Regulation of neurotensin receptor function by the arachidonic acid-lipoxygenase pathway in prostate cancer PC3 cells.
Neurotensin (NT) elevates leukotriene levels in animals and stimulates 5-HETE formation in prostate cancer PC3 cells. PC3 cell growth is stimulated by NT and inhibited by lipoxygenase (LOX) blockers. This led us to test LOX blockers (NDGA, MK886, ETYA, Rev5901, AA861 and others) for effects on NT binding and signaling. LOX blockers dramatically enhanced 125I-neurotensin binding to NT receptor NTR1 in PC3 cells, whereas they inhibited NT-induced inositol phosphate formation. These effects were indirect (binding to isolated membranes was unaffected), receptor-specific (binding to beta2-adrenergic, V1a-vasopressin, EGF and bombesin receptor was unaffected) and pathway-specific (cyclooxygenase inhibitors were inactive). NT receptor affinity was increased but receptor number and % internalization were unchanged. Also supporting the involvement of arachidonic acid metabolism in NTR1 regulation was the finding that inhibitors of PLA2 and DAG lipase enhanced NT binding. These findings suggest that NTR1 is regulated by specific feedback mechanism(s) involving lipid peroxidation and/or LOX-dependent processes.
Carraway
Robert E
RE
Department of Physiology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA. robert.carraway@umassmed.edu
Hassan
Sazzad
S
Cochrane
David E
DE
D001091:Arachidonate Lipoxygenases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D001667:Binding, Competitive / Q000187:drug effects; D045744:Cell Line, Tumor; D025461:Feedback, Physiological / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007295:Inositol Phosphates / Q000096:biosynthesis; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology; D008297:Male; D009496:Neurotensin / Q000378:metabolism / Q000494:pharmacology; D016877:Oxidants / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D011485:Protein Binding; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors / Q000378:metabolism; D018028:Receptors, Neurotensin / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D015854:Up-Regulation
D007295:Inositol Phosphates; D016859:Lipoxygenase Inhibitors; D016877:Oxidants; D017382:Reactive Oxygen Species; D018028:Receptors, Neurotensin; D009496:Neurotensin; D006861:Hydrogen Peroxide; D001091:Arachidonate Lipoxygenases