CHANGES IN LIPOXYGENASE ACTIVITIES IN HUMAN ERYTHROLEUKEMIA (HEL) CELLS DURING DIOSGENIN-INDUCED DIFFERENTIATION

A human erythroleukemia (HEL) cell line was used as a model to study dynamic changes in human 12-, 15-, 5-lipoxygenases, five lipoxygenase activating protein (FLAP), and leukotriene A(4) (LTA(4)) hydrolase gene expression during megakaryocytic differentiation induced by diosgenin (Beneytout, J.L, Nappez, C., Leboutet, M.J. and Malinvaud, G., Biochem. Biophys. Res. Commun., 207 (1995) 398-404). The study was performed at the transcriptional level: 12- and 5-lipoxygenase mRNAs, FLAP mRNA and LTA(4) hydrolase mRNA were detected before and after diosgenin treatment in HEL cells while 15-lipoxygenase mRNA was undetected. When HEL cells were incubated with arachidonic acid, 5-, 12-, 15-hydroxyeicosatetraenoic acids (HETE) and LTC(4) were synthesized. In contrast, the diosgenin treatment induced the suppression of 12-lipoxygenase activity and only 5-, 15-HETEs and LTC(4) were synthesized.