12(S)-hydroxyeicosatetraenoic acid regulates DNA synthesis and protooncogene expression induced by epidermal growth factor and insulin in rat lens epithelium.
Neonatal rat lens epithelium has a high 12(S)-hydroxyeicosatetraenoic acid [12(S)-HETE] synthetic capacity, which decreases as epithelial cell proliferation decreases with age. To determine whether products of the 12-lipoxygenase pathway are involved in lens cell proliferation, we measured the effect of 12-lipoxygenase inhibitors on endogenous 12-HETE production, epidermal growth factor/insulin-stimulated DNA synthesis and protooncogene expression in cultured neonatal rat lens epithelial cells. Incubation of neonatal rat lenses in epidermal growth factor plus insulin, which stimulated endogenous 12-HETE production 8- to 10-fold, also produced a transient induction of c-fos and c-myc mRNAs after 2 to 3 h, followed by a round of DNA synthesis approximately 20 h later. The lipoxygenase inhibitor, cinnamyl-3,4-dihydroxy-alpha-cyanocinnamate, strongly inhibited both the endogenous 12-HETE synthesis and growth factor-stimulated DNA synthesis with a half-maximal inhibition between 10 and 20 microM. Cinnamyl-3,4-dihydroxy-alpha-cyanocinnamate (10 microM) also inhibited the expression of c-fos and c-myc mRNA and, to a lesser extent, c-jun mRNA. The inhibitory effects of cinnamyl-3,4-dihydroxy-alpha-cyanocinnamate on protooncogene expression and DNA synthesis were prevented by 0.3 microM 12(S)-HETE but not by equivalent concentrations of either 5(S)-HETE or 15(S)-HETE. These findings suggest that endogenously synthesized 12(S)-HETE may mediate epidermal growth factor/insulin-stimulated DNA synthesis in neonatal rat lens epithelial cells by regulating protooncogene expression.
Lysz
T W
TW
Department of Surgery, UMD-New Jersey Medical School, Newark 07103-2714.
Arora
J K
JK
Lin
C
C
Zelenka
P S
PS
D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D000818:Animals; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis*; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006893:Hydroxyeicosatetraenoic Acids / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology*; D007908:Lens, Crystalline / Q000187:drug effects*; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013268:Stimulation, Chemical
D006893:Hydroxyeicosatetraenoic Acids; D007328:Insulin; D016859:Lipoxygenase Inhibitors; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D016271:Proto-Oncogene Proteins c-myc; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D004815:Epidermal Growth Factor; D004247:DNA