Opposing effects of 15-lipoxygenase-1 and -2 metabolites on MAPK signaling in prostate. Alteration in peroxisome proliferator-activated receptor gamma.
Human prostate tumors have elevated levels of 15-lipoxygenase-1 (15-LOX-1) and data suggest that 15-LOX-1 may play a role in the development of prostate cancer. In contrast, 15-LOX-2 expression is higher in normal rather than in tumor prostate tissue and appears to suppress cancer development. We recently reported that 13-(S)-HODE, the 15-LOX-1 metabolite, up-regulates the MAP kinase signaling pathway and subsequently down-regulates PPARgamma in human colorectal carcinoma cells. To determine whether this mechanism is applicable to prostate cancer and what the effects of 15-LOX-2 are, we investigated the effect of 15-LOX-1, 15-LOX-2, and their metabolites on epidermal growth factor (EGF)- and insulin-like growth factor (IGF)-1 signaling in prostate carcinoma cells. In PC3 cells, 13-(S)-HODE, a 15-LOX-1 metabolite, up-regulated MAP kinase while in contrast 15-(S)-HETE, a 15-LOX-2 metabolite, down-regulated MAP kinase. As a result, 13-(S)-HODE increased PPARgamma phosphorylation while a subsequent decrease in PPARgamma phosphorylation was observed with 15-(S)-HETE. Thus, 15-LOX metabolites have opposing effects on the regulation of the MAP kinase signaling pathway and a downstream target of MAP kinase signaling like PPARgamma. In addition to the EGF signaling pathway, the IGF signaling pathway appears to be linked to prostate cancer. 13-(S)-HODE and 15-(S)-HETE up-regulate or down-regulate, respectively, both the MAPK and Akt pathways after activation with IGF-1. Thus, the effect of these lipid metabolites is not solely restricted to EGF signaling and not solely restricted to MAPK signaling. These results provide a plausible mechanism to explain the apparent opposing effects 15-LOX-1 and 15-LOX-2 play in prostate cancer.
Hsi
Linda C
LC
Eicosanoid Biochemistry Section, Laboratory of Molecular Carcinogenesis, NIEHS/National Institutes of Health, Research Triangle Park, NC 27709, USA.
Wilson
Leigh C
LC
Eling
Thomas E
TE
D001093:Arachidonate 15-Lipoxygenase / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000378:metabolism; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism*; D008041:Linoleic Acids / Q000494:pharmacology; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation; D011467:Prostate / Q000201:enzymology* / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D006893:Hydroxyeicosatetraenoic Acids; D007527:Isoenzymes; D008041:Linoleic Acids; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; C024348:13-hydroxy-9,11-octadecadienoic acid; D004815:Epidermal Growth Factor; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid; D001093:Arachidonate 15-Lipoxygenase; D020928:Mitogen-Activated Protein Kinases