13(S)-HODE started to reduce at 26 and 30 weeks, respectively, after NNK treatment. The time frame of 15(S)-HETE reduction was in line with the decrease in 12/15-LOX mRNA and protein. A significant difference in the number of tumours in NNK-treated mice and controls was not observed until week 34 (p<0.05) and week 38 (p<0.01). The reduction in 12/15-LOX and 15(S)-HETE therefore predated the appearance of lung tumour. Furthermore, PPARgamma activity was decreased in NNK-treated mouse lungs compared with the control, and the decreased PPARgamma activity occurred at the same time points as the reduction in 12/15-LOX and 15(S)-HETE.. These findings indicate that the reduction in 15-LOX, 15(S)-HETE and 13(S)-HODE results in the decreased PPARgamma activity seen in lung tumours and contributes to the development of lung tumours induced by tobacco smoking.

Topics: Animals; Arachidonate 15-Lipoxygenase; Biomarkers, Tumor; Carcinoma, Non-Small-Cell Lung; Cell Transformation, Neoplastic; Disease Models, Animal; Disease Progression; Female; Humans; Hydroxyeicosatetraenoic Acids; Linoleic Acids; Lung; Lung Neoplasms; Mice; Mice, Inbred A; Neoplasm Proteins; Nitrosamines; PPAR gamma

15-Lipoxygenase 2 (15-LOX2) is a recently cloned human lipoxygenase that shows tissue-restricted expression in prostate, lung, skin, and cornea. The protein level and enzymatic activity of 15-LOX2 have been shown to be down-regulated in prostate cancers compared with normal and benign prostate tissues. The biological function of 15-LOX2 and the role of loss of 15-LOX2 expression in prostate tumorigenesis, however, remain unknown. We report the cloning and functional characterization of 15-LOX2 and its three splice variants (termed 15-LOX2sv-a, 15-LOX2sv-b, and 15-LOX2sv-c) from primary prostate epithelial cells. Western blotting with multiple primary prostate cell strains and prostate cancer cell lines reveals that the expression of 15-LOX2 is lost in all prostate cancer cell lines, accompanied by decreased enzymatic activity revealed by liquid chromatography/tandem mass spectrometry analyses. Further experiments show that the loss of 15-LOX2 expression results from transcriptional repression caused by mechanism(s) other than promoter hypermethylation or histone deacetylation. Subsequent functional studies indicate the following: 1) the 15-LOX2 product, 15(S)-hydroxyeicosatetraenoic acid, inhibits prostate cancer cell cycle progression; 2) 15-LOX2 expression in primary prostate epithelial cells is inversely correlated with cell cycle; and 3) restoration of 15-LOX2 expression in prostate cancer cells partially inhibits cell cycle progression. Taken together, these results suggest that 15-LOX2 could be a suppressor of prostate cancer development, which functions by restricting cell cycle progression.

Topics: Alternative Splicing; Amino Acid Sequence; Arachidonate 15-Lipoxygenase; Base Sequence; Cell Cycle; Cell Transformation, Neoplastic; Cells, Cultured; Cloning, Molecular; DNA Primers; Epithelial Cells; Genetic Variation; Genetic Vectors; Humans; Hydroxyeicosatetraenoic Acids; Kinetics; Male; Molecular Sequence Data; Prostate; Prostatic Neoplasms; Recombinant Proteins; Reference Values; RNA, Messenger; Sequence Alignment; Sequence Homology, Amino Acid; Transcription, Genetic

Topics: Animals; Arachidonic Acid; Cell Division; Cell Line, Transformed; Cell Transformation, Neoplastic; Cricetinae; Cyclooxygenase Inhibitors; Dexamethasone; DNA Replication; Epidermal Growth Factor; Fibroblasts; Hydroxyeicosatetraenoic Acids; Indomethacin; Linoleic Acid; Linoleic Acids; Lipoxygenase; Masoprocol; Mesocricetus; Receptor, ErbB-2; Recombinant Fusion Proteins; Transfection

Isolated dog mastocytoma cells sensitized with dog anti-ragweed IgE and challenged with ragweed antigen or incubated with ionophore A23187 or the carboxy-terminal dodecapeptide of platelet factor 4, PF4(59-70), release histamine and concurrently generate leukotrienes B4, C4, and D4. In contrast, the exposure of mastocytoma cells to 0.1-3 micrograms/ml of 15-hydroxyeicosatetraenoic acid (15-HETE) stimulates selectively the generation of leukotrienes, in the absence of histamine release, while 0.1-1 micrograms/ml of compound 48/80 releases histamine without enhancing the generation of leukotrienes. That natural stimuli are capable of selectively activating one synthetic or secretory compartment of mast cells suggests that separate subsets of receptors as well as different biochemical events may serve to mobilize each class of mediators.

Topics: Allergens; Animals; Arachidonic Acids; Calcimycin; Cell Transformation, Neoplastic; Dogs; Histamine Release; Hydroxyeicosatetraenoic Acids; Kinetics; Leukotriene B4; Mast-Cell Sarcoma; p-Methoxy-N-methylphenethylamine; Platelet Factor 4; SRS-A